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SubjectRe: [PATCH v3 6/9] arm64: Recover kretprobe modified return address in stacktrace
On Thu, Oct 21, 2021 at 09:55:09AM +0900, Masami Hiramatsu wrote:
> Since the kretprobe replaces the function return address with
> the kretprobe_trampoline on the stack, stack unwinder shows it
> instead of the correct return address.
>
> This checks whether the next return address is the
> __kretprobe_trampoline(), and if so, try to find the correct
> return address from the kretprobe instance list. For this purpose
> this adds 'kr_cur' loop cursor to memorize the current kretprobe
> instance.
>
> With this fix, now arm64 can enable
> CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE, and pass the
> kprobe self tests.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
> Changes in v2:
> - Add comment for kr_cur.
> - Make the kretprobe related code depends on CONFIG_KRETPROBES.
> - Initialize "kr_cur" directly in start_backtrace() instead
> of clearing "frame" data structure by memset().
> ---
> arch/arm64/Kconfig | 1 +
> arch/arm64/include/asm/stacktrace.h | 4 ++++
> arch/arm64/kernel/stacktrace.c | 7 +++++++
> 3 files changed, 12 insertions(+)

Acked-by: Will Deacon <will@kernel.org>

I'm not sure how you're planning to merge this, so please let me know if
you want me to queue any of the arm64 bits.

Will

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