aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/traps.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/kernel/traps.c')
-rw-r--r--arch/x86/kernel/traps.c55
1 files changed, 32 insertions, 23 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index ad25e51f40c..77da5b475ad 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++;
}