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authorSuresh Siddha <suresh.b.siddha@intel.com>2012-09-06 14:58:52 -0700
committerH. Peter Anvin <hpa@linux.intel.com>2012-09-18 15:52:22 -0700
commit5d2bd7009f306c82afddd1ca4d9763ad8473c216 (patch)
tree772bc888c48766b892e216c19e938c82657e2b0e /arch/x86/kernel/i387.c
parent304bceda6a18ae0b0240b8aac9a6bdf8ce2d2469 (diff)
downloadlinux-next-5d2bd7009f306c82afddd1ca4d9763ad8473c216.tar.gz
x86, fpu: decouple non-lazy/eager fpu restore from xsave
Decouple non-lazy/eager fpu restore policy from the existence of the xsave feature. Introduce a synthetic CPUID flag to represent the eagerfpu policy. "eagerfpu=on" boot paramter will enable the policy. Requested-by: H. Peter Anvin <hpa@zytor.com> Requested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Link: http://lkml.kernel.org/r/1347300665-6209-2-git-send-email-suresh.b.siddha@intel.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/i387.c')
-rw-r--r--arch/x86/kernel/i387.c25
1 files changed, 8 insertions, 17 deletions
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 528557470ddb..6782e3983865 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -22,9 +22,8 @@
/*
* Were we in an interrupt that interrupted kernel mode?
*
- * For now, on xsave platforms we will return interrupted
- * kernel FPU as not-idle. TBD: As we use non-lazy FPU restore
- * for xsave platforms, ideally we can change the return value
+ * For now, with eagerfpu we will return interrupted kernel FPU
+ * state as not-idle. TBD: Ideally we can change the return value
* to something like __thread_has_fpu(current). But we need to
* be careful of doing __thread_clear_has_fpu() before saving
* the FPU etc for supporting nested uses etc. For now, take
@@ -38,7 +37,7 @@
*/
static inline bool interrupted_kernel_fpu_idle(void)
{
- if (use_xsave())
+ if (use_eager_fpu())
return 0;
return !__thread_has_fpu(current) &&
@@ -84,7 +83,7 @@ void kernel_fpu_begin(void)
__save_init_fpu(me);
__thread_clear_has_fpu(me);
/* We do 'stts()' in kernel_fpu_end() */
- } else if (!use_xsave()) {
+ } else if (!use_eager_fpu()) {
this_cpu_write(fpu_owner_task, NULL);
clts();
}
@@ -93,7 +92,7 @@ EXPORT_SYMBOL(kernel_fpu_begin);
void kernel_fpu_end(void)
{
- if (use_xsave())
+ if (use_eager_fpu())
math_state_restore();
else
stts();
@@ -122,7 +121,6 @@ static void __cpuinit mxcsr_feature_mask_init(void)
{
unsigned long mask = 0;
- clts();
if (cpu_has_fxsr) {
memset(&fx_scratch, 0, sizeof(struct i387_fxsave_struct));
asm volatile("fxsave %0" : : "m" (fx_scratch));
@@ -131,7 +129,6 @@ static void __cpuinit mxcsr_feature_mask_init(void)
mask = 0x0000ffbf;
}
mxcsr_feature_mask &= mask;
- stts();
}
static void __cpuinit init_thread_xstate(void)
@@ -185,9 +182,8 @@ void __cpuinit fpu_init(void)
init_thread_xstate();
mxcsr_feature_mask_init();
- /* clean state in init */
- current_thread_info()->status = 0;
- clear_used_math();
+ xsave_init();
+ eager_fpu_init();
}
void fpu_finit(struct fpu *fpu)
@@ -198,12 +194,7 @@ void fpu_finit(struct fpu *fpu)
}
if (cpu_has_fxsr) {
- struct i387_fxsave_struct *fx = &fpu->state->fxsave;
-
- memset(fx, 0, xstate_size);
- fx->cwd = 0x37f;
- if (cpu_has_xmm)
- fx->mxcsr = MXCSR_DEFAULT;
+ fx_finit(&fpu->state->fxsave);
} else {
struct i387_fsave_struct *fp = &fpu->state->fsave;
memset(fp, 0, xstate_size);