* [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS
@ 2023-06-08 14:24 Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 01/11] Revert "[PATCH] uml: export symbols added by GCC hardened" Masahiro Yamada
` (10 more replies)
0 siblings, 11 replies; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
This patch set refactors modpost first to make it easier to
add new code.
My goals:
- Refactors EXPORT_SYMBOL, <linux/export.h> and <asm/export.h>.
You can still put EXPORT_SYMBOL() in *.S file, very close to the definition,
but you do not need to care about whether it is a function or a data.
This removes EXPORT_DATA_SYMBOL().
- Re-implement TRIM_UNUSED_KSYMS in one-pass.
This makes the building faster.
- Move the static EXPORT_SYMBOL check to modpost.
This also makes the building faster.
This patch set is applicable to linux-next 20230608.
Previous version
v6: https://lore.kernel.org/linux-kbuild/CAK7LNARjzGnj+sYX=_5yQ+8qoOQ2KB5N-_Ye53Ru3=XicezTYw@mail.gmail.com/T/#t
v5: https://lore.kernel.org/linux-kbuild/CAK7LNARBiOywrMLbR=9N35sk19U0QM3xcPy7d1WqV-eyb4W23w@mail.gmail.com/T/#t
v4: https://lore.kernel.org/linux-kbuild/CAK7LNASDzy9RERN6+q6WgR4ROYZQue=SBqgbcoYuVePByHtk6Q@mail.gmail.com/T/#t
v3: https://lore.kernel.org/all/20220928063947.299333-1-masahiroy@kernel.org/
Masahiro Yamada (11):
Revert "[PATCH] uml: export symbols added by GCC hardened"
modpost: pass struct module pointer to check_section_mismatch()
kbuild: generate KSYMTAB entries by modpost
ia64,export.h: replace EXPORT_DATA_SYMBOL* with EXPORT_SYMBOL*
modpost: check static EXPORT_SYMBOL* by modpost again
modpost: squash sym_update_namespace() into sym_add_exported()
modpost: use null string instead of NULL pointer for default namespace
kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion
modpost: merge two similar section mismatch warnings
modpost: show offset from symbol for section mismatch warnings
linux/export.h: rename 'sec' argument to 'license'
.gitignore | 2 -
Makefile | 22 +--
arch/ia64/include/asm/Kbuild | 1 +
arch/ia64/include/asm/export.h | 3 -
arch/ia64/kernel/head.S | 2 +-
arch/ia64/kernel/ivt.S | 2 +-
arch/um/os-Linux/user_syms.c | 7 -
include/asm-generic/export.h | 83 +----------
include/asm-generic/vmlinux.lds.h | 1 +
include/linux/export-internal.h | 49 +++++++
include/linux/export.h | 127 ++++------------
include/linux/pm.h | 14 +-
kernel/module/internal.h | 12 ++
scripts/Makefile.build | 27 +---
scripts/Makefile.modpost | 7 +
scripts/adjust_autoksyms.sh | 73 ----------
scripts/basic/fixdep.c | 3 +-
scripts/check-local-export | 70 ---------
scripts/gen_autoksyms.sh | 62 --------
scripts/gen_ksymdeps.sh | 30 ----
scripts/mod/modpost.c | 233 +++++++++++++++++++-----------
scripts/mod/modpost.h | 1 +
scripts/remove-stale-files | 4 +
23 files changed, 266 insertions(+), 569 deletions(-)
delete mode 100644 arch/ia64/include/asm/export.h
delete mode 100755 scripts/adjust_autoksyms.sh
delete mode 100755 scripts/check-local-export
delete mode 100755 scripts/gen_autoksyms.sh
delete mode 100755 scripts/gen_ksymdeps.sh
--
2.39.2
^ permalink raw reply [flat|nested] 20+ messages in thread
* [PATCH v7 01/11] Revert "[PATCH] uml: export symbols added by GCC hardened"
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
@ 2023-06-08 14:24 ` Masahiro Yamada
2023-06-09 21:23 ` Nick Desaulniers
2023-06-08 14:24 ` [PATCH v7 02/11] modpost: pass struct module pointer to check_section_mismatch() Masahiro Yamada
` (9 subsequent siblings)
10 siblings, 1 reply; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
This reverts commit cead61a6717a9873426b08d73a34a325e3546f5d.
It exported __stack_smash_handler and __guard, while they may not be
defined by anyone.
The code *declares* __stack_smash_handler and __guard. It does not
create weak symbols. When the stack-protector is disabled, they are
left undefined, but yet exported.
If a loadable module tries to access non-existing symbols, bad things
(a page fault, NULL pointer dereference, etc.) will happen. So, the
current code is wrong.
If the code were written as follows, it would *define* them as weak
symbols so modules would be able to get access to them.
void (*__stack_smash_handler)(void *) __attribute__((weak));
EXPORT_SYMBOL(__stack_smash_handler);
long __guard __attribute__((weak));
EXPORT_SYMBOL(__guard);
In fact, modpost forbids exporting undefined symbols. It shows an error
message if it detects such a mistake.
ERROR: modpost: "..." [...] was exported without definition
Unfortunately, it is checked only when the code is built as modular.
The problem described above has been unnoticed for a long time because
arch/um/os-Linux/user_syms.c is always built-in.
With a planned change in Kbuild, exporting undefined symbols will always
result in a build error instead of a run-time error. It is a good thing,
but we need to fix the breakage in advance.
One fix is to *define* weak symbols as shown above. An alternative is
to export them conditionally as follows:
#ifdef CONFIG_STACKPROTECTOR
extern void __stack_smash_handler(void *);
EXPORT_SYMBOL(__stack_smash_handler);
external long __guard;
EXPORT_SYMBOL(__guard);
#endif
This is what other architectures do; EXPORT_SYMBOL(__stack_chk_guard)
is guarded by #ifdef CONFIG_STACKPROTECTOR.
However, adding the #ifdef guard is not sensible because UML cannot
enable the stack-protector in the first place! (Please note UML does
not select HAVE_STACKPROTECTOR in Kconfig.)
So, the code is already broken (and unused) in multiple ways.
Just remove.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---
Changes in v7:
- New patch
arch/um/os-Linux/user_syms.c | 7 -------
1 file changed, 7 deletions(-)
diff --git a/arch/um/os-Linux/user_syms.c b/arch/um/os-Linux/user_syms.c
index 9b62a9d352b3..a310ae27b479 100644
--- a/arch/um/os-Linux/user_syms.c
+++ b/arch/um/os-Linux/user_syms.c
@@ -37,13 +37,6 @@ EXPORT_SYMBOL(vsyscall_ehdr);
EXPORT_SYMBOL(vsyscall_end);
#endif
-/* Export symbols used by GCC for the stack protector. */
-extern void __stack_smash_handler(void *) __attribute__((weak));
-EXPORT_SYMBOL(__stack_smash_handler);
-
-extern long __guard __attribute__((weak));
-EXPORT_SYMBOL(__guard);
-
#ifdef _FORTIFY_SOURCE
extern int __sprintf_chk(char *str, int flag, size_t len, const char *format);
EXPORT_SYMBOL(__sprintf_chk);
--
2.39.2
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v7 02/11] modpost: pass struct module pointer to check_section_mismatch()
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 01/11] Revert "[PATCH] uml: export symbols added by GCC hardened" Masahiro Yamada
@ 2023-06-08 14:24 ` Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost Masahiro Yamada
` (8 subsequent siblings)
10 siblings, 0 replies; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
The next commit will use it.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
---
scripts/mod/modpost.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 8decf04633bc..403ba4d923f5 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1211,7 +1211,7 @@ static void default_mismatch_handler(const char *modname, struct elf_info *elf,
}
}
-static void check_section_mismatch(const char *modname, struct elf_info *elf,
+static void check_section_mismatch(struct module *mod, struct elf_info *elf,
Elf_Sym *sym,
unsigned int fsecndx, const char *fromsec,
Elf_Addr faddr, Elf_Addr taddr)
@@ -1222,7 +1222,7 @@ static void check_section_mismatch(const char *modname, struct elf_info *elf,
if (!mismatch)
return;
- default_mismatch_handler(modname, elf, mismatch, sym,
+ default_mismatch_handler(mod->name, elf, mismatch, sym,
fsecndx, fromsec, faddr,
tosec, taddr);
}
@@ -1406,7 +1406,7 @@ static int addend_mips_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
#define R_LARCH_SUB32 55
#endif
-static void section_rela(const char *modname, struct elf_info *elf,
+static void section_rela(struct module *mod, struct elf_info *elf,
Elf_Shdr *sechdr)
{
Elf_Rela *rela;
@@ -1452,12 +1452,12 @@ static void section_rela(const char *modname, struct elf_info *elf,
break;
}
- check_section_mismatch(modname, elf, elf->symtab_start + r_sym,
+ check_section_mismatch(mod, elf, elf->symtab_start + r_sym,
fsecndx, fromsec, r.r_offset, r.r_addend);
}
}
-static void section_rel(const char *modname, struct elf_info *elf,
+static void section_rel(struct module *mod, struct elf_info *elf,
Elf_Shdr *sechdr)
{
Elf_Rel *rel;
@@ -1507,7 +1507,7 @@ static void section_rel(const char *modname, struct elf_info *elf,
fatal("Please add code to calculate addend for this architecture\n");
}
- check_section_mismatch(modname, elf, elf->symtab_start + r_sym,
+ check_section_mismatch(mod, elf, elf->symtab_start + r_sym,
fsecndx, fromsec, r.r_offset, r.r_addend);
}
}
@@ -1524,19 +1524,19 @@ static void section_rel(const char *modname, struct elf_info *elf,
* to find all references to a section that reference a section that will
* be discarded and warns about it.
**/
-static void check_sec_ref(const char *modname, struct elf_info *elf)
+static void check_sec_ref(struct module *mod, struct elf_info *elf)
{
int i;
Elf_Shdr *sechdrs = elf->sechdrs;
/* Walk through all sections */
for (i = 0; i < elf->num_sections; i++) {
- check_section(modname, elf, &elf->sechdrs[i]);
+ check_section(mod->name, elf, &elf->sechdrs[i]);
/* We want to process only relocation sections and not .init */
if (sechdrs[i].sh_type == SHT_RELA)
- section_rela(modname, elf, &elf->sechdrs[i]);
+ section_rela(mod, elf, &elf->sechdrs[i]);
else if (sechdrs[i].sh_type == SHT_REL)
- section_rel(modname, elf, &elf->sechdrs[i]);
+ section_rel(mod, elf, &elf->sechdrs[i]);
}
}
@@ -1707,7 +1707,7 @@ static void read_symbols(const char *modname)
sym_get_data(&info, sym));
}
- check_sec_ref(modname, &info);
+ check_sec_ref(mod, &info);
if (!mod->is_vmlinux) {
version = get_modinfo(&info, "version");
--
2.39.2
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 01/11] Revert "[PATCH] uml: export symbols added by GCC hardened" Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 02/11] modpost: pass struct module pointer to check_section_mismatch() Masahiro Yamada
@ 2023-06-08 14:24 ` Masahiro Yamada
2023-06-09 21:34 ` Nick Desaulniers
` (2 more replies)
2023-06-08 14:24 ` [PATCH v7 04/11] ia64,export.h: replace EXPORT_DATA_SYMBOL* with EXPORT_SYMBOL* Masahiro Yamada
` (7 subsequent siblings)
10 siblings, 3 replies; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing
CONFIG_MODULE_REL_CRCS") made modpost output CRCs in the same way
whether the EXPORT_SYMBOL() is placed in *.c or *.S.
For further cleanups, this commit applies a similar approach to the
entire data structure of EXPORT_SYMBOL().
The EXPORT_SYMBOL() compilation is split into two stages.
When a source file is compiled, EXPORT_SYMBOL() is converted into a
dummy symbol in the .export_symbol section.
For example,
EXPORT_SYMBOL(foo);
EXPORT_SYMBOL_NS_GPL(bar, BAR_NAMESPACE);
will be encoded into the following assembly code:
.section ".export_symbol","a"
__export_symbol__foo:
.asciz ""
.balign 4
.long foo - .
.previous
.section ".export_symbol","a"
__export_symbol_gpl_bar:
.asciz "BAR_NAMESPACE"
.balign 4
.long bar - .
.previous
They are mere markers to tell modpost the name, license, and namespace
of the symbols. They will be dropped from the final vmlinux and modules
because the *(.export_symbol) will go into /DISCARD/ in the linker script.
Then, modpost extracts all the information about EXPORT_SYMBOL() from the
.export_symbol section, and generates the final C code:
KSYMTAB_FUNC(foo, "", "");
KSYMTAB_FUNC(bar, "_gpl", "BAR_NAMESPACE");
KSYMTAB_FUNC() (or KSYMTAB_DATA() if it is data) is expanded to struct
kernel_symbol that will be linked to the vmlinux or a module.
With this change, EXPORT_SYMBOL() works in the same way for *.c and *.S
files, providing the following benefits.
[1] Deprecate EXPORT_DATA_SYMBOL()
In the old days, EXPORT_SYMBOL() was only available in C files. To export
a symbol in *.S, EXPORT_SYMBOL() was placed in a separate *.c file.
arch/arm/kernel/armksyms.c is one example written in the classic manner.
Commit 22823ab419d8 ("EXPORT_SYMBOL() for asm") removed this limitation.
Since then, EXPORT_SYMBOL() can be placed close to the symbol definition
in *.S files. It was a nice improvement.
However, as that commit mentioned, you need to use EXPORT_DATA_SYMBOL()
for data objects on some architectures.
In the new approach, modpost checks symbol's type (STT_FUNC or not),
and outputs KSYMTAB_FUNC() or KSYMTAB_DATA() accordingly.
There are only two users of EXPORT_DATA_SYMBOL:
EXPORT_DATA_SYMBOL_GPL(empty_zero_page) (arch/ia64/kernel/head.S)
EXPORT_DATA_SYMBOL(ia64_ivt) (arch/ia64/kernel/ivt.S)
They are transformed as follows and output into .vmlinux.export.c
KSYMTAB_DATA(empty_zero_page, "_gpl", "");
KSYMTAB_DATA(ia64_ivt, "", "");
The other EXPORT_SYMBOL users in ia64 assembly are output as
KSYMTAB_FUNC().
EXPORT_DATA_SYMBOL() is now deprecated.
[2] merge <linux/export.h> and <asm-generic/export.h>
There are two similar header implementations:
include/linux/export.h for .c files
include/asm-generic/export.h for .S files
Ideally, the functionality should be consistent between them, but they
tend to diverge.
Commit 8651ec01daed ("module: add support for symbol namespaces.") did
not support the namespace for *.S files.
This commit shifts the essential implementation part to C, which supports
EXPORT_SYMBOL_NS() for *.S files.
