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Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fpu updates from Ingo Molnar: "Initial round of kernel_fpu_begin/end cleanups from Oleg Nesterov, plus a cleanup from Borislav Petkov" * 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86, fpu: Fix math_state_restore() race with kernel_fpu_begin() x86, fpu: Don't abuse has_fpu in __kernel_fpu_begin/end() x86, fpu: Introduce per-cpu in_kernel_fpu state x86/fpu: Use a symbolic name for asm operand
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c93ecedab3
@ -207,7 +207,7 @@ static inline void fpu_fxsave(struct fpu *fpu)
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if (config_enabled(CONFIG_X86_32))
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asm volatile( "fxsave %[fx]" : [fx] "=m" (fpu->state->fxsave));
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else if (config_enabled(CONFIG_AS_FXSAVEQ))
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asm volatile("fxsaveq %0" : "=m" (fpu->state->fxsave));
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asm volatile("fxsaveq %[fx]" : [fx] "=m" (fpu->state->fxsave));
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else {
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/* Using "rex64; fxsave %0" is broken because, if the memory
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* operand uses any extended registers for addressing, a second
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@ -290,9 +290,11 @@ static inline int fpu_restore_checking(struct fpu *fpu)
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static inline int restore_fpu_checking(struct task_struct *tsk)
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{
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/* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception
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is pending. Clear the x87 state here by setting it to fixed
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values. "m" is a random variable that should be in L1 */
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/*
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* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception is
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* pending. Clear the x87 state here by setting it to fixed values.
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* "m" is a random variable that should be in L1.
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*/
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if (unlikely(static_cpu_has_bug_safe(X86_BUG_FXSAVE_LEAK))) {
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asm volatile(
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"fnclex\n\t"
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@ -40,8 +40,8 @@ extern void __kernel_fpu_end(void);
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static inline void kernel_fpu_begin(void)
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{
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WARN_ON_ONCE(!irq_fpu_usable());
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preempt_disable();
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WARN_ON_ONCE(!irq_fpu_usable());
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__kernel_fpu_begin();
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}
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@ -51,6 +51,10 @@ static inline void kernel_fpu_end(void)
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preempt_enable();
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}
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/* Must be called with preempt disabled */
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extern void kernel_fpu_disable(void);
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extern void kernel_fpu_enable(void);
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/*
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* Some instructions like VIA's padlock instructions generate a spurious
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* DNA fault but don't modify SSE registers. And these instructions
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@ -19,6 +19,19 @@
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#include <asm/fpu-internal.h>
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#include <asm/user.h>
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static DEFINE_PER_CPU(bool, in_kernel_fpu);
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void kernel_fpu_disable(void)
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{
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WARN_ON(this_cpu_read(in_kernel_fpu));
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this_cpu_write(in_kernel_fpu, true);
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}
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void kernel_fpu_enable(void)
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{
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this_cpu_write(in_kernel_fpu, false);
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}
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/*
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* Were we in an interrupt that interrupted kernel mode?
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*
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@ -33,6 +46,9 @@
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*/
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static inline bool interrupted_kernel_fpu_idle(void)
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{
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if (this_cpu_read(in_kernel_fpu))
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return false;
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if (use_eager_fpu())
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return __thread_has_fpu(current);
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@ -73,10 +89,10 @@ void __kernel_fpu_begin(void)
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{
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struct task_struct *me = current;
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this_cpu_write(in_kernel_fpu, true);
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if (__thread_has_fpu(me)) {
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__thread_clear_has_fpu(me);
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__save_init_fpu(me);
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/* We do 'stts()' in __kernel_fpu_end() */
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} else if (!use_eager_fpu()) {
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this_cpu_write(fpu_owner_task, NULL);
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clts();
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@ -86,19 +102,16 @@ EXPORT_SYMBOL(__kernel_fpu_begin);
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void __kernel_fpu_end(void)
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{
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if (use_eager_fpu()) {
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/*
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* For eager fpu, most the time, tsk_used_math() is true.
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* Restore the user math as we are done with the kernel usage.
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* At few instances during thread exit, signal handling etc,
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* tsk_used_math() is false. Those few places will take proper
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* actions, so we don't need to restore the math here.
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*/
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if (likely(tsk_used_math(current)))
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math_state_restore();
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} else {
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struct task_struct *me = current;
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if (__thread_has_fpu(me)) {
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if (WARN_ON(restore_fpu_checking(me)))
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drop_init_fpu(me);
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} else if (!use_eager_fpu()) {
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stts();
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}
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this_cpu_write(in_kernel_fpu, false);
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}
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EXPORT_SYMBOL(__kernel_fpu_end);
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@ -859,18 +859,16 @@ void math_state_restore(void)
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local_irq_disable();
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}
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/* Avoid __kernel_fpu_begin() right after __thread_fpu_begin() */
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kernel_fpu_disable();
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__thread_fpu_begin(tsk);
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/*
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* Paranoid restore. send a SIGSEGV if we fail to restore the state.
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*/
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if (unlikely(restore_fpu_checking(tsk))) {
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drop_init_fpu(tsk);
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force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
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return;
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}
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} else {
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tsk->thread.fpu_counter++;
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}
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kernel_fpu_enable();
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}
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EXPORT_SYMBOL_GPL(math_state_restore);
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