* [PATCH RESEND v11 00/13] nommu UML
@ 2025-09-18 7:38 Hajime Tazaki
2025-09-18 7:38 ` [PATCH RESEND v11 01/13] x86/um: nommu: elf loader for fdpic Hajime Tazaki
` (13 more replies)
0 siblings, 14 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:38 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
This patchset is another spin of nommu mode addition to UML. It would
be nice to hear about your opinions on that.
There are still several limitations/issues which we already found;
here is the list of those issues.
- memory mapped by loadable modules are not distinguished from
userspace memory.
-- Hajime
v11:
- clean up userspace return routine and integrate to userspace() ([04/13])
- fix direction flag issue on using nolibc memcpy ([04/13])
- fix a crash issue when using usermode helper ([06/13])
- test with out-of-tree kunit-uapi patches (which uses umh)
- https://lore.kernel.org/all/20250626-kunit-kselftests-v4-0-48760534fef5@linutronix.de/
- https://lore.kernel.org/all/20250626195714.2123694-3-benjamin@sipsolutions.net/
v10:
- fix wrong comment on gs register handling ([09/13])
- remove unnecessary code of early syscall implementation ([04/13])
- https://lore.kernel.org/all/cover.1750594487.git.thehajime@gmail.com/
v9:
- rebase with the latest uml/next branch
- add performance numbers of new SECCOMP mode, and update results ([12/13])
- add a workaround for upstream change on MMU depedency to PCI drivers ([10/13])
- https://lore.kernel.org/all/cover.1750294482.git.thehajime@gmail.com/
v8:
- rebase with the latest uml/next branch
- clean up segv_handler to align with the latest uml ([9/12])
- https://lore.kernel.org/all/cover.1745980082.git.thehajime@gmail.com/
v7:
- properly handle FP register upon signal delivery [10/13]
- update benchmark result with new FP register handling [12/13]
- fix arch_has_single_step() for !MMU case [07/13]
- revert stack alignment as it is in uml/fixes tree [10/13]
- https://lore.kernel.org/all/cover.1737348399.git.thehajime@gmail.com/
v6:
- rebase to the latest uml/next tree
- more clean up on mmu/nommu for signal handling [10/13]
- rename functions of mcontext routines [06,10/13]
- added Acked-by tag for binfmt_elf_fdpic [02/13]
- https://lore.kernel.org/linux-um/cover.1736853925.git.thehajime@gmail.com/
v5:
- clean up stack manipulation code [05,06,07,10/13]
- https://lore.kernel.org/linux-um/cover.1733998168.git.thehajime@gmail.com/
v4:
- add arch/um/nommu, arch/x86/um/nommu to contain !MMU specific codes
- remove zpoline patch
- drop binfmt_elf_fdpic patch
- reduce ifndef CONFIG_MMU if possible
- split to elf header cleanup patch [01/13]
- fix kernel test robot warnings [06/13]
- fix coding styles [07/13]
- move task_top_of_stack definition [05/13]
- https://lore.kernel.org/linux-um/cover.1733652929.git.thehajime@gmail.com/
v3:
- https://lore.kernel.org/linux-um/cover.1733199769.git.thehajime@gmail.com/
- add seccomp-based syscall hook in addition to zpoline [06/13]
- remove RFC, add a line to MAINTAINERS file
- fix kernel test robot warnings [02/13,08/13,10/13]
- add base-commit tag to cover letter
- pull the latest uml/next
- clean up SIGSEGV handling [10/13]
- detect fsgsbase availability with elf aux vector [08/13]
- simplify vdso code with macros [09/13]
RFC v2:
- https://lore.kernel.org/linux-um/cover.1731290567.git.thehajime@gmail.com/
- base branch is now uml/linux.git instead of torvalds/linux.git.
- reorganize the patch series to clean up
- fixed various coding styles issues
- clean up exec code path [07/13]
- fixed the crash/SIGSEGV case on userspace programs [10/13]
- add seccomp filter to limit syscall caller address [06/13]
- detect fsgsbase availability with sigsetjmp/siglongjmp [08/13]
- removes unrelated changes
- removes unneeded ifndef CONFIG_MMU
- convert UML_CONFIG_MMU to CONFIG_MMU as using uml/linux.git
- proposed a patch of maple-tree issue (resolving a limitation in RFC v1)
https://lore.kernel.org/linux-mm/20241108222834.3625217-1-thehajime@gmail.com/
RFC:
- https://lore.kernel.org/linux-um/cover.1729770373.git.thehajime@gmail.com/
Hajime Tazaki (13):
x86/um: nommu: elf loader for fdpic
um: decouple MMU specific code from the common part
um: nommu: memory handling
x86/um: nommu: syscall handling
um: nommu: seccomp syscalls hook
x86/um: nommu: process/thread handling
um: nommu: configure fs register on host syscall invocation
x86/um/vdso: nommu: vdso memory update
x86/um: nommu: signal handling
um: nommu: a work around for MMU dependency to PCI driver
um: change machine name for uname output
um: nommu: add documentation of nommu UML
um: nommu: plug nommu code into build system
Documentation/virt/uml/nommu-uml.rst | 180 ++++++++++++++++++++++
MAINTAINERS | 1 +
arch/um/Kconfig | 14 +-
arch/um/Makefile | 10 ++
arch/um/configs/x86_64_nommu_defconfig | 54 +++++++
arch/um/include/asm/dma.h | 13 ++
arch/um/include/asm/futex.h | 4 +
arch/um/include/asm/mmu.h | 8 +
arch/um/include/asm/mmu_context.h | 2 +
arch/um/include/asm/ptrace-generic.h | 8 +-
arch/um/include/asm/uaccess.h | 7 +-
arch/um/include/shared/kern_util.h | 6 +
arch/um/include/shared/os.h | 16 ++
arch/um/kernel/Makefile | 5 +-
arch/um/kernel/mem-pgtable.c | 55 +++++++
arch/um/kernel/mem.c | 38 +----
arch/um/kernel/process.c | 25 +++
arch/um/kernel/skas/process.c | 25 ---
arch/um/kernel/um_arch.c | 3 +
arch/um/nommu/Makefile | 3 +
arch/um/nommu/os-Linux/Makefile | 7 +
arch/um/nommu/os-Linux/seccomp.c | 87 +++++++++++
arch/um/nommu/os-Linux/signal.c | 24 +++
arch/um/nommu/trap.c | 201 +++++++++++++++++++++++++
arch/um/os-Linux/Makefile | 3 +-
arch/um/os-Linux/mem.c | 4 +
arch/um/os-Linux/process.c | 138 ++++++++++++++++-
arch/um/os-Linux/signal.c | 11 +-
arch/um/os-Linux/skas/process.c | 126 ----------------
arch/um/os-Linux/start_up.c | 25 ++-
arch/um/os-Linux/util.c | 3 +-
arch/x86/um/Makefile | 7 +-
arch/x86/um/asm/elf.h | 8 +-
arch/x86/um/asm/syscall.h | 6 +
arch/x86/um/nommu/Makefile | 8 +
arch/x86/um/nommu/do_syscall_64.c | 75 +++++++++
arch/x86/um/nommu/entry_64.S | 114 ++++++++++++++
arch/x86/um/nommu/os-Linux/Makefile | 6 +
arch/x86/um/nommu/os-Linux/mcontext.c | 26 ++++
arch/x86/um/nommu/syscalls.h | 18 +++
arch/x86/um/nommu/syscalls_64.c | 121 +++++++++++++++
arch/x86/um/shared/sysdep/mcontext.h | 5 +
arch/x86/um/shared/sysdep/ptrace.h | 2 +-
arch/x86/um/vdso/vma.c | 17 ++-
fs/Kconfig.binfmt | 2 +-
45 files changed, 1312 insertions(+), 209 deletions(-)
create mode 100644 Documentation/virt/uml/nommu-uml.rst
create mode 100644 arch/um/configs/x86_64_nommu_defconfig
create mode 100644 arch/um/kernel/mem-pgtable.c
create mode 100644 arch/um/nommu/Makefile
create mode 100644 arch/um/nommu/os-Linux/Makefile
create mode 100644 arch/um/nommu/os-Linux/seccomp.c
create mode 100644 arch/um/nommu/os-Linux/signal.c
create mode 100644 arch/um/nommu/trap.c
create mode 100644 arch/x86/um/nommu/Makefile
create mode 100644 arch/x86/um/nommu/do_syscall_64.c
create mode 100644 arch/x86/um/nommu/entry_64.S
create mode 100644 arch/x86/um/nommu/os-Linux/Makefile
create mode 100644 arch/x86/um/nommu/os-Linux/mcontext.c
create mode 100644 arch/x86/um/nommu/syscalls.h
create mode 100644 arch/x86/um/nommu/syscalls_64.c
base-commit: e66ae377fe219c98d3d5b8a0d35da4413a5390ca
--
2.43.0
^ permalink raw reply [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 01/13] x86/um: nommu: elf loader for fdpic
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
@ 2025-09-18 7:38 ` Hajime Tazaki
2025-09-18 7:38 ` [PATCH RESEND v11 02/13] um: decouple MMU specific code from the common part Hajime Tazaki
` (12 subsequent siblings)
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:38 UTC (permalink / raw)
To: linux-um
Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel, Eric Biederman,
Kees Cook, Alexander Viro, Christian Brauner, Jan Kara, linux-mm,
linux-fsdevel
As UML supports CONFIG_MMU=n case, it has to use an alternate ELF
loader, FDPIC ELF loader. In this commit, we added necessary
definitions in the arch, as UML has not been used so far. It also
updates Kconfig file to use BINFMT_ELF_FDPIC under !MMU environment.
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: linux-mm@kvack.org
Cc: linux-fsdevel@vger.kernel.org
Acked-by: Kees Cook <kees@kernel.org>
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
---
arch/um/include/asm/mmu.h | 5 +++++
arch/um/include/asm/ptrace-generic.h | 6 ++++++
arch/x86/um/asm/elf.h | 8 ++++++--
fs/Kconfig.binfmt | 2 +-
4 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/arch/um/include/asm/mmu.h b/arch/um/include/asm/mmu.h
index 4d0e4239f3cc..e9661846b4a3 100644
--- a/arch/um/include/asm/mmu.h
+++ b/arch/um/include/asm/mmu.h
@@ -17,6 +17,11 @@ typedef struct mm_context {
/* Address range in need of a TLB sync */
unsigned long sync_tlb_range_from;
unsigned long sync_tlb_range_to;
+
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+ unsigned long exec_fdpic_loadmap;
+ unsigned long interp_fdpic_loadmap;
+#endif
} mm_context_t;
#endif
diff --git a/arch/um/include/asm/ptrace-generic.h b/arch/um/include/asm/ptrace-generic.h
index 86d74f9d33cf..62e9916078ec 100644
--- a/arch/um/include/asm/ptrace-generic.h
+++ b/arch/um/include/asm/ptrace-generic.h
@@ -29,6 +29,12 @@ struct pt_regs {
#define PTRACE_OLDSETOPTIONS 21
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+#define PTRACE_GETFDPIC 31
+#define PTRACE_GETFDPIC_EXEC 0
+#define PTRACE_GETFDPIC_INTERP 1
+#endif
+
struct task_struct;
extern long subarch_ptrace(struct task_struct *child, long request,
diff --git a/arch/x86/um/asm/elf.h b/arch/x86/um/asm/elf.h
index 62ed5d68a978..33f69f1eac10 100644
--- a/arch/x86/um/asm/elf.h
+++ b/arch/x86/um/asm/elf.h
@@ -9,6 +9,7 @@
#include <skas.h>
#define CORE_DUMP_USE_REGSET
+#define ELF_FDPIC_CORE_EFLAGS 0
#ifdef CONFIG_X86_32
@@ -190,8 +191,11 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm,
extern unsigned long um_vdso_addr;
#define AT_SYSINFO_EHDR 33
-#define ARCH_DLINFO NEW_AUX_ENT(AT_SYSINFO_EHDR, um_vdso_addr)
-
+#define ARCH_DLINFO \
+do { \
+ NEW_AUX_ENT(AT_SYSINFO_EHDR, um_vdso_addr); \
+ NEW_AUX_ENT(AT_MINSIGSTKSZ, 0); \
+} while (0)
#endif
typedef unsigned long elf_greg_t;
diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index bd2f530e5740..419ba0282806 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -58,7 +58,7 @@ config ARCH_USE_GNU_PROPERTY
config BINFMT_ELF_FDPIC
bool "Kernel support for FDPIC ELF binaries"
default y if !BINFMT_ELF
- depends on ARM || ((M68K || RISCV || SUPERH || XTENSA) && !MMU)
+ depends on ARM || ((M68K || RISCV || SUPERH || UML || XTENSA) && !MMU)
select ELFCORE
help
ELF FDPIC binaries are based on ELF, but allow the individual load
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 02/13] um: decouple MMU specific code from the common part
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
2025-09-18 7:38 ` [PATCH RESEND v11 01/13] x86/um: nommu: elf loader for fdpic Hajime Tazaki
@ 2025-09-18 7:38 ` Hajime Tazaki
2025-09-18 7:38 ` [PATCH RESEND v11 03/13] um: nommu: memory handling Hajime Tazaki
` (11 subsequent siblings)
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:38 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
This splits the memory, process related code with common and MMU
specific parts in order to avoid ifdefs in .c file and duplication
between MMU and !MMU.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
---
arch/um/kernel/Makefile | 5 +-
arch/um/kernel/mem-pgtable.c | 55 ++++++++++++++
arch/um/kernel/mem.c | 35 ---------
arch/um/kernel/process.c | 25 +++++++
arch/um/kernel/skas/process.c | 25 -------
arch/um/os-Linux/Makefile | 3 +-
arch/um/os-Linux/process.c | 128 ++++++++++++++++++++++++++++++++
arch/um/os-Linux/skas/process.c | 126 -------------------------------
8 files changed, 213 insertions(+), 189 deletions(-)
create mode 100644 arch/um/kernel/mem-pgtable.c
diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile
index b8f4e9281599..11ede105f3a9 100644
--- a/arch/um/kernel/Makefile
+++ b/arch/um/kernel/Makefile
@@ -16,9 +16,10 @@ always-$(KBUILD_BUILTIN) := vmlinux.lds
obj-y = config.o exec.o exitcode.o irq.o ksyms.o mem.o \
physmem.o process.o ptrace.o reboot.o sigio.o \
- signal.o sysrq.o time.o tlb.o trap.o \
- um_arch.o umid.o kmsg_dump.o capflags.o skas/
+ signal.o sysrq.o time.o \
+ um_arch.o umid.o kmsg_dump.o capflags.o
obj-y += load_file.o
+obj-$(CONFIG_MMU) += mem-pgtable.o tlb.o trap.o skas/
obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
obj-$(CONFIG_GPROF) += gprof_syms.o
diff --git a/arch/um/kernel/mem-pgtable.c b/arch/um/kernel/mem-pgtable.c
new file mode 100644
index 000000000000..549da1d3bff0
--- /dev/null
+++ b/arch/um/kernel/mem-pgtable.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#include <linux/stddef.h>
+#include <linux/module.h>
+#include <linux/memblock.h>
+#include <linux/swap.h>
+#include <linux/slab.h>
+#include <asm/page.h>
+#include <asm/pgalloc.h>
+#include <as-layout.h>
+#include <init.h>
+#include <kern.h>
+#include <kern_util.h>
+#include <mem_user.h>
+#include <os.h>
+#include <um_malloc.h>
+
+
+/* Allocate and free page tables. */
+
+pgd_t *pgd_alloc(struct mm_struct *mm)
+{
+ pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
+
+ if (pgd) {
+ memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
+ memcpy(pgd + USER_PTRS_PER_PGD,
+ swapper_pg_dir + USER_PTRS_PER_PGD,
+ (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
+ }
+ return pgd;
+}
+
+static const pgprot_t protection_map[16] = {
+ [VM_NONE] = PAGE_NONE,
+ [VM_READ] = PAGE_READONLY,
+ [VM_WRITE] = PAGE_COPY,
+ [VM_WRITE | VM_READ] = PAGE_COPY,
+ [VM_EXEC] = PAGE_READONLY,
+ [VM_EXEC | VM_READ] = PAGE_READONLY,
+ [VM_EXEC | VM_WRITE] = PAGE_COPY,
+ [VM_EXEC | VM_WRITE | VM_READ] = PAGE_COPY,
+ [VM_SHARED] = PAGE_NONE,
+ [VM_SHARED | VM_READ] = PAGE_READONLY,
+ [VM_SHARED | VM_WRITE] = PAGE_SHARED,
+ [VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED,
+ [VM_SHARED | VM_EXEC] = PAGE_READONLY,
+ [VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY,
+ [VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED,
+ [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED
+};
+DECLARE_VM_GET_PAGE_PROT
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 76bec7de81b5..106a2f85ab5c 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -6,7 +6,6 @@
#include <linux/stddef.h>
#include <linux/module.h>
#include <linux/memblock.h>
-#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include <linux/init.h>
@@ -207,45 +206,11 @@ void free_initmem(void)
{
}
-/* Allocate and free page tables. */
-
-pgd_t *pgd_alloc(struct mm_struct *mm)
-{
- pgd_t *pgd = __pgd_alloc(mm, 0);
-
- if (pgd)
- memcpy(pgd + USER_PTRS_PER_PGD,
- swapper_pg_dir + USER_PTRS_PER_PGD,
- (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
-
- return pgd;
-}
-
void *uml_kmalloc(int size, int flags)
{
return kmalloc(size, flags);
}
-static const pgprot_t protection_map[16] = {
- [VM_NONE] = PAGE_NONE,
- [VM_READ] = PAGE_READONLY,
- [VM_WRITE] = PAGE_COPY,
- [VM_WRITE | VM_READ] = PAGE_COPY,
- [VM_EXEC] = PAGE_READONLY,
- [VM_EXEC | VM_READ] = PAGE_READONLY,
- [VM_EXEC | VM_WRITE] = PAGE_COPY,
- [VM_EXEC | VM_WRITE | VM_READ] = PAGE_COPY,
- [VM_SHARED] = PAGE_NONE,
- [VM_SHARED | VM_READ] = PAGE_READONLY,
- [VM_SHARED | VM_WRITE] = PAGE_SHARED,
- [VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED,
- [VM_SHARED | VM_EXEC] = PAGE_READONLY,
- [VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY,
- [VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED,
- [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED
-};
-DECLARE_VM_GET_PAGE_PROT
-
void mark_rodata_ro(void)
{
unsigned long rodata_start = PFN_ALIGN(__start_rodata);
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 1be644de9e41..bfbfee0d401a 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -25,6 +25,7 @@
#include <linux/tick.h>
#include <linux/threads.h>
#include <linux/resume_user_mode.h>
+#include <linux/start_kernel.h>
#include <asm/current.h>
#include <asm/mmu_context.h>
#include <asm/switch_to.h>
@@ -46,6 +47,8 @@
struct task_struct *cpu_tasks[NR_CPUS];
EXPORT_SYMBOL(cpu_tasks);
+static char cpu0_irqstack[THREAD_SIZE] __aligned(THREAD_SIZE);
+
void free_stack(unsigned long stack, int order)
{
free_pages(stack, order);
@@ -299,3 +302,25 @@ unsigned long __get_wchan(struct task_struct *p)
return 0;
}
+
+
+static int __init start_kernel_proc(void *unused)
+{
+ block_signals_trace();
+
+ start_kernel();
+ return 0;
+}
+
+int __init start_uml(void)
+{
+ stack_protections((unsigned long) &cpu0_irqstack);
+ set_sigstack(cpu0_irqstack, THREAD_SIZE);
+
+ init_new_thread_signals();
+
+ init_task.thread.request.thread.proc = start_kernel_proc;
+ init_task.thread.request.thread.arg = NULL;
+ return start_idle_thread(task_stack_page(&init_task),
+ &init_task.thread.switch_buf);
+}
diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c
index 5881b17eb987..5247121d3419 100644
--- a/arch/um/kernel/skas/process.c
+++ b/arch/um/kernel/skas/process.c
@@ -16,31 +16,6 @@
#include <skas.h>
#include <kern_util.h>
-extern void start_kernel(void);
-
-static int __init start_kernel_proc(void *unused)
-{
- block_signals_trace();
-
- start_kernel();
- return 0;
-}
-
-static char cpu0_irqstack[THREAD_SIZE] __aligned(THREAD_SIZE);
-
-int __init start_uml(void)
-{
- stack_protections((unsigned long) &cpu0_irqstack);
- set_sigstack(cpu0_irqstack, THREAD_SIZE);
-
- init_new_thread_signals();
-
- init_task.thread.request.thread.proc = start_kernel_proc;
- init_task.thread.request.thread.arg = NULL;
- return start_idle_thread(task_stack_page(&init_task),
- &init_task.thread.switch_buf);
-}
-
unsigned long current_stub_stack(void)
{
if (current->mm == NULL)
diff --git a/arch/um/os-Linux/Makefile b/arch/um/os-Linux/Makefile
index fae836713487..c048fc838068 100644
--- a/arch/um/os-Linux/Makefile
+++ b/arch/um/os-Linux/Makefile
@@ -8,7 +8,8 @@ KCOV_INSTRUMENT := n
obj-y = execvp.o file.o helper.o irq.o main.o mem.o process.o \
registers.o sigio.o signal.o start_up.o time.o tty.o \
- umid.o user_syms.o util.o skas/
+ umid.o user_syms.o util.o
+obj-$(CONFIG_MMU) += skas/
CFLAGS_signal.o += -Wframe-larger-than=4096
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index 00b49e90d05f..d000907ec796 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -6,6 +6,7 @@
#include <stdio.h>
#include <stdlib.h>
+#include <stdbool.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
@@ -15,10 +16,16 @@
#include <sys/prctl.h>
#include <sys/wait.h>
#include <asm/unistd.h>
+#include <linux/threads.h>
#include <init.h>
#include <longjmp.h>
#include <os.h>
#include <skas/skas.h>
+#include <as-layout.h>
+#include <kern_util.h>
+
+int using_seccomp;
+static int unscheduled_userspace_iterations;
void os_alarm_process(int pid)
{
@@ -189,3 +196,124 @@ void os_set_pdeathsig(void)
{
prctl(PR_SET_PDEATHSIG, SIGKILL);
}
+
+int is_skas_winch(int pid, int fd, void *data)
+{
+ return pid == getpgrp();
+}
+
+void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
+{
+ (*buf)[0].JB_IP = (unsigned long) handler;
+ (*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
+ sizeof(void *);
+}
+
+#define INIT_JMP_NEW_THREAD 0
+#define INIT_JMP_CALLBACK 1
+#define INIT_JMP_HALT 2
+#define INIT_JMP_REBOOT 3
+
+void switch_threads(jmp_buf *me, jmp_buf *you)
+{
+ unscheduled_userspace_iterations = 0;
+
+ if (UML_SETJMP(me) == 0)
+ UML_LONGJMP(you, 1);
+}
+
+static jmp_buf initial_jmpbuf;
+
+/* XXX Make these percpu */
+static void (*cb_proc)(void *arg);
+static void *cb_arg;
+static jmp_buf *cb_back;
+
+int start_idle_thread(void *stack, jmp_buf *switch_buf)
+{
+ int n;
+
+ set_handler(SIGWINCH);
+
+ /*
+ * Can't use UML_SETJMP or UML_LONGJMP here because they save
+ * and restore signals, with the possible side-effect of
+ * trying to handle any signals which came when they were
+ * blocked, which can't be done on this stack.
