diff options
| author | Ingo Molnar <mingo@elte.hu> | 2008-03-05 10:24:37 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-04-17 17:40:52 +0200 |
| commit | 23b55bd9f33a1812a664e548803db34c9bec56e8 (patch) | |
| tree | 0559906e87b50567941f983560017671de13f9b3 | |
| parent | ecd94c0809eb0ff50b628fa061c531a6fbf2fbbc (diff) | |
x86: clean up switch_to()
Make the code more readable and more hackable:
- use symbolic asm parameters
- use readable indentation
- add comments that explains the details
No code changed:
kernel/sched.o:
text data bss dec hex filename
28626 684 2640 31950 7cce sched.o.before
28626 684 2640 31950 7cce sched.o.after
md5:
2823d406c18b781975cdb2e7cfea0059 sched.o.before.asm
2823d406c18b781975cdb2e7cfea0059 sched.o.after.asm
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | include/asm-x86/system.h | 46 |
1 files changed, 31 insertions, 15 deletions
diff --git a/include/asm-x86/system.h b/include/asm-x86/system.h index 428d9471497f..299ae9605cb1 100644 --- a/include/asm-x86/system.h +++ b/include/asm-x86/system.h @@ -27,22 +27,38 @@ struct task_struct *__switch_to(struct task_struct *prev, * Saving eflags is important. It switches not only IOPL between tasks, * it also protects other tasks from NT leaking through sysenter etc. */ -#define switch_to(prev, next, last) do { \ +#define switch_to(prev, next, last) \ +do { \ unsigned long esi, edi; \ - asm volatile("pushfl\n\t" /* Save flags */ \ - "pushl %%ebp\n\t" \ - "movl %%esp,%0\n\t" /* save ESP */ \ - "movl %5,%%esp\n\t" /* restore ESP */ \ - "movl $1f,%1\n\t" /* save EIP */ \ - "pushl %6\n\t" /* restore EIP */ \ - "jmp __switch_to\n" \ - "1:\t" \ - "popl %%ebp\n\t" \ - "popfl" \ - :"=m" (prev->thread.sp), "=m" (prev->thread.ip), \ - "=a" (last), "=S" (esi), "=D" (edi) \ - :"m" (next->thread.sp), "m" (next->thread.ip), \ - "2" (prev), "d" (next)); \ + \ + asm volatile( \ + "pushfl \n\t" /* save flags */ \ + "pushl %%ebp \n\t" /* save EBP */ \ + "movl %%esp,%[prev_sp] \n\t" /* save ESP */ \ + "movl %[next_sp],%%esp \n\t" /* restore ESP */ \ + "movl $1f,%[prev_ip] \n\t" /* save EIP */ \ + "pushl %[next_ip] \n\t" /* restore EIP */ \ + "jmp __switch_to \n" /* regparm call */ \ + "1: \t" \ + "popl %%ebp \n\t" /* restore EBP */ \ + "popfl \n" /* restore flags */ \ + \ + /* output parameters */ \ + : [prev_sp] "=m" (prev->thread.sp), \ + [prev_ip] "=m" (prev->thread.ip), \ + "=a" (last), \ + \ + /* clobbered output registers: */ \ + "=S" (esi), "=D" (edi) \ + \ + /* input parameters: */ \ + : [next_sp] "m" (next->thread.sp), \ + [next_ip] "m" (next->thread.ip), \ + \ + /* regparm parameters for __switch_to(): */ \ + [prev] "a" (prev), \ + [next] "d" (next) \ + ); \ } while (0) /* |