<asm/export.h> and <asm-generic/export.h> will remain as a wrapper of
<linux/export.h> for a while.
They will be removed after #include <asm/export.h> directives are all
replaced with #include <linux/export.h>.
[3] Implement CONFIG_TRIM_UNUSED_KSYMS in one-pass algorithm (by a later commit)
When CONFIG_TRIM_UNUSED_KSYMS is enabled, Kbuild recursively traverses
the directory tree to determine which EXPORT_SYMBOL to trim. If an
EXPORT_SYMBOL turns out to be unused by anyone, Kbuild begins the
second traverse, where some source files are recompiled with their
EXPORT_SYMBOL() tuned into a no-op.
We can do this better now; modpost can selectively emit KSYMTAB entries
that are really used by modules.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---
Changes in v7:
- Fix sparse warning reported by 0day bot
https://lore.kernel.org/linux-kbuild/202305280830.Rj5ltc9M-lkp@intel.com/
Changes in v6:
- Fix build error on UML
Changes in v5:
- Fix build error on ARM
Changes in v4:
- Version 3 did not work if a same name symbol exists in a different compilation unit
Fix it.
Changes in v3:
- Move struct kernel_symbol to kernel/module/internal.h
Changes in v2:
- Use KSYMTAB_FUNC and KSYMTAB_DATA for functions and data, respectively
This distinction is needed for ia64.
arch/ia64/include/asm/Kbuild | 1 +
arch/ia64/include/asm/export.h | 3 -
include/asm-generic/export.h | 84 ++-----------------------
include/asm-generic/vmlinux.lds.h | 1 +
include/linux/export-internal.h | 49 +++++++++++++++
include/linux/export.h | 98 ++++++++++-------------------
include/linux/pm.h | 8 +--
kernel/module/internal.h | 12 ++++
scripts/Makefile.build | 8 +--
scripts/check-local-export | 4 +-
scripts/mod/modpost.c | 100 ++++++++++++++++++++----------
scripts/mod/modpost.h | 1 +
12 files changed, 179 insertions(+), 190 deletions(-)
delete mode 100644 arch/ia64/include/asm/export.h
diff --git a/arch/ia64/include/asm/Kbuild b/arch/ia64/include/asm/Kbuild
index aefae2efde9f..33733245f42b 100644
--- a/arch/ia64/include/asm/Kbuild
+++ b/arch/ia64/include/asm/Kbuild
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
generated-y += syscall_table.h
generic-y += agp.h
+generic-y += export.h
generic-y += kvm_para.h
generic-y += mcs_spinlock.h
generic-y += vtime.h
diff --git a/arch/ia64/include/asm/export.h b/arch/ia64/include/asm/export.h
deleted file mode 100644
index ad18c6583252..000000000000
--- a/arch/ia64/include/asm/export.h
+++ /dev/null
@@ -1,3 +0,0 @@
-/* EXPORT_DATA_SYMBOL != EXPORT_SYMBOL here */
-#define KSYM_FUNC(name) @fptr(name)
-#include <asm-generic/export.h>
diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h
index 5e4b1f2369d2..0ae9f38a904c 100644
--- a/include/asm-generic/export.h
+++ b/include/asm-generic/export.h
@@ -3,86 +3,12 @@
#define __ASM_GENERIC_EXPORT_H
/*
- * This comment block is used by fixdep. Please do not remove.
- *
- * When CONFIG_MODVERSIONS is changed from n to y, all source files having
- * EXPORT_SYMBOL variants must be re-compiled because genksyms is run as a
- * side effect of the *.o build rule.
+ * <asm/export.h> and <asm-generic/export.h> are deprecated.
+ * Please include <linux/export.h> directly.
*/
+#include <linux/export.h>
-#ifndef KSYM_FUNC
-#define KSYM_FUNC(x) x
-#endif
-#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
-#define KSYM_ALIGN 4
-#elif defined(CONFIG_64BIT)
-#define KSYM_ALIGN 8
-#else
-#define KSYM_ALIGN 4
-#endif
-
-.macro __put, val, name
-#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
- .long \val - ., \name - ., 0
-#elif defined(CONFIG_64BIT)
- .quad \val, \name, 0
-#else
- .long \val, \name, 0
-#endif
-.endm
-
-/*
- * note on .section use: we specify progbits since usage of the "M" (SHF_MERGE)
- * section flag requires it. Use '%progbits' instead of '@progbits' since the
- * former apparently works on all arches according to the binutils source.
- */
-
-.macro ___EXPORT_SYMBOL name,val,sec
-#if defined(CONFIG_MODULES) && !defined(__DISABLE_EXPORTS)
- .section ___ksymtab\sec+\name,"a"
- .balign KSYM_ALIGN
-__ksymtab_\name:
- __put \val, __kstrtab_\name
- .previous
- .section __ksymtab_strings,"aMS",%progbits,1
-__kstrtab_\name:
- .asciz "\name"
- .previous
-#endif
-.endm
-
-#if defined(CONFIG_TRIM_UNUSED_KSYMS)
-
-#include <linux/kconfig.h>
-#include <generated/autoksyms.h>
-
-.macro __ksym_marker sym
- .section ".discard.ksym","a"
-__ksym_marker_\sym:
- .previous
-.endm
-
-#define __EXPORT_SYMBOL(sym, val, sec) \
- __ksym_marker sym; \
- __cond_export_sym(sym, val, sec, __is_defined(__KSYM_##sym))
-#define __cond_export_sym(sym, val, sec, conf) \
- ___cond_export_sym(sym, val, sec, conf)
-#define ___cond_export_sym(sym, val, sec, enabled) \
- __cond_export_sym_##enabled(sym, val, sec)
-#define __cond_export_sym_1(sym, val, sec) ___EXPORT_SYMBOL sym, val, sec
-#define __cond_export_sym_0(sym, val, sec) /* nothing */
-
-#else
-#define __EXPORT_SYMBOL(sym, val, sec) ___EXPORT_SYMBOL sym, val, sec
-#endif
-
-#define EXPORT_SYMBOL(name) \
- __EXPORT_SYMBOL(name, KSYM_FUNC(name),)
-#define EXPORT_SYMBOL_GPL(name) \
- __EXPORT_SYMBOL(name, KSYM_FUNC(name), _gpl)
-#define EXPORT_DATA_SYMBOL(name) \
- __EXPORT_SYMBOL(name, name,)
-#define EXPORT_DATA_SYMBOL_GPL(name) \
- __EXPORT_SYMBOL(name, name,_gpl)
+#define EXPORT_DATA_SYMBOL(name) EXPORT_SYMBOL(name)
+#define EXPORT_DATA_SYMBOL_GPL(name) EXPORT_SYMBOL_GPL(name)
#endif
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index d1f57e4868ed..e65d55e8819c 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -1006,6 +1006,7 @@
PATCHABLE_DISCARDS \
*(.discard) \
*(.discard.*) \
+ *(.export_symbol) \
*(.modinfo) \
/* ld.bfd warns about .gnu.version* even when not emitted */ \
*(.gnu.version*) \
diff --git a/include/linux/export-internal.h b/include/linux/export-internal.h
index fe7e6ba918f1..1c849db953a5 100644
--- a/include/linux/export-internal.h
+++ b/include/linux/export-internal.h
@@ -10,6 +10,55 @@
#include <linux/compiler.h>
#include <linux/types.h>
+#if defined(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)
+/*
+ * relative reference: this reduces the size by half on 64-bit architectures,
+ * and eliminates the need for absolute relocations that require runtime
+ * processing on relocatable kernels.
+ */
+#define __KSYM_REF(sym) ".long " #sym "- ."
+#elif defined(CONFIG_64BIT)
+#define __KSYM_REF(sym) ".quad " #sym
+#else
+#define __KSYM_REF(sym) ".long " #sym
+#endif
+
+/*
+ * For every exported symbol, do the following:
+ *
+ * - Put the name of the symbol and namespace (empty string "" for none) in
+ * __ksymtab_strings.
+ * - Place a struct kernel_symbol entry in the __ksymtab section.
+ *
+ * Note on .section use: we specify progbits since usage of the "M" (SHF_MERGE)
+ * section flag requires it. Use '%progbits' instead of '@progbits' since the
+ * former apparently works on all arches according to the binutils source.
+ */
+#define __KSYMTAB(name, sym, sec, ns) \
+ asm(" .section \"__ksymtab_strings\",\"aMS\",%progbits,1" "\n" \
+ "__kstrtab_" #name ":" "\n" \
+ " .asciz \"" #name "\"" "\n" \
+ "__kstrtabns_" #name ":" "\n" \
+ " .asciz \"" ns "\"" "\n" \
+ " .previous" "\n" \
+ " .section \"___ksymtab" sec "+" #name "\", \"a\"" "\n" \
+ " .balign 4" "\n" \
+ "__ksymtab_" #name ":" "\n" \
+ __KSYM_REF(sym) "\n" \
+ __KSYM_REF(__kstrtab_ ##name) "\n" \
+ __KSYM_REF(__kstrtabns_ ##name) "\n" \
+ " .previous" "\n" \
+ )
+
+#ifdef CONFIG_IA64
+#define KSYM_FUNC(name) @fptr(name)
+#else
+#define KSYM_FUNC(name) name
+#endif
+
+#define KSYMTAB_FUNC(name, sec, ns) __KSYMTAB(name, KSYM_FUNC(name), sec, ns)
+#define KSYMTAB_DATA(name, sec, ns) __KSYMTAB(name, name, sec, ns)
+
#define SYMBOL_CRC(sym, crc, sec) \
asm(".section \"___kcrctab" sec "+" #sym "\",\"a\"" "\n" \
"__crc_" #sym ":" "\n" \
diff --git a/include/linux/export.h b/include/linux/export.h
index 3f31ced0d977..529435a821c0 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -2,6 +2,7 @@
#ifndef _LINUX_EXPORT_H
#define _LINUX_EXPORT_H
+#include <linux/compiler.h>
#include <linux/stringify.h>
/*
@@ -28,72 +29,31 @@ extern struct module __this_module;
#else
#define THIS_MODULE ((struct module *)0)
#endif
+#endif /* __ASSEMBLY__ */
-#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
-#include <linux/compiler.h>
-/*
- * Emit the ksymtab entry as a pair of relative references: this reduces
- * the size by half on 64-bit architectures, and eliminates the need for
- * absolute relocations that require runtime processing on relocatable
- * kernels.
- */
-#define __KSYMTAB_ENTRY(sym, sec) \
- __ADDRESSABLE(sym) \
- asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \
- " .balign 4 \n" \
- "__ksymtab_" #sym ": \n" \
- " .long " #sym "- . \n" \
- " .long __kstrtab_" #sym "- . \n" \
- " .long __kstrtabns_" #sym "- . \n" \
- " .previous \n")
-
-struct kernel_symbol {
- int value_offset;
- int name_offset;
- int namespace_offset;
-};
-#else
-#define __KSYMTAB_ENTRY(sym, sec) \
- static const struct kernel_symbol __ksymtab_##sym \
- __attribute__((section("___ksymtab" sec "+" #sym), used)) \
- __aligned(sizeof(void *)) \
- = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym }
-
-struct kernel_symbol {
- unsigned long value;
- const char *name;
- const char *namespace;
-};
-#endif
+#define ____EXPORT_SYMBOL(sym, license, ns) \
+ .section ".export_symbol","a" ; \
+ __export_symbol_##license##_##sym: ; \
+ .asciz ns ; \
+ .balign 4 ; \
+ .long sym - . ; \
+ .previous
#ifdef __GENKSYMS__
#define ___EXPORT_SYMBOL(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym)
+#elif defined(__ASSEMBLY__)
+
+#define ___EXPORT_SYMBOL(sym, license, ns) \
+ ____EXPORT_SYMBOL(sym, license, ns)
+
#else
-/*
- * For every exported symbol, do the following:
- *
- * - Put the name of the symbol and namespace (empty string "" for none) in
- * __ksymtab_strings.
- * - Place a struct kernel_symbol entry in the __ksymtab section.
- *
- * note on .section use: we specify progbits since usage of the "M" (SHF_MERGE)
- * section flag requires it. Use '%progbits' instead of '@progbits' since the
- * former apparently works on all arches according to the binutils source.
- */
-#define ___EXPORT_SYMBOL(sym, sec, ns) \
- extern typeof(sym) sym; \
- extern const char __kstrtab_##sym[]; \
- extern const char __kstrtabns_##sym[]; \
- asm(" .section \"__ksymtab_strings\",\"aMS\",%progbits,1 \n" \
- "__kstrtab_" #sym ": \n" \
- " .asciz \"" #sym "\" \n" \
- "__kstrtabns_" #sym ": \n" \
- " .asciz \"" ns "\" \n" \
- " .previous \n"); \
- __KSYMTAB_ENTRY(sym, sec)
+#define ___EXPORT_SYMBOL(sym, license, ns) \
+ extern typeof(sym) sym; \
+ __ADDRESSABLE(sym) \
+ asm(__stringify(____EXPORT_SYMBOL(sym, license, ns)))
#endif
@@ -117,9 +77,21 @@ struct kernel_symbol {
* from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are
* discarded in the final link stage.
