[PATCH v3 3/3] x86/speculation: Support intra-function call validation

[Rui Qi]

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@xxxxxxxxxxxxxxx> # v5.4.250+
Signed-off-by: Rui Qi <qirui.001@xxxxxxxxxxxxx>
---
 arch/x86/include/asm/nospec-branch.h | 7 +++++++
 arch/x86/include/asm/unwind_hints.h  | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

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_\@:
diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h
index 0bcdb1279361..0fd9a22b2eca 100644
--- a/arch/x86/include/asm/unwind_hints.h
+++ b/arch/x86/include/asm/unwind_hints.h
@@ -101,7 +101,7 @@
 	".popsection\n\t"
 
 #define UNWIND_HINT_SAVE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_SAVE, 0)
-
+#define UNWIND_HINT_EMPTY
 #define UNWIND_HINT_RESTORE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_RESTORE, 0)
 
 #endif /* __ASSEMBLY__ */
-- 
2.20.1