+ * Signals must be blocked when jumping back here and restored
+ * after returning to the jumper.
+ */
+ n = setjmp(initial_jmpbuf);
+ switch (n) {
+ case INIT_JMP_NEW_THREAD:
+ (*switch_buf)[0].JB_IP = (unsigned long) uml_finishsetup;
+ (*switch_buf)[0].JB_SP = (unsigned long) stack +
+ UM_THREAD_SIZE - sizeof(void *);
+ break;
+ case INIT_JMP_CALLBACK:
+ (*cb_proc)(cb_arg);
+ longjmp(*cb_back, 1);
+ break;
+ case INIT_JMP_HALT:
+ kmalloc_ok = 0;
+ return 0;
+ case INIT_JMP_REBOOT:
+ kmalloc_ok = 0;
+ return 1;
+ default:
+ printk(UM_KERN_ERR "Bad sigsetjmp return in %s - %d\n",
+ __func__, n);
+ fatal_sigsegv();
+ }
+ longjmp(*switch_buf, 1);
+
+ /* unreachable */
+ printk(UM_KERN_ERR "impossible long jump!");
+ fatal_sigsegv();
+ return 0;
+}
+
+void initial_thread_cb_skas(void (*proc)(void *), void *arg)
+{
+ jmp_buf here;
+
+ cb_proc = proc;
+ cb_arg = arg;
+ cb_back = &here;
+
+ block_signals_trace();
+ if (UML_SETJMP(&here) == 0)
+ UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
+ unblock_signals_trace();
+
+ cb_proc = NULL;
+ cb_arg = NULL;
+ cb_back = NULL;
+}
+
+void halt_skas(void)
+{
+ block_signals_trace();
+ UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
+}
+
+static bool noreboot;
+
+static int __init noreboot_cmd_param(char *str, int *add)
+{
+ *add = 0;
+ noreboot = true;
+ return 0;
+}
+
+__uml_setup("noreboot", noreboot_cmd_param,
+"noreboot\n"
+" Rather than rebooting, exit always, akin to QEMU's -no-reboot option.\n"
+" This is useful if you're using CONFIG_PANIC_TIMEOUT in order to catch\n"
+" crashes in CI\n\n");
+
+void reboot_skas(void)
+{
+ block_signals_trace();
+ UML_LONGJMP(&initial_jmpbuf, noreboot ? INIT_JMP_HALT : INIT_JMP_REBOOT);
+}
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 0bc10cd4cbed..92278107007e 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -18,7 +18,6 @@
#include <sys/stat.h>
#include <sys/socket.h>
#include <asm/unistd.h>
-#include <as-layout.h>
#include <init.h>
#include <kern_util.h>
#include <mem.h>
@@ -29,16 +28,10 @@
#include <sysdep/stub.h>
#include <sysdep/mcontext.h>
#include <linux/futex.h>
-#include <linux/threads.h>
#include <timetravel.h>
#include <asm-generic/rwonce.h>
#include "../internal.h"
-int is_skas_winch(int pid, int fd, void *data)
-{
- return pid == getpgrp();
-}
-
static const char *ptrace_reg_name(int idx)
{
#define R(n) case HOST_##n: return #n
@@ -433,8 +426,6 @@ static int __init init_stub_exe_fd(void)
}
__initcall(init_stub_exe_fd);
-int using_seccomp;
-
/**
* start_userspace() - prepare a new userspace process
* @mm_id: The corresponding struct mm_id
@@ -547,7 +538,6 @@ int start_userspace(struct mm_id *mm_id)
return err;
}
-static int unscheduled_userspace_iterations;
extern unsigned long tt_extra_sched_jiffies;
void userspace(struct uml_pt_regs *regs)
@@ -786,119 +776,3 @@ void userspace(struct uml_pt_regs *regs)
}
}
}
-
-void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
-{
- (*buf)[0].JB_IP = (unsigned long) handler;
- (*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
- sizeof(void *);
-}
-
-#define INIT_JMP_NEW_THREAD 0
-#define INIT_JMP_CALLBACK 1
-#define INIT_JMP_HALT 2
-#define INIT_JMP_REBOOT 3
-
-void switch_threads(jmp_buf *me, jmp_buf *you)
-{
- unscheduled_userspace_iterations = 0;
-
- if (UML_SETJMP(me) == 0)
- UML_LONGJMP(you, 1);
-}
-
-static jmp_buf initial_jmpbuf;
-
-/* XXX Make these percpu */
-static void (*cb_proc)(void *arg);
-static void *cb_arg;
-static jmp_buf *cb_back;
-
-int start_idle_thread(void *stack, jmp_buf *switch_buf)
-{
- int n;
-
- set_handler(SIGWINCH);
-
- /*
- * Can't use UML_SETJMP or UML_LONGJMP here because they save
- * and restore signals, with the possible side-effect of
- * trying to handle any signals which came when they were
- * blocked, which can't be done on this stack.
- * Signals must be blocked when jumping back here and restored
- * after returning to the jumper.
- */
- n = setjmp(initial_jmpbuf);
- switch (n) {
- case INIT_JMP_NEW_THREAD:
- (*switch_buf)[0].JB_IP = (unsigned long) uml_finishsetup;
- (*switch_buf)[0].JB_SP = (unsigned long) stack +
- UM_THREAD_SIZE - sizeof(void *);
- break;
- case INIT_JMP_CALLBACK:
- (*cb_proc)(cb_arg);
- longjmp(*cb_back, 1);
- break;
- case INIT_JMP_HALT:
- kmalloc_ok = 0;
- return 0;
- case INIT_JMP_REBOOT:
- kmalloc_ok = 0;
- return 1;
- default:
- printk(UM_KERN_ERR "Bad sigsetjmp return in %s - %d\n",
- __func__, n);
- fatal_sigsegv();
- }
- longjmp(*switch_buf, 1);
-
- /* unreachable */
- printk(UM_KERN_ERR "impossible long jump!");
- fatal_sigsegv();
- return 0;
-}
-
-void initial_thread_cb_skas(void (*proc)(void *), void *arg)
-{
- jmp_buf here;
-
- cb_proc = proc;
- cb_arg = arg;
- cb_back = &here;
-
- block_signals_trace();
- if (UML_SETJMP(&here) == 0)
- UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
- unblock_signals_trace();
-
- cb_proc = NULL;
- cb_arg = NULL;
- cb_back = NULL;
-}
-
-void halt_skas(void)
-{
- block_signals_trace();
- UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
-}
-
-static bool noreboot;
-
-static int __init noreboot_cmd_param(char *str, int *add)
-{
- *add = 0;
- noreboot = true;
- return 0;
-}
-
-__uml_setup("noreboot", noreboot_cmd_param,
-"noreboot\n"
-" Rather than rebooting, exit always, akin to QEMU's -no-reboot option.\n"
-" This is useful if you're using CONFIG_PANIC_TIMEOUT in order to catch\n"
-" crashes in CI\n\n");
-
-void reboot_skas(void)
-{
- block_signals_trace();
- UML_LONGJMP(&initial_jmpbuf, noreboot ? INIT_JMP_HALT : INIT_JMP_REBOOT);
-}
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 03/13] um: nommu: memory handling
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
2025-09-18 7:38 ` [PATCH RESEND v11 01/13] x86/um: nommu: elf loader for fdpic Hajime Tazaki
2025-09-18 7:38 ` [PATCH RESEND v11 02/13] um: decouple MMU specific code from the common part Hajime Tazaki
@ 2025-09-18 7:38 ` Hajime Tazaki
2025-09-18 7:38 ` [PATCH RESEND v11 04/13] x86/um: nommu: syscall handling Hajime Tazaki
` (10 subsequent siblings)
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:38 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
This commit adds memory operations on UML under !MMU environment.
Some part of the original UML code relying on CONFIG_MMU are excluded
from compilation when !CONFIG_MMU. Additionally, generic functions such as
uaccess, futex, memcpy/strnlen/strncpy can be used as user- and
kernel-space share the address space in !CONFIG_MMU mode.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
---
arch/um/Makefile | 4 ++++
arch/um/include/asm/futex.h | 4 ++++
arch/um/include/asm/mmu.h | 3 +++
arch/um/include/asm/mmu_context.h | 2 ++
arch/um/include/asm/uaccess.h | 7 ++++---
arch/um/kernel/mem.c | 3 ++-
arch/um/os-Linux/mem.c | 4 ++++
arch/um/os-Linux/process.c | 4 ++--
8 files changed, 25 insertions(+), 6 deletions(-)
diff --git a/arch/um/Makefile b/arch/um/Makefile
index 7be0143b5ba3..5371c9a1b11e 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -46,6 +46,10 @@ ARCH_INCLUDE := -I$(srctree)/$(SHARED_HEADERS)
ARCH_INCLUDE += -I$(srctree)/$(HOST_DIR)/um/shared
KBUILD_CPPFLAGS += -I$(srctree)/$(HOST_DIR)/um
+ifneq ($(CONFIG_MMU),y)
+core-y += $(ARCH_DIR)/nommu/
+endif
+
# -Dvmap=kernel_vmap prevents anything from referencing the libpcap.o symbol so
# named - it's a common symbol in libpcap, so we get a binary which crashes.
#
diff --git a/arch/um/include/asm/futex.h b/arch/um/include/asm/futex.h
index 780aa6bfc050..785fd6649aa2 100644
--- a/arch/um/include/asm/futex.h
+++ b/arch/um/include/asm/futex.h
@@ -7,8 +7,12 @@
#include <asm/errno.h>
+#ifdef CONFIG_MMU
int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr);
int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval);
+#else
+#include <asm-generic/futex.h>
+#endif
#endif
diff --git a/arch/um/include/asm/mmu.h b/arch/um/include/asm/mmu.h
index e9661846b4a3..9f30c69e5278 100644
--- a/arch/um/include/asm/mmu.h
+++ b/arch/um/include/asm/mmu.h
@@ -18,10 +18,13 @@ typedef struct mm_context {
unsigned long sync_tlb_range_from;
unsigned long sync_tlb_range_to;
+#ifndef CONFIG_MMU
+ unsigned long end_brk;
#ifdef CONFIG_BINFMT_ELF_FDPIC
unsigned long exec_fdpic_loadmap;
unsigned long interp_fdpic_loadmap;
#endif
+#endif /* !CONFIG_MMU */
} mm_context_t;
#endif
diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h
index c727e56ba116..528b217da285 100644
--- a/arch/um/include/asm/mmu_context.h
+++ b/arch/um/include/asm/mmu_context.h
@@ -18,11 +18,13 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
{
}
+#ifdef CONFIG_MMU
#define init_new_context init_new_context
extern int init_new_context(struct task_struct *task, struct mm_struct *mm);
#define destroy_context destroy_context
extern void destroy_context(struct mm_struct *mm);
+#endif
#include <asm-generic/mmu_context.h>
diff --git a/arch/um/include/asm/uaccess.h b/arch/um/include/asm/uaccess.h
index 1c6e0ae41b0c..b9677758e759 100644
--- a/arch/um/include/asm/uaccess.h
+++ b/arch/um/include/asm/uaccess.h
@@ -23,6 +23,7 @@
#define __addr_range_nowrap(addr, size) \
((unsigned long) (addr) <= ((unsigned long) (addr) + (size)))
+#ifdef CONFIG_MMU
extern unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n);
extern unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n);
extern unsigned long __clear_user(void __user *mem, unsigned long len);
@@ -34,9 +35,6 @@ static inline int __access_ok(const void __user *ptr, unsigned long size);
#define INLINE_COPY_FROM_USER
#define INLINE_COPY_TO_USER
-
-#include <asm-generic/uaccess.h>
-
static inline int __access_ok(const void __user *ptr, unsigned long size)
{
unsigned long addr = (unsigned long)ptr;
@@ -70,5 +68,8 @@ do { \
barrier(); \
current->thread.segv_continue = NULL; \
} while (0)
+#endif
+
+#include <asm-generic/uaccess.h>
#endif
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 106a2f85ab5c..4be1cf240d71 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -64,7 +64,8 @@ void __init arch_mm_preinit(void)
* to be turned on.
*/
brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
- map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
+ map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1,
+ !IS_ENABLED(CONFIG_MMU));
memblock_free((void *)brk_end, uml_reserved - brk_end);
uml_reserved = brk_end;
min_low_pfn = PFN_UP(__pa(uml_reserved));
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 72f302f4d197..4f5d9a94f8e2 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -213,6 +213,10 @@ int __init create_mem_file(unsigned long long len)
{
int err, fd;
+ /* NOMMU kernel uses -1 as a fd for further use (e.g., mmap) */
+ if (!IS_ENABLED(CONFIG_MMU))
+ return -1;
+
fd = create_tmp_file(len);
err = os_set_exec_close(fd);
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index d000907ec796..bc598e661ec6 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -98,8 +98,8 @@ int os_map_memory(void *virt, int fd, unsigned long long off, unsigned long len,
prot = (r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
(x ? PROT_EXEC : 0);
- loc = mmap64((void *) virt, len, prot, MAP_SHARED | MAP_FIXED,
- fd, off);
+ loc = mmap64((void *) virt, len, prot, MAP_SHARED | MAP_FIXED |
+ (!IS_ENABLED(CONFIG_MMU) ? MAP_ANONYMOUS : 0), fd, off);
if (loc == MAP_FAILED)
return -errno;
return 0;
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 04/13] x86/um: nommu: syscall handling
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
` (2 preceding siblings ...)
2025-09-18 7:38 ` [PATCH RESEND v11 03/13] um: nommu: memory handling Hajime Tazaki
@ 2025-09-18 7:38 ` Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 05/13] um: nommu: seccomp syscalls hook Hajime Tazaki
` (9 subsequent siblings)
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:38 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
This commit introduces an entry point of syscall interface for !MMU
mode. It uses an entry function, __kernel_vsyscall, a kernel-wide global
symbol accessible from any locations.
Although it isn't in the scope of this commit, it can be also exposed
via vdso image which is directly accessible from userspace. A standard
library (i.e., libc) can utilize this entry point to implement syscall
wrapper; we can also use this by hooking syscall for unmodified userspace
applications/libraries, which will be implemented in the subsequent
commit.