*/
+
+#ifdef __ASSEMBLY__
+
+#define __ksym_marker(sym) \
+ .section ".discard.ksym","a" ; \
+__ksym_marker_##sym: ; \
+ .previous
+
+#else
+
#define __ksym_marker(sym) \
static int __ksym_marker_##sym[0] __section(".discard.ksym") __used
+#endif
+
#define __EXPORT_SYMBOL(sym, sec, ns) \
__ksym_marker(sym); \
__cond_export_sym(sym, sec, ns, __is_defined(__KSYM_##sym))
@@ -147,11 +119,9 @@ struct kernel_symbol {
#define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, "")
#endif
-#define EXPORT_SYMBOL(sym) _EXPORT_SYMBOL(sym, "")
-#define EXPORT_SYMBOL_GPL(sym) _EXPORT_SYMBOL(sym, "_gpl")
-#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL(sym, "", __stringify(ns))
-#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL(sym, "_gpl", __stringify(ns))
-
-#endif /* !__ASSEMBLY__ */
+#define EXPORT_SYMBOL(sym) _EXPORT_SYMBOL(sym,)
+#define EXPORT_SYMBOL_GPL(sym) _EXPORT_SYMBOL(sym,gpl)
+#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL(sym,, __stringify(ns))
+#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL(sym,gpl, __stringify(ns))
#endif /* _LINUX_EXPORT_H */
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 035d9649eba4..aabb6bd8f89e 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -388,10 +388,10 @@ const struct dev_pm_ops name = { \
#define EXPORT_PM_FN_NS_GPL(name, ns)
#endif
-#define EXPORT_DEV_PM_OPS(name) _EXPORT_DEV_PM_OPS(name, "", "")
-#define EXPORT_GPL_DEV_PM_OPS(name) _EXPORT_DEV_PM_OPS(name, "_gpl", "")
-#define EXPORT_NS_DEV_PM_OPS(name, ns) _EXPORT_DEV_PM_OPS(name, "", #ns)
-#define EXPORT_NS_GPL_DEV_PM_OPS(name, ns) _EXPORT_DEV_PM_OPS(name, "_gpl", #ns)
+#define EXPORT_DEV_PM_OPS(name) _EXPORT_DEV_PM_OPS(name,, "")
+#define EXPORT_GPL_DEV_PM_OPS(name) _EXPORT_DEV_PM_OPS(name,gpl, "")
+#define EXPORT_NS_DEV_PM_OPS(name, ns) _EXPORT_DEV_PM_OPS(name,, #ns)
+#define EXPORT_NS_GPL_DEV_PM_OPS(name, ns) _EXPORT_DEV_PM_OPS(name,gpl, #ns)
/*
* Use this if you want to use the same suspend and resume callbacks for suspend
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index dc7b0160c480..c8b7b4dcf782 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -32,6 +32,18 @@
/* Maximum number of characters written by module_flags() */
#define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)
+struct kernel_symbol {
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+ int value_offset;
+ int name_offset;
+ int namespace_offset;
+#else
+ unsigned long value;
+ const char *name;
+ const char *namespace;
+#endif
+};
+
extern struct mutex module_mutex;
extern struct list_head modules;
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 9f94fc83f086..6bf026a304e4 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -161,7 +161,7 @@ quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
ifdef CONFIG_MODVERSIONS
# When module versioning is enabled the following steps are executed:
# o compile a <file>.o from <file>.c
-# o if <file>.o doesn't contain a __ksymtab version, i.e. does
+# o if <file>.o doesn't contain a __export_symbol*, i.e. does
# not export symbols, it's done.
# o otherwise, we calculate symbol versions using the good old
# genksyms on the preprocessed source and dump them into the .cmd file.
@@ -169,7 +169,7 @@ ifdef CONFIG_MODVERSIONS
# be compiled and linked to the kernel and/or modules.
gen_symversions = \
- if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then \
+ if $(NM) $@ 2>/dev/null | grep -q '__export_symbol_[^_]*_'; then \
$(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
>> $(dot-target).cmd; \
fi
@@ -340,9 +340,7 @@ $(obj)/%.ll: $(src)/%.rs FORCE
cmd_gensymtypes_S = \
{ echo "\#include <linux/kernel.h>" ; \
echo "\#include <asm/asm-prototypes.h>" ; \
- $(CPP) $(a_flags) $< | \
- grep "\<___EXPORT_SYMBOL\>" | \
- sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \
+ $(NM) $@ | sed -n 's/.*__export_symbol_[^_]*_\(.*\)/EXPORT_SYMBOL(\1);/p' ; } | \
$(CPP) -D__GENKSYMS__ $(c_flags) -xc - | $(genksyms)
quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
diff --git a/scripts/check-local-export b/scripts/check-local-export
index f90b5a9c67b3..969a313b9299 100755
--- a/scripts/check-local-export
+++ b/scripts/check-local-export
@@ -46,9 +46,9 @@ BEGIN {
{ symbol_types[$3]=$2 }
# append the exported symbol to the array
-($3 ~ /^__ksymtab_/) {
+($3 ~ /^__export_symbol_(gpl)?_.*/) {
export_symbols[i] = $3
- sub(/^__ksymtab_/, "", export_symbols[i])
+ sub(/^__export_symbol_(gpl)?_/, "", export_symbols[i])
i++
}
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 403ba4d923f5..0ae6c9c5bdf6 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -217,6 +217,7 @@ struct symbol {
unsigned int crc;
bool crc_valid;
bool weak;
+ bool is_func;
bool is_gpl_only; /* exported by EXPORT_SYMBOL_GPL */
char name[];
};
@@ -533,6 +534,8 @@ static int parse_elf(struct elf_info *info, const char *filename)
fatal("%s has NOBITS .modinfo\n", filename);
info->modinfo = (void *)hdr + sechdrs[i].sh_offset;
info->modinfo_len = sechdrs[i].sh_size;
+ } else if (!strcmp(secname, ".export_symbol")) {
+ info->export_symbol_secndx = i;
}
if (sechdrs[i].sh_type == SHT_SYMTAB) {
@@ -655,18 +658,6 @@ static void handle_symbol(struct module *mod, struct elf_info *info,
ELF_ST_BIND(sym->st_info) == STB_WEAK);
break;
default:
- /* All exported symbols */
- if (strstarts(symname, "__ksymtab_")) {
- const char *name, *secname;
-
- name = symname + strlen("__ksymtab_");
- secname = sec_name(info, get_secindex(info, sym));
-
- if (strstarts(secname, "___ksymtab_gpl+"))
- sym_add_exported(name, mod, true);
- else if (strstarts(secname, "___ksymtab+"))
- sym_add_exported(name, mod, false);
- }
if (strcmp(symname, "init_module") == 0)
mod->has_init = true;
if (strcmp(symname, "cleanup_module") == 0)
@@ -848,7 +839,6 @@ enum mismatch {
XXXEXIT_TO_SOME_EXIT,
ANY_INIT_TO_ANY_EXIT,
ANY_EXIT_TO_ANY_INIT,
- EXPORT_TO_INIT_EXIT,
EXTABLE_TO_NON_TEXT,
};
@@ -920,12 +910,6 @@ static const struct sectioncheck sectioncheck[] = {
.bad_tosec = { INIT_SECTIONS, NULL },
.mismatch = ANY_INIT_TO_ANY_EXIT,
},
-/* Do not export init/exit functions or data */
-{
- .fromsec = { "___ksymtab*", NULL },
- .bad_tosec = { INIT_SECTIONS, EXIT_SECTIONS, NULL },
- .mismatch = EXPORT_TO_INIT_EXIT,
-},
{
.fromsec = { "__ex_table", NULL },
/* If you're adding any new black-listed sections in here, consider
@@ -1180,10 +1164,6 @@ static void default_mismatch_handler(const char *modname, struct elf_info *elf,
warn("%s: section mismatch in reference: %s (section: %s) -> %s (section: %s)\n",
modname, fromsym, fromsec, tosym, tosec);
break;
- case EXPORT_TO_INIT_EXIT:
- warn("%s: EXPORT_SYMBOL used for init/exit symbol: %s (section: %s)\n",
- modname, tosym, tosec);
- break;
case EXTABLE_TO_NON_TEXT:
warn("%s(%s+0x%lx): Section mismatch in reference to the %s:%s\n",
modname, fromsec, (long)faddr, tosec, tosym);
@@ -1211,14 +1191,69 @@ static void default_mismatch_handler(const char *modname, struct elf_info *elf,
}
}
+static void check_export_symbol(struct module *mod, struct elf_info *elf,
+ Elf_Addr faddr, const char *secname,
+ Elf_Sym *sym)
+{
+ const char *label_name, *name, *prefix;
+ Elf_Sym *label;
+ struct symbol *s;
+ bool is_gpl;
+
+ label = find_fromsym(elf, faddr, elf->export_symbol_secndx);
+ label_name = sym_name(elf, label);
+
+ name = sym_name(elf, sym);
+
+ if (strstarts(label_name, "__export_symbol_gpl_")) {
+ prefix = "__export_symbol_gpl_";
+ is_gpl = true;
+ } else if (strstarts(label_name, "__export_symbol__")) {
+ prefix = "__export_symbol__";
+ is_gpl = false;
+ } else {
+ error("%s: .export_symbol section contains strange symbol '%s'\n",
+ mod->name, label_name);
+ return;
+ }
+
+ if (strcmp(label_name + strlen(prefix), name)) {
+ error("%s: .export_symbol section references '%s', but it does not seem to be an export symbol\n",
+ mod->name, name);
+ return;
+ }
+
+ s = sym_add_exported(name, mod, is_gpl);
+ sym_update_namespace(name, sym_get_data(elf, label));
+
+ /*
+ * We need to be aware whether we are exporting a function or
+ * a data on some architectures.
+ */
+ s->is_func = (ELF_ST_TYPE(sym->st_info) == STT_FUNC);
+
+ if (match(secname, PATTERNS(INIT_SECTIONS)))
+ error("%s: %s: EXPORT_SYMBOL used for init symbol. Remove __init or EXPORT_SYMBOL.\n",
+ mod->name, name);
+ else if (match(secname, PATTERNS(EXIT_SECTIONS)))
+ error("%s: %s: EXPORT_SYMBOL used for exit symbol. Remove __exit or EXPORT_SYMBOL.\n",
+ mod->name, name);
+}
+
static void check_section_mismatch(struct module *mod, struct elf_info *elf,
Elf_Sym *sym,
unsigned int fsecndx, const char *fromsec,
Elf_Addr faddr, Elf_Addr taddr)
{
const char *tosec = sec_name(elf, get_secindex(elf, sym));
- const struct sectioncheck *mismatch = section_mismatch(fromsec, tosec);
+ const struct sectioncheck *mismatch;
+ if (elf->export_symbol_secndx == fsecndx) {
+ check_export_symbol(mod, elf, faddr, tosec, sym);
+ return;
+ }
+
+ mismatch = section_mismatch(fromsec, tosec);
if (!mismatch)
return;
@@ -1698,15 +1733,6 @@ static void read_symbols(const char *modname)
handle_moddevtable(mod, &info, sym, symname);
}
- for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
- symname = remove_dot(info.strtab + sym->st_name);
-
- /* Apply symbol namespaces from __kstrtabns_<symbol> entries. */
- if (strstarts(symname, "__kstrtabns_"))
- sym_update_namespace(symname + strlen("__kstrtabns_"),
- sym_get_data(&info, sym));
- }
-
check_sec_ref(mod, &info);
if (!mod->is_vmlinux) {
@@ -1890,6 +1916,14 @@ static void add_exported_symbols(struct buffer *buf, struct module *mod)
{
struct symbol *sym;
+ /* generate struct for exported symbols */
+ buf_printf(buf, "\n");
+ list_for_each_entry(sym, &mod->exported_symbols, list)
+ buf_printf(buf, "KSYMTAB_%s(%s, \"%s\", \"%s\");\n",
+ sym->is_func ? "FUNC" : "DATA", sym->name,
+ sym->is_gpl_only ? "_gpl" : "",
+ sym->namespace ?: "");
+
if (!modversions)
return;
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index b1e2d95f8047..dfdb9484e325 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -137,6 +137,7 @@ struct elf_info {
Elf_Shdr *sechdrs;
Elf_Sym *symtab_start;
Elf_Sym *symtab_stop;
+ unsigned int export_symbol_secndx; /* .export_symbol section */
char *strtab;
char *modinfo;
unsigned int modinfo_len;
--
2.39.2
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v7 04/11] ia64,export.h: replace EXPORT_DATA_SYMBOL* with EXPORT_SYMBOL*
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
` (2 preceding siblings ...)
2023-06-08 14:24 ` [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost Masahiro Yamada
@ 2023-06-08 14:24 ` Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 05/11] modpost: check static EXPORT_SYMBOL* by modpost again Masahiro Yamada
` (6 subsequent siblings)
10 siblings, 0 replies; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
With the previous refactoring, you can always use EXPORT_SYMBOL*.
Replace two instances in ia64, then remove EXPORT_DATA_SYMBOL*.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/ia64/kernel/head.S | 2 +-
arch/ia64/kernel/ivt.S | 2 +-
include/asm-generic/export.h | 3 ---
3 files changed, 2 insertions(+), 5 deletions(-)
diff --git a/arch/ia64/kernel/head.S b/arch/ia64/kernel/head.S
index f22469f1c1fc..c096500590e9 100644
--- a/arch/ia64/kernel/head.S
+++ b/arch/ia64/kernel/head.S
@@ -170,7 +170,7 @@ RestRR: \
__PAGE_ALIGNED_DATA
.global empty_zero_page
-EXPORT_DATA_SYMBOL_GPL(empty_zero_page)
+EXPORT_SYMBOL_GPL(empty_zero_page)
empty_zero_page:
.skip PAGE_SIZE
diff --git a/arch/ia64/kernel/ivt.S b/arch/ia64/kernel/ivt.S
index d6d4229b28db..7a418e324d30 100644
--- a/arch/ia64/kernel/ivt.S
+++ b/arch/ia64/kernel/ivt.S
@@ -87,7 +87,7 @@
.align 32768 // align on 32KB boundary
.global ia64_ivt
- EXPORT_DATA_SYMBOL(ia64_ivt)
+ EXPORT_SYMBOL(ia64_ivt)
ia64_ivt:
/////////////////////////////////////////////////////////////////////////////////////////
// 0x0000 Entry 0 (size 64 bundles) VHPT Translation (8,20,47)
diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h
index 0ae9f38a904c..570cd4da7210 100644
--- a/include/asm-generic/export.h
+++ b/include/asm-generic/export.h
@@ -8,7 +8,4 @@
*/
#include <linux/export.h>
-#define EXPORT_DATA_SYMBOL(name) EXPORT_SYMBOL(name)
-#define EXPORT_DATA_SYMBOL_GPL(name) EXPORT_SYMBOL_GPL(name)
-
#endif
--
2.39.2
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v7 05/11] modpost: check static EXPORT_SYMBOL* by modpost again
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
` (3 preceding siblings ...)
2023-06-08 14:24 ` [PATCH v7 04/11] ia64,export.h: replace EXPORT_DATA_SYMBOL* with EXPORT_SYMBOL* Masahiro Yamada
@ 2023-06-08 14:24 ` Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 06/11] modpost: squash sym_update_namespace() into sym_add_exported() Masahiro Yamada
` (5 subsequent siblings)
10 siblings, 0 replies; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
Commit 31cb50b5590f ("kbuild: check static EXPORT_SYMBOL* by script
instead of modpost") moved the static EXPORT_SYMBOL* check from the
mostpost to a shell script because I thought it must be checked per
compilation unit to avoid false negatives.
I came up with an idea to do this in modpost, against combined ELF
files. The relocation entries in ELF will find the correct exported
symbol even if there exist symbols with the same name in different
compilation units.
Again, the same sample code.
Makefile:
obj-y += foo1.o foo2.o
foo1.c:
#include <linux/export.h>
static void foo(void) {}
EXPORT_SYMBOL(foo);
foo2.c:
void foo(void) {}
Then, modpost can catch it correctly.
