__copy_user_zeroing
2.6内核和2.4相比，又加入了一个异常修复地址
#define __copy_user_zeroing(to,from,size) \
do { \
int __d0, __d1, __d2; \
__asm__ __volatile__( \
" cmp $7,%0\n" \
" jbe1f \n" \
" movl %1,%0\n" \
" negl %0\n" \
" andl $7,%0\n" \
" subl %0,%3\n" \
"4: rep; movsb\n" \
" movl %3,%0\n" \
" shrl $2,%0\n" \
" andl $3,%3\n" \
" .align 2,0x90\n" \
"0: rep; movsl\n" \
" movl %3,%0\n" \
"1: rep; movsb\n" \也是字节数
"2:\n" \
".section .fixup,\"ax\"\n" \
"5: addl %3,%0\n" \
" jmp6f \n" \
"3: lea 0(%3,%0,4),%0\n" \计算复制失败后剩余的字节数
"6: pushl %0\n" \
" pushl %%eax\n" \
" xorl %%eax,%%eax\n" \将eax清零
" rep; stosb\n" \ 将AL的值复制到esx:edi中
" popl %%eax\n" \
" popl %0\n" \
" jmp 2b\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .align 4\n" \
" .long 4b,5b\n" \
" .long 0b,3b\n" \
" .long 1b,6b\n" \
".previous" \
: "=&c"(size), "=&D" (__d0), "=&S" (__d1), "=r"(__d2) \
: "3"(size), "0"(size), "1"(to), "2"(from) \
: "memory"); \
} while (0)
#define __copy_user_zeroing(to,from,size) \
do { \
int __d0, __d1, __d2; \
__asm__ __volatile__( \
" cmp $7,%0\n" \
" jbe
" movl %1,%0\n" \
" negl %0\n" \
" andl $7,%0\n" \
" subl %0,%3\n" \
"4: rep; movsb\n" \
" movl %3,%0\n" \
" shrl $2,%0\n" \
" andl $3,%3\n" \
" .align 2,0x90\n" \
"0: rep; movsl\n" \
" movl %3,%0\n" \
"1: rep; movsb\n" \也是字节数
"2:\n" \
".section .fixup,\"ax\"\n" \
"5: addl %3,%0\n" \
" jmp
"3: lea 0(%3,%0,4),%0\n" \计算复制失败后剩余的字节数
"6: pushl %0\n" \
" pushl %%eax\n" \
" xorl %%eax,%%eax\n" \将eax清零
" rep; stosb\n" \ 将AL的值复制到esx:edi中
" popl %%eax\n" \
" popl %0\n" \
" jmp 2b\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .align 4\n" \
" .long 4b,5b\n" \
" .long 0b,3b\n" \
" .long 1b,6b\n" \
".previous" \
: "=&c"(size), "=&D" (__d0), "=&S" (__d1), "=r"(__d2) \
: "3"(size), "0"(size), "1"(to), "2"(from) \
: "memory"); \
} while (0)
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