From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Tue, 14 Sep 2021 23:41:32 +0900
Subject: x86/kprobes: Add UNWIND_HINT_FUNC on kretprobe_trampoline()
Git-commit: eb4a3f7d78c7cf03654dfebdb2df64bd00a7af10
Patch-mainline: v5.16-rc1
References: bsc#1193277
Add UNWIND_HINT_FUNC on __kretprobe_trampoline() code so that ORC
information is generated on the __kretprobe_trampoline() correctly.
Also, this uses STACK_FRAME_NON_STANDARD_FP(), CONFIG_FRAME_POINTER-
-specific version of STACK_FRAME_NON_STANDARD().
Link: https://lkml.kernel.org/r/163163049242.489837.11970969750993364293.stgit@devnote2
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Miroslav Benes <mbenes@suse.cz>
---
arch/x86/include/asm/unwind_hints.h | 5 +++++
arch/x86/kernel/kprobes/core.c | 13 +++++++++++--
2 files changed, 16 insertions(+), 2 deletions(-)
--- a/arch/x86/include/asm/unwind_hints.h
+++ b/arch/x86/include/asm/unwind_hints.h
@@ -52,6 +52,11 @@
UNWIND_HINT sp_reg=ORC_REG_SP sp_offset=8 type=UNWIND_HINT_TYPE_FUNC
.endm
+#else
+
+#define UNWIND_HINT_FUNC \
+ UNWIND_HINT(ORC_REG_SP, 8, UNWIND_HINT_TYPE_FUNC, 0)
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_UNWIND_HINTS_H */
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -1025,6 +1025,7 @@ asm(
/* We don't bother saving the ss register */
#ifdef CONFIG_X86_64
" pushq %rsp\n"
+ UNWIND_HINT_FUNC
" pushfq\n"
SAVE_REGS_STRING
" movq %rsp, %rdi\n"
@@ -1035,6 +1036,7 @@ asm(
" popfq\n"
#else
" pushl %esp\n"
+ UNWIND_HINT_FUNC
" pushfl\n"
SAVE_REGS_STRING
" movl %esp, %eax\n"
@@ -1048,8 +1050,15 @@ asm(
".size __kretprobe_trampoline, .-__kretprobe_trampoline\n"
);
NOKPROBE_SYMBOL(__kretprobe_trampoline);
-STACK_FRAME_NON_STANDARD(__kretprobe_trampoline);
-
+/*
+ * __kretprobe_trampoline() skips updating frame pointer. The frame pointer
+ * saved in trampoline_handler() points to the real caller function's
+ * frame pointer. Thus the __kretprobe_trampoline() doesn't have a
+ * standard stack frame with CONFIG_FRAME_POINTER=y.
+ * Let's mark it non-standard function. Anyway, FP unwinder can correctly
+ * unwind without the hint.
+ */
+STACK_FRAME_NON_STANDARD_FP(__kretprobe_trampoline);
/*
* Called from __kretprobe_trampoline