Messages in this thread Patch in this message | | | From | Masami Hiramatsu <> | Subject | [PATCH v3 5/9] arm64: kprobes: Make a frame pointer on __kretprobe_trampoline | Date | Thu, 21 Oct 2021 09:55:00 +0900 |
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Make a frame pointer (make the x29 register points the address of pt_regs->regs[29]) on __kretprobe_trampoline.
This frame pointer will be used by the stacktracer when it is called from the kretprobe handlers. In this case, the stack tracer will unwind stack to trampoline_probe_handler() and find the next frame pointer in the stack frame of the __kretprobe_trampoline().
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Will Deacon <will@kernel.org> --- arch/arm64/kernel/probes/kprobes_trampoline.S | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/arch/arm64/kernel/probes/kprobes_trampoline.S b/arch/arm64/kernel/probes/kprobes_trampoline.S index 520ee8711db1..9a6499bed58b 100644 --- a/arch/arm64/kernel/probes/kprobes_trampoline.S +++ b/arch/arm64/kernel/probes/kprobes_trampoline.S @@ -66,6 +66,9 @@ SYM_CODE_START(__kretprobe_trampoline) save_all_base_regs + /* Setup a frame pointer. */ + add x29, sp, #S_FP + mov x0, sp bl trampoline_probe_handler /* @@ -74,6 +77,7 @@ SYM_CODE_START(__kretprobe_trampoline) */ mov lr, x0 + /* The frame pointer (x29) is restored with other registers. */ restore_all_base_regs add sp, sp, #PT_REGS_SIZE
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