| Message ID | 161639527851.895304.14313883616251450754.stgit@devnote2 (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | kprobes: Fix stacktrace with kretprobes on x86 | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Mon, 22 Mar 2021 15:41:18 +0900 Masami Hiramatsu <mhiramat@kernel.org> wrote: > Change kretprobe_trampoline to make a space for regs->ARM_pc so that > kretprobe_trampoline_handler can call instruction_pointer_set() > safely. BTW, if kretprobe_trampoline is replaced with the assembly code, I think it should fill all the regs as much as possible, because originally it is written by a software break. Thus the regs->sp should point the stack address at the entry of kretprobe_trampoline, and also regs->lr and regs->pc will be kretprobe_trampoline, so that user handler can access caller stack. Thanks, > > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> > --- > 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 1782b41df095..5f3c2b42787f 100644 > --- a/arch/arm/probes/kprobes/core.c > +++ b/arch/arm/probes/kprobes/core.c > @@ -397,11 +397,13 @@ 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 >
diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c index 1782b41df095..5f3c2b42787f 100644 --- a/arch/arm/probes/kprobes/core.c +++ b/arch/arm/probes/kprobes/core.c @@ -397,11 +397,13 @@ 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
Change kretprobe_trampoline to make a space for regs->ARM_pc so that kretprobe_trampoline_handler can call instruction_pointer_set() safely. Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> --- arch/arm/probes/kprobes/core.c | 2 ++ 1 file changed, 2 insertions(+)