diff options
| author | Avi Kivity <avi@redhat.com> | 2010-05-06 12:45:45 +0400 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2010-05-10 21:39:33 +0400 |
| commit | c9ad488289144ae5ef53b012e15895ef1f5e4bb6 (patch) | |
| tree | 06c29cda09e204d3b0b5b3d9a2a97bda0b4e340d /arch/x86/include | |
| parent | 250825008f1f94887bc039e9227a8adfb5ba366e (diff) | |
| download | linux-c9ad488289144ae5ef53b012e15895ef1f5e4bb6.tar.xz | |
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>
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/i387.h | 20 | ||||
| -rw-r--r-- | arch/x86/include/asm/thread_info.h | 1 |
2 files changed, 16 insertions, 5 deletions
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h index da2930924501..a301a6825c3a 100644 --- a/arch/x86/include/asm/i387.h +++ b/arch/x86/include/asm/i387.h @@ -56,6 +56,18 @@ extern int restore_i387_xstate_ia32(void __user *buf); #define X87_FSW_ES (1 << 7) /* Exception Summary */ +static inline bool use_xsave(void) +{ + u8 has_xsave; + + alternative_io("mov $0, %0", + "mov $1, %0", + X86_FEATURE_XSAVE, + "=g"(has_xsave)); + + return has_xsave; +} + #ifdef CONFIG_X86_64 /* Ignore delayed exceptions from user space */ @@ -99,7 +111,7 @@ static inline void clear_fpu_state(struct task_struct *tsk) /* * xsave header may indicate the init state of the FP. */ - if ((task_thread_info(tsk)->status & TS_XSAVE) && + if (use_xsave() && !(xstate->xsave_hdr.xstate_bv & XSTATE_FP)) return; @@ -164,7 +176,7 @@ static inline void fxsave(struct task_struct *tsk) static inline void __save_init_fpu(struct task_struct *tsk) { - if (task_thread_info(tsk)->status & TS_XSAVE) + if (use_xsave()) xsave(tsk); else fxsave(tsk); @@ -218,7 +230,7 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx) */ static inline void __save_init_fpu(struct task_struct *tsk) { - if (task_thread_info(tsk)->status & TS_XSAVE) { + if (use_xsave()) { struct xsave_struct *xstate = &tsk->thread.xstate->xsave; struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave; @@ -266,7 +278,7 @@ end: static inline int restore_fpu_checking(struct task_struct *tsk) { - if (task_thread_info(tsk)->status & TS_XSAVE) + if (use_xsave()) return xrstor_checking(&tsk->thread.xstate->xsave); else return fxrstor_checking(&tsk->thread.xstate->fxsave); diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index e0d28901e969..e9e341505ab3 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -244,7 +244,6 @@ static inline struct thread_info *current_thread_info(void) #define TS_POLLING 0x0004 /* true if in idle loop and not sleeping */ #define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */ -#define TS_XSAVE 0x0010 /* Use xsave/xrstor */ #define tsk_is_polling(t) (task_thread_info(t)->status & TS_POLLING) |