This only supports 64-bit mode of x86 architecture.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
---
arch/x86/um/Makefile | 4 ++
arch/x86/um/asm/syscall.h | 6 ++
arch/x86/um/nommu/Makefile | 8 +++
arch/x86/um/nommu/do_syscall_64.c | 32 +++++++++
arch/x86/um/nommu/entry_64.S | 112 ++++++++++++++++++++++++++++++
arch/x86/um/nommu/syscalls.h | 16 +++++
6 files changed, 178 insertions(+)
create mode 100644 arch/x86/um/nommu/Makefile
create mode 100644 arch/x86/um/nommu/do_syscall_64.c
create mode 100644 arch/x86/um/nommu/entry_64.S
create mode 100644 arch/x86/um/nommu/syscalls.h
diff --git a/arch/x86/um/Makefile b/arch/x86/um/Makefile
index b42c31cd2390..227af2a987e2 100644
--- a/arch/x86/um/Makefile
+++ b/arch/x86/um/Makefile
@@ -32,6 +32,10 @@ obj-y += syscalls_64.o vdso/
subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o \
../lib/memmove_64.o ../lib/memset_64.o
+ifneq ($(CONFIG_MMU),y)
+obj-y += nommu/
+endif
+
endif
subarch-$(CONFIG_MODULES) += ../kernel/module.o
diff --git a/arch/x86/um/asm/syscall.h b/arch/x86/um/asm/syscall.h
index d6208d0fad51..bb4f6f011667 100644
--- a/arch/x86/um/asm/syscall.h
+++ b/arch/x86/um/asm/syscall.h
@@ -20,4 +20,10 @@ static inline int syscall_get_arch(struct task_struct *task)
#endif
}
+#ifndef CONFIG_MMU
+extern void do_syscall_64(struct pt_regs *regs);
+extern long __kernel_vsyscall(int64_t a0, int64_t a1, int64_t a2, int64_t a3,
+ int64_t a4, int64_t a5, int64_t a6);
+#endif
+
#endif /* __UM_ASM_SYSCALL_H */
diff --git a/arch/x86/um/nommu/Makefile b/arch/x86/um/nommu/Makefile
new file mode 100644
index 000000000000..d72c63afffa5
--- /dev/null
+++ b/arch/x86/um/nommu/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+ifeq ($(CONFIG_X86_32),y)
+ BITS := 32
+else
+ BITS := 64
+endif
+
+obj-y = do_syscall_$(BITS).o entry_$(BITS).o
diff --git a/arch/x86/um/nommu/do_syscall_64.c b/arch/x86/um/nommu/do_syscall_64.c
new file mode 100644
index 000000000000..292d7c578622
--- /dev/null
+++ b/arch/x86/um/nommu/do_syscall_64.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/kernel.h>
+#include <linux/ptrace.h>
+#include <kern_util.h>
+#include <asm/syscall.h>
+#include <os.h>
+
+__visible void do_syscall_64(struct pt_regs *regs)
+{
+ int syscall;
+
+ syscall = PT_SYSCALL_NR(regs->regs.gp);
+ UPT_SYSCALL_NR(®s->regs) = syscall;
+
+ if (likely(syscall < NR_syscalls)) {
+ unsigned long ret;
+
+ ret = (*sys_call_table[syscall])(UPT_SYSCALL_ARG1(®s->regs),
+ UPT_SYSCALL_ARG2(®s->regs),
+ UPT_SYSCALL_ARG3(®s->regs),
+ UPT_SYSCALL_ARG4(®s->regs),
+ UPT_SYSCALL_ARG5(®s->regs),
+ UPT_SYSCALL_ARG6(®s->regs));
+ PT_REGS_SET_SYSCALL_RETURN(regs, ret);
+ }
+
+ PT_REGS_SYSCALL_RET(regs) = regs->regs.gp[HOST_AX];
+
+ /* handle tasks and signals at the end */
+ interrupt_end();
+}
diff --git a/arch/x86/um/nommu/entry_64.S b/arch/x86/um/nommu/entry_64.S
new file mode 100644
index 000000000000..485c578aae64
--- /dev/null
+++ b/arch/x86/um/nommu/entry_64.S
@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <asm/errno.h>
+
+#include <linux/linkage.h>
+#include <asm/percpu.h>
+#include <asm/desc.h>
+
+#include "../entry/calling.h"
+
+#ifdef CONFIG_SMP
+#error need to stash these variables somewhere else
+#endif
+
+#define UM_GLOBAL_VAR(x) .data; .align 8; .globl x; x:; .long 0
+
+UM_GLOBAL_VAR(current_top_of_stack)
+UM_GLOBAL_VAR(current_ptregs)
+
+.code64
+.section .entry.text, "ax"
+
+.align 8
+#undef ENTRY
+#define ENTRY(x) .text; .globl x; .type x,%function; x:
+#undef END
+#define END(x) .size x, . - x
+
+/*
+ * %rcx has the return address (we set it before entering __kernel_vsyscall).
+ *
+ * Registers on entry:
+ * rax system call number
+ * rcx return address
+ * rdi arg0
+ * rsi arg1
+ * rdx arg2
+ * r10 arg3
+ * r8 arg4
+ * r9 arg5
+ *
+ * (note: we are allowed to mess with r11: r11 is callee-clobbered
+ * register in C ABI)
+ */
+ENTRY(__kernel_vsyscall)
+
+ movq %rsp, %r11
+
+ /* Point rsp to the top of the ptregs array, so we can
+ just fill it with a bunch of push'es. */
+ movq current_ptregs, %rsp
+
+ /* 8 bytes * 20 registers (plus 8 for the push) */
+ addq $168, %rsp
+
+ /* Construct struct pt_regs on stack */
+ pushq $0 /* pt_regs->ss (index 20) */
+ pushq %r11 /* pt_regs->sp */
+ pushfq /* pt_regs->flags */
+ pushq $0 /* pt_regs->cs */
+ pushq %rcx /* pt_regs->ip */
+ pushq %rax /* pt_regs->orig_ax */
+
+ PUSH_AND_CLEAR_REGS rax=$-ENOSYS
+
+ mov %rsp, %rdi
+
+ /*
+ * Switch to current top of stack, so "current->" points
+ * to the right task.
+ */
+ movq current_top_of_stack, %rsp
+
+ call do_syscall_64
+
+ jmp userspace
+
+END(__kernel_vsyscall)
+
+/*
+ * common userspace returning routine
+ *
+ * all procedures like syscalls, signal handlers, umh processes, will gate
+ * this routine to properly configure registers/stacks.
+ *
+ * void userspace(struct uml_pt_regs *regs)
+ */
+ENTRY(userspace)
+
+ /* clear direction flag to meet ABI */
+ cld
+ /* align the stack for x86_64 ABI */
+ and $-0x10, %rsp
+ /* Handle any immediate reschedules or signals */
+ call interrupt_end
+
+ movq current_ptregs, %rsp
+
+ POP_REGS
+
+ addq $8, %rsp /* skip orig_ax */
+ popq %rcx /* pt_regs->ip */
+ addq $8, %rsp /* skip cs */
+ addq $8, %rsp /* skip flags */
+ popq %rsp
+
+ /*
+ * not return w/ ret but w/ jmp as the stack is already popped before
+ * entering __kernel_vsyscall
+ */
+ jmp *%rcx
+
+END(userspace)
diff --git a/arch/x86/um/nommu/syscalls.h b/arch/x86/um/nommu/syscalls.h
new file mode 100644
index 000000000000..a2433756b1fc
--- /dev/null
+++ b/arch/x86/um/nommu/syscalls.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __UM_NOMMU_SYSCALLS_H
+#define __UM_NOMMU_SYSCALLS_H
+
+
+#define task_top_of_stack(task) \
+({ \
+ unsigned long __ptr = (unsigned long)task->stack; \
+ __ptr += THREAD_SIZE; \
+ __ptr; \
+})
+
+extern long current_top_of_stack;
+extern long current_ptregs;
+
+#endif
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 05/13] um: nommu: seccomp syscalls hook
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
` (3 preceding siblings ...)
2025-09-18 7:38 ` [PATCH RESEND v11 04/13] x86/um: nommu: syscall handling Hajime Tazaki
@ 2025-09-18 7:39 ` Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 06/13] x86/um: nommu: process/thread handling Hajime Tazaki
` (8 subsequent siblings)
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:39 UTC (permalink / raw)
To: linux-um
Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel, Kenichi Yasukata
This commit adds syscall hook with seccomp.
Using seccomp raises SIGSYS to UML process, which is captured in the
(UML) kernel, then jumps to the syscall entry point, __kernel_vsyscall,
to hook the original syscall instructions.
The SIGSYS signal is raised upon the execution from uml_reserved and
high_physmem, which locates userspace memory.
It also renames existing static function, sigsys_handler(), in
start_up.c to avoid name conflicts between them.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Kenichi Yasukata <kenichi.yasukata@gmail.com>
---
arch/um/include/shared/kern_util.h | 2 +
arch/um/include/shared/os.h | 10 +++
arch/um/kernel/um_arch.c | 3 +
arch/um/nommu/Makefile | 3 +
arch/um/nommu/os-Linux/Makefile | 7 +++
arch/um/nommu/os-Linux/seccomp.c | 87 +++++++++++++++++++++++++++
arch/um/nommu/os-Linux/signal.c | 16 +++++
arch/um/os-Linux/signal.c | 8 +++
arch/um/os-Linux/start_up.c | 4 +-
arch/x86/um/nommu/Makefile | 2 +-
arch/x86/um/nommu/os-Linux/Makefile | 6 ++
arch/x86/um/nommu/os-Linux/mcontext.c | 15 +++++
arch/x86/um/shared/sysdep/mcontext.h | 4 ++
13 files changed, 164 insertions(+), 3 deletions(-)
create mode 100644 arch/um/nommu/Makefile
create mode 100644 arch/um/nommu/os-Linux/Makefile
create mode 100644 arch/um/nommu/os-Linux/seccomp.c
create mode 100644 arch/um/nommu/os-Linux/signal.c
create mode 100644 arch/x86/um/nommu/os-Linux/Makefile
create mode 100644 arch/x86/um/nommu/os-Linux/mcontext.c
diff --git a/arch/um/include/shared/kern_util.h b/arch/um/include/shared/kern_util.h
index 00ca3e12fd9a..ec8ba1f13c58 100644
--- a/arch/um/include/shared/kern_util.h
+++ b/arch/um/include/shared/kern_util.h
@@ -66,6 +66,8 @@ extern void segv_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs
extern void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs,
void *mc);
extern void fatal_sigsegv(void) __attribute__ ((noreturn));
+extern void sigsys_handler(int sig, struct siginfo *si, struct uml_pt_regs *regs,
+ void *mc);
void um_idle_sleep(void);
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index b35cc8ce333b..1251f08e26d0 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -338,4 +338,14 @@ extern void um_trace_signals_off(void);
/* time-travel */
extern void deliver_time_travel_irqs(void);
+/* seccomp.c */
+#ifdef CONFIG_MMU
+static inline int os_setup_seccomp(void)
+{
+ return 0;
+}
+#else
+extern int os_setup_seccomp(void);
+#endif
+
#endif
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index cfbbbf8500c3..e90b8744144a 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -426,6 +426,9 @@ void __init setup_arch(char **cmdline_p)
add_bootloader_randomness(rng_seed, sizeof(rng_seed));
memzero_explicit(rng_seed, sizeof(rng_seed));
}
+
+ /* install seccomp filter */
+ os_setup_seccomp();
}
void __init arch_cpu_finalize_init(void)
diff --git a/arch/um/nommu/Makefile b/arch/um/nommu/Makefile
new file mode 100644
index 000000000000..baab7c2f57c2
--- /dev/null
+++ b/arch/um/nommu/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-y := os-Linux/
diff --git a/arch/um/nommu/os-Linux/Makefile b/arch/um/nommu/os-Linux/Makefile
new file mode 100644
index 000000000000..805e26ccf63b
--- /dev/null
+++ b/arch/um/nommu/os-Linux/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-y := seccomp.o signal.o
+USER_OBJS := $(obj-y)
+
+include $(srctree)/arch/um/scripts/Makefile.rules
+USER_CFLAGS+=-I$(srctree)/arch/um/os-Linux
diff --git a/arch/um/nommu/os-Linux/seccomp.c b/arch/um/nommu/os-Linux/seccomp.c
new file mode 100644
index 000000000000..d1cfa6e3d632
--- /dev/null
+++ b/arch/um/nommu/os-Linux/seccomp.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <signal.h>
+#include <sys/prctl.h>
+#include <sys/syscall.h> /* For SYS_xxx definitions */
+#include <init.h>
+#include <as-layout.h>
+#include <os.h>
+#include <linux/filter.h>
+#include <linux/seccomp.h>
+
+int __init os_setup_seccomp(void)
+{
+ int err;
+ unsigned long __userspace_start = uml_reserved,
+ __userspace_end = high_physmem;
+
+ struct sock_filter filter[] = {
+ /* if (IP_high > __userspace_end) allow; */
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS,
+ offsetof(struct seccomp_data, instruction_pointer) + 4),
+ BPF_JUMP(BPF_JMP + BPF_JGT + BPF_K, __userspace_end >> 32,
+ /*true-skip=*/0, /*false-skip=*/1),
+ BPF_STMT(BPF_RET + BPF_K, SECCOMP_RET_ALLOW),
+
+ /* if (IP_high == __userspace_end && IP_low >= __userspace_end) allow; */
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS,
+ offsetof(struct seccomp_data, instruction_pointer) + 4),
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, __userspace_end >> 32,
+ /*true-skip=*/0, /*false-skip=*/3),
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS,
+ offsetof(struct seccomp_data, instruction_pointer)),
+ BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, __userspace_end,
+ /*true-skip=*/0, /*false-skip=*/1),
+ BPF_STMT(BPF_RET + BPF_K, SECCOMP_RET_ALLOW),
+
+ /* if (IP_high < __userspace_start) allow; */
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS,
+ offsetof(struct seccomp_data, instruction_pointer) + 4),
+ BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, __userspace_start >> 32,
+ /*true-skip=*/1, /*false-skip=*/0),
+ BPF_STMT(BPF_RET + BPF_K, SECCOMP_RET_ALLOW),
+
+ /* if (IP_high == __userspace_start && IP_low < __userspace_start) allow; */
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS,
+ offsetof(struct seccomp_data, instruction_pointer) + 4),
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, __userspace_start >> 32,
+ /*true-skip=*/0, /*false-skip=*/3),
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS,
+ offsetof(struct seccomp_data, instruction_pointer)),
+ BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, __userspace_start,
+ /*true-skip=*/1, /*false-skip=*/0),
+ BPF_STMT(BPF_RET + BPF_K, SECCOMP_RET_ALLOW),
+
+ /* other address; trap */
+ BPF_STMT(BPF_RET + BPF_K, SECCOMP_RET_TRAP),
+ };
+ struct sock_fprog prog = {
+ .len = ARRAY_SIZE(filter),
+ .filter = filter,
+ };
+
+ err = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+ if (err)
+ os_warn("PR_SET_NO_NEW_PRIVS (err=%d, ernro=%d)\n",
+ err, errno);
+
+ err = syscall(SYS_seccomp, SECCOMP_SET_MODE_FILTER,
+ SECCOMP_FILTER_FLAG_TSYNC, &prog);
+ if (err) {
+ os_warn("SECCOMP_SET_MODE_FILTER (err=%d, ernro=%d)\n",
+ err, errno);
+ exit(1);
+ }
+
+ set_handler(SIGSYS);
+
+ os_info("seccomp: setup filter syscalls in the range: 0x%lx-0x%lx\n",
+ __userspace_start, __userspace_end);
+
+ return 0;
+}
+
diff --git a/arch/um/nommu/os-Linux/signal.c b/arch/um/nommu/os-Linux/signal.c
new file mode 100644
index 000000000000..19043b9652e2
--- /dev/null
+++ b/arch/um/nommu/os-Linux/signal.c
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <signal.h>
+#include <kern_util.h>
+#include <os.h>
+#include <sysdep/mcontext.h>
+#include <sys/ucontext.h>
+
+void sigsys_handler(int sig, struct siginfo *si,
+ struct uml_pt_regs *regs, void *ptr)
+{
+ mcontext_t *mc = (mcontext_t *) ptr;
+
+ /* hook syscall via SIGSYS */
+ set_mc_sigsys_hook(mc);
+}
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 11f07f498270..53e276e81b37 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -20,6 +20,7 @@
#include <um_malloc.h>
#include <sys/ucontext.h>
#include <timetravel.h>
+#include <linux/compiler_attributes.h>
void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *, void *mc) = {
[SIGTRAP] = relay_signal,
@@ -30,6 +31,7 @@ void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *, void *mc) =
[SIGSEGV] = segv_handler,
[SIGIO] = sigio_handler,
[SIGCHLD] = sigchld_handler,
+ [SIGSYS] = sigsys_handler,
};
static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
@@ -176,6 +178,11 @@ static void sigusr1_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
uml_pm_wake();
}
+__weak void sigsys_handler(int sig, struct siginfo *unused_si,
+ struct uml_pt_regs *regs, void *mc)
+{
+}
+
void register_pm_wake_signal(void)
{
set_handler(SIGUSR1);
@@ -187,6 +194,7 @@ static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = {
[SIGILL] = sig_handler,
[SIGFPE] = sig_handler,
[SIGTRAP] = sig_handler,
+ [SIGSYS] = sig_handler,
[SIGIO] = sig_handler,
[SIGWINCH] = sig_handler,
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index a827c2e01aa5..4e1f05360c49 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -238,7 +238,7 @@ extern unsigned long *exec_fp_regs;
__initdata static struct stub_data *seccomp_test_stub_data;
-static void __init sigsys_handler(int sig, siginfo_t *info, void *p)
+static void __init _sigsys_handler(int sig, siginfo_t *info, void *p)
{
ucontext_t *uc = p;
@@ -273,7 +273,7 @@ static int __init seccomp_helper(void *data)
sizeof(seccomp_test_stub_data->sigstack));
sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO;
- sa.sa_sigaction = (void *) sigsys_handler;
+ sa.sa_sigaction = (void *) _sigsys_handler;
sa.sa_restorer = NULL;
if (sigaction(SIGSYS, &sa, NULL) < 0)
exit(2);
diff --git a/arch/x86/um/nommu/Makefile b/arch/x86/um/nommu/Makefile
index d72c63afffa5..ebe47d4836f4 100644
--- a/arch/x86/um/nommu/Makefile
+++ b/arch/x86/um/nommu/Makefile
@@ -5,4 +5,4 @@ else
BITS := 64
endif
-obj-y = do_syscall_$(BITS).o entry_$(BITS).o
+obj-y = do_syscall_$(BITS).o entry_$(BITS).o os-Linux/
diff --git a/arch/x86/um/nommu/os-Linux/Makefile b/arch/x86/um/nommu/os-Linux/Makefile
new file mode 100644
index 000000000000..4571e403a6ff
--- /dev/null
+++ b/arch/x86/um/nommu/os-Linux/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-y = mcontext.o
+USER_OBJS := mcontext.o
+
+include $(srctree)/arch/um/scripts/Makefile.rules
diff --git a/arch/x86/um/nommu/os-Linux/mcontext.c b/arch/x86/um/nommu/os-Linux/mcontext.c
new file mode 100644
index 000000000000..b62a6195096f
--- /dev/null
+++ b/arch/x86/um/nommu/os-Linux/mcontext.c
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <sys/ucontext.h>
+#define __FRAME_OFFSETS
+#include <asm/ptrace.h>
+#include <sysdep/ptrace.h>
+#include <sysdep/mcontext.h>
+
+extern long __kernel_vsyscall(int64_t a0, int64_t a1, int64_t a2, int64_t a3,
+ int64_t a4, int64_t a5, int64_t a6);
+
+void set_mc_sigsys_hook(mcontext_t *mc)
+{
+ mc->gregs[REG_RCX] = mc->gregs[REG_RIP];
+ mc->gregs[REG_RIP] = (unsigned long) __kernel_vsyscall;
+}
diff --git a/arch/x86/um/shared/sysdep/mcontext.h b/arch/x86/um/shared/sysdep/mcontext.h
index 6fe490cc5b98..9a0d6087f357 100644
--- a/arch/x86/um/shared/sysdep/mcontext.h
+++ b/arch/x86/um/shared/sysdep/mcontext.h
@@ -17,6 +17,10 @@ extern int get_stub_state(struct uml_pt_regs *regs, struct stub_data *data,
extern int set_stub_state(struct uml_pt_regs *regs, struct stub_data *data,
int single_stepping);
+#ifndef CONFIG_MMU
+extern void set_mc_sigsys_hook(mcontext_t *mc);
+#endif
+
#ifdef __i386__
#define GET_FAULTINFO_FROM_MC(fi, mc) \
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 06/13] x86/um: nommu: process/thread handling
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
` (4 preceding siblings ...)
