From: Torsten Duwe <duwe@lst.de>
To: Steven Rostedt <rostedt@goodmis.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: Jiri Kosina <jkosina@suse.cz>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
live-patching@vger.kernel.org
Subject: [PATCH v6 8/9] Implement kernel live patching for ppc64le (ABIv2)
Date: Mon, 25 Jan 2016 16:33:00 +0100 [thread overview]
Message-ID: <20160125170804.A11DB692DD@newverein.lst.de> (raw)
In-Reply-To: <20160125170459.14DB7692CE@newverein.lst.de>
* create the appropriate files+functions
arch/powerpc/include/asm/livepatch.h
klp_check_compiler_support,
klp_arch_set_pc
arch/powerpc/kernel/livepatch.c with a stub for
klp_write_module_reloc
This is architecture-independent work in progress.
* introduce a fixup in arch/powerpc/kernel/entry_64.S
for local calls that are becoming global due to live patching.
And of course do the main KLP thing: return to a maybe different
address, possibly altered by the live patching ftrace op.
Signed-off-by: Torsten Duwe <duwe@suse.de>
---
arch/powerpc/include/asm/livepatch.h | 45 +++++++++++++++++++++++++++++++
arch/powerpc/kernel/entry_64.S | 51 +++++++++++++++++++++++++++++++++---
arch/powerpc/kernel/livepatch.c | 38 +++++++++++++++++++++++++++
3 files changed, 130 insertions(+), 4 deletions(-)
create mode 100644 arch/powerpc/include/asm/livepatch.h
create mode 100644 arch/powerpc/kernel/livepatch.c
diff --git a/arch/powerpc/include/asm/livepatch.h b/arch/powerpc/include/asm/livepatch.h
new file mode 100644
index 0000000..44e8a2d
--- /dev/null
+++ b/arch/powerpc/include/asm/livepatch.h
@@ -0,0 +1,45 @@
+/*
+ * livepatch.h - powerpc-specific Kernel Live Patching Core
+ *
+ * Copyright (C) 2015 SUSE
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef _ASM_POWERPC64_LIVEPATCH_H
+#define _ASM_POWERPC64_LIVEPATCH_H
+
+#include <linux/module.h>
+#include <linux/ftrace.h>
+
+#ifdef CONFIG_LIVEPATCH
+static inline int klp_check_compiler_support(void)
+{
+#if !defined(_CALL_ELF) || _CALL_ELF != 2 || !defined(CC_USING_MPROFILE_KERNEL)
+ return 1;
+#endif
+ return 0;
+}
+
+extern int klp_write_module_reloc(struct module *mod, unsigned long type,
+ unsigned long loc, unsigned long value);
+
+static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
+{
+ regs->nip = ip;
+}
+#else
+#error Live patching support is disabled; check CONFIG_LIVEPATCH
+#endif
+
+#endif /* _ASM_POWERPC64_LIVEPATCH_H */
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 9e98aa1..f6e3ee7 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -1267,6 +1267,9 @@ _GLOBAL(ftrace_caller)
mflr r3
std r3, _NIP(r1)
std r3, 16(r1)
+#ifdef CONFIG_LIVEPATCH
+ mr r14,r3 /* remember old NIP */
+#endif
subi r3, r3, MCOUNT_INSN_SIZE
mfmsr r4
std r4, _MSR(r1)
@@ -1283,7 +1286,10 @@ ftrace_call:
nop
ld r3, _NIP(r1)
- mtlr r3
+ mtctr r3 /* prepare to jump there */
+#ifdef CONFIG_LIVEPATCH
+ cmpd r14,r3 /* has NIP been altered? */
+#endif
REST_8GPRS(0,r1)
REST_8GPRS(8,r1)
@@ -1296,6 +1302,27 @@ ftrace_call:
mtlr r12
mr r2,r0 /* restore callee's TOC */
+#ifdef CONFIG_LIVEPATCH
+ beq+ 4f /* likely(old_NIP == new_NIP) */
+
+ /* For a local call, restore this TOC after calling the patch function.
+ * For a global call, it does not matter what we restore here,
+ * since the global caller does its own restore right afterwards,
+ * anyway. Just insert a KLP_return_helper frame in any case,
+ * so a patch function can always count on the changed stack offsets.
+ */
+ stdu r1,-32(r1) /* open new mini stack frame */
+ std r0,24(r1) /* save TOC now, unconditionally. */
+ bl 5f
+5: mflr r12
+ addi r12,r12,(KLP_return_helper+4-.)@l
+ std r12,LRSAVE(r1)
+ mtlr r12
+ mfctr r12 /* allow for TOC calculation in newfunc */
+ bctr
+4:
+#endif
+
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
stdu r1, -112(r1)
.globl ftrace_graph_call
@@ -1305,15 +1332,31 @@ _GLOBAL(ftrace_graph_stub)
addi r1, r1, 112
#endif
- mflr r0 /* move this LR to CTR */
- mtctr r0
-
ld r0,LRSAVE(r1) /* restore callee's lr at _mcount site */
mtlr r0
bctr /* jump after _mcount site */
#endif /* CC_USING_MPROFILE_KERNEL */
_GLOBAL(ftrace_stub)
blr
+
+#ifdef CONFIG_LIVEPATCH
+/* Helper function for local calls that are becoming global
+ due to live patching.