MODPOST Module.symvers
ERROR: modpost: vmlinux: local symbol 'foo' was exported
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
---
(no changes since v6)
Changes in v6:
- Make the symbol name in the warning more precise
scripts/Makefile.build | 4 ---
scripts/check-local-export | 70 --------------------------------------
scripts/mod/modpost.c | 7 ++++
3 files changed, 7 insertions(+), 74 deletions(-)
delete mode 100755 scripts/check-local-export
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 6bf026a304e4..bd4123795299 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -220,8 +220,6 @@ cmd_gen_ksymdeps = \
$(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd
endif
-cmd_check_local_export = $(srctree)/scripts/check-local-export $@
-
ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
cmd_warn_shared_object = $(if $(word 2, $(modname-multi)),$(warning $(kbuild-file): $*.o is added to multiple modules: $(modname-multi)))
endif
@@ -229,7 +227,6 @@ endif
define rule_cc_o_c
$(call cmd_and_fixdep,cc_o_c)
$(call cmd,gen_ksymdeps)
- $(call cmd,check_local_export)
$(call cmd,checksrc)
$(call cmd,checkdoc)
$(call cmd,gen_objtooldep)
@@ -241,7 +238,6 @@ endef
define rule_as_o_S
$(call cmd_and_fixdep,as_o_S)
$(call cmd,gen_ksymdeps)
- $(call cmd,check_local_export)
$(call cmd,gen_objtooldep)
$(call cmd,gen_symversions_S)
$(call cmd,warn_shared_object)
diff --git a/scripts/check-local-export b/scripts/check-local-export
deleted file mode 100755
index 969a313b9299..000000000000
--- a/scripts/check-local-export
+++ /dev/null
@@ -1,70 +0,0 @@
-#!/bin/sh
-# SPDX-License-Identifier: GPL-2.0-only
-#
-# Copyright (C) 2022 Masahiro Yamada <masahiroy@kernel.org>
-# Copyright (C) 2022 Owen Rafferty <owen@owenrafferty.com>
-#
-# Exit with error if a local exported symbol is found.
-# EXPORT_SYMBOL should be used for global symbols.
-
-set -e
-pid=$$
-
-# If there is no symbol in the object, ${NM} (both GNU nm and llvm-nm) shows
-# 'no symbols' diagnostic (but exits with 0). It is harmless and hidden by
-# '2>/dev/null'. However, it suppresses real error messages as well. Add a
-# hand-crafted error message here.
-#
-# TODO:
-# Use --quiet instead of 2>/dev/null when we upgrade the minimum version of
-# binutils to 2.37, llvm to 13.0.0.
-# Then, the following line will be simpler:
-# { ${NM} --quiet ${1} || kill 0; } |
-
-{ ${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; kill $pid; } } |
-${AWK} -v "file=${1}" '
-BEGIN {
- i = 0
-}
-
-# Skip the line if the number of fields is less than 3.
-#
-# case 1)
-# For undefined symbols, the first field (value) is empty.
-# The outout looks like this:
-# " U _printk"
-# It is unneeded to record undefined symbols.
-#
-# case 2)
-# For Clang LTO, llvm-nm outputs a line with type t but empty name:
-# "---------------- t"
-!length($3) {
- next
-}
-
-# save (name, type) in the associative array
-{ symbol_types[$3]=$2 }
-
-# append the exported symbol to the array
-($3 ~ /^__export_symbol_(gpl)?_.*/) {
- export_symbols[i] = $3
- sub(/^__export_symbol_(gpl)?_/, "", export_symbols[i])
- i++
-}
-
-END {
- exit_code = 0
- for (j = 0; j < i; ++j) {
- name = export_symbols[j]
- # nm(3) says "If lowercase, the symbol is usually local"
- if (symbol_types[name] ~ /[a-z]/) {
- printf "%s: error: local symbol %s was exported\n",
- file, name | "cat 1>&2"
- exit_code = 1
- }
- }
-
- exit exit_code
-}'
-
-exit $?
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 0ae6c9c5bdf6..a3185ee6ec1a 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1217,6 +1217,13 @@ static void check_export_symbol(struct module *mod, struct elf_info *elf,
return;
}
+ if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL &&
+ ELF_ST_BIND(sym->st_info) != STB_WEAK) {
+ error("%s: local symbol '%s' was exported\n", mod->name,
+ label_name + strlen(prefix));
+ return;
+ }
+
if (strcmp(label_name + strlen(prefix), name)) {
error("%s: .export_symbol section references '%s', but it does not seem to be an export symbol\n",
mod->name, name);
--
2.39.2
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v7 06/11] modpost: squash sym_update_namespace() into sym_add_exported()
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
` (4 preceding siblings ...)
2023-06-08 14:24 ` [PATCH v7 05/11] modpost: check static EXPORT_SYMBOL* by modpost again Masahiro Yamada
@ 2023-06-08 14:24 ` Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 07/11] modpost: use null string instead of NULL pointer for default namespace Masahiro Yamada
` (4 subsequent siblings)
10 siblings, 0 replies; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
Pass a set of the name, license, and namespace to sym_add_exported().
sym_update_namespace() is unneeded.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
---
scripts/mod/modpost.c | 27 ++++-----------------------
1 file changed, 4 insertions(+), 23 deletions(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index a3185ee6ec1a..4b0a009de0fb 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -355,26 +355,8 @@ static const char *sec_name(const struct elf_info *info, unsigned int secindex)
#define strstarts(str, prefix) (strncmp(str, prefix, strlen(prefix)) == 0)
-static void sym_update_namespace(const char *symname, const char *namespace)
-{
- struct symbol *s = find_symbol(symname);
-
- /*
- * That symbol should have been created earlier and thus this is
- * actually an assertion.
- */
- if (!s) {
- error("Could not update namespace(%s) for symbol %s\n",
- namespace, symname);
- return;
- }
-
- free(s->namespace);
- s->namespace = namespace[0] ? NOFAIL(strdup(namespace)) : NULL;
-}
-
static struct symbol *sym_add_exported(const char *name, struct module *mod,
- bool gpl_only)
+ bool gpl_only, const char *namespace)
{
struct symbol *s = find_symbol(name);
@@ -387,6 +369,7 @@ static struct symbol *sym_add_exported(const char *name, struct module *mod,
s = alloc_symbol(name);
s->module = mod;
s->is_gpl_only = gpl_only;
+ s->namespace = namespace[0] ? NOFAIL(strdup(namespace)) : NULL;
list_add_tail(&s->list, &mod->exported_symbols);
hash_add_symbol(s);
@@ -1230,8 +1213,7 @@ static void check_export_symbol(struct module *mod, struct elf_info *elf,
return;
}
- s = sym_add_exported(name, mod, is_gpl);
- sym_update_namespace(name, sym_get_data(elf, label));
+ s = sym_add_exported(name, mod, is_gpl, sym_get_data(elf, label));
/*
* We need to be aware whether we are exporting a function or
@@ -2174,9 +2156,8 @@ static void read_dump(const char *fname)
mod = new_module(modname, strlen(modname));
mod->from_dump = true;
}
- s = sym_add_exported(symname, mod, gpl_only);
+ s = sym_add_exported(symname, mod, gpl_only, namespace);
sym_set_crc(s, crc);
- sym_update_namespace(symname, namespace);
}
free(buf);
return;
--
2.39.2
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v7 07/11] modpost: use null string instead of NULL pointer for default namespace
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
` (5 preceding siblings ...)
2023-06-08 14:24 ` [PATCH v7 06/11] modpost: squash sym_update_namespace() into sym_add_exported() Masahiro Yamada
@ 2023-06-08 14:24 ` Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 08/11] kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion Masahiro Yamada
` (3 subsequent siblings)
10 siblings, 0 replies; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
The default namespace is the null string, "".
When set, the null string "" is converted to NULL:
s->namespace = namespace[0] ? NOFAIL(strdup(namespace)) : NULL;
When printed, the NULL pointer is get back to the null string:
sym->namespace ?: ""
This saves 1 byte memory allocated for "", but loses the readability.
In kernel-space, we strive to save memory, but modpost is a userspace
tool used to build the kernel. On modern systems, such small piece of
memory is not a big deal.
Handle the namespace string as is.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
---
scripts/mod/modpost.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 4b0a009de0fb..7044b257424a 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -300,6 +300,13 @@ static bool contains_namespace(struct list_head *head, const char *namespace)
{
struct namespace_list *list;
+ /*
+ * The default namespace is null string "", which is always implicitly
+ * contained.
+ */
+ if (!namespace[0])
+ return true;
+
list_for_each_entry(list, head, list) {
if (!strcmp(list->namespace, namespace))
return true;
@@ -369,7 +376,7 @@ static struct symbol *sym_add_exported(const char *name, struct module *mod,
s = alloc_symbol(name);
s->module = mod;
s->is_gpl_only = gpl_only;
- s->namespace = namespace[0] ? NOFAIL(strdup(namespace)) : NULL;
+ s->namespace = NOFAIL(strdup(namespace));
list_add_tail(&s->list, &mod->exported_symbols);
hash_add_symbol(s);
@@ -1823,8 +1830,7 @@ static void check_exports(struct module *mod)
else
basename = mod->name;
- if (exp->namespace &&
- !contains_namespace(&mod->imported_namespaces, exp->namespace)) {
+ if (!contains_namespace(&mod->imported_namespaces, exp->namespace)) {
modpost_log(allow_missing_ns_imports ? LOG_WARN : LOG_ERROR,
"module %s uses symbol %s from namespace %s, but does not import it.\n",
basename, exp->name, exp->namespace);
@@ -1910,8 +1916,7 @@ static void add_exported_symbols(struct buffer *buf, struct module *mod)
list_for_each_entry(sym, &mod->exported_symbols, list)
buf_printf(buf, "KSYMTAB_%s(%s, \"%s\", \"%s\");\n",
sym->is_func ? "FUNC" : "DATA", sym->name,
- sym->is_gpl_only ? "_gpl" : "",
- sym->namespace ?: "");
+ sym->is_gpl_only ? "_gpl" : "", sym->namespace);
if (!modversions)
return;
@@ -2179,7 +2184,7 @@ static void write_dump(const char *fname)
buf_printf(&buf, "0x%08x\t%s\t%s\tEXPORT_SYMBOL%s\t%s\n",
sym->crc, sym->name, mod->name,
sym->is_gpl_only ? "_GPL" : "",
- sym->namespace ?: "");
+ sym->namespace);
}
}
write_buf(&buf, fname);
--
2.39.2
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v7 08/11] kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
` (6 preceding siblings ...)
2023-06-08 14:24 ` [PATCH v7 07/11] modpost: use null string instead of NULL pointer for default namespace Masahiro Yamada
@ 2023-06-08 14:24 ` Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 09/11] modpost: merge two similar section mismatch warnings Masahiro Yamada
` (2 subsequent siblings)
10 siblings, 0 replies; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
When CONFIG_TRIM_UNUSED_KSYMS is enabled, Kbuild recursively traverses
the directory tree to determine which EXPORT_SYMBOL to trim. If an
EXPORT_SYMBOL turns out to be unused by anyone, Kbuild begins the
second traverse, where some source files are recompiled with their
EXPORT_SYMBOL() tuned into a no-op.
Linus stated negative opinions about this slowness in commits:
- 5cf0fd591f2e ("Kbuild: disable TRIM_UNUSED_KSYMS option")
- a555bdd0c58c ("Kbuild: enable TRIM_UNUSED_KSYMS again, with some guarding")
We can do this better now. The final data structures of EXPORT_SYMBOL
are generated by the modpost stage, so modpost can selectively emit
KSYMTAB entries that are really used by modules.
Commit f73edc8951b2 ("kbuild: unify two modpost invocations") is another
ground-work to do this in a one-pass algorithm. With the list of modules,
modpost sets sym->used if it is used by a module. modpost emits KSYMTAB
only for symbols with sym->used==true.
BTW, Nicolas explained why the trimming was implemented with recursion:
https://lore.kernel.org/all/2o2rpn97-79nq-p7s2-nq5-8p83391473r@syhkavp.arg/
Actually, we never achieved that level of optimization where the chain
reaction of trimming comes into play because:
- CONFIG_LTO_CLANG cannot remove any unused symbols
- CONFIG_LD_DEAD_CODE_DATA_ELIMINATION is enabled only for vmlinux,
but not modules
If deeper trimming is required, we need to revisit this, but I guess
that is unlikely to happen.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---
Changes in v7:
- Remove *.usyms
Changes in v5:
- Clean up more
.gitignore | 2 -
Makefile | 22 ++---------
include/linux/export.h | 67 +++++-----------------------------
scripts/Makefile.build | 15 +-------
scripts/Makefile.modpost | 7 ++++
scripts/adjust_autoksyms.sh | 73 -------------------------------------
scripts/basic/fixdep.c | 3 +-
scripts/gen_autoksyms.sh | 62 -------------------------------
scripts/gen_ksymdeps.sh | 30 ---------------
scripts/mod/modpost.c | 54 ++++++++++++++++++++++++---
scripts/remove-stale-files | 4 ++
11 files changed, 75 insertions(+), 264 deletions(-)
delete mode 100755 scripts/adjust_autoksyms.sh
delete mode 100755 scripts/gen_autoksyms.sh
delete mode 100755 scripts/gen_ksymdeps.sh
diff --git a/.gitignore b/.gitignore
index 7f86e0837909..c3ce78ca20d2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -51,7 +51,6 @@
*.symversions
*.tab.[ch]
