From: Masami Hiramatsu <mhiramat@kernel.org>
Date: Tue, 14 Sep 2021 23:42:02 +0900
Subject: arm: kprobes: Make space for instruction pointer on stack
Git-commit: 7391dd19027cec4e0edf81b7c27079ae0ecd2d6b
Patch-mainline: v5.16-rc1
References: bsc#1193277

Since arm's __kretprobe_trampoline() saves partial 'pt_regs' on the
stack, 'regs->ARM_pc' (instruction pointer) is not accessible from
the kretprobe handler. This means if instruction_pointer_set() is
used from kretprobe handler, it will break the data on the stack.

Make space for instruction pointer (ARM_pc) on the stack in the
__kretprobe_trampoline() for fixing this problem.

Link: https://lkml.kernel.org/r/163163052262.489837.10327621053231461255.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Miroslav Benes <mbenes@suse.cz>
---
 arch/arm/probes/kprobes/core.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/arm/probes/kprobes/core.c
+++ b/arch/arm/probes/kprobes/core.c
@@ -376,11 +376,13 @@ int __kprobes kprobe_exceptions_notify(s
 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