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authorJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2009-04-24 09:40:59 +0200
committerJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2009-06-17 22:21:25 +0200
commite6e9cac8c3417b43498b243c1f8f11780e157168 (patch)
tree4a3a2995f8d930f7baaf19b827043c6f9bf62db3 /arch
parentMerge branch 'kmemleak' of git://linux-arm.org/linux-2.6 (diff)
downloadlinux-e6e9cac8c3417b43498b243c1f8f11780e157168.tar.xz
linux-e6e9cac8c3417b43498b243c1f8f11780e157168.zip
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')
-rw-r--r--arch/x86/include/asm/i387.h1
-rw-r--r--arch/x86/kernel/traps.c33
2 files changed, 24 insertions, 10 deletions
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 175adf58dd4f..2e7529295f55 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -26,6 +26,7 @@ extern void fpu_init(void);
extern void mxcsr_feature_mask_init(void);
extern int init_fpu(struct task_struct *child);
extern asmlinkage void math_state_restore(void);
+extern void __math_state_restore(void);
extern void init_thread_xstate(void);
extern int dump_fpu(struct pt_regs *, struct user_i387_struct *);
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)
}
/*
+ * __math_state_restore assumes that cr0.TS is already clear and the
+ * fpu state is all ready for use. Used during context switch.
+ */
+void __math_state_restore(void)
+{
+ struct thread_info *thread = current_thread_info();
+ struct task_struct *tsk = thread->task;
+
+ /*
+ * Paranoid restore. send a SIGSEGV if we fail to restore the state.
+ */
+ if (unlikely(restore_fpu_checking(tsk))) {
+ stts();
+ force_sig(SIGSEGV, tsk);
+ return;
+ }
+
+ thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */
+ tsk->fpu_counter++;
+}
+
+/*
* 'math_state_restore()' saves the current math information in the
* old math state array, and gets the new ones from the current task
*
@@ -844,17 +866,8 @@ asmlinkage void math_state_restore(void)
}
clts(); /* Allow maths ops (or we recurse) */
- /*
- * Paranoid restore. send a SIGSEGV if we fail to restore the state.
- */
- if (unlikely(restore_fpu_checking(tsk))) {
- stts();
- force_sig(SIGSEGV, tsk);
- return;
- }
- thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */
- tsk->fpu_counter++;
+ __math_state_restore();
}
EXPORT_SYMBOL_GPL(math_state_restore);