diff options
| author | Ingo Molnar <mingo@elte.hu> | 2008-03-05 04:24:37 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-04-17 11:40:52 -0400 |
| commit | 23b55bd9f33a1812a664e548803db34c9bec56e8 (patch) | |
| tree | 0559906e87b50567941f983560017671de13f9b3 /include/asm-x86/system.h | |
| 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>
Diffstat (limited to 'include/asm-x86/system.h')
| -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 428d9471497..299ae9605cb 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, | |||
| 27 | * Saving eflags is important. It switches not only IOPL between tasks, | 27 | * Saving eflags is important. It switches not only IOPL between tasks, |
| 28 | * it also protects other tasks from NT leaking through sysenter etc. | 28 | * it also protects other tasks from NT leaking through sysenter etc. |
| 29 | */ | 29 | */ |
| 30 | #define switch_to(prev, next, last) do { \ | 30 | #define switch_to(prev, next, last) \ |
| 31 | do { \ | ||
| 31 | unsigned long esi, edi; \ | 32 | unsigned long esi, edi; \ |
| 32 | asm volatile("pushfl\n\t" /* Save flags */ \ | 33 | \ |
| 33 | "pushl %%ebp\n\t" \ | 34 | asm volatile( \ |
| 34 | "movl %%esp,%0\n\t" /* save ESP */ \ | 35 | "pushfl \n\t" /* save flags */ \ |
| 35 | "movl %5,%%esp\n\t" /* restore ESP */ \ | 36 | "pushl %%ebp \n\t" /* save EBP */ \ |
| 36 | "movl $1f,%1\n\t" /* save EIP */ \ | 37 | "movl %%esp,%[prev_sp] \n\t" /* save ESP */ \ |
| 37 | "pushl %6\n\t" /* restore EIP */ \ | 38 | "movl %[next_sp],%%esp \n\t" /* restore ESP */ \ |
| 38 | "jmp __switch_to\n" \ | 39 | "movl $1f,%[prev_ip] \n\t" /* save EIP */ \ |
| 39 | "1:\t" \ | 40 | "pushl %[next_ip] \n\t" /* restore EIP */ \ |
| 40 | "popl %%ebp\n\t" \ | 41 | "jmp __switch_to \n" /* regparm call */ \ |
| 41 | "popfl" \ | 42 | "1: \t" \ |
| 42 | :"=m" (prev->thread.sp), "=m" (prev->thread.ip), \ | 43 | "popl %%ebp \n\t" /* restore EBP */ \ |
| 43 | "=a" (last), "=S" (esi), "=D" (edi) \ | 44 | "popfl \n" /* restore flags */ \ |
| 44 | :"m" (next->thread.sp), "m" (next->thread.ip), \ | 45 | \ |
| 45 | "2" (prev), "d" (next)); \ | 46 | /* output parameters */ \ |
| 47 | : [prev_sp] "=m" (prev->thread.sp), \ | ||
| 48 | [prev_ip] "=m" (prev->thread.ip), \ | ||
| 49 | "=a" (last), \ | ||
| 50 | \ | ||
| 51 | /* clobbered output registers: */ \ | ||
| 52 | "=S" (esi), "=D" (edi) \ | ||
| 53 | \ | ||
| 54 | /* input parameters: */ \ | ||
| 55 | : [next_sp] "m" (next->thread.sp), \ | ||
| 56 | [next_ip] "m" (next->thread.ip), \ | ||
| 57 | \ | ||
| 58 | /* regparm parameters for __switch_to(): */ \ | ||
| 59 | [prev] "a" (prev), \ | ||
| 60 | [next] "d" (next) \ | ||
| 61 | ); \ | ||
| 46 | } while (0) | 62 | } while (0) |
| 47 | 63 | ||
| 48 | /* | 64 | /* |