*.tar
-*.usyms
*.xz
*.zst
Module.symvers
@@ -112,7 +111,6 @@ modules.order
#
/include/config/
/include/generated/
-/include/ksym/
/arch/*/include/generated/
# stgit generated dirs
diff --git a/Makefile b/Makefile
index f836936fb4d8..cc3fe09c4dec 100644
--- a/Makefile
+++ b/Makefile
@@ -1193,28 +1193,12 @@ endif
export KBUILD_VMLINUX_LIBS
export KBUILD_LDS := arch/$(SRCARCH)/kernel/vmlinux.lds
-# Recurse until adjust_autoksyms.sh is satisfied
-PHONY += autoksyms_recursive
ifdef CONFIG_TRIM_UNUSED_KSYMS
# For the kernel to actually contain only the needed exported symbols,
# we have to build modules as well to determine what those symbols are.
-# (this can be evaluated only once include/config/auto.conf has been included)
KBUILD_MODULES := 1
-
-autoksyms_recursive: $(build-dir) modules.order
- $(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh \
- "$(MAKE) -f $(srctree)/Makefile autoksyms_recursive"
endif
-autoksyms_h := $(if $(CONFIG_TRIM_UNUSED_KSYMS), include/generated/autoksyms.h)
-
-quiet_cmd_autoksyms_h = GEN $@
- cmd_autoksyms_h = mkdir -p $(dir $@); \
- $(CONFIG_SHELL) $(srctree)/scripts/gen_autoksyms.sh $@
-
-$(autoksyms_h):
- $(call cmd,autoksyms_h)
-
# '$(AR) mPi' needs 'T' to workaround the bug of llvm-ar <= 14
quiet_cmd_ar_vmlinux.a = AR $@
cmd_ar_vmlinux.a = \
@@ -1223,7 +1207,7 @@ quiet_cmd_ar_vmlinux.a = AR $@
$(AR) mPiT $$($(AR) t $@ | sed -n 1p) $@ $$($(AR) t $@ | grep -F -f $(srctree)/scripts/head-object-list.txt)
targets += vmlinux.a
-vmlinux.a: $(KBUILD_VMLINUX_OBJS) scripts/head-object-list.txt autoksyms_recursive FORCE
+vmlinux.a: $(KBUILD_VMLINUX_OBJS) scripts/head-object-list.txt FORCE
$(call if_changed,ar_vmlinux.a)
PHONY += vmlinux_o
@@ -1279,7 +1263,7 @@ scripts: scripts_basic scripts_dtc
PHONY += prepare archprepare
archprepare: outputmakefile archheaders archscripts scripts include/config/kernel.release \
- asm-generic $(version_h) $(autoksyms_h) include/generated/utsrelease.h \
+ asm-generic $(version_h) include/generated/utsrelease.h \
include/generated/compile.h include/generated/autoconf.h remove-stale-files
prepare0: archprepare
@@ -2039,7 +2023,7 @@ clean: $(clean-dirs)
-o -name '*.dtb.S' -o -name '*.dtbo.S' \
-o -name '*.dt.yaml' \
-o -name '*.dwo' -o -name '*.lst' \
- -o -name '*.su' -o -name '*.mod' -o -name '*.usyms' \
+ -o -name '*.su' -o -name '*.mod' \
-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
-o -name '*.lex.c' -o -name '*.tab.[ch]' \
-o -name '*.asn1.[ch]' \
diff --git a/include/linux/export.h b/include/linux/export.h
index 529435a821c0..fed2e5717461 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -31,7 +31,7 @@ extern struct module __this_module;
#endif
#endif /* __ASSEMBLY__ */
-#define ____EXPORT_SYMBOL(sym, license, ns) \
+#define ___EXPORT_SYMBOL(sym, license, ns) \
.section ".export_symbol","a" ; \
__export_symbol_##license##_##sym: ; \
.asciz ns ; \
@@ -39,24 +39,6 @@ extern struct module __this_module;
.long sym - . ; \
.previous
-#ifdef __GENKSYMS__
-
-#define ___EXPORT_SYMBOL(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym)
-
-#elif defined(__ASSEMBLY__)
-
-#define ___EXPORT_SYMBOL(sym, license, ns) \
- ____EXPORT_SYMBOL(sym, license, ns)
-
-#else
-
-#define ___EXPORT_SYMBOL(sym, license, ns) \
- extern typeof(sym) sym; \
- __ADDRESSABLE(sym) \
- asm(__stringify(____EXPORT_SYMBOL(sym, license, ns)))
-
-#endif
-
#if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS)
/*
@@ -66,50 +48,21 @@ extern struct module __this_module;
*/
#define __EXPORT_SYMBOL(sym, sec, ns)
-#elif defined(CONFIG_TRIM_UNUSED_KSYMS)
+#elif defined(__GENKSYMS__)
-#include <generated/autoksyms.h>
+#define __EXPORT_SYMBOL(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym)
-/*
- * For fine grained build dependencies, we want to tell the build system
- * about each possible exported symbol even if they're not actually exported.
- * We use a symbol pattern __ksym_marker_<symbol> that the build system filters
- * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are
- * discarded in the final link stage.
- */
+#elif defined(__ASSEMBLY__)
-#ifdef __ASSEMBLY__
-
-#define __ksym_marker(sym) \
- .section ".discard.ksym","a" ; \
-__ksym_marker_##sym: ; \
- .previous
+#define __EXPORT_SYMBOL(sym, license, ns) \
+ ___EXPORT_SYMBOL(sym, license, ns)
#else
-#define __ksym_marker(sym) \
- static int __ksym_marker_##sym[0] __section(".discard.ksym") __used
-
-#endif
-
-#define __EXPORT_SYMBOL(sym, sec, ns) \
- __ksym_marker(sym); \
- __cond_export_sym(sym, sec, ns, __is_defined(__KSYM_##sym))
-#define __cond_export_sym(sym, sec, ns, conf) \
- ___cond_export_sym(sym, sec, ns, conf)
-#define ___cond_export_sym(sym, sec, ns, enabled) \
- __cond_export_sym_##enabled(sym, sec, ns)
-#define __cond_export_sym_1(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns)
-
-#ifdef __GENKSYMS__
-#define __cond_export_sym_0(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym)
-#else
-#define __cond_export_sym_0(sym, sec, ns) /* nothing */
-#endif
-
-#else
-
-#define __EXPORT_SYMBOL(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns)
+#define __EXPORT_SYMBOL(sym, license, ns) \
+ extern typeof(sym) sym; \
+ __ADDRESSABLE(sym) \
+ asm(__stringify(___EXPORT_SYMBOL(sym, license, ns)))
#endif /* CONFIG_MODULES */
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index bd4123795299..7e1b9ed178e8 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -82,7 +82,7 @@ ifdef need-builtin
targets-for-builtin += $(obj)/built-in.a
endif
-targets-for-modules := $(foreach x, o mod $(if $(CONFIG_TRIM_UNUSED_KSYMS), usyms), \
+targets-for-modules := $(foreach x, o mod, \
$(patsubst %.o, %.$x, $(filter %.o, $(obj-m))))
ifdef need-modorder
@@ -215,18 +215,12 @@ is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(basetar
$(obj)/%.o: objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y))
-ifdef CONFIG_TRIM_UNUSED_KSYMS
-cmd_gen_ksymdeps = \
- $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd
-endif
-
ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
cmd_warn_shared_object = $(if $(word 2, $(modname-multi)),$(warning $(kbuild-file): $*.o is added to multiple modules: $(modname-multi)))
endif
define rule_cc_o_c
$(call cmd_and_fixdep,cc_o_c)
- $(call cmd,gen_ksymdeps)
$(call cmd,checksrc)
$(call cmd,checkdoc)
$(call cmd,gen_objtooldep)
@@ -237,7 +231,6 @@ endef
define rule_as_o_S
$(call cmd_and_fixdep,as_o_S)
- $(call cmd,gen_ksymdeps)
$(call cmd,gen_objtooldep)
$(call cmd,gen_symversions_S)
$(call cmd,warn_shared_object)
@@ -256,12 +249,6 @@ cmd_mod = printf '%s\n' $(call real-search, $*.o, .o, -objs -y -m) | \
$(obj)/%.mod: FORCE
$(call if_changed,mod)
-# List module undefined symbols
-cmd_undefined_syms = $(NM) $< | sed -n 's/^ *U //p' > $@
-
-$(obj)/%.usyms: $(obj)/%.o FORCE
- $(call if_changed,undefined_syms)
-
quiet_cmd_cc_lst_c = MKLST $@
cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
$(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index 074e27c0c140..65133fcdd5b8 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -91,6 +91,13 @@ targets += .vmlinux.objs
.vmlinux.objs: vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE
$(call if_changed,vmlinux_objs)
+ifdef CONFIG_TRIM_UNUSED_KSYMS
+ksym-wl := $(CONFIG_UNUSED_KSYMS_WHITELIST)
+ksym-wl := $(if $(filter-out /%, $(ksym-wl)),$(srctree)/)$(ksym-wl)
+modpost-args += -t $(addprefix -u, $(ksym-wl))
+modpost-deps += $(ksym-wl)
+endif
+
ifeq ($(wildcard vmlinux.o),)
missing-input := vmlinux.o
output-symdump := modules-only.symvers
diff --git a/scripts/adjust_autoksyms.sh b/scripts/adjust_autoksyms.sh
deleted file mode 100755
index f1b5ac818411..000000000000
--- a/scripts/adjust_autoksyms.sh
+++ /dev/null
@@ -1,73 +0,0 @@
-#!/bin/sh
-# SPDX-License-Identifier: GPL-2.0-only
-
-# Script to update include/generated/autoksyms.h and dependency files
-#
-# Copyright: (C) 2016 Linaro Limited
-# Created by: Nicolas Pitre, January 2016
-#
-
-# Update the include/generated/autoksyms.h file.
-#
-# For each symbol being added or removed, the corresponding dependency
-# file's timestamp is updated to force a rebuild of the affected source
-# file. All arguments passed to this script are assumed to be a command
-# to be exec'd to trigger a rebuild of those files.
-
-set -e
-
-cur_ksyms_file="include/generated/autoksyms.h"
-new_ksyms_file="include/generated/autoksyms.h.tmpnew"
-
-info() {
- if [ "$quiet" != "silent_" ]; then
- printf " %-7s %s\n" "$1" "$2"
- fi
-}
-
-info "CHK" "$cur_ksyms_file"
-
-# Use "make V=1" to debug this script.
-case "$KBUILD_VERBOSE" in
-*1*)
- set -x
- ;;
-esac
-
-# Generate a new symbol list file
-$CONFIG_SHELL $srctree/scripts/gen_autoksyms.sh --modorder "$new_ksyms_file"
-
-# Extract changes between old and new list and touch corresponding
-# dependency files.
-changed=$(
-count=0
-sort "$cur_ksyms_file" "$new_ksyms_file" | uniq -u |
-sed -n 's/^#define __KSYM_\(.*\) 1/\1/p' |
-while read sympath; do
- if [ -z "$sympath" ]; then continue; fi
- depfile="include/ksym/${sympath}"
- mkdir -p "$(dirname "$depfile")"
- touch "$depfile"
- # Filesystems with coarse time precision may create timestamps
- # equal to the one from a file that was very recently built and that
- # needs to be rebuild. Let's guard against that by making sure our
- # dep files are always newer than the first file we created here.
- while [ ! "$depfile" -nt "$new_ksyms_file" ]; do
- touch "$depfile"
- done
- echo $((count += 1))
-done | tail -1 )
-changed=${changed:-0}
-
-if [ $changed -gt 0 ]; then
- # Replace the old list with tne new one
- old=$(grep -c "^#define __KSYM_" "$cur_ksyms_file" || true)
- new=$(grep -c "^#define __KSYM_" "$new_ksyms_file" || true)
- info "KSYMS" "symbols: before=$old, after=$new, changed=$changed"
- info "UPD" "$cur_ksyms_file"
- mv -f "$new_ksyms_file" "$cur_ksyms_file"
- # Then trigger a rebuild of affected source files
- exec $@
-else
- rm -f "$new_ksyms_file"
-fi
diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
index fa562806c2be..84b6efa849f4 100644
--- a/scripts/basic/fixdep.c
+++ b/scripts/basic/fixdep.c
@@ -246,8 +246,7 @@ static void *read_file(const char *filename)
/* Ignore certain dependencies */
static int is_ignored_file(const char *s, int len)
{
- return str_ends_with(s, len, "include/generated/autoconf.h") ||
- str_ends_with(s, len, "include/generated/autoksyms.h");
+ return str_ends_with(s, len, "include/generated/autoconf.h");
}
/* Do not parse these files */
diff --git a/scripts/gen_autoksyms.sh b/scripts/gen_autoksyms.sh
deleted file mode 100755
index 12bcfae940ee..000000000000
--- a/scripts/gen_autoksyms.sh
+++ /dev/null
@@ -1,62 +0,0 @@
-#!/bin/sh
-# SPDX-License-Identifier: GPL-2.0-only
-
-# Create an autoksyms.h header file from the list of all module's needed symbols
-# as recorded in *.usyms files and the user-provided symbol whitelist.
-
-set -e
-
-# Use "make V=1" to debug this script.
-case "$KBUILD_VERBOSE" in
-*1*)
- set -x
- ;;
-esac
-
-read_modorder=
-
-if [ "$1" = --modorder ]; then
- shift
- read_modorder=1
-fi
-
-output_file="$1"
-
-needed_symbols=
-
-# Special case for modversions (see modpost.c)
-if grep -q "^CONFIG_MODVERSIONS=y$" include/config/auto.conf; then
- needed_symbols="$needed_symbols module_layout"
-fi
-
-ksym_wl=$(sed -n 's/^CONFIG_UNUSED_KSYMS_WHITELIST=\(.*\)$/\1/p' include/config/auto.conf)
-if [ -n "$ksym_wl" ]; then
- [ "${ksym_wl}" != "${ksym_wl#/}" ] || ksym_wl="$abs_srctree/$ksym_wl"
- if [ ! -f "$ksym_wl" ] || [ ! -r "$ksym_wl" ]; then
- echo "ERROR: '$ksym_wl' whitelist file not found" >&2
- exit 1
- fi
-fi
-
-# Generate a new ksym list file with symbols needed by the current
-# set of modules.
-cat > "$output_file" << EOT
-/*
- * Automatically generated file; DO NOT EDIT.
- */
-
-EOT
-
-{
- [ -n "${read_modorder}" ] && sed 's/o$/usyms/' modules.order | xargs cat
- echo "$needed_symbols"
- [ -n "$ksym_wl" ] && cat "$ksym_wl"
-} | sed -e 's/ /\n/g' | sed -n -e '/^$/!p' |
-# Remove the dot prefix for ppc64; symbol names with a dot (.) hold entry
-# point addresses.
-sed -e 's/^\.//' |
-sort -u |
-# Ignore __this_module. It's not an exported symbol, and will be resolved
-# when the final .ko's are linked.
-grep -v '^__this_module$' |
-sed -e 's/\(.*\)/#define __KSYM_\1 1/' >> "$output_file"
diff --git a/scripts/gen_ksymdeps.sh b/scripts/gen_ksymdeps.sh
deleted file mode 100755
index 8ee533f33659..000000000000
--- a/scripts/gen_ksymdeps.sh
+++ /dev/null
@@ -1,30 +0,0 @@
-#!/bin/sh
-# SPDX-License-Identifier: GPL-2.0
-
-set -e
-
-# List of exported symbols
-#
-# If the object has no symbol, $NM warns 'no symbols'.
-# Suppress the stderr.
-# TODO:
-# Use -q instead of 2>/dev/null when we upgrade the minimum version of
-# binutils to 2.37, llvm to 13.0.0.
