Commit a9b3c699 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

x86/stackframe: Move ENCODE_FRAME_POINTER to asm/frame.h 



In preparation for wider use, move the ENCODE_FRAME_POINTER macros to
a common header and provide inline asm versions.

These macros are used to encode a pt_regs frame for the unwinder; see
unwind_frame.c:decode_frame_pointer().

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 5e1246ff

arch/x86/entry/calling.h

+0 −15
Original line number Diff line number Diff line
@@ -172,21 +172,6 @@ For 32-bit we have the following conventions - kernel is built with 
	.endif

.endm



/*

 * This is a sneaky trick to help the unwinder find pt_regs on the stack.  The

 * frame pointer is replaced with an encoded pointer to pt_regs.  The encoding

 * is just setting the LSB, which makes it an invalid stack address and is also

 * a signal to the unwinder that it's a pt_regs pointer in disguise.

 *

 * NOTE: This macro must be used *after* PUSH_AND_CLEAR_REGS because it corrupts

 * the original rbp.

 */

.macro ENCODE_FRAME_POINTER ptregs_offset=0

#ifdef CONFIG_FRAME_POINTER

	leaq 1+\ptregs_offset(%rsp), %rbp

#endif

.endm



#ifdef CONFIG_PAGE_TABLE_ISOLATION



/*

arch/x86/entry/entry_32.S

+0 −16
Original line number Diff line number Diff line
@@ -246,22 +246,6 @@ 
.Lend_\@:

.endm



/*

 * This is a sneaky trick to help the unwinder find pt_regs on the stack.  The

 * frame pointer is replaced with an encoded pointer to pt_regs.  The encoding

 * is just clearing the MSB, which makes it an invalid stack address and is also

 * a signal to the unwinder that it's a pt_regs pointer in disguise.

 *

 * NOTE: This macro must be used *after* SAVE_ALL because it corrupts the

 * original rbp.

 */

.macro ENCODE_FRAME_POINTER

#ifdef CONFIG_FRAME_POINTER

	mov %esp, %ebp

	andl $0x7fffffff, %ebp

#endif

.endm



.macro RESTORE_INT_REGS

	popl	%ebx

	popl	%ecx

arch/x86/include/asm/frame.h

+49 −0
Original line number Diff line number Diff line
@@ -22,6 +22,35 @@ 
	pop %_ASM_BP

.endm



#ifdef CONFIG_X86_64

/*

 * This is a sneaky trick to help the unwinder find pt_regs on the stack.  The

 * frame pointer is replaced with an encoded pointer to pt_regs.  The encoding

 * is just setting the LSB, which makes it an invalid stack address and is also

 * a signal to the unwinder that it's a pt_regs pointer in disguise.

 *

 * NOTE: This macro must be used *after* PUSH_AND_CLEAR_REGS because it corrupts

 * the original rbp.

 */

.macro ENCODE_FRAME_POINTER ptregs_offset=0

	leaq 1+\ptregs_offset(%rsp), %rbp

.endm

#else /* !CONFIG_X86_64 */

/*

 * This is a sneaky trick to help the unwinder find pt_regs on the stack.  The

 * frame pointer is replaced with an encoded pointer to pt_regs.  The encoding

 * is just clearing the MSB, which makes it an invalid stack address and is also

 * a signal to the unwinder that it's a pt_regs pointer in disguise.

 *

 * NOTE: This macro must be used *after* SAVE_ALL because it corrupts the

 * original ebp.

 */

.macro ENCODE_FRAME_POINTER

	mov %esp, %ebp

	andl $0x7fffffff, %ebp

.endm

#endif /* CONFIG_X86_64 */



#else /* !__ASSEMBLY__ */



#define FRAME_BEGIN				\
@@ -30,12 +59,32 @@ 


#define FRAME_END "pop %" _ASM_BP "\n"



#ifdef CONFIG_X86_64

#define ENCODE_FRAME_POINTER			\

	"lea 1(%rsp), %rbp\n\t"

#else /* !CONFIG_X86_64 */

#define ENCODE_FRAME_POINTER			\

	"movl %esp, %ebp\n\t"			\

	"andl $0x7fffffff, %ebp\n\t"

#endif /* CONFIG_X86_64 */



#endif /* __ASSEMBLY__ */



#define FRAME_OFFSET __ASM_SEL(4, 8)



#else /* !CONFIG_FRAME_POINTER */



#ifdef __ASSEMBLY__



.macro ENCODE_FRAME_POINTER ptregs_offset=0

.endm



#else /* !__ASSEMBLY */



#define ENCODE_FRAME_POINTER



#endif



#define FRAME_BEGIN

#define FRAME_END

#define FRAME_OFFSET 0

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