From: Masami Hiramatsu <mhiramat@kernel.org>
Date: Thu, 21 Oct 2021 09:54:51 +0900
Subject: arm64: kprobes: Record frame pointer with kretprobe instance
Patch-mainline: v5.16-rc1
Git-commit: f8717410621571b182d3f2c45ffc52796c418787
References: jsc#PED-1377

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).

This will allow the stacktrace code to find the original return
address from the FP alone.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 arch/arm64/kernel/probes/kprobes.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -401,14 +401,14 @@ int __init arch_populate_kprobe_blacklis
 
 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;