1. 根目录:
2. arch
3. x86
4. include
5. asm
6. asm.h

#ifndef _ASM_X86_ASM_H
#define _ASM_X86_ASM_H

#ifdef __ASSEMBLY__
# define __ASM_FORM(x)	x
# define __ASM_FORM_RAW(x)     x
# define __ASM_FORM_COMMA(x) x,
#else
# define __ASM_FORM(x)	" " #x " "
# define __ASM_FORM_RAW(x)     #x
# define __ASM_FORM_COMMA(x) " " #x ","
#endif

#ifdef CONFIG_X86_32
# define __ASM_SEL(a,b) __ASM_FORM(a)
# define __ASM_SEL_RAW(a,b) __ASM_FORM_RAW(a)
#else
# define __ASM_SEL(a,b) __ASM_FORM(b)
# define __ASM_SEL_RAW(a,b) __ASM_FORM_RAW(b)
#endif

#define __ASM_SIZE(inst, ...)	__ASM_SEL(inst##l##__VA_ARGS__, \
					  inst##q##__VA_ARGS__)
#define __ASM_REG(reg)         __ASM_SEL_RAW(e##reg, r##reg)

#define _ASM_PTR	__ASM_SEL(.long, .quad)
#define _ASM_ALIGN	__ASM_SEL(.balign 4, .balign 8)

#define _ASM_MOV	__ASM_SIZE(mov)
#define _ASM_INC	__ASM_SIZE(inc)
#define _ASM_DEC	__ASM_SIZE(dec)
#define _ASM_ADD	__ASM_SIZE(add)
#define _ASM_SUB	__ASM_SIZE(sub)
#define _ASM_XADD	__ASM_SIZE(xadd)

#define _ASM_AX		__ASM_REG(ax)
#define _ASM_BX		__ASM_REG(bx)
#define _ASM_CX		__ASM_REG(cx)
#define _ASM_DX		__ASM_REG(dx)
#define _ASM_SP		__ASM_REG(sp)
#define _ASM_BP		__ASM_REG(bp)
#define _ASM_SI		__ASM_REG(si)
#define _ASM_DI		__ASM_REG(di)

/* Exception table entry */
#ifdef __ASSEMBLY__
# define _ASM_EXTABLE(from,to)					\
	.pushsection "__ex_table","a" ;				\
	.balign 8 ;						\
	.long (from) - . ;					\
	.long (to) - . ;					\
	.popsection

# define _ASM_EXTABLE_EX(from,to)				\
	.pushsection "__ex_table","a" ;				\
	.balign 8 ;						\
	.long (from) - . ;					\
	.long (to) - . + 0x7ffffff0 ;				\
	.popsection

# define _ASM_NOKPROBE(entry)					\
	.pushsection "_kprobe_blacklist","aw" ;			\
	_ASM_ALIGN ;						\
	_ASM_PTR (entry);					\
	.popsection

.macro ALIGN_DESTINATION
	/* check for bad alignment of destination */
	movl %edi,%ecx
	andl $7,%ecx
	jz 102f				/* already aligned */
	subl $8,%ecx
	negl %ecx
	subl %ecx,%edx
100:	movb (%rsi),%al
101:	movb %al,(%rdi)
	incq %rsi
	incq %rdi
	decl %ecx
	jnz 100b
102:
	.section .fixup,"ax"
103:	addl %ecx,%edx			/* ecx is zerorest also */
	jmp copy_user_handle_tail
	.previous

	_ASM_EXTABLE(100b,103b)
	_ASM_EXTABLE(101b,103b)
	.endm

#else
# define _ASM_EXTABLE(from,to)					\
	" .pushsection \"__ex_table\",\"a\"\n"			\
	" .balign 8\n"						\
	" .long (" #from ") - .\n"				\
	" .long (" #to ") - .\n"				\
	" .popsection\n"

# define _ASM_EXTABLE_EX(from,to)				\
	" .pushsection \"__ex_table\",\"a\"\n"			\
	" .balign 8\n"						\
	" .long (" #from ") - .\n"				\
	" .long (" #to ") - . + 0x7ffffff0\n"			\
	" .popsection\n"
/* For C file, we already have NOKPROBE_SYMBOL macro */
#endif

#endif /* _ASM_X86_ASM_H */