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Commit 03b19c7f authored by Rui Qi's avatar Rui Qi Committed by Greg Kroah-Hartman
Browse files

x86/speculation: Support intra-function call validation 



commit 8afd1c7d ("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: 8afd1c7d ("x86/speculation: Change FILL_RETURN_BUFFER to work with objtool")
Cc: <stable@vger.kernel.org> # v5.4.250+
Signed-off-by: default avatarRui Qi <qirui.001@bytedance.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f8f25fde

arch/x86/include/asm/nospec-branch.h

+7 −0
Original line number Diff line number Diff line
@@ -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_\@:

arch/x86/include/asm/unwind_hints.h

+1 −1
Original line number Diff line number Diff line
@@ -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__ */