-ksyms=$($NM $1 2>/dev/null | sed -n 's/.*__ksym_marker_\(.*\)/\1/p')
-
-if [ -z "$ksyms" ]; then
- exit 0
-fi
-
-echo
-echo "ksymdeps_$1 := \\"
-
-for s in $ksyms
-do
- printf ' $(wildcard include/ksym/%s) \\\n' "$s"
-done
-
-echo
-echo "$1: \$(ksymdeps_$1)"
-echo
-echo "\$(ksymdeps_$1):"
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 7044b257424a..decb7d23ef9f 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -35,6 +35,9 @@ static bool warn_unresolved;
static int sec_mismatch_count;
static bool sec_mismatch_warn_only = true;
+/* Trim EXPORT_SYMBOLs that are unused by in-tree modules */
+static bool trim_unused_exports;
+
/* ignore missing files */
static bool ignore_missing_files;
/* If set to 1, only warn (instead of error) about missing ns imports */
@@ -219,6 +222,7 @@ struct symbol {
bool weak;
bool is_func;
bool is_gpl_only; /* exported by EXPORT_SYMBOL_GPL */
+ bool used; /* there exists a user of this symbol */
char name[];
};
@@ -1820,6 +1824,7 @@ static void check_exports(struct module *mod)
continue;
}
+ exp->used = true;
s->module = exp->module;
s->crc_valid = exp->crc_valid;
s->crc = exp->crc;
@@ -1843,6 +1848,23 @@ static void check_exports(struct module *mod)
}
}
+static void handle_white_list_exports(const char *white_list)
+{
+ char *buf, *p, *name;
+
+ buf = read_text_file(white_list);
+ p = buf;
+
+ while ((name = strsep(&p, "\n"))) {
+ struct symbol *sym = find_symbol(name);
+
+ if (sym)
+ sym->used = true;
+ }
+
+ free(buf);
+}
+
static void check_modname_len(struct module *mod)
{
const char *mod_name;
@@ -1913,10 +1935,14 @@ static void add_exported_symbols(struct buffer *buf, struct module *mod)
/* generate struct for exported symbols */
buf_printf(buf, "\n");
- list_for_each_entry(sym, &mod->exported_symbols, list)
+ list_for_each_entry(sym, &mod->exported_symbols, list) {
+ if (trim_unused_exports && !sym->used)
+ continue;
+
buf_printf(buf, "KSYMTAB_%s(%s, \"%s\", \"%s\");\n",
sym->is_func ? "FUNC" : "DATA", sym->name,
sym->is_gpl_only ? "_gpl" : "", sym->namespace);
+ }
if (!modversions)
return;
@@ -1924,6 +1950,9 @@ static void add_exported_symbols(struct buffer *buf, struct module *mod)
/* record CRCs for exported symbols */
buf_printf(buf, "\n");
list_for_each_entry(sym, &mod->exported_symbols, list) {
+ if (trim_unused_exports && !sym->used)
+ continue;
+
if (!sym->crc_valid)
warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n"
"Is \"%s\" prototyped in <asm/asm-prototypes.h>?\n",
@@ -2087,9 +2116,6 @@ static void write_mod_c_file(struct module *mod)
char fname[PATH_MAX];
int ret;
- check_modname_len(mod);
- check_exports(mod);
-
add_header(&buf, mod);
add_exported_symbols(&buf, mod);
add_versions(&buf, mod);
@@ -2223,12 +2249,13 @@ int main(int argc, char **argv)
{
struct module *mod;
char *missing_namespace_deps = NULL;
+ char *unused_exports_white_list = NULL;
char *dump_write = NULL, *files_source = NULL;
int opt;
LIST_HEAD(dump_lists);
struct dump_list *dl, *dl2;
- while ((opt = getopt(argc, argv, "ei:mnT:o:aWwENd:")) != -1) {
+ while ((opt = getopt(argc, argv, "ei:mnTt:o:auWwENd:")) != -1) {
switch (opt) {
case 'e':
external_module = true;
@@ -2253,6 +2280,12 @@ int main(int argc, char **argv)
case 'T':
files_source = optarg;
break;
+ case 't':
+ trim_unused_exports = true;
+ break;
+ case 'u':
+ unused_exports_white_list = optarg;
+ break;
case 'W':
extra_warn = true;
break;
@@ -2285,6 +2318,17 @@ int main(int argc, char **argv)
if (files_source)
read_symbols_from_files(files_source);
+ list_for_each_entry(mod, &modules, list) {
+ if (mod->from_dump || mod->is_vmlinux)
+ continue;
+
+ check_modname_len(mod);
+ check_exports(mod);
+ }
+
+ if (unused_exports_white_list)
+ handle_white_list_exports(unused_exports_white_list);
+
list_for_each_entry(mod, &modules, list) {
if (mod->from_dump)
continue;
diff --git a/scripts/remove-stale-files b/scripts/remove-stale-files
index 7f432900671a..f3659ea0335b 100755
--- a/scripts/remove-stale-files
+++ b/scripts/remove-stale-files
@@ -33,3 +33,7 @@ rm -f rust/target.json
rm -f scripts/bin2c
rm -f .scmversion
+
+rm -rf include/ksym
+
+find . -name '*.usyms' | xargs rm -f
--
2.39.2
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v7 09/11] modpost: merge two similar section mismatch warnings
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
` (7 preceding siblings ...)
2023-06-08 14:24 ` [PATCH v7 08/11] kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion Masahiro Yamada
@ 2023-06-08 14:24 ` Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 10/11] modpost: show offset from symbol for " Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 11/11] linux/export.h: rename 'sec' argument to 'license' Masahiro Yamada
10 siblings, 0 replies; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
In case of section mismatch, modpost shows slightly different messages.
For extable section mismatch:
"%s(%s+0x%lx): Section mismatch in reference to the %s:%s\n"
For the other cases:
"%s: section mismatch in reference: %s (section: %s) -> %s (section: %s)\n"
They are similar. Merge them.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
---
scripts/mod/modpost.c | 18 +++---------------
1 file changed, 3 insertions(+), 15 deletions(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index decb7d23ef9f..85df3f3ba9ee 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1147,21 +1147,10 @@ static void default_mismatch_handler(const char *modname, struct elf_info *elf,
sec_mismatch_count++;
- switch (mismatch->mismatch) {
- case TEXT_TO_ANY_INIT:
- case DATA_TO_ANY_INIT:
- case TEXTDATA_TO_ANY_EXIT:
- case XXXINIT_TO_SOME_INIT:
- case XXXEXIT_TO_SOME_EXIT:
- case ANY_INIT_TO_ANY_EXIT:
- case ANY_EXIT_TO_ANY_INIT:
- warn("%s: section mismatch in reference: %s (section: %s) -> %s (section: %s)\n",
- modname, fromsym, fromsec, tosym, tosec);
- break;
- case EXTABLE_TO_NON_TEXT:
- warn("%s(%s+0x%lx): Section mismatch in reference to the %s:%s\n",
- modname, fromsec, (long)faddr, tosec, tosym);
+ warn("%s: section mismatch in reference: %s (section: %s) -> %s (section: %s)\n",
+ modname, fromsym, fromsec, tosym, tosec);
+ if (mismatch->mismatch == EXTABLE_TO_NON_TEXT) {
if (match(tosec, mismatch->bad_tosec))
fatal("The relocation at %s+0x%lx references\n"
"section \"%s\" which is black-listed.\n"
@@ -1181,7 +1170,6 @@ static void default_mismatch_handler(const char *modname, struct elf_info *elf,
else
error("%s+0x%lx references non-executable section '%s'\n",
fromsec, (long)faddr, tosec);
- break;
}
}
--
2.39.2
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v7 10/11] modpost: show offset from symbol for section mismatch warnings
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
` (8 preceding siblings ...)
2023-06-08 14:24 ` [PATCH v7 09/11] modpost: merge two similar section mismatch warnings Masahiro Yamada
@ 2023-06-08 14:24 ` Masahiro Yamada
2023-06-09 21:26 ` Nick Desaulniers
2023-06-08 14:24 ` [PATCH v7 11/11] linux/export.h: rename 'sec' argument to 'license' Masahiro Yamada
10 siblings, 1 reply; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
Currently, modpost only shows the symbol names and section names, so it
repeats the same message if there are multiple relocations in the same
symbol. It is common the relocation spans across multiple instructions.
It is better to show the offset from the symbol.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---
scripts/mod/modpost.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 85df3f3ba9ee..40967ed816df 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1147,8 +1147,8 @@ static void default_mismatch_handler(const char *modname, struct elf_info *elf,
sec_mismatch_count++;
- warn("%s: section mismatch in reference: %s (section: %s) -> %s (section: %s)\n",
- modname, fromsym, fromsec, tosym, tosec);
+ warn("%s: section mismatch in reference: %s+0x%x (section: %s) -> %s (section: %s)\n",
+ modname, fromsym, (unsigned int)(faddr - from->st_value), fromsec, tosym, tosec);
if (mismatch->mismatch == EXTABLE_TO_NON_TEXT) {
if (match(tosec, mismatch->bad_tosec))
--
2.39.2
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v7 11/11] linux/export.h: rename 'sec' argument to 'license'
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
` (9 preceding siblings ...)
2023-06-08 14:24 ` [PATCH v7 10/11] modpost: show offset from symbol for " Masahiro Yamada
@ 2023-06-08 14:24 ` Masahiro Yamada
2023-06-09 21:29 ` Nick Desaulniers
10 siblings, 1 reply; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-08 14:24 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um, Masahiro Yamada
Now, EXPORT_SYMBOL() is populated in two stages. In the first stage,
all of EXPORT_SYMBOL/EXPORT_SYMBOL_GPL go into the same section,
.export_symbol.
'sec' does not make sense any more. Rename it to 'license'.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---
Changes in v7:
- New patch
include/linux/export.h | 8 ++++----
include/linux/pm.h | 6 +++---
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/include/linux/export.h b/include/linux/export.h
index fed2e5717461..b411fdb88720 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -46,11 +46,11 @@ extern struct module __this_module;
* be reused in other execution contexts such as the UEFI stub or the
* decompressor.
*/
-#define __EXPORT_SYMBOL(sym, sec, ns)
+#define __EXPORT_SYMBOL(sym, license, ns)
#elif defined(__GENKSYMS__)
-#define __EXPORT_SYMBOL(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym)
+#define __EXPORT_SYMBOL(sym, license, ns) __GENKSYMS_EXPORT_SYMBOL(sym)
#elif defined(__ASSEMBLY__)
@@ -67,9 +67,9 @@ extern struct module __this_module;
#endif /* CONFIG_MODULES */
#ifdef DEFAULT_SYMBOL_NAMESPACE
-#define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, __stringify(DEFAULT_SYMBOL_NAMESPACE))
+#define _EXPORT_SYMBOL(sym, license) __EXPORT_SYMBOL(sym, license, __stringify(DEFAULT_SYMBOL_NAMESPACE))
#else
-#define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, "")
+#define _EXPORT_SYMBOL(sym, license) __EXPORT_SYMBOL(sym, license, "")
#endif
#define EXPORT_SYMBOL(sym) _EXPORT_SYMBOL(sym,)
diff --git a/include/linux/pm.h b/include/linux/pm.h
index aabb6bd8f89e..1810d776e84a 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -375,14 +375,14 @@ const struct dev_pm_ops name = { \
}
#ifdef CONFIG_PM
-#define _EXPORT_DEV_PM_OPS(name, sec, ns) \
+#define _EXPORT_DEV_PM_OPS(name, license, ns) \
const struct dev_pm_ops name; \
- __EXPORT_SYMBOL(name, sec, ns); \
+ __EXPORT_SYMBOL(name, license, ns); \
const struct dev_pm_ops name
#define EXPORT_PM_FN_GPL(name) EXPORT_SYMBOL_GPL(name)
#define EXPORT_PM_FN_NS_GPL(name, ns) EXPORT_SYMBOL_NS_GPL(name, ns)
#else
-#define _EXPORT_DEV_PM_OPS(name, sec, ns) \
+#define _EXPORT_DEV_PM_OPS(name, license, ns) \
static __maybe_unused const struct dev_pm_ops __static_##name
#define EXPORT_PM_FN_GPL(name)
#define EXPORT_PM_FN_NS_GPL(name, ns)
--
2.39.2
^ permalink raw reply related [flat|nested] 20+ messages in thread
* Re: [PATCH v7 01/11] Revert "[PATCH] uml: export symbols added by GCC hardened"
2023-06-08 14:24 ` [PATCH v7 01/11] Revert "[PATCH] uml: export symbols added by GCC hardened" Masahiro Yamada
@ 2023-06-09 21:23 ` Nick Desaulniers
0 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2023-06-09 21:23 UTC (permalink / raw)
To: Masahiro Yamada
Cc: linux-kbuild, linux-kernel, Nathan Chancellor, Nicolas Schier,
linux-um
On Thu, Jun 8, 2023 at 7:24 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> This reverts commit cead61a6717a9873426b08d73a34a325e3546f5d.
>
> It exported __stack_smash_handler and __guard, while they may not be
> defined by anyone.
>
> The code *declares* __stack_smash_handler and __guard. It does not
> create weak symbols. When the stack-protector is disabled, they are
> left undefined, but yet exported.
>
> If a loadable module tries to access non-existing symbols, bad things
> (a page fault, NULL pointer dereference, etc.) will happen. So, the
> current code is wrong.
>
> If the code were written as follows, it would *define* them as weak
> symbols so modules would be able to get access to them.
>
> void (*__stack_smash_handler)(void *) __attribute__((weak));
> EXPORT_SYMBOL(__stack_smash_handler);
>
> long __guard __attribute__((weak));
> EXPORT_SYMBOL(__guard);
>
> In fact, modpost forbids exporting undefined symbols. It shows an error
> message if it detects such a mistake.
>
> ERROR: modpost: "..." [...] was exported without definition
>
> Unfortunately, it is checked only when the code is built as modular.
> The problem described above has been unnoticed for a long time because
> arch/um/os-Linux/user_syms.c is always built-in.
>
> With a planned change in Kbuild, exporting undefined symbols will always
> result in a build error instead of a run-time error. It is a good thing,
> but we need to fix the breakage in advance.
>
> One fix is to *define* weak symbols as shown above. An alternative is
> to export them conditionally as follows:
>
> #ifdef CONFIG_STACKPROTECTOR
> extern void __stack_smash_handler(void *);
> EXPORT_SYMBOL(__stack_smash_handler);
>
> external long __guard;
> EXPORT_SYMBOL(__guard);
> #endif
>
> This is what other architectures do; EXPORT_SYMBOL(__stack_chk_guard)
> is guarded by #ifdef CONFIG_STACKPROTECTOR.
>
> However, adding the #ifdef guard is not sensible because UML cannot
> enable the stack-protector in the first place! (Please note UML does
> not select HAVE_STACKPROTECTOR in Kconfig.)
>
> So, the code is already broken (and unused) in multiple ways.