2025-09-18 7:39 ` [PATCH RESEND v11 05/13] um: nommu: seccomp syscalls hook Hajime Tazaki
@ 2025-09-18 7:39 ` Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 07/13] um: nommu: configure fs register on host syscall invocation Hajime Tazaki
` (7 subsequent siblings)
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:39 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
Since ptrace facility isn't used under !MMU of UML, there is different
code path to invoke processes/threads; there are no external process
used, and need to properly configure some of registers (fs segment
register for TLS, etc) on every context switch, etc.
Signals aren't delivered in non-ptrace syscall entry/leave so, we also
need to handle pending signal by ourselves.
ptrace related syscalls are not tested yet so, marked
arch_has_single_step() unsupported in !MMU environment.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
---
arch/um/include/asm/ptrace-generic.h | 2 +-
arch/x86/um/Makefile | 3 +-
arch/x86/um/nommu/Makefile | 2 +-
arch/x86/um/nommu/entry_64.S | 2 ++
arch/x86/um/nommu/syscalls.h | 2 ++
arch/x86/um/nommu/syscalls_64.c | 50 ++++++++++++++++++++++++++++
6 files changed, 58 insertions(+), 3 deletions(-)
create mode 100644 arch/x86/um/nommu/syscalls_64.c
diff --git a/arch/um/include/asm/ptrace-generic.h b/arch/um/include/asm/ptrace-generic.h
index 62e9916078ec..5aa38fe6b2fb 100644
--- a/arch/um/include/asm/ptrace-generic.h
+++ b/arch/um/include/asm/ptrace-generic.h
@@ -14,7 +14,7 @@ struct pt_regs {
struct uml_pt_regs regs;
};
-#define arch_has_single_step() (1)
+#define arch_has_single_step() (IS_ENABLED(CONFIG_MMU))
#define EMPTY_REGS { .regs = EMPTY_UML_PT_REGS }
diff --git a/arch/x86/um/Makefile b/arch/x86/um/Makefile
index 227af2a987e2..53c9ebb3c41c 100644
--- a/arch/x86/um/Makefile
+++ b/arch/x86/um/Makefile
@@ -27,7 +27,8 @@ subarch-y += ../kernel/sys_ia32.o
else
-obj-y += syscalls_64.o vdso/
+obj-y += vdso/
+obj-$(CONFIG_MMU) += syscalls_64.o
subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o \
../lib/memmove_64.o ../lib/memset_64.o
diff --git a/arch/x86/um/nommu/Makefile b/arch/x86/um/nommu/Makefile
index ebe47d4836f4..4018d9e0aba0 100644
--- a/arch/x86/um/nommu/Makefile
+++ b/arch/x86/um/nommu/Makefile
@@ -5,4 +5,4 @@ else
BITS := 64
endif
-obj-y = do_syscall_$(BITS).o entry_$(BITS).o os-Linux/
+obj-y = do_syscall_$(BITS).o entry_$(BITS).o syscalls_$(BITS).o os-Linux/
diff --git a/arch/x86/um/nommu/entry_64.S b/arch/x86/um/nommu/entry_64.S
index 485c578aae64..a58922fc81e5 100644
--- a/arch/x86/um/nommu/entry_64.S
+++ b/arch/x86/um/nommu/entry_64.S
@@ -86,6 +86,8 @@ END(__kernel_vsyscall)
*/
ENTRY(userspace)
+ /* set stack and pt_regs to the current task */
+ call arch_set_stack_to_current
/* clear direction flag to meet ABI */
cld
/* align the stack for x86_64 ABI */
diff --git a/arch/x86/um/nommu/syscalls.h b/arch/x86/um/nommu/syscalls.h
index a2433756b1fc..ce16bf8abd59 100644
--- a/arch/x86/um/nommu/syscalls.h
+++ b/arch/x86/um/nommu/syscalls.h
@@ -13,4 +13,6 @@
extern long current_top_of_stack;
extern long current_ptregs;
+void arch_set_stack_to_current(void);
+
#endif
diff --git a/arch/x86/um/nommu/syscalls_64.c b/arch/x86/um/nommu/syscalls_64.c
new file mode 100644
index 000000000000..d56027ebc651
--- /dev/null
+++ b/arch/x86/um/nommu/syscalls_64.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Copyright 2003 PathScale, Inc.
+ *
+ * Licensed under the GPL
+ */
+
+#include <linux/sched.h>
+#include <linux/sched/mm.h>
+#include <linux/syscalls.h>
+#include <linux/uaccess.h>
+#include <asm/prctl.h> /* XXX This should get the constants from libc */
+#include <registers.h>
+#include <os.h>
+#include "syscalls.h"
+
+void arch_set_stack_to_current(void)
+{
+ current_top_of_stack = task_top_of_stack(current);
+ current_ptregs = (long)task_pt_regs(current);
+}
+
+void arch_switch_to(struct task_struct *to)
+{
+ /*
+ * In !CONFIG_MMU, it doesn't ptrace thus,
+ * The FS_BASE registers are saved here.
+ */
+ current_top_of_stack = task_top_of_stack(to);
+ current_ptregs = (long)task_pt_regs(to);
+
+ if ((to->thread.regs.regs.gp[FS_BASE / sizeof(unsigned long)] == 0) ||
+ (to->mm == NULL))
+ return;
+
+ /* this changes the FS on every context switch */
+ arch_prctl(to, ARCH_SET_FS,
+ (void __user *) to->thread.regs.regs.gp[FS_BASE / sizeof(unsigned long)]);
+}
+
+SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
+ unsigned long, prot, unsigned long, flags,
+ unsigned long, fd, unsigned long, off)
+{
+ if (off & ~PAGE_MASK)
+ return -EINVAL;
+
+ return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
+}
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 07/13] um: nommu: configure fs register on host syscall invocation
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
` (5 preceding siblings ...)
2025-09-18 7:39 ` [PATCH RESEND v11 06/13] x86/um: nommu: process/thread handling Hajime Tazaki
@ 2025-09-18 7:39 ` Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 08/13] x86/um/vdso: nommu: vdso memory update Hajime Tazaki
` (6 subsequent siblings)
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:39 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
As userspace on UML/!MMU also need to configure %fs register when it is
running to correctly access thread structure, host syscalls implemented
in os-Linux drivers may be puzzled when they are called. Thus it has to
configure %fs register via arch_prctl(SET_FS) on every host syscalls.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
---
arch/um/include/shared/os.h | 6 +++
arch/um/os-Linux/process.c | 6 +++
arch/um/os-Linux/start_up.c | 21 +++++++++
arch/x86/um/nommu/do_syscall_64.c | 37 ++++++++++++++++
arch/x86/um/nommu/syscalls_64.c | 71 +++++++++++++++++++++++++++++++
5 files changed, 141 insertions(+)
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index 1251f08e26d0..7c6a8bc0447c 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -189,6 +189,7 @@ extern void check_host_supports_tls(int *supports_tls, int *tls_min);
extern void get_host_cpu_features(
void (*flags_helper_func)(char *line),
void (*cache_helper_func)(char *line));
+extern int host_has_fsgsbase;
/* mem.c */
extern int create_mem_file(unsigned long long len);
@@ -213,6 +214,11 @@ extern int os_protect_memory(void *addr, unsigned long len,
extern int os_unmap_memory(void *addr, int len);
extern int os_drop_memory(void *addr, int length);
extern int can_drop_memory(void);
+extern int os_arch_prctl(int pid, int option, unsigned long *arg);
+#ifndef CONFIG_MMU
+extern long long host_fs;
+#endif
+
void os_set_pdeathsig(void);
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index bc598e661ec6..0a1d078dce19 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -16,6 +16,7 @@
#include <sys/prctl.h>
#include <sys/wait.h>
#include <asm/unistd.h>
+#include <sys/syscall.h> /* For SYS_xxx definitions */
#include <linux/threads.h>
#include <init.h>
#include <longjmp.h>
@@ -177,6 +178,11 @@ int __init can_drop_memory(void)
return ok;
}
+int os_arch_prctl(int pid, int option, unsigned long *arg2)
+{
+ return syscall(SYS_arch_prctl, option, arg2);
+}
+
void init_new_thread_signals(void)
{
set_handler(SIGSEGV);
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index 4e1f05360c49..55dd92bd2a0b 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -20,6 +20,8 @@
#include <sys/resource.h>
#include <asm/ldt.h>
#include <asm/unistd.h>
+#include <sys/auxv.h>
+#include <asm/hwcap2.h>
#include <init.h>
#include <os.h>
#include <kern_util.h>
@@ -36,6 +38,8 @@
#include <skas.h>
#include "internal.h"
+int host_has_fsgsbase;
+
static void ptrace_child(void)
{
int ret;
@@ -459,6 +463,20 @@ __uml_setup("seccomp=", uml_seccomp_config,
" This is insecure and should only be used with a trusted userspace\n\n"
);
+static void __init check_fsgsbase(void)
+{
+ unsigned long auxv = getauxval(AT_HWCAP2);
+
+ os_info("Checking FSGSBASE instructions...");
+ if (auxv & HWCAP2_FSGSBASE) {
+ host_has_fsgsbase = 1;
+ os_info("OK\n");
+ } else {
+ host_has_fsgsbase = 0;
+ os_info("disabled\n");
+ }
+}
+
void __init os_early_checks(void)
{
int pid;
@@ -484,6 +502,9 @@ void __init os_early_checks(void)
using_seccomp = 0;
check_ptrace();
+ /* probe fsgsbase instruction */
+ check_fsgsbase();
+
pid = start_ptraced_child();
if (init_pid_registers(pid))
fatal("Failed to initialize default registers");
diff --git a/arch/x86/um/nommu/do_syscall_64.c b/arch/x86/um/nommu/do_syscall_64.c
index 292d7c578622..9bc630995df9 100644
--- a/arch/x86/um/nommu/do_syscall_64.c
+++ b/arch/x86/um/nommu/do_syscall_64.c
@@ -2,10 +2,38 @@
#include <linux/kernel.h>
#include <linux/ptrace.h>
+#include <asm/fsgsbase.h>
+#include <asm/prctl.h>
#include <kern_util.h>
#include <asm/syscall.h>
#include <os.h>
+static int os_x86_arch_prctl(int pid, int option, unsigned long *arg2)
+{
+ if (!host_has_fsgsbase)
+ return os_arch_prctl(pid, option, arg2);
+
+ switch (option) {
+ case ARCH_SET_FS:
+ wrfsbase(*arg2);
+ break;
+ case ARCH_SET_GS:
+ wrgsbase(*arg2);
+ break;
+ case ARCH_GET_FS:
+ *arg2 = rdfsbase();
+ break;
+ case ARCH_GET_GS:
+ *arg2 = rdgsbase();
+ break;
+ default:
+ pr_warn("%s: unsupported option: 0x%x", __func__, option);
+ break;
+ }
+
+ return 0;
+}
+
__visible void do_syscall_64(struct pt_regs *regs)
{
int syscall;
@@ -13,6 +41,9 @@ __visible void do_syscall_64(struct pt_regs *regs)
syscall = PT_SYSCALL_NR(regs->regs.gp);
UPT_SYSCALL_NR(®s->regs) = syscall;
+ /* set fs register to the original host one */
+ os_x86_arch_prctl(0, ARCH_SET_FS, (void *)host_fs);
+
if (likely(syscall < NR_syscalls)) {
unsigned long ret;
@@ -29,4 +60,10 @@ __visible void do_syscall_64(struct pt_regs *regs)
/* handle tasks and signals at the end */
interrupt_end();
+
+ /* restore back fs register to userspace configured one */
+ os_x86_arch_prctl(0, ARCH_SET_FS,
+ (void *)(current->thread.regs.regs.gp[FS_BASE
+ / sizeof(unsigned long)]));
+
}
diff --git a/arch/x86/um/nommu/syscalls_64.c b/arch/x86/um/nommu/syscalls_64.c
index d56027ebc651..19d23686fc5b 100644
--- a/arch/x86/um/nommu/syscalls_64.c
+++ b/arch/x86/um/nommu/syscalls_64.c
@@ -13,8 +13,70 @@
#include <asm/prctl.h> /* XXX This should get the constants from libc */
#include <registers.h>
#include <os.h>
+#include <asm/thread_info.h>
+#include <asm/mman.h>
#include "syscalls.h"
+/*
+ * The guest libc can change FS, which confuses the host libc.
+ * In fact, changing FS directly is not supported (check
+ * man arch_prctl). So, whenever we make a host syscall,
+ * we should be changing FS to the original FS (not the
+ * one set by the guest libc). This original FS is stored
+ * in host_fs.
+ */
+long long host_fs = -1;
+
+long arch_prctl(struct task_struct *task, int option,
+ unsigned long __user *arg2)
+{
+ long ret = -EINVAL;
+ unsigned long *ptr = arg2, tmp;
+
+ switch (option) {
+ case ARCH_SET_FS:
+ if (host_fs == -1)
+ os_arch_prctl(0, ARCH_GET_FS, (void *)&host_fs);
+ ret = 0;
+ break;
+ case ARCH_SET_GS:
+ ret = 0;
+ break;
+ case ARCH_GET_FS:
+ case ARCH_GET_GS:
+ ptr = &tmp;
+ break;
+ }
+
+ ret = os_arch_prctl(0, option, ptr);
+ if (ret)
+ return ret;
+
+ switch (option) {
+ case ARCH_SET_FS:
+ current->thread.regs.regs.gp[FS_BASE / sizeof(unsigned long)] =
+ (unsigned long) arg2;
+ break;
+ case ARCH_SET_GS:
+ current->thread.regs.regs.gp[GS_BASE / sizeof(unsigned long)] =
+ (unsigned long) arg2;
+ break;
+ case ARCH_GET_FS:
+ ret = put_user(current->thread.regs.regs.gp[FS_BASE / sizeof(unsigned long)], arg2);
+ break;
+ case ARCH_GET_GS:
+ ret = put_user(current->thread.regs.regs.gp[GS_BASE / sizeof(unsigned long)], arg2);
+ break;
+ }
+
+ return ret;
+}
+
+SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
+{
+ return arch_prctl(current, option, (unsigned long __user *) arg2);
+}
+
void arch_set_stack_to_current(void)
{
current_top_of_stack = task_top_of_stack(current);
@@ -48,3 +110,12 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
}
+
+static int __init um_nommu_setup_hostfs(void)
+{
+ /* initialize the host_fs value at boottime */
+ os_arch_prctl(0, ARCH_GET_FS, (void *)&host_fs);
+
+ return 0;
+}
+arch_initcall(um_nommu_setup_hostfs);
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 08/13] x86/um/vdso: nommu: vdso memory update
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
` (6 preceding siblings ...)
2025-09-18 7:39 ` [PATCH RESEND v11 07/13] um: nommu: configure fs register on host syscall invocation Hajime Tazaki
@ 2025-09-18 7:39 ` Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 09/13] x86/um: nommu: signal handling Hajime Tazaki
` (5 subsequent siblings)
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:39 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
On !MMU mode, the address of vdso is accessible from userspace. This
commit implements the entry point by pointing a block of page address.
This commit also add memory permission configuration of vdso page to be
executable.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
---
arch/x86/um/vdso/vma.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/arch/x86/um/vdso/vma.c b/arch/x86/um/vdso/vma.c
index dc8dfb2abd80..1c8c39f87681 100644
--- a/arch/x86/um/vdso/vma.c
+++ b/arch/x86/um/vdso/vma.c
@@ -9,6 +9,7 @@
#include <asm/page.h>
#include <asm/elf.h>
#include <linux/init.h>
+#include <os.h>
static unsigned int __read_mostly vdso_enabled = 1;
unsigned long um_vdso_addr;
@@ -21,14 +22,24 @@ static int __init init_vdso(void)
{
BUG_ON(vdso_end - vdso_start > PAGE_SIZE);
- um_vdso_addr = task_size - PAGE_SIZE;
-
um_vdso = alloc_page(GFP_KERNEL);
if (!um_vdso)
goto oom;
copy_page(page_address(um_vdso), vdso_start);
+#ifdef CONFIG_MMU
+ um_vdso_addr = task_size - PAGE_SIZE;
+#else
+ /* this is fine with NOMMU as everything is accessible */
+ um_vdso_addr = (unsigned long)page_address(um_vdso);
+ os_protect_memory((void *)um_vdso_addr, vdso_end - vdso_start, 1, 0, 1);
+#endif
+
+ pr_info("vdso_start=%lx um_vdso_addr=%lx pg_um_vdso=%lx",
+ (unsigned long)vdso_start, um_vdso_addr,
+ (unsigned long)page_address(um_vdso));
+
return 0;
oom:
@@ -39,6 +50,7 @@ static int __init init_vdso(void)
}
subsys_initcall(init_vdso);
+#ifdef CONFIG_MMU
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct vm_area_struct *vma;
@@ -63,3 +75,4 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
return IS_ERR(vma) ? PTR_ERR(vma) : 0;
}
+#endif
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 09/13] x86/um: nommu: signal handling
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
` (7 preceding siblings ...)
2025-09-18 7:39 ` [PATCH RESEND v11 08/13] x86/um/vdso: nommu: vdso memory update Hajime Tazaki
@ 2025-09-18 7:39 ` Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver Hajime Tazaki
` (4 subsequent siblings)
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:39 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
This commit updates the behavior of signal handling under !MMU
environment. It adds the alignment code for signal frame as the frame
is used in userspace as-is.
floating point register is carefully handling upon entry/leave of
syscall routine so that signal handlers can read/write the contents of
the register.
