[PATCH v2 3/3] x86/speculation: Support intra-function call validation

Rui Qi
2024-02-28T02:46:19Z

commit 8afd1c7da2b0 ("x86/speculation: Change FILL_RETURN_BUFFER
to work with objtool") does not support intra-function call
stack validation, which causes kernel live patching to fail.
This commit adds support for this, and after testing, the kernel
live patching feature is restored to normal.

Fixes: 8afd1c7da2b0 ("x86/speculation: Change FILL_RETURN_BUFFER to work with objtool")
Cc: <stable@vger.kernel.org> # v5.4.250+
Signed-off-by: Rui Qi <qirui.001@bytedance.com>
---
arch/x86/include/asm/nospec-branch.h | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index c8819358a332..a88135c358c0 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -13,6 +13,8 @@
#include <asm/unwind_hints.h>
#include <asm/percpu.h>

+#include <linux/frame.h>
+#include <asm/unwind_hints.h>
/*
* This should be used immediately before a retpoline alternative. It tells
* objtool where the retpolines are so that it can make sense of the control
@@ -51,14 +53,18 @@
#define __FILL_RETURN_BUFFER(reg, nr, sp) \
mov $(nr/2), reg; \
771: \
+ ANNOTATE_INTRA_FUNCTION_CALL; \
call 772f; \
773: /* speculation trap */ \
+ UNWIND_HINT_EMPTY; \
pause; \
lfence; \
jmp 773b; \
772: \
+ ANNOTATE_INTRA_FUNCTION_CALL; \
call 774f; \
775: /* speculation trap */ \
+ UNWIND_HINT_EMPTY; \
pause; \
lfence; \
jmp 775b; \
@@ -152,6 +158,7 @@
.endm

.macro ISSUE_UNBALANCED_RET_GUARD
+ ANNOTATE_INTRA_FUNCTION_CALL;
call .Lunbalanced_ret_guard_\@
int3
.Lunbalanced_ret_guard_\@:
--
2.39.2 (Apple Git-143)