>
> Just remove.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Thanks for the patch!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
>
> Changes in v7:
> - New patch
>
> arch/um/os-Linux/user_syms.c | 7 -------
> 1 file changed, 7 deletions(-)
>
> diff --git a/arch/um/os-Linux/user_syms.c b/arch/um/os-Linux/user_syms.c
> index 9b62a9d352b3..a310ae27b479 100644
> --- a/arch/um/os-Linux/user_syms.c
> +++ b/arch/um/os-Linux/user_syms.c
> @@ -37,13 +37,6 @@ EXPORT_SYMBOL(vsyscall_ehdr);
> EXPORT_SYMBOL(vsyscall_end);
> #endif
>
> -/* Export symbols used by GCC for the stack protector. */
> -extern void __stack_smash_handler(void *) __attribute__((weak));
> -EXPORT_SYMBOL(__stack_smash_handler);
> -
> -extern long __guard __attribute__((weak));
> -EXPORT_SYMBOL(__guard);
> -
> #ifdef _FORTIFY_SOURCE
> extern int __sprintf_chk(char *str, int flag, size_t len, const char *format);
> EXPORT_SYMBOL(__sprintf_chk);
> --
> 2.39.2
>
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v7 10/11] modpost: show offset from symbol for section mismatch warnings
2023-06-08 14:24 ` [PATCH v7 10/11] modpost: show offset from symbol for " Masahiro Yamada
@ 2023-06-09 21:26 ` Nick Desaulniers
0 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2023-06-09 21:26 UTC (permalink / raw)
To: Masahiro Yamada
Cc: linux-kbuild, linux-kernel, Nathan Chancellor, Nicolas Schier,
linux-um
On Thu, Jun 8, 2023 at 7:24 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> Currently, modpost only shows the symbol names and section names, so it
> repeats the same message if there are multiple relocations in the same
> symbol. It is common the relocation spans across multiple instructions.
>
> It is better to show the offset from the symbol.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Thanks for the patch!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
>
> scripts/mod/modpost.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 85df3f3ba9ee..40967ed816df 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -1147,8 +1147,8 @@ static void default_mismatch_handler(const char *modname, struct elf_info *elf,
>
> sec_mismatch_count++;
>
> - warn("%s: section mismatch in reference: %s (section: %s) -> %s (section: %s)\n",
> - modname, fromsym, fromsec, tosym, tosec);
> + warn("%s: section mismatch in reference: %s+0x%x (section: %s) -> %s (section: %s)\n",
> + modname, fromsym, (unsigned int)(faddr - from->st_value), fromsec, tosym, tosec);
>
> if (mismatch->mismatch == EXTABLE_TO_NON_TEXT) {
> if (match(tosec, mismatch->bad_tosec))
> --
> 2.39.2
>
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v7 11/11] linux/export.h: rename 'sec' argument to 'license'
2023-06-08 14:24 ` [PATCH v7 11/11] linux/export.h: rename 'sec' argument to 'license' Masahiro Yamada
@ 2023-06-09 21:29 ` Nick Desaulniers
0 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2023-06-09 21:29 UTC (permalink / raw)
To: Masahiro Yamada
Cc: linux-kbuild, linux-kernel, Nathan Chancellor, Nicolas Schier,
linux-um
On Thu, Jun 8, 2023 at 7:24 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> Now, EXPORT_SYMBOL() is populated in two stages. In the first stage,
> all of EXPORT_SYMBOL/EXPORT_SYMBOL_GPL go into the same section,
> .export_symbol.
>
> 'sec' does not make sense any more. Rename it to 'license'.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Thanks for the patch!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
>
> Changes in v7:
> - New patch
>
> include/linux/export.h | 8 ++++----
> include/linux/pm.h | 6 +++---
> 2 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/export.h b/include/linux/export.h
> index fed2e5717461..b411fdb88720 100644
> --- a/include/linux/export.h
> +++ b/include/linux/export.h
> @@ -46,11 +46,11 @@ extern struct module __this_module;
> * be reused in other execution contexts such as the UEFI stub or the
> * decompressor.
> */
> -#define __EXPORT_SYMBOL(sym, sec, ns)
> +#define __EXPORT_SYMBOL(sym, license, ns)
>
> #elif defined(__GENKSYMS__)
>
> -#define __EXPORT_SYMBOL(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym)
> +#define __EXPORT_SYMBOL(sym, license, ns) __GENKSYMS_EXPORT_SYMBOL(sym)
>
> #elif defined(__ASSEMBLY__)
>
> @@ -67,9 +67,9 @@ extern struct module __this_module;
> #endif /* CONFIG_MODULES */
>
> #ifdef DEFAULT_SYMBOL_NAMESPACE
> -#define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, __stringify(DEFAULT_SYMBOL_NAMESPACE))
> +#define _EXPORT_SYMBOL(sym, license) __EXPORT_SYMBOL(sym, license, __stringify(DEFAULT_SYMBOL_NAMESPACE))
> #else
> -#define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, "")
> +#define _EXPORT_SYMBOL(sym, license) __EXPORT_SYMBOL(sym, license, "")
> #endif
>
> #define EXPORT_SYMBOL(sym) _EXPORT_SYMBOL(sym,)
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index aabb6bd8f89e..1810d776e84a 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -375,14 +375,14 @@ const struct dev_pm_ops name = { \
> }
>
> #ifdef CONFIG_PM
> -#define _EXPORT_DEV_PM_OPS(name, sec, ns) \
> +#define _EXPORT_DEV_PM_OPS(name, license, ns) \
> const struct dev_pm_ops name; \
> - __EXPORT_SYMBOL(name, sec, ns); \
> + __EXPORT_SYMBOL(name, license, ns); \
> const struct dev_pm_ops name
> #define EXPORT_PM_FN_GPL(name) EXPORT_SYMBOL_GPL(name)
> #define EXPORT_PM_FN_NS_GPL(name, ns) EXPORT_SYMBOL_NS_GPL(name, ns)
> #else
> -#define _EXPORT_DEV_PM_OPS(name, sec, ns) \
> +#define _EXPORT_DEV_PM_OPS(name, license, ns) \
> static __maybe_unused const struct dev_pm_ops __static_##name
> #define EXPORT_PM_FN_GPL(name)
> #define EXPORT_PM_FN_NS_GPL(name, ns)
> --
> 2.39.2
>
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost
2023-06-08 14:24 ` [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost Masahiro Yamada
@ 2023-06-09 21:34 ` Nick Desaulniers
2023-06-10 8:56 ` Masahiro Yamada
2023-06-21 16:15 ` Guenter Roeck
2 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2023-06-09 21:34 UTC (permalink / raw)
To: Masahiro Yamada
Cc: linux-kbuild, linux-kernel, Nathan Chancellor, Nicolas Schier,
linux-um
On Thu, Jun 8, 2023 at 7:24 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing
> CONFIG_MODULE_REL_CRCS") made modpost output CRCs in the same way
> whether the EXPORT_SYMBOL() is placed in *.c or *.S.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Thanks for the patch!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost
2023-06-08 14:24 ` [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost Masahiro Yamada
2023-06-09 21:34 ` Nick Desaulniers
@ 2023-06-10 8:56 ` Masahiro Yamada
2023-06-21 16:15 ` Guenter Roeck
2 siblings, 0 replies; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-10 8:56 UTC (permalink / raw)
To: linux-kbuild
Cc: linux-kernel, Nathan Chancellor, Nick Desaulniers, Nicolas Schier,
linux-um
On Thu, Jun 8, 2023 at 11:24 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing
> CONFIG_MODULE_REL_CRCS") made modpost output CRCs in the same way
> whether the EXPORT_SYMBOL() is placed in *.c or *.S.
>
> For further cleanups, this commit applies a similar approach to the
> entire data structure of EXPORT_SYMBOL().
>
> The EXPORT_SYMBOL() compilation is split into two stages.
>
> When a source file is compiled, EXPORT_SYMBOL() is converted into a
> dummy symbol in the .export_symbol section.
>
> For example,
>
> EXPORT_SYMBOL(foo);
> EXPORT_SYMBOL_NS_GPL(bar, BAR_NAMESPACE);
>
> will be encoded into the following assembly code:
>
> .section ".export_symbol","a"
> __export_symbol__foo:
> .asciz ""
> .balign 4
> .long foo - .
I hope this will work for all arches, but
unfortunately, the 0day bot reported breakages
on xtensa.
I will restore the code in v6.
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost
2023-06-08 14:24 ` [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost Masahiro Yamada
2023-06-09 21:34 ` Nick Desaulniers
2023-06-10 8:56 ` Masahiro Yamada
@ 2023-06-21 16:15 ` Guenter Roeck
2023-06-22 2:26 ` Masahiro Yamada
2 siblings, 1 reply; 20+ messages in thread
From: Guenter Roeck @ 2023-06-21 16:15 UTC (permalink / raw)
To: Masahiro Yamada
Cc: linux-kbuild, linux-kernel, Nathan Chancellor, Nick Desaulniers,
Nicolas Schier, linux-um
On Thu, Jun 08, 2023 at 11:24:20PM +0900, Masahiro Yamada wrote:
> Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing
> CONFIG_MODULE_REL_CRCS") made modpost output CRCs in the same way
> whether the EXPORT_SYMBOL() is placed in *.c or *.S.
>
...
> We can do this better now; modpost can selectively emit KSYMTAB entries
> that are really used by modules.
>
This patch results in
Building alpha:defconfig ... failed
--------------
Error log:
<stdin>:1519:2: warning: #warning syscall clone3 not implemented [-Wcpp]
WARNING: modpost: "saved_config" [vmlinux] is COMMON symbol
ERROR: modpost: vmlinux: page_is_ram: EXPORT_SYMBOL used for init symbol. Remove __init or EXPORT_SYMBOL.
I don't know if other architectures are affected - linux-next is so broken
that it is difficult to find root causes for all the breakages.
Guenter
---
Bisect log:
# bad: [15e71592dbae49a674429c618a10401d7f992ac3] Add linux-next specific files for 20230621
# good: [45a3e24f65e90a047bef86f927ebdc4c710edaa1] Linux 6.4-rc7
git bisect start 'HEAD' 'v6.4-rc7'
# bad: [e867e67cd55ae460c860ffd896c7fc96add2821c] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git
git bisect bad e867e67cd55ae460c860ffd896c7fc96add2821c
# bad: [57b289d5b1005a9c39d6d6567e0ef6115bd59cea] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git
git bisect bad 57b289d5b1005a9c39d6d6567e0ef6115bd59cea
# bad: [dc6399fc9ae6d2530fc38fb3ae96bcc8393bd66f] Merge branch 'for-next/perf' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git
git bisect bad dc6399fc9ae6d2530fc38fb3ae96bcc8393bd66f
# good: [6d366ba598334a0457d917a7bf38efd118c5b7be] Merge branch 'mm-stable' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
git bisect good 6d366ba598334a0457d917a7bf38efd118c5b7be
# good: [82fe2e45cdb00de4fa648050ae33bdadf9b3294a] perf pmus: Check if we can encode the PMU number in perf_event_attr.type
git bisect good 82fe2e45cdb00de4fa648050ae33bdadf9b3294a
# bad: [d2fa756910f88c2f5871775483744407cbf67933] Merge branch 'for-next' of git://git.infradead.org/users/hch/dma-mapping.git
git bisect bad d2fa756910f88c2f5871775483744407cbf67933
# good: [1b990bc8edc396a37a3ff1a43f7c329c361ee07c] Merge branch 'mm-nonmm-unstable' into mm-everything
git bisect good 1b990bc8edc396a37a3ff1a43f7c329c361ee07c
# good: [cff6e7f50bd315e5b39c4e46c704ac587ceb965f] kbuild: Add CLANG_FLAGS to as-instr
git bisect good cff6e7f50bd315e5b39c4e46c704ac587ceb965f
# bad: [8f3847e175a0044e2212fef772e7fa912270cd6d] ia64,export.h: replace EXPORT_DATA_SYMBOL* with EXPORT_SYMBOL*
git bisect bad 8f3847e175a0044e2212fef772e7fa912270cd6d
# good: [3a3f1e573a105328a2cca45a7cfbebabbf5e3192] modpost: fix off by one in is_executable_section()
git bisect good 3a3f1e573a105328a2cca45a7cfbebabbf5e3192
# good: [92e74fb6e6196d642505ae2b74a8e327202afef9] scripts/kallsyms: constify long_options
git bisect good 92e74fb6e6196d642505ae2b74a8e327202afef9
# good: [92e2921eeafdfca9acd9b83f07d2b7ca099bac24] ARC: define ASM_NL and __ALIGN(_STR) outside #ifdef __ASSEMBLY__ guard
git bisect good 92e2921eeafdfca9acd9b83f07d2b7ca099bac24
# bad: [bb2aa9a94b41b883037a56709d995c269204ade0] kbuild: generate KSYMTAB entries by modpost
git bisect bad bb2aa9a94b41b883037a56709d995c269204ade0
# good: [94d6cb68124b7a63f24fcc345795ba5f9a27e694] modpost: pass struct module pointer to check_section_mismatch()
git bisect good 94d6cb68124b7a63f24fcc345795ba5f9a27e694
# first bad commit: [bb2aa9a94b41b883037a56709d995c269204ade0] kbuild: generate KSYMTAB entries by modpost
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost
2023-06-21 16:15 ` Guenter Roeck
@ 2023-06-22 2:26 ` Masahiro Yamada
2023-06-22 16:20 ` Nick Desaulniers
0 siblings, 1 reply; 20+ messages in thread
From: Masahiro Yamada @ 2023-06-22 2:26 UTC (permalink / raw)
To: Guenter Roeck
Cc: linux-kbuild, linux-kernel, Nathan Chancellor, Nick Desaulniers,
Nicolas Schier, linux-um
On Thu, Jun 22, 2023 at 1:15 AM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On Thu, Jun 08, 2023 at 11:24:20PM +0900, Masahiro Yamada wrote:
> > Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing
> > CONFIG_MODULE_REL_CRCS") made modpost output CRCs in the same way
> > whether the EXPORT_SYMBOL() is placed in *.c or *.S.
> >
> ...
>
> > We can do this better now; modpost can selectively emit KSYMTAB entries
> > that are really used by modules.
> >
>
> This patch results in
>
> Building alpha:defconfig ... failed
> --------------
> Error log:
> <stdin>:1519:2: warning: #warning syscall clone3 not implemented [-Wcpp]
> WARNING: modpost: "saved_config" [vmlinux] is COMMON symbol
> ERROR: modpost: vmlinux: page_is_ram: EXPORT_SYMBOL used for init symbol. Remove __init or EXPORT_SYMBOL.
>
> I don't know if other architectures are affected - linux-next is so broken
> that it is difficult to find root causes for all the breakages.
Thanks for the comprehensive build tests.
If you compare the build log, you will see
what has happened.
In Linus' tree (without this patch),
MODPOST Module.symvers
WARNING: modpost: "saved_config" [vmlinux] is COMMON symbol
WARNING: modpost: vmlinux.o: EXPORT_SYMBOL used for init/exit symbol:
page_is_ram (section: .init.text)
In linux-next (with this patch),
MODPOST Module.symvers
WARNING: modpost: "saved_config" [vmlinux] is COMMON symbol
ERROR: modpost: vmlinux: page_is_ram: EXPORT_SYMBOL used for init
symbol. Remove __init or EXPORT_SYMBOL.