It also adds the follow up routine for SIGSEGV as a signal delivery runs
in the same stack frame while we have to avoid endless SIGSEGV.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
---
arch/um/include/shared/kern_util.h | 4 +
arch/um/nommu/Makefile | 2 +-
arch/um/nommu/os-Linux/signal.c | 8 +
arch/um/nommu/trap.c | 201 ++++++++++++++++++++++++++
arch/um/os-Linux/signal.c | 3 +-
arch/x86/um/nommu/do_syscall_64.c | 6 +
arch/x86/um/nommu/os-Linux/mcontext.c | 11 ++
arch/x86/um/shared/sysdep/mcontext.h | 1 +
arch/x86/um/shared/sysdep/ptrace.h | 2 +-
9 files changed, 235 insertions(+), 3 deletions(-)
create mode 100644 arch/um/nommu/trap.c
diff --git a/arch/um/include/shared/kern_util.h b/arch/um/include/shared/kern_util.h
index ec8ba1f13c58..7f55402b6385 100644
--- a/arch/um/include/shared/kern_util.h
+++ b/arch/um/include/shared/kern_util.h
@@ -73,4 +73,8 @@ void um_idle_sleep(void);
void kasan_map_memory(void *start, size_t len);
+#ifndef CONFIG_MMU
+extern void nommu_relay_signal(void *ptr);
+#endif
+
#endif
diff --git a/arch/um/nommu/Makefile b/arch/um/nommu/Makefile
index baab7c2f57c2..096221590cfd 100644
--- a/arch/um/nommu/Makefile
+++ b/arch/um/nommu/Makefile
@@ -1,3 +1,3 @@
# SPDX-License-Identifier: GPL-2.0
-obj-y := os-Linux/
+obj-y := trap.o os-Linux/
diff --git a/arch/um/nommu/os-Linux/signal.c b/arch/um/nommu/os-Linux/signal.c
index 19043b9652e2..6febb178dcda 100644
--- a/arch/um/nommu/os-Linux/signal.c
+++ b/arch/um/nommu/os-Linux/signal.c
@@ -5,6 +5,7 @@
#include <os.h>
#include <sysdep/mcontext.h>
#include <sys/ucontext.h>
+#include <as-layout.h>
void sigsys_handler(int sig, struct siginfo *si,
struct uml_pt_regs *regs, void *ptr)
@@ -14,3 +15,10 @@ void sigsys_handler(int sig, struct siginfo *si,
/* hook syscall via SIGSYS */
set_mc_sigsys_hook(mc);
}
+
+void nommu_relay_signal(void *ptr)
+{
+ mcontext_t *mc = (mcontext_t *) ptr;
+
+ set_mc_relay_signal(mc);
+}
diff --git a/arch/um/nommu/trap.c b/arch/um/nommu/trap.c
new file mode 100644
index 000000000000..430297517455
--- /dev/null
+++ b/arch/um/nommu/trap.c
@@ -0,0 +1,201 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/hardirq.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/sched/debug.h>
+#include <asm/current.h>
+#include <asm/tlbflush.h>
+#include <arch.h>
+#include <as-layout.h>
+#include <kern_util.h>
+#include <os.h>
+#include <skas.h>
+
+/*
+ * Note this is constrained to return 0, -EFAULT, -EACCES, -ENOMEM by
+ * segv().
+ */
+int handle_page_fault(unsigned long address, unsigned long ip,
+ int is_write, int is_user, int *code_out)
+{
+ /* !MMU has no pagefault */
+ return -EFAULT;
+}
+
+static void show_segv_info(struct uml_pt_regs *regs)
+{
+ struct task_struct *tsk = current;
+ struct faultinfo *fi = UPT_FAULTINFO(regs);
+
+ if (!unhandled_signal(tsk, SIGSEGV))
+ return;
+
+ pr_warn_ratelimited("%s%s[%d]: segfault at %lx ip %p sp %p error %x",
+ task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
+ tsk->comm, task_pid_nr(tsk), FAULT_ADDRESS(*fi),
+ (void *)UPT_IP(regs), (void *)UPT_SP(regs),
+ fi->error_code);
+}
+
+static void bad_segv(struct faultinfo fi, unsigned long ip)
+{
+ current->thread.arch.faultinfo = fi;
+ force_sig_fault(SIGSEGV, SEGV_ACCERR, (void __user *) FAULT_ADDRESS(fi));
+}
+
+void fatal_sigsegv(void)
+{
+ force_fatal_sig(SIGSEGV);
+ do_signal(¤t->thread.regs);
+ /*
+ * This is to tell gcc that we're not returning - do_signal
+ * can, in general, return, but in this case, it's not, since
+ * we just got a fatal SIGSEGV queued.
+ */
+ os_dump_core();
+}
+
+/**
+ * segv_handler() - the SIGSEGV handler
+ * @sig: the signal number
+ * @unused_si: the signal info struct; unused in this handler
+ * @regs: the ptrace register information
+ *
+ * The handler first extracts the faultinfo from the UML ptrace regs struct.
+ * If the userfault did not happen in an UML userspace process, bad_segv is called.
+ * Otherwise the signal did happen in a cloned userspace process, handle it.
+ */
+void segv_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs,
+ void *mc)
+{
+ struct faultinfo *fi = UPT_FAULTINFO(regs);
+
+ /* !MMU specific part; detection of userspace */
+ /* mark is_user=1 when the IP is from userspace code. */
+ if (UPT_IP(regs) > uml_reserved && UPT_IP(regs) < high_physmem)
+ regs->is_user = 1;
+
+ if (UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)) {
+ show_segv_info(regs);
+ bad_segv(*fi, UPT_IP(regs));
+ return;
+ }
+ segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs, mc);
+
+ /* !MMU specific part; detection of userspace */
+ relay_signal(sig, unused_si, regs, mc);
+}
+
+/*
+ * We give a *copy* of the faultinfo in the regs to segv.
+ * This must be done, since nesting SEGVs could overwrite
+ * the info in the regs. A pointer to the info then would
+ * give us bad data!
+ */
+unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user,
+ struct uml_pt_regs *regs, void *mc)
+{
+ int si_code;
+ int err;
+ int is_write = FAULT_WRITE(fi);
+ unsigned long address = FAULT_ADDRESS(fi);
+
+ if (!is_user && regs)
+ current->thread.segv_regs = container_of(regs, struct pt_regs, regs);
+
+ if (current->mm == NULL) {
+ show_regs(container_of(regs, struct pt_regs, regs));
+ panic("Segfault with no mm");
+ } else if (!is_user && address > PAGE_SIZE && address < TASK_SIZE) {
+ show_regs(container_of(regs, struct pt_regs, regs));
+ panic("Kernel tried to access user memory at addr 0x%lx, ip 0x%lx",
+ address, ip);
+ }
+
+ if (SEGV_IS_FIXABLE(&fi))
+ err = handle_page_fault(address, ip, is_write, is_user,
+ &si_code);
+ else {
+ err = -EFAULT;
+ /*
+ * A thread accessed NULL, we get a fault, but CR2 is invalid.
+ * This code is used in __do_copy_from_user() of TT mode.
+ * XXX tt mode is gone, so maybe this isn't needed any more
+ */
+ address = 0;
+ }
+
+ if (!err)
+ goto out;
+ else if (!is_user && arch_fixup(ip, regs))
+ goto out;
+
+ if (!is_user) {
+ show_regs(container_of(regs, struct pt_regs, regs));
+ panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
+ address, ip);
+ }
+
+ show_segv_info(regs);
+
+ if (err == -EACCES) {
+ current->thread.arch.faultinfo = fi;
+ force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
+ } else {
+ WARN_ON_ONCE(err != -EFAULT);
+ current->thread.arch.faultinfo = fi;
+ force_sig_fault(SIGSEGV, si_code, (void __user *) address);
+ }
+
+out:
+ if (regs)
+ current->thread.segv_regs = NULL;
+
+ return 0;
+}
+
+void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs,
+ void *mc)
+{
+ int code, err;
+
+ /* !MMU specific part; detection of userspace */
+ /* mark is_user=1 when the IP is from userspace code. */
+ if (UPT_IP(regs) > uml_reserved && UPT_IP(regs) < high_physmem)
+ regs->is_user = 1;
+
+ if (!UPT_IS_USER(regs)) {
+ if (sig == SIGBUS)
+ pr_err("Bus error - the host /dev/shm or /tmp mount likely just ran out of space\n");
+ panic("Kernel mode signal %d", sig);
+ }
+ /* if is_user==1, set return to userspace sig handler to relay signal */
+ nommu_relay_signal(mc);
+
+ arch_examine_signal(sig, regs);
+
+ /* Is the signal layout for the signal known?
+ * Signal data must be scrubbed to prevent information leaks.
+ */
+ code = si->si_code;
+ err = si->si_errno;
+ if ((err == 0) && (siginfo_layout(sig, code) == SIL_FAULT)) {
+ struct faultinfo *fi = UPT_FAULTINFO(regs);
+
+ current->thread.arch.faultinfo = *fi;
+ force_sig_fault(sig, code, (void __user *)FAULT_ADDRESS(*fi));
+ } else {
+ pr_err("Attempted to relay unknown signal %d (si_code = %d) with errno %d\n",
+ sig, code, err);
+ force_sig(sig);
+ }
+}
+
+void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs,
+ void *mc)
+{
+ do_IRQ(WINCH_IRQ, regs);
+}
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 53e276e81b37..67dcd88b45b1 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -40,9 +40,10 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
int save_errno = errno;
r.is_user = 0;
+ if (mc)
+ get_regs_from_mc(&r, mc);
if (sig == SIGSEGV) {
/* For segfaults, we want the data from the sigcontext. */
- get_regs_from_mc(&r, mc);
GET_FAULTINFO_FROM_MC(r.faultinfo, mc);
}
diff --git a/arch/x86/um/nommu/do_syscall_64.c b/arch/x86/um/nommu/do_syscall_64.c
index 9bc630995df9..cf5a347ee9b1 100644
--- a/arch/x86/um/nommu/do_syscall_64.c
+++ b/arch/x86/um/nommu/do_syscall_64.c
@@ -44,6 +44,9 @@ __visible void do_syscall_64(struct pt_regs *regs)
/* set fs register to the original host one */
os_x86_arch_prctl(0, ARCH_SET_FS, (void *)host_fs);
+ /* save fp registers */
+ asm volatile("fxsaveq %0" : "=m"(*(struct _xstate *)regs->regs.fp));
+
if (likely(syscall < NR_syscalls)) {
unsigned long ret;
@@ -61,6 +64,9 @@ __visible void do_syscall_64(struct pt_regs *regs)
/* handle tasks and signals at the end */
interrupt_end();
+ /* restore fp registers */
+ asm volatile("fxrstorq %0" : : "m"((current->thread.regs.regs.fp)));
+
/* restore back fs register to userspace configured one */
os_x86_arch_prctl(0, ARCH_SET_FS,
(void *)(current->thread.regs.regs.gp[FS_BASE
diff --git a/arch/x86/um/nommu/os-Linux/mcontext.c b/arch/x86/um/nommu/os-Linux/mcontext.c
index b62a6195096f..afa20f1e235a 100644
--- a/arch/x86/um/nommu/os-Linux/mcontext.c
+++ b/arch/x86/um/nommu/os-Linux/mcontext.c
@@ -4,10 +4,21 @@
#include <asm/ptrace.h>
#include <sysdep/ptrace.h>
#include <sysdep/mcontext.h>
+#include <os.h>
+#include "../syscalls.h"
extern long __kernel_vsyscall(int64_t a0, int64_t a1, int64_t a2, int64_t a3,
int64_t a4, int64_t a5, int64_t a6);
+void set_mc_relay_signal(mcontext_t *mc)
+{
+ /* configure stack and userspace returning routine as
+ * instruction pointer
+ */
+ mc->gregs[REG_RSP] = (unsigned long) current_top_of_stack;
+ mc->gregs[REG_RIP] = (unsigned long) userspace;
+}
+
void set_mc_sigsys_hook(mcontext_t *mc)
{
mc->gregs[REG_RCX] = mc->gregs[REG_RIP];
diff --git a/arch/x86/um/shared/sysdep/mcontext.h b/arch/x86/um/shared/sysdep/mcontext.h
index 9a0d6087f357..82a5f38b350f 100644
--- a/arch/x86/um/shared/sysdep/mcontext.h
+++ b/arch/x86/um/shared/sysdep/mcontext.h
@@ -19,6 +19,7 @@ extern int set_stub_state(struct uml_pt_regs *regs, struct stub_data *data,
#ifndef CONFIG_MMU
extern void set_mc_sigsys_hook(mcontext_t *mc);
+extern void set_mc_relay_signal(mcontext_t *mc);
#endif
#ifdef __i386__
diff --git a/arch/x86/um/shared/sysdep/ptrace.h b/arch/x86/um/shared/sysdep/ptrace.h
index 572ea2d79131..6ed6bb1ca50e 100644
--- a/arch/x86/um/shared/sysdep/ptrace.h
+++ b/arch/x86/um/shared/sysdep/ptrace.h
@@ -53,7 +53,7 @@ struct uml_pt_regs {
int is_user;
/* Dynamically sized FP registers (holds an XSTATE) */
- unsigned long fp[];
+ unsigned long fp[] __attribute__((aligned(16)));
};
#define EMPTY_UML_PT_REGS { }
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
` (8 preceding siblings ...)
2025-09-18 7:39 ` [PATCH RESEND v11 09/13] x86/um: nommu: signal handling Hajime Tazaki
@ 2025-09-18 7:39 ` Hajime Tazaki
2025-09-18 8:30 ` Johannes Berg
2025-09-18 7:39 ` [PATCH RESEND v11 11/13] um: change machine name for uname output Hajime Tazaki
` (3 subsequent siblings)
13 siblings, 1 reply; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:39 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
The commit 8fe743b5eba0 ("PCI: Add CONFIG_MMU dependency") restricts the
PCI base driver to depend on MMU. While nommu UML _can_ implement PCI
drivers over PCI devices (e.g., virtio-pci), the current nommu UML
doesn't implement it.
But without PCI drivers kunit complains as config for kunit
(arch_uml.config) defines the dependency to PCI drivers.
This commit fixes the issue of this compile failures when building PCI
drivers with nommu UML. In particular, the fix is to undefine the
constant PCI_IOBASE to be able to bypass pci_unmap_iospace() call.
When we will support PCI drivers for nommu UML, we will refactor this
code.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
---
arch/um/include/asm/dma.h | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/arch/um/include/asm/dma.h b/arch/um/include/asm/dma.h
index fdc53642c718..643d74555671 100644
--- a/arch/um/include/asm/dma.h
+++ b/arch/um/include/asm/dma.h
@@ -4,6 +4,19 @@
#include <asm/io.h>
+/**
+ * now the PCI core driver depends on CONFIG_MMU in linus tree, nommu
+ * UML cannot build with PCI but without PCI kunit doesn't build due
+ * to the dependency to the CONFIG_VIRTIO_UML.
+ *
+ * This is a workaround to silence build failures on kunit, which is
+ * valid until nommu UML supports PCI drivers (e.g., virtio-pci) in a
+ * future.
+ */
+#ifndef CONFIG_MMU
+#undef PCI_IOBASE
+#endif
+
extern unsigned long uml_physmem;
#define MAX_DMA_ADDRESS (uml_physmem)
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 11/13] um: change machine name for uname output
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
` (9 preceding siblings ...)
2025-09-18 7:39 ` [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver Hajime Tazaki
@ 2025-09-18 7:39 ` Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 12/13] um: nommu: add documentation of nommu UML Hajime Tazaki
` (2 subsequent siblings)
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:39 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
This commit tries to display MMU/!MMU mode from the output of uname(2)
so that users can distinguish which mode of UML is running right now.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
---
arch/um/Makefile | 6 ++++++
arch/um/os-Linux/util.c | 3 ++-
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/um/Makefile b/arch/um/Makefile
index 5371c9a1b11e..9bc8fc149514 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -153,6 +153,12 @@ export CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE) $(CC_FLAGS_
CLEAN_FILES += linux x.i gmon.out
MRPROPER_FILES += $(HOST_DIR)/include/generated
+ifeq ($(CONFIG_MMU),y)
+UTS_MACHINE := "um"
+else
+UTS_MACHINE := "um\(nommu\)"
+endif
+
archclean:
@find . \( -name '*.bb' -o -name '*.bbg' -o -name '*.da' \
-o -name '*.gcov' \) -type f -print | xargs rm -f
diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
index 4193e04d7e4a..20421e9f0f77 100644
--- a/arch/um/os-Linux/util.c
+++ b/arch/um/os-Linux/util.c
@@ -65,7 +65,8 @@ void setup_machinename(char *machine_out)
}
# endif
#endif
- strcpy(machine_out, host.machine);
+ strcat(machine_out, "/");
+ strcat(machine_out, host.machine);
}
void setup_hostinfo(char *buf, int len)
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 12/13] um: nommu: add documentation of nommu UML
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
` (10 preceding siblings ...)
2025-09-18 7:39 ` [PATCH RESEND v11 11/13] um: change machine name for uname output Hajime Tazaki
@ 2025-09-18 7:39 ` Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 13/13] um: nommu: plug nommu code into build system Hajime Tazaki
2025-09-18 10:39 ` [PATCH RESEND v11 00/13] nommu UML Lorenzo Stoakes
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:39 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
This commit adds an initial documentation for !MMU mode of UML.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
---
Documentation/virt/uml/nommu-uml.rst | 180 +++++++++++++++++++++++++++
MAINTAINERS | 1 +
2 files changed, 181 insertions(+)
create mode 100644 Documentation/virt/uml/nommu-uml.rst
diff --git a/Documentation/virt/uml/nommu-uml.rst b/Documentation/virt/uml/nommu-uml.rst
new file mode 100644
index 000000000000..f049bbc697d1
--- /dev/null
+++ b/Documentation/virt/uml/nommu-uml.rst
@@ -0,0 +1,180 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+UML has been built with CONFIG_MMU since day 0. The patchset
+introduces the nommu mode on UML in a different angle from what Linux
+Kernel Library tried.
+
+.. contents:: :local:
+
+What is it for ?
+================
+
+- Alleviate syscall hook overhead implemented with ptrace(2)
+- To exercises nommu code over UML (and over KUnit)
+- Less dependency to host facilities
+
+
+How it works ?
+==============
+
+To illustrate how this feature works, the below shows how syscalls are
+called under nommu/UML environment.
+
+- boot kernel, install seccomp filter if ``syscall`` instructions are
+ called from userspace memory based on the address of instruction
+ pointer
+- (userspace starts)
+- calls ``vfork``/``execve`` syscalls
+- ``SIGSYS`` signal raised, handler calls syscall entry point ``__kernel_vsyscall``
+- call handler function in ``sys_call_table[]`` and follow how UML syscall
+ works.
+- return to userspace
+
+
+What are the differences from MMU-full UML ?
