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Message-Id: <162756765964.301564.5697343919087076371.stgit@devnote2>
Date: Thu, 29 Jul 2021 23:07:39 +0900
From: Masami Hiramatsu <mhiramat@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Ingo Molnar <mingo@...nel.org>
Cc: X86 ML <x86@...nel.org>, Masami Hiramatsu <mhiramat@...nel.org>,
Daniel Xu <dxu@...uu.xyz>, linux-kernel@...r.kernel.org,
bpf@...r.kernel.org, kuba@...nel.org, mingo@...hat.com,
ast@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>,
Peter Zijlstra <peterz@...radead.org>, kernel-team@...com,
yhs@...com, linux-ia64@...r.kernel.org,
Abhishek Sagar <sagar.abhishek@...il.com>,
Andrii Nakryiko <andrii.nakryiko@...il.com>
Subject: [PATCH -tip v10 11/16] arm: kprobes: Make space for instruction pointer on stack
Since arm's __kretprobe_trampoline() saves partial 'pt_regs' on the
stack, 'regs->ARM_pc' (instruction pointer) is not accessible from
the kretprobe handler. This means if instruction_pointer_set() is
used from kretprobe handler, it will break the data on the stack.
Make space for instruction pointer (ARM_pc) on the stack in the
__kretprobe_trampoline() for fixing this problem.
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
Changes in v9:
- Update changelog.
---
arch/arm/probes/kprobes/core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c
index 67ce7eb8f285..95f23b47ba27 100644
--- a/arch/arm/probes/kprobes/core.c
+++ b/arch/arm/probes/kprobes/core.c
@@ -376,11 +376,13 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
void __naked __kprobes __kretprobe_trampoline(void)
{
__asm__ __volatile__ (
+ "sub sp, sp, #16 \n\t"
"stmdb sp!, {r0 - r11} \n\t"
"mov r0, sp \n\t"
"bl trampoline_handler \n\t"
"mov lr, r0 \n\t"
"ldmia sp!, {r0 - r11} \n\t"
+ "add sp, sp, #16 \n\t"
#ifdef CONFIG_THUMB2_KERNEL
"bx lr \n\t"
#else
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