The change is obvious - I just turned the combination
of __init and EXPORT_SYMBOL into an error.
But, it seemed too early to do this.
I will hold it back as a warning for now, as follows:
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index bdf4244da993..412115a8202a 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1239,10 +1239,10 @@ static void check_export_symbol(struct module
*mod, struct elf_info *elf,
s->is_func = (ELF_ST_TYPE(sym->st_info) == STT_FUNC);
if (match(secname, PATTERNS(INIT_SECTIONS)))
- error("%s: %s: EXPORT_SYMBOL used for init symbol.
Remove __init or EXPORT_SYMBOL.\n",
+ warn("%s: %s: EXPORT_SYMBOL used for init symbol.
Remove __init or EXPORT_SYMBOL.\n",
mod->name, name);
else if (match(secname, PATTERNS(EXIT_SECTIONS)))
- error("%s: %s: EXPORT_SYMBOL used for exit symbol.
Remove __exit or EXPORT_SYMBOL.\n",
+ warn("%s: %s: EXPORT_SYMBOL used for exit symbol.
Remove __exit or EXPORT_SYMBOL.\n",
mod->name, name);
}
Fixing the alpha code is trivial.
diff --git a/arch/alpha/kernel/setup.c b/arch/alpha/kernel/setup.c
index 33bf3a627002..22131e2a9f57 100644
--- a/arch/alpha/kernel/setup.c
+++ b/arch/alpha/kernel/setup.c
@@ -385,7 +385,7 @@ setup_memory(void *kernel_end)
#endif /* CONFIG_BLK_DEV_INITRD */
}
-int __init
+int
page_is_ram(unsigned long pfn)
{
struct memclust_struct * cluster;
I do not know much about the warning for "saved_config".
__attribute((common)) was added in the following commit:
https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=3c7940961fbf9f252e20f9c455f2fe63f273294c
It was more than 20 years ago, and there is
no commit description.
I do not know the intention of __attribute((common)).
I hope the maintainers will fix the warnings,
but I do not know if it is likely to happen.
MAINTAINERS says "Odd Fixes"
If you find a build regression, please let me know.
So far, I did not get new reports from 0day bot.
Thanks.
> Guenter
>
> ---
> Bisect log:
>
> # bad: [15e71592dbae49a674429c618a10401d7f992ac3] Add linux-next specific files for 20230621
> # good: [45a3e24f65e90a047bef86f927ebdc4c710edaa1] Linux 6.4-rc7
> git bisect start 'HEAD' 'v6.4-rc7'
> # bad: [e867e67cd55ae460c860ffd896c7fc96add2821c] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git
> git bisect bad e867e67cd55ae460c860ffd896c7fc96add2821c
> # bad: [57b289d5b1005a9c39d6d6567e0ef6115bd59cea] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git
> git bisect bad 57b289d5b1005a9c39d6d6567e0ef6115bd59cea
> # bad: [dc6399fc9ae6d2530fc38fb3ae96bcc8393bd66f] Merge branch 'for-next/perf' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git
> git bisect bad dc6399fc9ae6d2530fc38fb3ae96bcc8393bd66f
> # good: [6d366ba598334a0457d917a7bf38efd118c5b7be] Merge branch 'mm-stable' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> git bisect good 6d366ba598334a0457d917a7bf38efd118c5b7be
> # good: [82fe2e45cdb00de4fa648050ae33bdadf9b3294a] perf pmus: Check if we can encode the PMU number in perf_event_attr.type
> git bisect good 82fe2e45cdb00de4fa648050ae33bdadf9b3294a
> # bad: [d2fa756910f88c2f5871775483744407cbf67933] Merge branch 'for-next' of git://git.infradead.org/users/hch/dma-mapping.git
> git bisect bad d2fa756910f88c2f5871775483744407cbf67933
> # good: [1b990bc8edc396a37a3ff1a43f7c329c361ee07c] Merge branch 'mm-nonmm-unstable' into mm-everything
> git bisect good 1b990bc8edc396a37a3ff1a43f7c329c361ee07c
> # good: [cff6e7f50bd315e5b39c4e46c704ac587ceb965f] kbuild: Add CLANG_FLAGS to as-instr
> git bisect good cff6e7f50bd315e5b39c4e46c704ac587ceb965f
> # bad: [8f3847e175a0044e2212fef772e7fa912270cd6d] ia64,export.h: replace EXPORT_DATA_SYMBOL* with EXPORT_SYMBOL*
> git bisect bad 8f3847e175a0044e2212fef772e7fa912270cd6d
> # good: [3a3f1e573a105328a2cca45a7cfbebabbf5e3192] modpost: fix off by one in is_executable_section()
> git bisect good 3a3f1e573a105328a2cca45a7cfbebabbf5e3192
> # good: [92e74fb6e6196d642505ae2b74a8e327202afef9] scripts/kallsyms: constify long_options
> git bisect good 92e74fb6e6196d642505ae2b74a8e327202afef9
> # good: [92e2921eeafdfca9acd9b83f07d2b7ca099bac24] ARC: define ASM_NL and __ALIGN(_STR) outside #ifdef __ASSEMBLY__ guard
> git bisect good 92e2921eeafdfca9acd9b83f07d2b7ca099bac24
> # bad: [bb2aa9a94b41b883037a56709d995c269204ade0] kbuild: generate KSYMTAB entries by modpost
> git bisect bad bb2aa9a94b41b883037a56709d995c269204ade0
> # good: [94d6cb68124b7a63f24fcc345795ba5f9a27e694] modpost: pass struct module pointer to check_section_mismatch()
> git bisect good 94d6cb68124b7a63f24fcc345795ba5f9a27e694
> # first bad commit: [bb2aa9a94b41b883037a56709d995c269204ade0] kbuild: generate KSYMTAB entries by modpost
--
Best Regards
Masahiro Yamada
^ permalink raw reply related [flat|nested] 20+ messages in thread
* Re: [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost
2023-06-22 2:26 ` Masahiro Yamada
@ 2023-06-22 16:20 ` Nick Desaulniers
0 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2023-06-22 16:20 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Guenter Roeck, linux-kbuild, linux-kernel, Nathan Chancellor,
Nicolas Schier, linux-um, Fangrui Song
On Wed, Jun 21, 2023 at 7:27 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Thu, Jun 22, 2023 at 1:15 AM Guenter Roeck <linux@roeck-us.net> wrote:
> >
> > On Thu, Jun 08, 2023 at 11:24:20PM +0900, Masahiro Yamada wrote:
> > > Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing
> > > CONFIG_MODULE_REL_CRCS") made modpost output CRCs in the same way
> > > whether the EXPORT_SYMBOL() is placed in *.c or *.S.
> > >
> > ...
> >
> > > We can do this better now; modpost can selectively emit KSYMTAB entries
> > > that are really used by modules.
> > >
> >
> > This patch results in
> >
> > Building alpha:defconfig ... failed
> > --------------
> > Error log:
> > <stdin>:1519:2: warning: #warning syscall clone3 not implemented [-Wcpp]
> > WARNING: modpost: "saved_config" [vmlinux] is COMMON symbol
> I do not know much about the warning for "saved_config".
>
>
>
> __attribute((common)) was added in the following commit:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=3c7940961fbf9f252e20f9c455f2fe63f273294c
>
>
> It was more than 20 years ago, and there is
> no commit description.
> I do not know the intention of __attribute((common)).
Adding __attribute__((common)) to a variable declaration, the
generated assembler will contain a .comm assembler directive.
https://godbolt.org/z/6jvoaGs8M
https://sourceware.org/binutils/docs/as/Comm.html
>>> .comm declares a common symbol named symbol. When linking, a common symbol in one object file may be merged with a defined or common symbol of the same name in another object file.
When I see this, I think some kind of ODR tricks are afoot. C doesn't
have ODR; C++ does, but this attribute allows for ODR-like linker
merging where the linker discards duplicates because "they ought to be
the same."
IIRC, I think C++ template instantiations are emitted with common
linkage. LLVM IR has a linkage type corresponding to this that I
initially didn't understand, because without this attribute, I don't
think that linkage type is ever emitted for C code.
Indeed, for alpha, we can see the same symbol marked common in arch/alpha/:
arch/alpha/kernel/core_tsunami.c:36:} saved_config[2] __attribute__((common));
arch/alpha/kernel/sys_sio.c:43:} saved_config __attribute((common));
arch/alpha/kernel/core_cia.c:577:} saved_config __attribute((common));
arch/alpha/kernel/core_titan.c:36:} saved_config[4] __attribute__((common));
All of these have different sizes, so according to the GAS manual,
this line comes into play:
>>> If ld sees multiple common symbols with the same name, and they do not all have the same size, it will allocate space using the largest size.
This kind of smells like some overcomplicating code to save like 30B
of static memory. Fixing this requires careful use of enums. For
arch/alpha/ not sure such a rework is worth it, given the imminent
demise of the architecture I sense looming on the horizon.
>
> I hope the maintainers will fix the warnings,
> but I do not know if it is likely to happen.
>
> MAINTAINERS says "Odd Fixes"
>
> If you find a build regression, please let me know.
> So far, I did not get new reports from 0day bot.
>
>
> Thanks.
>
>
>
>
> > Guenter
> >
> > ---
> > Bisect log:
> >
> > # bad: [15e71592dbae49a674429c618a10401d7f992ac3] Add linux-next specific files for 20230621
> > # good: [45a3e24f65e90a047bef86f927ebdc4c710edaa1] Linux 6.4-rc7
> > git bisect start 'HEAD' 'v6.4-rc7'
> > # bad: [e867e67cd55ae460c860ffd896c7fc96add2821c] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git
> > git bisect bad e867e67cd55ae460c860ffd896c7fc96add2821c
> > # bad: [57b289d5b1005a9c39d6d6567e0ef6115bd59cea] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git
> > git bisect bad 57b289d5b1005a9c39d6d6567e0ef6115bd59cea
> > # bad: [dc6399fc9ae6d2530fc38fb3ae96bcc8393bd66f] Merge branch 'for-next/perf' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git
> > git bisect bad dc6399fc9ae6d2530fc38fb3ae96bcc8393bd66f
> > # good: [6d366ba598334a0457d917a7bf38efd118c5b7be] Merge branch 'mm-stable' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> > git bisect good 6d366ba598334a0457d917a7bf38efd118c5b7be
> > # good: [82fe2e45cdb00de4fa648050ae33bdadf9b3294a] perf pmus: Check if we can encode the PMU number in perf_event_attr.type
> > git bisect good 82fe2e45cdb00de4fa648050ae33bdadf9b3294a
> > # bad: [d2fa756910f88c2f5871775483744407cbf67933] Merge branch 'for-next' of git://git.infradead.org/users/hch/dma-mapping.git
> > git bisect bad d2fa756910f88c2f5871775483744407cbf67933
> > # good: [1b990bc8edc396a37a3ff1a43f7c329c361ee07c] Merge branch 'mm-nonmm-unstable' into mm-everything
> > git bisect good 1b990bc8edc396a37a3ff1a43f7c329c361ee07c
> > # good: [cff6e7f50bd315e5b39c4e46c704ac587ceb965f] kbuild: Add CLANG_FLAGS to as-instr
> > git bisect good cff6e7f50bd315e5b39c4e46c704ac587ceb965f
> > # bad: [8f3847e175a0044e2212fef772e7fa912270cd6d] ia64,export.h: replace EXPORT_DATA_SYMBOL* with EXPORT_SYMBOL*
> > git bisect bad 8f3847e175a0044e2212fef772e7fa912270cd6d
> > # good: [3a3f1e573a105328a2cca45a7cfbebabbf5e3192] modpost: fix off by one in is_executable_section()
> > git bisect good 3a3f1e573a105328a2cca45a7cfbebabbf5e3192
> > # good: [92e74fb6e6196d642505ae2b74a8e327202afef9] scripts/kallsyms: constify long_options
> > git bisect good 92e74fb6e6196d642505ae2b74a8e327202afef9
> > # good: [92e2921eeafdfca9acd9b83f07d2b7ca099bac24] ARC: define ASM_NL and __ALIGN(_STR) outside #ifdef __ASSEMBLY__ guard
> > git bisect good 92e2921eeafdfca9acd9b83f07d2b7ca099bac24
> > # bad: [bb2aa9a94b41b883037a56709d995c269204ade0] kbuild: generate KSYMTAB entries by modpost
> > git bisect bad bb2aa9a94b41b883037a56709d995c269204ade0
> > # good: [94d6cb68124b7a63f24fcc345795ba5f9a27e694] modpost: pass struct module pointer to check_section_mismatch()
> > git bisect good 94d6cb68124b7a63f24fcc345795ba5f9a27e694
> > # first bad commit: [bb2aa9a94b41b883037a56709d995c269204ade0] kbuild: generate KSYMTAB entries by modpost
>
>
>
> --
> Best Regards
> Masahiro Yamada
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 20+ messages in thread
end of thread, other threads:[~2023-06-22 16:20 UTC | newest]
Thread overview: 20+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-06-08 14:24 [PATCH v7 00/11] Unify <linux/export.h> and <asm/export.h>, remove EXPORT_DATA_SYMBOL(), faster TRIM_UNUSED_KSYMS Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 01/11] Revert "[PATCH] uml: export symbols added by GCC hardened" Masahiro Yamada
2023-06-09 21:23 ` Nick Desaulniers
2023-06-08 14:24 ` [PATCH v7 02/11] modpost: pass struct module pointer to check_section_mismatch() Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 03/11] kbuild: generate KSYMTAB entries by modpost Masahiro Yamada
2023-06-09 21:34 ` Nick Desaulniers
2023-06-10 8:56 ` Masahiro Yamada
2023-06-21 16:15 ` Guenter Roeck
2023-06-22 2:26 ` Masahiro Yamada
2023-06-22 16:20 ` Nick Desaulniers
2023-06-08 14:24 ` [PATCH v7 04/11] ia64,export.h: replace EXPORT_DATA_SYMBOL* with EXPORT_SYMBOL* Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 05/11] modpost: check static EXPORT_SYMBOL* by modpost again Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 06/11] modpost: squash sym_update_namespace() into sym_add_exported() Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 07/11] modpost: use null string instead of NULL pointer for default namespace Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 08/11] kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 09/11] modpost: merge two similar section mismatch warnings Masahiro Yamada
2023-06-08 14:24 ` [PATCH v7 10/11] modpost: show offset from symbol for " Masahiro Yamada
2023-06-09 21:26 ` Nick Desaulniers
2023-06-08 14:24 ` [PATCH v7 11/11] linux/export.h: rename 'sec' argument to 'license' Masahiro Yamada
2023-06-09 21:29 ` Nick Desaulniers
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