+============================================
+
+The current nommu implementation adds 3 different functions which
+MMU-full UML doesn't have:
+
+- kernel address space can directly be accessible from userspace
+ - so, ``uaccess()`` always returns 1
+ - generic implementation of memcpy/strcpy/futex is also used
+- alternate syscall entrypoint without ptrace
+- alternate syscall hook
+ - hook syscall by seccomp filter
+
+With those modifications, it allows us to use unmodified userspace
+binaries with nommu UML.
+
+
+History
+=======
+
+This feature was originally introduced by Ricardo Koller at Open
+Source Summit NA 2020, then integrated with the syscall translation
+functionality with the clean up to the original code.
+
+Building and run
+================
+
+::
+
+ make ARCH=um x86_64_nommu_defconfig
+ make ARCH=um
+
+will build UML with ``CONFIG_MMU=n`` applied.
+
+Kunit tests can run with the following command::
+
+ ./tools/testing/kunit/kunit.py run --kconfig_add CONFIG_MMU=n
+
+To run a typical Linux distribution, we need nommu-aware userspace.
+We can use a stock version of Alpine Linux with nommu-built version of
+busybox and musl-libc.
+
+
+Preparing root filesystem
+=========================
+
+nommu UML requires to use a specific standard library which is aware
+of nommu kernel. We have tested custom-build musl-libc and busybox,
+both of which have built-in support for nommu kernels.
+
+There are no available Linux distributions for nommu under x86_64
+architecture, so we need to prepare our own image for the root
+filesystem. We use Alpine Linux as a base distribution and replace
+busybox and musl-libc on top of that. The following are the step to
+prepare the filesystem for the quick start::
+
+ container_id=$(docker create ghcr.io/thehajime/alpine:3.20.3-um-nommu)
+ docker start $container_id
+ docker wait $container_id
+ docker export $container_id > alpine.tar
+ docker rm $container_id
+
+ mnt=$(mktemp -d)
+ dd if=/dev/zero of=alpine.ext4 bs=1 count=0 seek=1G
+ sudo chmod og+wr "alpine.ext4"
+ yes 2>/dev/null | mkfs.ext4 "alpine.ext4" || true
+ sudo mount "alpine.ext4" $mnt
+ sudo tar -xf alpine.tar -C $mnt
+ sudo umount $mnt
+
+This will create a file image, ``alpine.ext4``, which contains busybox
+and musl with nommu build on the Alpine Linux root filesystem. The
+file can be specified to the argument ``ubd0=`` to the UML command line::
+
+ ./vmlinux ubd0=./alpine.ext4 rw mem=1024m loglevel=8 init=/sbin/init
+
+We plan to upstream apk packages for busybox and musl so that we can
+follow the proper procedure to set up the root filesystem.
+
+
+Quick start with docker
+=======================
+
+There is a docker image that you can quickly start with a simple step::
+
+ docker run -it -v /dev/shm:/dev/shm --rm ghcr.io/thehajime/alpine:3.20.3-um-nommu
+
+This will launch a UML instance with an pre-configured root filesystem.
+
+Benchmark
+=========
+
+The below shows an example of performance measurement conducted with
+lmbench and (self-crafted) getpid benchmark (with v6.17-rc5 uml/next
+tree).
+
+.. csv-table:: lmbench (usec)
+ :header: ,native,um,um-mmu(s),um-nommu(s)
+
+ select-10 ,0.5319,36.1214,24.2795,2.9174
+ select-100 ,1.6019,34.6049,28.8865,3.8080
+ select-1000 ,12.2588,43.6838,48.7438,12.7872
+ syscall ,0.1644,35.0321,53.2119,2.5981
+ read ,0.3055,31.5509,45.8538,2.7068
+ write ,0.2512,31.3609,29.2636,2.6948
+ stat ,1.8894,43.8477,49.6121,3.1908
+ open/close ,3.2973,77.5123,68.9431,6.2575
+ fork+sh ,1110.3000,7359.5000,4618.6667,439.4615
+ fork+execve ,510.8182,2834.0000,2461.1667,139.7848
+
+.. csv-table:: do_getpid bench (nsec)
+ :header: ,native,um,um-mmu(s),um-nommu(s)
+
+ getpid , 161 , 34477 , 26242 , 2599
+
+(um-nommu(s) is with seccomp syscall hook, um-mmu(s) is SECCOMP mode,
+respectively)
+
+Limitations
+===========
+
+generic nommu limitations
+-------------------------
+Since this port is a kernel of nommu architecture so, the
+implementation inherits the characteristics of other nommu kernels
+(riscv, arm, etc), described below.
+
+- vfork(2) should be used instead of fork(2)
+- ELF loader only loads PIE (position independent executable) binaries
+- processes share the address space among others
+- mmap(2) offers a subset of functionalities (e.g., unsupported
+ MMAP_FIXED)
+
+Thus, we have limited options to userspace programs. We have tested
+Alpine Linux with musl-libc, which has a support nommu kernel.
+
+supported architecture
+----------------------
+The current implementation of nommu UML only works on x86_64 SUBARCH.
+We have not tested with 32-bit environment.
+
+
+Further readings about NOMMU UML
+================================
+
+- NOMMU UML (original code by Ricardo Koller)
+ - https://static.sched.com/hosted_files/ossna2020/ec/kollerr_linux_um_nommu.pdf
diff --git a/MAINTAINERS b/MAINTAINERS
index cd7ff55b5d32..2bc267220b07 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26300,6 +26300,7 @@ USER-MODE LINUX (UML)
M: Richard Weinberger <richard@nod.at>
M: Anton Ivanov <anton.ivanov@cambridgegreys.com>
M: Johannes Berg <johannes@sipsolutions.net>
+M: Hajime Tazaki <thehajime@gmail.com>
L: linux-um@lists.infradead.org
S: Maintained
W: http://user-mode-linux.sourceforge.net
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* [PATCH RESEND v11 13/13] um: nommu: plug nommu code into build system
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
` (11 preceding siblings ...)
2025-09-18 7:39 ` [PATCH RESEND v11 12/13] um: nommu: add documentation of nommu UML Hajime Tazaki
@ 2025-09-18 7:39 ` Hajime Tazaki
2025-09-18 10:39 ` [PATCH RESEND v11 00/13] nommu UML Lorenzo Stoakes
13 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-18 7:39 UTC (permalink / raw)
To: linux-um; +Cc: thehajime, ricarkol, Liam.Howlett, linux-kernel
Add nommu kernel for um build. defconfig is also provided.
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
---
arch/um/Kconfig | 14 ++++++-
arch/um/configs/x86_64_nommu_defconfig | 54 ++++++++++++++++++++++++++
2 files changed, 66 insertions(+), 2 deletions(-)
create mode 100644 arch/um/configs/x86_64_nommu_defconfig
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 8161cc5ae6f7..b3d2716836ac 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -32,16 +32,19 @@ config UML
select ARCH_SUPPORTS_LTO_CLANG_THIN
select TRACE_IRQFLAGS_SUPPORT
select TTY # Needed for line.c
- select HAVE_ARCH_VMAP_STACK
+ select HAVE_ARCH_VMAP_STACK if MMU
select HAVE_RUST
select ARCH_HAS_UBSAN
select HAVE_ARCH_TRACEHOOK
select HAVE_SYSCALL_TRACEPOINTS
select THREAD_INFO_IN_TASK
select SPARSE_IRQ
+ select UACCESS_MEMCPY if !MMU
+ select GENERIC_STRNLEN_USER if !MMU
+ select GENERIC_STRNCPY_FROM_USER if !MMU
config MMU
- bool
+ bool "MMU-based Paged Memory Management Support" if 64BIT
default y
config UML_DMA_EMULATION
@@ -185,8 +188,15 @@ config MAGIC_SYSRQ
The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
unless you really know what this hack does.
+config ARCH_FORCE_MAX_ORDER
+ int "Order of maximal physically contiguous allocations" if EXPERT
+ default "10" if MMU
+ default "16" if !MMU
+
config KERNEL_STACK_ORDER
int "Kernel stack size order"
+ default 3 if !MMU
+ range 3 10 if !MMU
default 2 if 64BIT
range 2 10 if 64BIT
default 1 if !64BIT
diff --git a/arch/um/configs/x86_64_nommu_defconfig b/arch/um/configs/x86_64_nommu_defconfig
new file mode 100644
index 000000000000..02cb87091c9f
--- /dev/null
+++ b/arch/um/configs/x86_64_nommu_defconfig
@@ -0,0 +1,54 @@
+CONFIG_SYSVIPC=y
+CONFIG_POSIX_MQUEUE=y
+CONFIG_NO_HZ=y
+CONFIG_HIGH_RES_TIMERS=y
+CONFIG_BSD_PROCESS_ACCT=y
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_LOG_BUF_SHIFT=14
+CONFIG_CGROUPS=y
+CONFIG_BLK_CGROUP=y
+CONFIG_CGROUP_SCHED=y
+CONFIG_CGROUP_DEVICE=y
+CONFIG_CGROUP_CPUACCT=y
+# CONFIG_PID_NS is not set
+CONFIG_CC_OPTIMIZE_FOR_SIZE=y
+# CONFIG_MMU is not set
+CONFIG_HOSTFS=y
+CONFIG_MAGIC_SYSRQ=y
+CONFIG_SSL=y
+CONFIG_NULL_CHAN=y
+CONFIG_PORT_CHAN=y
+CONFIG_PTY_CHAN=y
+CONFIG_TTY_CHAN=y
+CONFIG_CON_CHAN="pts"
+CONFIG_SSL_CHAN="pts"
+CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
+CONFIG_IOSCHED_BFQ=m
+CONFIG_BINFMT_MISC=m
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_INET=y
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+CONFIG_BLK_DEV_UBD=y
+CONFIG_BLK_DEV_LOOP=m
+CONFIG_BLK_DEV_NBD=m
+CONFIG_DUMMY=m
+CONFIG_TUN=m
+CONFIG_PPP=m
+CONFIG_SLIP=m
+CONFIG_LEGACY_PTY_COUNT=32
+CONFIG_UML_RANDOM=y
+CONFIG_EXT4_FS=y
+CONFIG_QUOTA=y
+CONFIG_AUTOFS_FS=m
+CONFIG_ISO9660_FS=m
+CONFIG_JOLIET=y
+CONFIG_NLS=y
+CONFIG_DEBUG_KERNEL=y
+CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
+CONFIG_FRAME_WARN=1024
+CONFIG_IPV6=y
--
2.43.0
^ permalink raw reply related [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-18 7:39 ` [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver Hajime Tazaki
@ 2025-09-18 8:30 ` Johannes Berg
2025-09-19 0:03 ` Hajime Tazaki
0 siblings, 1 reply; 31+ messages in thread
From: Johannes Berg @ 2025-09-18 8:30 UTC (permalink / raw)
To: Hajime Tazaki, linux-um; +Cc: ricarkol, Liam.Howlett, linux-kernel
On Thu, 2025-09-18 at 16:39 +0900, Hajime Tazaki wrote:
> The commit 8fe743b5eba0 ("PCI: Add CONFIG_MMU dependency") restricts the
> PCI base driver to depend on MMU. While nommu UML _can_ implement PCI
> drivers over PCI devices (e.g., virtio-pci), the current nommu UML
> doesn't implement it.
>
> But without PCI drivers kunit complains as config for kunit
> (arch_uml.config) defines the dependency to PCI drivers.
>
> This commit fixes the issue of this compile failures when building PCI
> drivers with nommu UML. In particular, the fix is to undefine the
> constant PCI_IOBASE to be able to bypass pci_unmap_iospace() call.
This doesn't make a lot of sense to me. Why would we even want to build
PCI on NOMMU-UML if PCI in general is dependent on MMU now?
It's not like ARCH=um with PCI and NOMMU has any value even for testing
if such a configuration cannot exist in reality?
johannes
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 00/13] nommu UML
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
` (12 preceding siblings ...)
2025-09-18 7:39 ` [PATCH RESEND v11 13/13] um: nommu: plug nommu code into build system Hajime Tazaki
@ 2025-09-18 10:39 ` Lorenzo Stoakes
13 siblings, 0 replies; 31+ messages in thread
From: Lorenzo Stoakes @ 2025-09-18 10:39 UTC (permalink / raw)
To: Hajime Tazaki; +Cc: linux-um, ricarkol, Liam.Howlett, linux-kernel
On Thu, Sep 18, 2025 at 04:38:55PM +0900, Hajime Tazaki wrote:
> This patchset is another spin of nommu mode addition to UML. It would
> be nice to hear about your opinions on that.
>
> There are still several limitations/issues which we already found;
> here is the list of those issues.
>
> - memory mapped by loadable modules are not distinguished from
> userspace memory.
>
> -- Hajime
I think this will need attention of um people etc. but THANK YOU for sending
this :)
If we can get this in that'd be _very useful_ for nommu testing for us in mm
especially :)
Cheers, Lorenzo
>
> v11:
> - clean up userspace return routine and integrate to userspace() ([04/13])
> - fix direction flag issue on using nolibc memcpy ([04/13])
> - fix a crash issue when using usermode helper ([06/13])
> - test with out-of-tree kunit-uapi patches (which uses umh)
> - https://lore.kernel.org/all/20250626-kunit-kselftests-v4-0-48760534fef5@linutronix.de/
> - https://lore.kernel.org/all/20250626195714.2123694-3-benjamin@sipsolutions.net/
>
> v10:
> - fix wrong comment on gs register handling ([09/13])
> - remove unnecessary code of early syscall implementation ([04/13])
> - https://lore.kernel.org/all/cover.1750594487.git.thehajime@gmail.com/
>
> v9:
> - rebase with the latest uml/next branch
> - add performance numbers of new SECCOMP mode, and update results ([12/13])
> - add a workaround for upstream change on MMU depedency to PCI drivers ([10/13])
> - https://lore.kernel.org/all/cover.1750294482.git.thehajime@gmail.com/
>
> v8:
> - rebase with the latest uml/next branch
> - clean up segv_handler to align with the latest uml ([9/12])
> - https://lore.kernel.org/all/cover.1745980082.git.thehajime@gmail.com/
>
> v7:
> - properly handle FP register upon signal delivery [10/13]
> - update benchmark result with new FP register handling [12/13]
> - fix arch_has_single_step() for !MMU case [07/13]
> - revert stack alignment as it is in uml/fixes tree [10/13]
> - https://lore.kernel.org/all/cover.1737348399.git.thehajime@gmail.com/
>
> v6:
> - rebase to the latest uml/next tree
> - more clean up on mmu/nommu for signal handling [10/13]
> - rename functions of mcontext routines [06,10/13]
> - added Acked-by tag for binfmt_elf_fdpic [02/13]
> - https://lore.kernel.org/linux-um/cover.1736853925.git.thehajime@gmail.com/
>
> v5:
> - clean up stack manipulation code [05,06,07,10/13]
> - https://lore.kernel.org/linux-um/cover.1733998168.git.thehajime@gmail.com/
>
> v4:
> - add arch/um/nommu, arch/x86/um/nommu to contain !MMU specific codes
> - remove zpoline patch
> - drop binfmt_elf_fdpic patch
> - reduce ifndef CONFIG_MMU if possible
> - split to elf header cleanup patch [01/13]
> - fix kernel test robot warnings [06/13]
> - fix coding styles [07/13]
> - move task_top_of_stack definition [05/13]
> - https://lore.kernel.org/linux-um/cover.1733652929.git.thehajime@gmail.com/
>
> v3:
> - https://lore.kernel.org/linux-um/cover.1733199769.git.thehajime@gmail.com/
> - add seccomp-based syscall hook in addition to zpoline [06/13]
> - remove RFC, add a line to MAINTAINERS file
> - fix kernel test robot warnings [02/13,08/13,10/13]
> - add base-commit tag to cover letter
> - pull the latest uml/next
> - clean up SIGSEGV handling [10/13]
> - detect fsgsbase availability with elf aux vector [08/13]
> - simplify vdso code with macros [09/13]
>
> RFC v2:
> - https://lore.kernel.org/linux-um/cover.1731290567.git.thehajime@gmail.com/
> - base branch is now uml/linux.git instead of torvalds/linux.git.
