diff options
Diffstat (limited to 'arch/x86/kernel/traps.c')
-rw-r--r-- | arch/x86/kernel/traps.c | 55 |
1 files changed, 32 insertions, 23 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index ad25e51f40c4..77da5b475ad2 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -571,6 +571,37 @@ asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void) } /* + * This gets called with the process already owning the + * FPU state, and with CR0.TS cleared. It just needs to + * restore the FPU register state. + */ +void __math_state_restore(struct task_struct *tsk) +{ + /* We need a safe address that is cheap to find and that is already + in L1. We've just brought in "tsk->thread.has_fpu", so use that */ +#define safe_address (tsk->thread.has_fpu) + + /* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception + is pending. Clear the x87 state here by setting it to fixed + values. safe_address is a random variable that should be in L1 */ + alternative_input( + ASM_NOP8 ASM_NOP2, + "emms\n\t" /* clear stack tags */ + "fildl %P[addr]", /* set F?P to defined value */ + X86_FEATURE_FXSAVE_LEAK, + [addr] "m" (safe_address)); + + /* + * Paranoid restore. send a SIGSEGV if we fail to restore the state. + */ + if (unlikely(restore_fpu_checking(tsk))) { + __thread_fpu_end(tsk); + force_sig(SIGSEGV, tsk); + return; + } +} + +/* * 'math_state_restore()' saves the current math information in the * old math state array, and gets the new ones from the current task * @@ -584,10 +615,6 @@ void math_state_restore(void) { struct task_struct *tsk = current; - /* We need a safe address that is cheap to find and that is already - in L1. We're just bringing in "tsk->thread.has_fpu", so use that */ -#define safe_address (tsk->thread.has_fpu) - if (!tsk_used_math(tsk)) { local_irq_enable(); /* @@ -604,25 +631,7 @@ void math_state_restore(void) } __thread_fpu_begin(tsk); - - /* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception - is pending. Clear the x87 state here by setting it to fixed - values. safe_address is a random variable that should be in L1 */ - alternative_input( - ASM_NOP8 ASM_NOP2, - "emms\n\t" /* clear stack tags */ - "fildl %P[addr]", /* set F?P to defined value */ - X86_FEATURE_FXSAVE_LEAK, - [addr] "m" (safe_address)); - - /* - * Paranoid restore. send a SIGSEGV if we fail to restore the state. - */ - if (unlikely(restore_fpu_checking(tsk))) { - __thread_fpu_end(tsk); - force_sig(SIGSEGV, tsk); - return; - } + __math_state_restore(tsk); tsk->fpu_counter++; } |