x86: Eliminate TS_XSAVE
The fpu code currently uses current->thread_info->status & TS_XSAVE as
a way to distinguish between XSAVE capable processors and older processors.
The decision is not really task specific; instead we use the task status to
avoid a global memory reference - the value should be the same across all
threads.
Eliminate this tie-in into the task structure by using an alternative
instruction keyed off the XSAVE cpu feature; this results in shorter and
faster code, without introducing a global memory reference.
[ hpa: in the future, this probably should use an asm jmp ]
Signed-off-by: Avi Kivity <avi@redhat.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <1273135546-29690-2-git-send-email-avi@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 4868e4a..c1c00d0 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1243,10 +1243,7 @@
/*
* Force FPU initialization:
*/
- if (cpu_has_xsave)
- current_thread_info()->status = TS_XSAVE;
- else
- current_thread_info()->status = 0;
+ current_thread_info()->status = 0;
clear_used_math();
mxcsr_feature_mask_init();
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 54c31c2..14ca1dc 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -102,10 +102,7 @@
mxcsr_feature_mask_init();
/* clean state in init */
- if (cpu_has_xsave)
- current_thread_info()->status = TS_XSAVE;
- else
- current_thread_info()->status = 0;
+ current_thread_info()->status = 0;
clear_used_math();
}
#endif /* CONFIG_X86_64 */
diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index 782c3a36..c1b0a11 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -99,7 +99,7 @@
if (err)
return err;
- if (task_thread_info(tsk)->status & TS_XSAVE)
+ if (use_xsave())
err = xsave_user(buf);
else
err = fxsave_user(buf);
@@ -116,7 +116,7 @@
clear_used_math(); /* trigger finit */
- if (task_thread_info(tsk)->status & TS_XSAVE) {
+ if (use_xsave()) {
struct _fpstate __user *fx = buf;
struct _xstate __user *x = buf;
u64 xstate_bv;
@@ -225,7 +225,7 @@
clts();
task_thread_info(current)->status |= TS_USEDFPU;
}
- if (task_thread_info(tsk)->status & TS_XSAVE)
+ if (use_xsave())
err = restore_user_xstate(buf);
else
err = fxrstor_checking((__force struct i387_fxsave_struct *)