> - reorganize the patch series to clean up
> - fixed various coding styles issues
> - clean up exec code path [07/13]
> - fixed the crash/SIGSEGV case on userspace programs [10/13]
> - add seccomp filter to limit syscall caller address [06/13]
> - detect fsgsbase availability with sigsetjmp/siglongjmp [08/13]
> - removes unrelated changes
> - removes unneeded ifndef CONFIG_MMU
> - convert UML_CONFIG_MMU to CONFIG_MMU as using uml/linux.git
> - proposed a patch of maple-tree issue (resolving a limitation in RFC v1)
> https://lore.kernel.org/linux-mm/20241108222834.3625217-1-thehajime@gmail.com/
>
> RFC:
> - https://lore.kernel.org/linux-um/cover.1729770373.git.thehajime@gmail.com/
>
> Hajime Tazaki (13):
> x86/um: nommu: elf loader for fdpic
> um: decouple MMU specific code from the common part
> um: nommu: memory handling
> x86/um: nommu: syscall handling
> um: nommu: seccomp syscalls hook
> x86/um: nommu: process/thread handling
> um: nommu: configure fs register on host syscall invocation
> x86/um/vdso: nommu: vdso memory update
> x86/um: nommu: signal handling
> um: nommu: a work around for MMU dependency to PCI driver
> um: change machine name for uname output
> um: nommu: add documentation of nommu UML
> um: nommu: plug nommu code into build system
>
> Documentation/virt/uml/nommu-uml.rst | 180 ++++++++++++++++++++++
> MAINTAINERS | 1 +
> arch/um/Kconfig | 14 +-
> arch/um/Makefile | 10 ++
> arch/um/configs/x86_64_nommu_defconfig | 54 +++++++
> arch/um/include/asm/dma.h | 13 ++
> arch/um/include/asm/futex.h | 4 +
> arch/um/include/asm/mmu.h | 8 +
> arch/um/include/asm/mmu_context.h | 2 +
> arch/um/include/asm/ptrace-generic.h | 8 +-
> arch/um/include/asm/uaccess.h | 7 +-
> arch/um/include/shared/kern_util.h | 6 +
> arch/um/include/shared/os.h | 16 ++
> arch/um/kernel/Makefile | 5 +-
> arch/um/kernel/mem-pgtable.c | 55 +++++++
> arch/um/kernel/mem.c | 38 +----
> arch/um/kernel/process.c | 25 +++
> arch/um/kernel/skas/process.c | 25 ---
> arch/um/kernel/um_arch.c | 3 +
> arch/um/nommu/Makefile | 3 +
> arch/um/nommu/os-Linux/Makefile | 7 +
> arch/um/nommu/os-Linux/seccomp.c | 87 +++++++++++
> arch/um/nommu/os-Linux/signal.c | 24 +++
> arch/um/nommu/trap.c | 201 +++++++++++++++++++++++++
> arch/um/os-Linux/Makefile | 3 +-
> arch/um/os-Linux/mem.c | 4 +
> arch/um/os-Linux/process.c | 138 ++++++++++++++++-
> arch/um/os-Linux/signal.c | 11 +-
> arch/um/os-Linux/skas/process.c | 126 ----------------
> arch/um/os-Linux/start_up.c | 25 ++-
> arch/um/os-Linux/util.c | 3 +-
> arch/x86/um/Makefile | 7 +-
> arch/x86/um/asm/elf.h | 8 +-
> arch/x86/um/asm/syscall.h | 6 +
> arch/x86/um/nommu/Makefile | 8 +
> arch/x86/um/nommu/do_syscall_64.c | 75 +++++++++
> arch/x86/um/nommu/entry_64.S | 114 ++++++++++++++
> arch/x86/um/nommu/os-Linux/Makefile | 6 +
> arch/x86/um/nommu/os-Linux/mcontext.c | 26 ++++
> arch/x86/um/nommu/syscalls.h | 18 +++
> arch/x86/um/nommu/syscalls_64.c | 121 +++++++++++++++
> arch/x86/um/shared/sysdep/mcontext.h | 5 +
> arch/x86/um/shared/sysdep/ptrace.h | 2 +-
> arch/x86/um/vdso/vma.c | 17 ++-
> fs/Kconfig.binfmt | 2 +-
> 45 files changed, 1312 insertions(+), 209 deletions(-)
> create mode 100644 Documentation/virt/uml/nommu-uml.rst
> create mode 100644 arch/um/configs/x86_64_nommu_defconfig
> create mode 100644 arch/um/kernel/mem-pgtable.c
> create mode 100644 arch/um/nommu/Makefile
> create mode 100644 arch/um/nommu/os-Linux/Makefile
> create mode 100644 arch/um/nommu/os-Linux/seccomp.c
> create mode 100644 arch/um/nommu/os-Linux/signal.c
> create mode 100644 arch/um/nommu/trap.c
> create mode 100644 arch/x86/um/nommu/Makefile
> create mode 100644 arch/x86/um/nommu/do_syscall_64.c
> create mode 100644 arch/x86/um/nommu/entry_64.S
> create mode 100644 arch/x86/um/nommu/os-Linux/Makefile
> create mode 100644 arch/x86/um/nommu/os-Linux/mcontext.c
> create mode 100644 arch/x86/um/nommu/syscalls.h
> create mode 100644 arch/x86/um/nommu/syscalls_64.c
>
>
> base-commit: e66ae377fe219c98d3d5b8a0d35da4413a5390ca
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-18 8:30 ` Johannes Berg
@ 2025-09-19 0:03 ` Hajime Tazaki
2025-09-19 7:24 ` Johannes Berg
0 siblings, 1 reply; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-19 0:03 UTC (permalink / raw)
To: johannes; +Cc: linux-um, ricarkol, Liam.Howlett, linux-kernel
On Thu, 18 Sep 2025 17:30:22 +0900,
Johannes Berg wrote:
>
> On Thu, 2025-09-18 at 16:39 +0900, Hajime Tazaki wrote:
> > The commit 8fe743b5eba0 ("PCI: Add CONFIG_MMU dependency") restricts the
> > PCI base driver to depend on MMU. While nommu UML _can_ implement PCI
> > drivers over PCI devices (e.g., virtio-pci), the current nommu UML
> > doesn't implement it.
> >
> > But without PCI drivers kunit complains as config for kunit
> > (arch_uml.config) defines the dependency to PCI drivers.
> >
> > This commit fixes the issue of this compile failures when building PCI
> > drivers with nommu UML. In particular, the fix is to undefine the
> > constant PCI_IOBASE to be able to bypass pci_unmap_iospace() call.
>
> This doesn't make a lot of sense to me. Why would we even want to build
> PCI on NOMMU-UML if PCI in general is dependent on MMU now?
>
> It's not like ARCH=um with PCI and NOMMU has any value even for testing
> if such a configuration cannot exist in reality?
totally understand your point.
now I see that we don't have to have this work around by using
--kconfig_add option to kunit.py.
# like --kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n (in addition to
--kconfig_add CONFIG_MMU=n).
so I'll drop this patch in the next version.
thanks,
-- Hajime
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-19 0:03 ` Hajime Tazaki
@ 2025-09-19 7:24 ` Johannes Berg
2025-09-19 9:32 ` Hajime Tazaki
0 siblings, 1 reply; 31+ messages in thread
From: Johannes Berg @ 2025-09-19 7:24 UTC (permalink / raw)
To: Hajime Tazaki; +Cc: linux-um, ricarkol, Liam.Howlett, linux-kernel
On Fri, 2025-09-19 at 09:03 +0900, Hajime Tazaki wrote:
> > This doesn't make a lot of sense to me. Why would we even want to build
> > PCI on NOMMU-UML if PCI in general is dependent on MMU now?
> >
> > It's not like ARCH=um with PCI and NOMMU has any value even for testing
> > if such a configuration cannot exist in reality?
>
> totally understand your point.
>
> now I see that we don't have to have this work around by using
> --kconfig_add option to kunit.py.
>
> # like --kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n (in addition to
> --kconfig_add CONFIG_MMU=n).
That's not what I mean. I think it should be made impossible to build
the broken code.
The problem is probably UML_PCI_OVER_VIRTIO selecting UML_PCI selecting
various PCI code, but nothing depends on PCI in the first place. Which
it should, then?
johannes
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-19 7:24 ` Johannes Berg
@ 2025-09-19 9:32 ` Hajime Tazaki
2025-09-19 9:38 ` Johannes Berg
2025-09-23 15:42 ` Geert Uytterhoeven
0 siblings, 2 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-19 9:32 UTC (permalink / raw)
To: johannes; +Cc: linux-um, ricarkol, Liam.Howlett, linux-kernel
On Fri, 19 Sep 2025 16:24:07 +0900,
Johannes Berg wrote:
>
> On Fri, 2025-09-19 at 09:03 +0900, Hajime Tazaki wrote:
> > > This doesn't make a lot of sense to me. Why would we even want to build
> > > PCI on NOMMU-UML if PCI in general is dependent on MMU now?
> > >
> > > It's not like ARCH=um with PCI and NOMMU has any value even for testing
> > > if such a configuration cannot exist in reality?
> >
> > totally understand your point.
> >
> > now I see that we don't have to have this work around by using
> > --kconfig_add option to kunit.py.
> >
> > # like --kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n (in addition to
> > --kconfig_add CONFIG_MMU=n).
>
> That's not what I mean. I think it should be made impossible to build
> the broken code.
okay.
# I think now I lost the point...
currently, drivers/pci/Kconfig (CONFIG_PCI) marks as depends on MMU,
so we cannot select it when CONFIG_MMU=n.
but it's different with kunit when using them via kunit.py config,
it first adds
CONFIG_VIRTIO_UML=y
CONFIG_UML_PCI_OVER_VIRTIO=y
via tools/testing/kunit/configs/arch_uml.config, and then add
CONIFG_MMU=n
via --kconfig_add CONFIG_MMU=n.
and then execute make ARCH=um olddefconfig, which in turn enables
CONFIG_UML_PCI_OVER_VIRTIO.
if we append "--kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n" to kunit.py,
it will overwrite the arch_uml.config.
# I don't know how kunit handles those appended CONFIG entries, though..
my goal is simple; to test !MMU code via kunit.
my original patch or the additional kconfig argument (--kconfig_add)
satisfies this goal.
> The problem is probably UML_PCI_OVER_VIRTIO selecting UML_PCI selecting
> various PCI code, but nothing depends on PCI in the first place. Which
> it should, then?
I don't understand the 'nothing depends on PCI...' part. care to
elaborate ?
thanks,
-- Hajime
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-19 9:32 ` Hajime Tazaki
@ 2025-09-19 9:38 ` Johannes Berg
2025-09-19 9:38 ` Johannes Berg
` (2 more replies)
2025-09-23 15:42 ` Geert Uytterhoeven
1 sibling, 3 replies; 31+ messages in thread
From: Johannes Berg @ 2025-09-19 9:38 UTC (permalink / raw)
To: Hajime Tazaki; +Cc: linux-um, ricarkol, Liam.Howlett, linux-kernel
On Fri, 2025-09-19 at 18:32 +0900, Hajime Tazaki wrote:
> currently, drivers/pci/Kconfig (CONFIG_PCI) marks as depends on MMU,
Right.
> so we cannot select it when CONFIG_MMU=n.
Actually, I believe that's not true, I think it *can* select something
even if you override the 'depends on' it has, it just causes a warning
in Kconfig.
But I don't think PCI is even selected, UML_PCI is selected, and then
that selects PCI_MSI which should really only be reachable when PCI is
enabled, so this perhaps does nothing? Not sure ...
> but it's different with kunit when using them via kunit.py config,
It really isn't, you just don't see everything because kunit.py hides
the build from you.
> it first adds
>
> CONFIG_VIRTIO_UML=y
> CONFIG_UML_PCI_OVER_VIRTIO=y
>
> via tools/testing/kunit/configs/arch_uml.config, and then add
>
> CONIFG_MMU=n
>
> via --kconfig_add CONFIG_MMU=n.
Sure. But that should disable CONFIG_UML_PCI_OVER_VIRTIO, and it doesn't
now.
> and then execute make ARCH=um olddefconfig, which in turn enables
> CONFIG_UML_PCI_OVER_VIRTIO.
Keeps it, let's say.
> if we append "--kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n" to kunit.py,
> it will overwrite the arch_uml.config.
Yeah but that being required doesn't make sense - the Kconfig should
express the correct dependencies.
> # I don't know how kunit handles those appended CONFIG entries, though..
It just puts them into the file and runs oldconfig, I guess?
> my goal is simple; to test !MMU code via kunit.
Sure.
> my original patch or the additional kconfig argument (--kconfig_add)
> satisfies this goal.
Sure. But both are the wrong solution, as I said, the Kconfig should
express the correct dependencies.
> > The problem is probably UML_PCI_OVER_VIRTIO selecting UML_PCI selecting
> > various PCI code, but nothing depends on PCI in the first place. Which
> > it should, then?
>
> I don't understand the 'nothing depends on PCI...' part. care to
> elaborate ?
See above, I think?
My gut feeling is that UML_PCI_OVER_VIRTIO should depend on PCI but I
don't know if that then doesn't end up in some kind of circular
dependency.
johannes
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-19 9:38 ` Johannes Berg
@ 2025-09-19 9:38 ` Johannes Berg
2025-09-19 9:43 ` Johannes Berg
2025-09-19 23:46 ` Hajime Tazaki
2 siblings, 0 replies; 31+ messages in thread
From: Johannes Berg @ 2025-09-19 9:38 UTC (permalink / raw)
To: Hajime Tazaki; +Cc: linux-um, ricarkol, Liam.Howlett, linux-kernel
On Fri, 2025-09-19 at 11:38 +0200, Johannes Berg wrote:
> My gut feeling is that UML_PCI_OVER_VIRTIO should depend on PCI but I
> don't know if that then doesn't end up in some kind of circular
> dependency.
And all the discussion is also true for UML_PCI_OVER_VFIO which also
selects UML_PCI.
johannes
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-19 9:38 ` Johannes Berg
2025-09-19 9:38 ` Johannes Berg
@ 2025-09-19 9:43 ` Johannes Berg
2025-09-19 23:46 ` Hajime Tazaki
2 siblings, 0 replies; 31+ messages in thread
From: Johannes Berg @ 2025-09-19 9:43 UTC (permalink / raw)
To: Hajime Tazaki; +Cc: linux-um, ricarkol, Liam.Howlett, linux-kernel
On Fri, 2025-09-19 at 11:38 +0200, Johannes Berg wrote:
>
> My gut feeling is that UML_PCI_OVER_VIRTIO should depend on PCI but I
> don't know if that then doesn't end up in some kind of circular
> dependency.
No, that _is_ wrong, and it will end up in a circular dependency,
because for UML_PCI we currently do FORCE_PCI and then we have PCI and
HAVE_PCI and it all messes up ... Which is all correct right now.
That still seems reasonable (why give the choice of selecting PCI after
having selected VFIO/virtio PCI), but then with !MMU it can't work, so
the pieces there just need to depend on MMU.
johannes
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-19 9:38 ` Johannes Berg
2025-09-19 9:38 ` Johannes Berg
2025-09-19 9:43 ` Johannes Berg
@ 2025-09-19 23:46 ` Hajime Tazaki
2025-09-22 6:32 ` Johannes Berg
2 siblings, 1 reply; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-19 23:46 UTC (permalink / raw)
To: johannes; +Cc: linux-um, ricarkol, Liam.Howlett, linux-kernel
thanks Johannes, I think I got a clearer view than before.
I guess Kconfig does the right thing.
And Kunit does the right too but an additional job which Kunit does
prevents run tests w/ !MMU.
> > CONIFG_MMU=n
> >
> > via --kconfig_add CONFIG_MMU=n.
>
> Sure. But that should disable CONFIG_UML_PCI_OVER_VIRTIO, and it doesn't
> now.
Kconfig (via kunit.py config) disables CONFIG_UML_PCI_OVER_VIRTIO
correctly.
But after that, Kunit does the additional job, validate_config() (in
kunit_kernel.py), which checks the configs (arch_uml.config +
--kconfig_add) is a subset of the final result of .config.
When I applied a patch below:
diff --git a/arch/um/drivers/Kconfig b/arch/um/drivers/Kconfig
index 6a0354ca032f..04025207a077 100644
--- a/arch/um/drivers/Kconfig
+++ b/arch/um/drivers/Kconfig
@@ -159,6 +159,7 @@ config UML_RTC
config UML_PCI
bool
+ depends on MMU
select FORCE_PCI
select IRQ_MSI_LIB
select UML_IOMEM_EMULATION
@@ -170,6 +171,7 @@ config UML_PCI_OVER_VIRTIO
bool "Enable PCI over VIRTIO device simulation"
# in theory, just VIRTIO is enough, but that causes recursion
depends on VIRTIO_UML
+ depends on MMU
select UML_PCI
and do
./tools/testing/kunit/kunit.py config --kconfig_add CONFIG_MMU=n
the validation currently gives the following error:
ERROR:root:Not all Kconfig options selected in kunitconfig were in the generated .config.
This is probably due to unsatisfied dependencies.
Missing: CONFIG_UML_PCI_OVER_VIRTIO=y
Note: many Kconfig options aren't available on UML. You can try
running on a different architecture with something like
"--arch=x86_64".
so, if I give an additional --kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n
to the command line, the validation passes, because the configs
(arch_uml.config + --kconfig_add) becomes the subset of the final
result.
what I can handle this would be either of them:
1) use --kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n when using kunit w/
!MMU, and drop this patch from the series (no modification to the tree)
2) prepare a different file for !MMU & ARCH=um testing (e.g.,
arch_uml_nommu.config), and add an option to kunit.py to switch MMU
or !MMU
3) implement virtio-pci for !MMU and propose to remove the restriction
of CONFIG_PCI depends on CONFIG_MMU.
2) will be removed when 3) is done so, I'm hesitating to propose a
patch used by whole tree.
so, I think 1) is (not the best but) a reasonable solution, with a
note in nommu-uml specific document (i.e., [PATCH 12/13]).
Let me know what you think.
-- Hajime
On Fri, 19 Sep 2025 18:38:03 +0900,
Johannes Berg wrote:
>
> On Fri, 2025-09-19 at 18:32 +0900, Hajime Tazaki wrote:
> > currently, drivers/pci/Kconfig (CONFIG_PCI) marks as depends on MMU,
>
> Right.
>
> > so we cannot select it when CONFIG_MMU=n.
>
> Actually, I believe that's not true, I think it *can* select something
> even if you override the 'depends on' it has, it just causes a warning
> in Kconfig.
>
> But I don't think PCI is even selected, UML_PCI is selected, and then
> that selects PCI_MSI which should really only be reachable when PCI is
> enabled, so this perhaps does nothing? Not sure ...
>
> > but it's different with kunit when using them via kunit.py config,
>
> It really isn't, you just don't see everything because kunit.py hides
> the build from you.
>
> > it first adds
> >
> > CONFIG_VIRTIO_UML=y
> > CONFIG_UML_PCI_OVER_VIRTIO=y
> >
> > via tools/testing/kunit/configs/arch_uml.config, and then add
> >
> > CONIFG_MMU=n
> >
> > via --kconfig_add CONFIG_MMU=n.
>
> Sure. But that should disable CONFIG_UML_PCI_OVER_VIRTIO, and it doesn't
> now.
>
> > and then execute make ARCH=um olddefconfig, which in turn enables
> > CONFIG_UML_PCI_OVER_VIRTIO.
>
> Keeps it, let's say.
>
> > if we append "--kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n" to kunit.py,
> > it will overwrite the arch_uml.config.
>
> Yeah but that being required doesn't make sense - the Kconfig should
> express the correct dependencies.
>
> > # I don't know how kunit handles those appended CONFIG entries, though..
>
> It just puts them into the file and runs oldconfig, I guess?
>
> > my goal is simple; to test !MMU code via kunit.
>
> Sure.
>
> > my original patch or the additional kconfig argument (--kconfig_add)
> > satisfies this goal.
>
> Sure. But both are the wrong solution, as I said, the Kconfig should
> express the correct dependencies.
>
> > > The problem is probably UML_PCI_OVER_VIRTIO selecting UML_PCI selecting
> > > various PCI code, but nothing depends on PCI in the first place. Which
> > > it should, then?
> >
> > I don't understand the 'nothing depends on PCI...' part. care to
> > elaborate ?
>
> See above, I think?
>
> My gut feeling is that UML_PCI_OVER_VIRTIO should depend on PCI but I
> don't know if that then doesn't end up in some kind of circular
> dependency.
>
> johannes
^ permalink raw reply related [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-19 23:46 ` Hajime Tazaki
@ 2025-09-22 6:32 ` Johannes Berg
2025-09-23 23:44 ` Hajime Tazaki
0 siblings, 1 reply; 31+ messages in thread
From: Johannes Berg @ 2025-09-22 6:32 UTC (permalink / raw)
To: Hajime Tazaki; +Cc: linux-um, ricarkol, Liam.Howlett, linux-kernel
On Sat, 2025-09-20 at 08:46 +0900, Hajime Tazaki wrote:
> diff --git a/arch/um/drivers/Kconfig b/arch/um/drivers/Kconfig
> index 6a0354ca032f..04025207a077 100644
> --- a/arch/um/drivers/Kconfig
> +++ b/arch/um/drivers/Kconfig
> @@ -159,6 +159,7 @@ config UML_RTC
>
> config UML_PCI
> bool
> + depends on MMU
That won't do anything since you elsewhere have "select UML_PCI"
independent of MMU.
> @@ -170,6 +171,7 @@ config UML_PCI_OVER_VIRTIO
> bool "Enable PCI over VIRTIO device simulation"
> # in theory, just VIRTIO is enough, but that causes recursion
> depends on VIRTIO_UML
> + depends on MMU
> select UML_PCI
Right, but you also need that for UML_PCI_OVER_VFIO.
