diff options
| -rw-r--r-- | arch/x86/include/asm/i387.h | 17 | ||||
| -rw-r--r-- | arch/x86/kernel/traps.c | 40 |
2 files changed, 22 insertions, 35 deletions
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h index 8df95849721..74c607b37e8 100644 --- a/arch/x86/include/asm/i387.h +++ b/arch/x86/include/asm/i387.h @@ -29,7 +29,6 @@ extern unsigned int sig_xstate_size; extern void fpu_init(void); extern void mxcsr_feature_mask_init(void); extern int init_fpu(struct task_struct *child); -extern void __math_state_restore(struct task_struct *); extern void math_state_restore(void); extern int dump_fpu(struct pt_regs *, struct user_i387_struct *); @@ -269,6 +268,16 @@ static inline int fpu_restore_checking(struct fpu *fpu) static inline int restore_fpu_checking(struct task_struct *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. "m" 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" (tsk->thread.has_fpu)); + return fpu_restore_checking(&tsk->thread.fpu); } @@ -378,8 +387,10 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta */ static inline void switch_fpu_finish(struct task_struct *new, fpu_switch_t fpu) { - if (fpu.preload) - __math_state_restore(new); + if (fpu.preload) { + if (unlikely(restore_fpu_checking(new))) + __thread_fpu_end(new); + } } /* diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 77da5b475ad..4bbe04d9674 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -571,37 +571,6 @@ 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 * @@ -631,7 +600,14 @@ void math_state_restore(void) } __thread_fpu_begin(tsk); - __math_state_restore(tsk); + /* + * 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; + } tsk->fpu_counter++; } |