+ We can't simply patch the NOP after the original call,
+ because, depending on the consistency model, some kernel
+ threads may still have called the original, local function
+ *without* saving their TOC in the respective stack frame slot,
+ so the decision is made per-thread during function return by
+ maybe inserting a KLP_return_helper frame or not.
+*/
+KLP_return_helper:
+ ld r2,24(r1) /* restore TOC (saved by ftrace_caller) */
+ addi r1, r1, 32 /* destroy mini stack frame */
+ ld r0,LRSAVE(r1) /* get the real return address */
+ mtlr r0
+ blr
+#endif
+
#else
_GLOBAL_TOC(_mcount)
/* Taken from output of objdump from lib64/glibc */
diff --git a/arch/powerpc/kernel/livepatch.c b/arch/powerpc/kernel/livepatch.c
new file mode 100644
index 0000000..564eafa
--- /dev/null
+++ b/arch/powerpc/kernel/livepatch.c
@@ -0,0 +1,38 @@
+/*
+ * livepatch.c - powerpc-specific Kernel Live Patching Core
+ *
+ * Copyright (C) 2015 SUSE
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/module.h>
+#include <asm/livepatch.h>
+
+/**
+ * klp_write_module_reloc() - write a relocation in a module
+ * @mod: module in which the section to be modified is found
+ * @type: ELF relocation type (see asm/elf.h)
+ * @loc: address that the relocation should be written to
+ * @value: relocation value (sym address + addend)
+ *
+ * This function writes a relocation to the specified location for
+ * a particular module.
+ */
+int klp_write_module_reloc(struct module *mod, unsigned long type,
+ unsigned long loc, unsigned long value)
+{
+ /* This requires infrastructure changes; we need the loadinfos. */
+ pr_err("lpc_write_module_reloc not yet supported\n");
+ return -ENOSYS;
+}
--
1.8.5.6
next prev parent reply other threads:[~2016-01-25 17:08 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-25 15:38 [PATCH v6 0/9] ftrace with regs + live patching for ppc64 LE (ABI v2) Torsten Duwe
2016-01-25 15:26 ` [PATCH v6 1/9] ppc64 (le): prepare for -mprofile-kernel Torsten Duwe
2016-01-27 10:19 ` Michael Ellerman
2016-01-27 10:44 ` Torsten Duwe
2016-01-28 4:26 ` Michael Ellerman
2016-01-28 11:50 ` Torsten Duwe
2016-01-27 12:58 ` Alan Modra
2016-01-27 13:45 ` Torsten Duwe
2016-01-28 3:39 ` Michael Ellerman
2016-02-03 7:23 ` AKASHI Takahiro
2016-02-03 8:55 ` Jiri Kosina
2016-02-03 11:24 ` Torsten Duwe
2016-02-04 9:31 ` AKASHI Takahiro
2016-02-04 11:02 ` Petr Mladek
2016-02-05 4:40 ` Balbir Singh
2016-02-05 10:22 ` Petr Mladek
2016-02-04 21:47 ` Jiri Kosina
2016-01-25 15:27 ` [PATCH v6 2/9] ppc64le FTRACE_WITH_REGS implementation Torsten Duwe
2016-01-25 15:29 ` [PATCH v6 3/9] ppc use ftrace_modify_all_code default Torsten Duwe
2016-01-25 15:29 ` [PATCH v6 4/9] ppc64 ftrace_with_regs configuration variables Torsten Duwe
2016-01-25 15:30 ` [PATCH v6 5/9] ppc64 ftrace_with_regs: spare early boot and low level Torsten Duwe
2016-01-25 15:31 ` [PATCH v6 6/9] ppc64 ftrace: disable profiling for some functions Torsten Duwe
2016-01-25 15:31 ` [PATCH v6 7/9] ppc64 ftrace: disable profiling for some files Torsten Duwe
2016-01-25 15:33 ` Torsten Duwe [this message]
2016-01-26 10:50 ` [PATCH v6 8/9] Implement kernel live patching for ppc64le (ABIv2) Miroslav Benes
2016-01-26 12:48 ` Petr Mladek
2016-01-26 13:56 ` Torsten Duwe
2016-02-02 12:12 ` Petr Mladek
2016-02-02 15:45 ` Torsten Duwe
2016-02-02 16:47 ` Petr Mladek
2016-02-02 20:39 ` Jiri Kosina
2016-01-26 14:00 ` Torsten Duwe
2016-01-26 14:14 ` Miroslav Benes
2016-01-27 1:53 ` Jessica Yu
2016-02-02 13:46 ` [PATCH v6 8/9] " Denis Kirjanov
2016-02-10 18:03 ` Torsten Duwe
2016-01-25 15:33 ` [PATCH v6 9/9] Enable LIVEPATCH to be configured on ppc64le and add livepatch.o if it is selected Torsten Duwe
2016-01-27 10:51 ` [PATCH v6 0/9] ftrace with regs + live patching for ppc64 LE (ABI v2) Balbir Singh
2016-01-27 12:19 ` Torsten Duwe
2016-01-28 2:41 ` Balbir Singh
2016-01-28 3:31 ` Michael Ellerman
2016-01-28 11:19 ` Torsten Duwe
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