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| author |   Linus Torvalds <torvalds@evo.osdl.org> | 2005-07-22 16:06:16 -0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@evo.osdl.org> | 2005-07-22 16:06:16 -0400 |
| commit | 8ed1383fb7b6685968588141d5934e0e6715e954 (patch) | |
| tree | 7ee8476ec114dbab907e3acf4e8a9d0342bf6751 /include/asm-i386 | |
| parent | Fix up incorrect "unlikely()" on %gs reload in x86 __switch_to (diff) | |
| download | linux-dev-8ed1383fb7b6685968588141d5934e0e6715e954.tar.xz linux-dev-8ed1383fb7b6685968588141d5934e0e6715e954.zip | |
x86: make restore_fpu() use alternative assembler instructions
It's really just a single instruction, conditional on whether the CPU
supports FXSR or not, so implement it as such instead of making it a
function that queries FXSR dynamically.
This means that the instruction just gets automatically rewritten to the
correct one at boot-time.
Diffstat (limited to 'include/asm-i386')
| -rw-r--r-- | include/asm-i386/i387.h | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/include/asm-i386/i387.h b/include/asm-i386/i387.h index f6feb98a9397..e678609bb57e 100644 --- a/include/asm-i386/i387.h +++ b/include/asm-i386/i387.h @@ -19,10 +19,21 @@ extern void mxcsr_feature_mask_init(void); extern void init_fpu(struct task_struct *); + /* * FPU lazy state save handling... */ -extern void restore_fpu( struct task_struct *tsk ); + +/* + * The "nop" is needed to make the instructions the same + * length. + */ +#define restore_fpu(tsk) \ + alternative_input( \ + "nop ; frstor %1", \ + "fxrstor %1", \ + X86_FEATURE_FXSR, \ + "m" ((tsk)->thread.i387.fsave)) extern void kernel_fpu_begin(void); #define kernel_fpu_end() do { stts(); preempt_enable(); } while(0) |