Hi,
ZelluX <zellux@xxxxxxxxx> writes:
> In Linux Kernel 2.6.11, the switch_to macro is defined as follows(on x86
> platform)
>
> 15#define switch_to(prev,next,last) do { \
> 16 unsigned long esi,edi; \
> 17 asm volatile("pushfl\n\t" \
> 18 "pushl %%ebp\n\t" \
> 19 "movl %%esp,%0\n\t" /* save ESP */ \
> 20 "movl %5,%%esp\n\t" /* restore ESP */ \
> 21 "movl $1f,%1\n\t" /* save EIP */ \
> 22 "pushl %6\n\t" /* restore EIP */ \
> 23 "jmp __switch_to\n" \
> 24 "1:\t" \
> 25 "popl %%ebp\n\t" \
> 26 "popfl" \
> 27 :"=m" (prev->thread.esp),"=m" (prev->thread.eip), \
> 28 "=a" (last),"=S" (esi),"=D" (edi) \
> 29 :"m" (next->thread.esp),"m" (next->thread.eip), \
> 30 "2" (prev), "d" (next)); \
> 31} while (0)
>
> In the middle of the code there's a movl instruction
> 21 "movl $1f,%1\n\t" /* save EIP
> */ \
>
> which saves the address labeled 1 in prev->thread.eip as ULK points out.
>
> My question is why there's an f after $1? Is there any specification to
> this grammar?
It specifies that the address referred to is further down the code
sequence. If it would be before the movl, it'd be 1b.
Hannes
--
To unsubscribe from this list: send an email with
"unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx
Please read the FAQ at http://kernelnewbies.org/FAQ
