diff options
author | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2009-04-24 03:40:59 -0400 |
---|---|---|
committer | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2009-06-17 16:21:25 -0400 |
commit | e6e9cac8c3417b43498b243c1f8f11780e157168 (patch) | |
tree | 4a3a2995f8d930f7baaf19b827043c6f9bf62db3 /arch/x86/kernel/traps.c | |
parent | 3fe0344faf7fdcb158bd5c1a9aec960a8d70c8e8 (diff) |
x86: split out core __math_state_restore
Split the core fpu state restoration out into __math_state_restore, which
assumes that cr0.TS is clear and that the fpu context has been initialized.
This will be used during context switch. There are two reasons this is
desireable:
- There's a small clarification. When __switch_to() calls math_state_restore,
it relies on the fact that tsk_used_math() returns true, and so will
never do a blocking init_fpu(). __math_state_restore() does not have
(or need) that logic, so the question never arises.
- It allows the clts() to be moved earler in __switch_to() so it can be performed
while cpu context updates are batched (will be done in a later patch).
[ Impact: refactor code to make reuse cleaner; no functional change ]
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'arch/x86/kernel/traps.c')
-rw-r--r-- | arch/x86/kernel/traps.c | 33 |
1 files changed, 23 insertions, 10 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 5f935f0d5861..71b91669ad19 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c | |||
@@ -814,6 +814,28 @@ asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void) | |||
814 | } | 814 | } |
815 | 815 | ||
816 | /* | 816 | /* |
817 | * __math_state_restore assumes that cr0.TS is already clear and the | ||
818 | * fpu state is all ready for use. Used during context switch. | ||
819 | */ | ||
820 | void __math_state_restore(void) | ||
821 | { | ||
822 | struct thread_info *thread = current_thread_info(); | ||
823 | struct task_struct *tsk = thread->task; | ||
824 | |||
825 | /* | ||
826 | * Paranoid restore. send a SIGSEGV if we fail to restore the state. | ||
827 | */ | ||
828 | if (unlikely(restore_fpu_checking(tsk))) { | ||
829 | stts(); | ||
830 | force_sig(SIGSEGV, tsk); | ||
831 | return; | ||
832 | } | ||
833 | |||
834 | thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */ | ||
835 | tsk->fpu_counter++; | ||
836 | } | ||
837 | |||
838 | /* | ||
817 | * 'math_state_restore()' saves the current math information in the | 839 | * 'math_state_restore()' saves the current math information in the |
818 | * old math state array, and gets the new ones from the current task | 840 | * old math state array, and gets the new ones from the current task |
819 | * | 841 | * |
@@ -844,17 +866,8 @@ asmlinkage void math_state_restore(void) | |||
844 | } | 866 | } |
845 | 867 | ||
846 | clts(); /* Allow maths ops (or we recurse) */ | 868 | clts(); /* Allow maths ops (or we recurse) */ |
847 | /* | ||
848 | * Paranoid restore. send a SIGSEGV if we fail to restore the state. | ||
849 | */ | ||
850 | if (unlikely(restore_fpu_checking(tsk))) { | ||
851 | stts(); | ||
852 | force_sig(SIGSEGV, tsk); | ||
853 | return; | ||
854 | } | ||
855 | 869 | ||
856 | thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */ | 870 | __math_state_restore(); |
857 | tsk->fpu_counter++; | ||
858 | } | 871 | } |
859 | EXPORT_SYMBOL_GPL(math_state_restore); | 872 | EXPORT_SYMBOL_GPL(math_state_restore); |
860 | 873 | ||