[PATCH 3/8] arm64: kprobes: Record frame pointer with kretprobe instance

Masami Hiramatsu
2021-10-08T12:34:07Z

Record the frame pointer instead of stack address with kretprobe
instance as the identifier on the instance list.
Since arm64 always enable CONFIG_FRAME_POINTER, we can use the
actual frame pointer (x29).

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
arch/arm64/kernel/probes/kprobes.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index e7ad6da980e8..d9dfa82c1f18 100644
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -401,14 +401,14 @@ int __init arch_populate_kprobe_blacklist(void)

void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs)
{
- return (void *)kretprobe_trampoline_handler(regs, (void *)kernel_stack_pointer(regs));
+ return (void *)kretprobe_trampoline_handler(regs, (void *)regs->regs[29]);
}

void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *)regs->regs[30];
- ri->fp = (void *)kernel_stack_pointer(regs);
+ ri->fp = (void *)regs->regs[29];

/* replace return addr (x30) with trampoline */
regs->regs[30] = (long)&__kretprobe_trampoline;