> and do
> ./tools/testing/kunit/kunit.py config --kconfig_add CONFIG_MMU=n
>
> the validation currently gives the following error:
>
> ERROR:root:Not all Kconfig options selected in kunitconfig were in the generated .config.
> This is probably due to unsatisfied dependencies.
> Missing: CONFIG_UML_PCI_OVER_VIRTIO=y
Well, OK, but that's fair - you did specifically override MMU=n, and
virtio-over-pci needs it.
> 1) use --kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n when using kunit w/
> !MMU, and drop this patch from the series (no modification to the tree)
> 2) prepare a different file for !MMU & ARCH=um testing (e.g.,
> arch_uml_nommu.config), and add an option to kunit.py to switch MMU
> or !MMU
> 3) implement virtio-pci for !MMU and propose to remove the restriction
> of CONFIG_PCI depends on CONFIG_MMU.
>
> 2) will be removed when 3) is done so, I'm hesitating to propose a
> patch used by whole tree.
>
> so, I think 1) is (not the best but) a reasonable solution, with a
> note in nommu-uml specific document (i.e., [PATCH 12/13]).
I don't think (3) makes any sense at all, we should just _never_ do
that. !MMU is really here in UML for testing to support other
architectures that are !MMU, and since by today's definitions no other
architecture can have PCI without MMU, it makes no sense for UML to have
that (and complicate the PCI code unnecessarily, etc.)
I think it's entirely reasonable to have overriding CONFIG_MMU=n to also
necessitate overriding CONFIG_UML_PCI_OVER_VIRTIO, i.e. (1).
As to whether or not to add a specific config file, honestly I don't
really know or even care - you'd have to ask the people who actually
want to test !MMU.
johannes
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-19 9:32 ` Hajime Tazaki
2025-09-19 9:38 ` Johannes Berg
@ 2025-09-23 15:42 ` Geert Uytterhoeven
2025-09-23 17:13 ` Johannes Berg
1 sibling, 1 reply; 31+ messages in thread
From: Geert Uytterhoeven @ 2025-09-23 15:42 UTC (permalink / raw)
To: Hajime Tazaki
Cc: johannes, linux-um, ricarkol, Liam.Howlett, linux-kernel,
Arnd Bergmann
Hi Tazaki-san,
CC arnd
On Fri, 19 Sept 2025 at 11:32, Hajime Tazaki <thehajime@gmail.com> wrote:
> On Fri, 19 Sep 2025 16:24:07 +0900,
> Johannes Berg wrote:
> > On Fri, 2025-09-19 at 09:03 +0900, Hajime Tazaki wrote:
> > > > This doesn't make a lot of sense to me. Why would we even want to build
> > > > PCI on NOMMU-UML if PCI in general is dependent on MMU now?
> > > >
> > > > It's not like ARCH=um with PCI and NOMMU has any value even for testing
> > > > if such a configuration cannot exist in reality?
> > >
> > > totally understand your point.
> > >
> > > now I see that we don't have to have this work around by using
> > > --kconfig_add option to kunit.py.
> > >
> > > # like --kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n (in addition to
> > > --kconfig_add CONFIG_MMU=n).
> >
> > That's not what I mean. I think it should be made impossible to build
> > the broken code.
>
> okay.
> # I think now I lost the point...
>
> currently, drivers/pci/Kconfig (CONFIG_PCI) marks as depends on MMU,
> so we cannot select it when CONFIG_MMU=n.
That is a fairly recent change, see commit 8fe743b5eba0abfb ("PCI:
Add CONFIG_MMU dependency") in v6.16-rc1. As this is not a "hard"
dependency, perhaps it should be reverted, iff you are willing to take
care of the casual breakage?
>
> but it's different with kunit when using them via kunit.py config,
>
> it first adds
>
> CONFIG_VIRTIO_UML=y
> CONFIG_UML_PCI_OVER_VIRTIO=y
>
> via tools/testing/kunit/configs/arch_uml.config, and then add
>
> CONIFG_MMU=n
>
> via --kconfig_add CONFIG_MMU=n.
>
> and then execute make ARCH=um olddefconfig, which in turn enables
> CONFIG_UML_PCI_OVER_VIRTIO.
>
> if we append "--kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n" to kunit.py,
> it will overwrite the arch_uml.config.
>
> # I don't know how kunit handles those appended CONFIG entries, though..
>
> my goal is simple; to test !MMU code via kunit.
> my original patch or the additional kconfig argument (--kconfig_add)
> satisfies this goal.
>
> > The problem is probably UML_PCI_OVER_VIRTIO selecting UML_PCI selecting
> > various PCI code, but nothing depends on PCI in the first place. Which
> > it should, then?
>
> I don't understand the 'nothing depends on PCI...' part. care to
> elaborate ?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-23 15:42 ` Geert Uytterhoeven
@ 2025-09-23 17:13 ` Johannes Berg
2025-09-23 23:51 ` Hajime Tazaki
0 siblings, 1 reply; 31+ messages in thread
From: Johannes Berg @ 2025-09-23 17:13 UTC (permalink / raw)
To: Geert Uytterhoeven, Hajime Tazaki
Cc: linux-um, ricarkol, Liam.Howlett, linux-kernel, Arnd Bergmann
On Tue, 2025-09-23 at 17:42 +0200, Geert Uytterhoeven wrote:
> >
> > currently, drivers/pci/Kconfig (CONFIG_PCI) marks as depends on MMU,
> > so we cannot select it when CONFIG_MMU=n.
>
> That is a fairly recent change, see commit 8fe743b5eba0abfb ("PCI:
> Add CONFIG_MMU dependency") in v6.16-rc1. As this is not a "hard"
> dependency, perhaps it should be reverted, iff you are willing to take
> care of the casual breakage?
Why though? UML with PCI can't really be a functional thing, only a
testing thing, and testing PCI on !MMU when that is actually impossible
in non-simulation is pointless?
johannes
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-22 6:32 ` Johannes Berg
@ 2025-09-23 23:44 ` Hajime Tazaki
0 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-23 23:44 UTC (permalink / raw)
To: johannes; +Cc: linux-um, ricarkol, Liam.Howlett, linux-kernel
On Mon, 22 Sep 2025 15:32:22 +0900,
Johannes Berg wrote:
>
> On Sat, 2025-09-20 at 08:46 +0900, Hajime Tazaki wrote:
> > diff --git a/arch/um/drivers/Kconfig b/arch/um/drivers/Kconfig
> > index 6a0354ca032f..04025207a077 100644
> > --- a/arch/um/drivers/Kconfig
> > +++ b/arch/um/drivers/Kconfig
> > @@ -159,6 +159,7 @@ config UML_RTC
> >
> > config UML_PCI
> > bool
> > + depends on MMU
>
> That won't do anything since you elsewhere have "select UML_PCI"
> independent of MMU.
i see.
> > @@ -170,6 +171,7 @@ config UML_PCI_OVER_VIRTIO
> > bool "Enable PCI over VIRTIO device simulation"
> > # in theory, just VIRTIO is enough, but that causes recursion
> > depends on VIRTIO_UML
> > + depends on MMU
> > select UML_PCI
>
> Right, but you also need that for UML_PCI_OVER_VFIO.
thanks, I understand too.
> > and do
> > ./tools/testing/kunit/kunit.py config --kconfig_add CONFIG_MMU=n
> >
> > the validation currently gives the following error:
> >
> > ERROR:root:Not all Kconfig options selected in kunitconfig were in the generated .config.
> > This is probably due to unsatisfied dependencies.
> > Missing: CONFIG_UML_PCI_OVER_VIRTIO=y
>
> Well, OK, but that's fair - you did specifically override MMU=n, and
> virtio-over-pci needs it.
>
> > 1) use --kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=n when using kunit w/
> > !MMU, and drop this patch from the series (no modification to the tree)
> > 2) prepare a different file for !MMU & ARCH=um testing (e.g.,
> > arch_uml_nommu.config), and add an option to kunit.py to switch MMU
> > or !MMU
> > 3) implement virtio-pci for !MMU and propose to remove the restriction
> > of CONFIG_PCI depends on CONFIG_MMU.
> >
> > 2) will be removed when 3) is done so, I'm hesitating to propose a
> > patch used by whole tree.
> >
> > so, I think 1) is (not the best but) a reasonable solution, with a
> > note in nommu-uml specific document (i.e., [PATCH 12/13]).
>
> I don't think (3) makes any sense at all, we should just _never_ do
> that. !MMU is really here in UML for testing to support other
> architectures that are !MMU, and since by today's definitions no other
> architecture can have PCI without MMU, it makes no sense for UML to have
> that (and complicate the PCI code unnecessarily, etc.)
>
> I think it's entirely reasonable to have overriding CONFIG_MMU=n to also
> necessitate overriding CONFIG_UML_PCI_OVER_VIRTIO, i.e. (1).
okay, I'll go for this direction in the next series.
> As to whether or not to add a specific config file, honestly I don't
> really know or even care - you'd have to ask the people who actually
> want to test !MMU.
indeed, this will be the out of this series if needed.
-- Hajime
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-23 17:13 ` Johannes Berg
@ 2025-09-23 23:51 ` Hajime Tazaki
2025-09-24 8:02 ` Geert Uytterhoeven
2025-09-24 11:03 ` Arnd Bergmann
0 siblings, 2 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-23 23:51 UTC (permalink / raw)
To: johannes; +Cc: geert, linux-um, ricarkol, Liam.Howlett, linux-kernel, arnd
Hello Geert, Johannes,
On Wed, 24 Sep 2025 02:13:47 +0900,
Johannes Berg wrote:
>
> On Tue, 2025-09-23 at 17:42 +0200, Geert Uytterhoeven wrote:
> > >
> > > currently, drivers/pci/Kconfig (CONFIG_PCI) marks as depends on MMU,
> > > so we cannot select it when CONFIG_MMU=n.
> >
> > That is a fairly recent change, see commit 8fe743b5eba0abfb ("PCI:
> > Add CONFIG_MMU dependency") in v6.16-rc1. As this is not a "hard"
> > dependency, perhaps it should be reverted, iff you are willing to take
> > care of the casual breakage?
>
> Why though? UML with PCI can't really be a functional thing, only a
> testing thing, and testing PCI on !MMU when that is actually impossible
> in non-simulation is pointless?
currently nommu UML doesn't come with using PCI except building under
kunit (ARCH=um), but I have in my mind to use it under !MMU
environment, so would be an option in the future.
and this series doesn't include PCI w/ !MMU.
so, I would propose the modification to revert the MMU dependency when
time has come.
btw, what do you mean by "hard" dependency in this context, Geert ?
-- Hajime
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-23 23:51 ` Hajime Tazaki
@ 2025-09-24 8:02 ` Geert Uytterhoeven
2025-09-24 11:03 ` Arnd Bergmann
1 sibling, 0 replies; 31+ messages in thread
From: Geert Uytterhoeven @ 2025-09-24 8:02 UTC (permalink / raw)
To: Hajime Tazaki
Cc: johannes, linux-um, ricarkol, Liam.Howlett, linux-kernel, arnd
Hi Hajime,
On Wed, 24 Sept 2025 at 01:51, Hajime Tazaki <thehajime@gmail.com> wrote:
> On Wed, 24 Sep 2025 02:13:47 +0900,
> Johannes Berg wrote:
> > On Tue, 2025-09-23 at 17:42 +0200, Geert Uytterhoeven wrote:
> > > > currently, drivers/pci/Kconfig (CONFIG_PCI) marks as depends on MMU,
> > > > so we cannot select it when CONFIG_MMU=n.
> > >
> > > That is a fairly recent change, see commit 8fe743b5eba0abfb ("PCI:
> > > Add CONFIG_MMU dependency") in v6.16-rc1. As this is not a "hard"
> > > dependency, perhaps it should be reverted, iff you are willing to take
> > > care of the casual breakage?
> >
> > Why though? UML with PCI can't really be a functional thing, only a
> > testing thing, and testing PCI on !MMU when that is actually impossible
> > in non-simulation is pointless?
>
> currently nommu UML doesn't come with using PCI except building under
> kunit (ARCH=um), but I have in my mind to use it under !MMU
> environment, so would be an option in the future.
>
> and this series doesn't include PCI w/ !MMU.
>
> so, I would propose the modification to revert the MMU dependency when
> time has come.
>
> btw, what do you mean by "hard" dependency in this context, Geert ?
I mean the PCI core does not really require an MMU, and PCI in-se
should work without it (e.g. on Coldfire MCF54xx). Arnd added the
dependency to avoid having to deal with future build regressions.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-23 23:51 ` Hajime Tazaki
2025-09-24 8:02 ` Geert Uytterhoeven
@ 2025-09-24 11:03 ` Arnd Bergmann
2025-09-24 23:27 ` Hajime Tazaki
1 sibling, 1 reply; 31+ messages in thread
From: Arnd Bergmann @ 2025-09-24 11:03 UTC (permalink / raw)
To: Hajime Tazaki, Johannes Berg
Cc: Geert Uytterhoeven, linux-um, Ricardo Koller, Liam R. Howlett,
linux-kernel, linux-mm
On Wed, Sep 24, 2025, at 01:51, Hajime Tazaki wrote:
> On Wed, 24 Sep 2025 02:13:47 +0900, Johannes Berg wrote:
>> On Tue, 2025-09-23 at 17:42 +0200, Geert Uytterhoeven wrote:
>> > >
>> > > currently, drivers/pci/Kconfig (CONFIG_PCI) marks as depends on MMU,
>> > > so we cannot select it when CONFIG_MMU=n.
>> >
>> > That is a fairly recent change, see commit 8fe743b5eba0abfb ("PCI:
>> > Add CONFIG_MMU dependency") in v6.16-rc1. As this is not a "hard"
>> > dependency, perhaps it should be reverted, iff you are willing to take
>> > care of the casual breakage?
>>
>> Why though? UML with PCI can't really be a functional thing, only a
>> testing thing, and testing PCI on !MMU when that is actually impossible
>> in non-simulation is pointless?
>
> currently nommu UML doesn't come with using PCI except building under
> kunit (ARCH=um), but I have in my mind to use it under !MMU
> environment, so would be an option in the future.
>
> and this series doesn't include PCI w/ !MMU.
>
> so, I would propose the modification to revert the MMU dependency when
> time has come.
The reason why it's currently disabled is that it was causing extra
work to fix build failures in random PCI drivers that individually
have a CONFIG_MMU dependency. Since we know that none of the NOMMU
boards we support uses PCI, this was an easy way to avoid work.
While there are still developers that care about NOMMU Linux
and test it on the platforms they use, the NOMMU build failures
usually end up in code that are irrelevant for their use cases,
so neither the platform owners nor the driver authors care deeply
about fixing that combination.
If you want to be able to use PCI drivers on UML-NOMMU,
you can probably use
config PCI
depends on MMU || UML
so it will be ignored by the build bots on other architectures.
You'll still have to decide whether to fix driver code when
regressions in PCI drivers happen, add 'depends on !UML'
to individual drivers, or just live with randconfig failures.
Arnd
^ permalink raw reply [flat|nested] 31+ messages in thread
* Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver
2025-09-24 11:03 ` Arnd Bergmann
@ 2025-09-24 23:27 ` Hajime Tazaki
0 siblings, 0 replies; 31+ messages in thread
From: Hajime Tazaki @ 2025-09-24 23:27 UTC (permalink / raw)
To: arnd
Cc: johannes, geert, linux-um, ricarkol, Liam.Howlett, linux-kernel,
linux-mm
Hello Arnd,
On Wed, 24 Sep 2025 20:03:11 +0900,
Arnd Bergmann wrote:
> > currently nommu UML doesn't come with using PCI except building under
> > kunit (ARCH=um), but I have in my mind to use it under !MMU
> > environment, so would be an option in the future.
> >
> > and this series doesn't include PCI w/ !MMU.
> >
> > so, I would propose the modification to revert the MMU dependency when
> > time has come.
>
> The reason why it's currently disabled is that it was causing extra
> work to fix build failures in random PCI drivers that individually
> have a CONFIG_MMU dependency. Since we know that none of the NOMMU
> boards we support uses PCI, this was an easy way to avoid work.
>
> While there are still developers that care about NOMMU Linux
> and test it on the platforms they use, the NOMMU build failures
> usually end up in code that are irrelevant for their use cases,
> so neither the platform owners nor the driver authors care deeply
> about fixing that combination.
>
> If you want to be able to use PCI drivers on UML-NOMMU,
> you can probably use
>
> config PCI
> depends on MMU || UML
>
> so it will be ignored by the build bots on other architectures.
> You'll still have to decide whether to fix driver code when
> regressions in PCI drivers happen, add 'depends on !UML'
> to individual drivers, or just live with randconfig failures.
thanks for the detail information.
yes, when nommu UML wish to use PCI drivers in the future, I'll take
this approach to be able to use it.
-- Hajime
^ permalink raw reply [flat|nested] 31+ messages in thread
end of thread, other threads:[~2025-09-24 23:27 UTC | newest]
Thread overview: 31+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-09-18 7:38 [PATCH RESEND v11 00/13] nommu UML Hajime Tazaki
2025-09-18 7:38 ` [PATCH RESEND v11 01/13] x86/um: nommu: elf loader for fdpic Hajime Tazaki
2025-09-18 7:38 ` [PATCH RESEND v11 02/13] um: decouple MMU specific code from the common part Hajime Tazaki
2025-09-18 7:38 ` [PATCH RESEND v11 03/13] um: nommu: memory handling Hajime Tazaki
2025-09-18 7:38 ` [PATCH RESEND v11 04/13] x86/um: nommu: syscall handling Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 05/13] um: nommu: seccomp syscalls hook Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 06/13] x86/um: nommu: process/thread handling Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 07/13] um: nommu: configure fs register on host syscall invocation Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 08/13] x86/um/vdso: nommu: vdso memory update Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 09/13] x86/um: nommu: signal handling Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver Hajime Tazaki
2025-09-18 8:30 ` Johannes Berg
2025-09-19 0:03 ` Hajime Tazaki
2025-09-19 7:24 ` Johannes Berg
2025-09-19 9:32 ` Hajime Tazaki
2025-09-19 9:38 ` Johannes Berg
2025-09-19 9:38 ` Johannes Berg
2025-09-19 9:43 ` Johannes Berg
2025-09-19 23:46 ` Hajime Tazaki
2025-09-22 6:32 ` Johannes Berg
2025-09-23 23:44 ` Hajime Tazaki
2025-09-23 15:42 ` Geert Uytterhoeven
2025-09-23 17:13 ` Johannes Berg
2025-09-23 23:51 ` Hajime Tazaki
2025-09-24 8:02 ` Geert Uytterhoeven
2025-09-24 11:03 ` Arnd Bergmann
2025-09-24 23:27 ` Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 11/13] um: change machine name for uname output Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 12/13] um: nommu: add documentation of nommu UML Hajime Tazaki
2025-09-18 7:39 ` [PATCH RESEND v11 13/13] um: nommu: plug nommu code into build system Hajime Tazaki
2025-09-18 10:39 ` [PATCH RESEND v11 00/13] nommu UML Lorenzo Stoakes
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