Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux-2.6-block.git] / arch / x86 / kernel / fpu / core.c

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index d5804adfa6da6c3d495b124faf47c288e2c0c6cf..0b1b9abd4d5fe002c2f31d70736dc3d785027305 100644 (file)
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -114,6 +114,10 @@ void __kernel_fpu_begin(void)
        kernel_fpu_disable();
 
        if (fpu->fpregs_active) {
+               /*
+                * Ignore return value -- we don't care if reg state
+                * is clobbered.
+                */
                copy_fpregs_to_fpstate(fpu);
        } else {
                this_cpu_write(fpu_fpregs_owner_ctx, NULL);
@@ -189,8 +193,12 @@ void fpu__save(struct fpu *fpu)
 
        preempt_disable();
        if (fpu->fpregs_active) {
-               if (!copy_fpregs_to_fpstate(fpu))
-                       fpregs_deactivate(fpu);
+               if (!copy_fpregs_to_fpstate(fpu)) {
+                       if (use_eager_fpu())
+                               copy_kernel_to_fpregs(&fpu->state);
+                       else
+                               fpregs_deactivate(fpu);
+               }
        }
        preempt_enable();
 }
@@ -223,14 +231,15 @@ void fpstate_init(union fpregs_state *state)
 }
 EXPORT_SYMBOL_GPL(fpstate_init);
 
-/*
- * Copy the current task's FPU state to a new task's FPU context.
- *
- * In both the 'eager' and the 'lazy' case we save hardware registers
- * directly to the destination buffer.
- */
-static void fpu_copy(struct fpu *dst_fpu, struct fpu *src_fpu)
+int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
 {
+       dst_fpu->counter = 0;
+       dst_fpu->fpregs_active = 0;
+       dst_fpu->last_cpu = -1;
+
+       if (!src_fpu->fpstate_active || !cpu_has_fpu)
+               return 0;
+
        WARN_ON_FPU(src_fpu != &current->thread.fpu);
 
        /*
@@ -243,10 +252,9 @@ static void fpu_copy(struct fpu *dst_fpu, struct fpu *src_fpu)
        /*
         * Save current FPU registers directly into the child
         * FPU context, without any memory-to-memory copying.
-        *
-        * If the FPU context got destroyed in the process (FNSAVE
-        * done on old CPUs) then copy it back into the source
-        * context and mark the current task for lazy restore.
+        * In lazy mode, if the FPU context isn't loaded into
+        * fpregs, CR0.TS will be set and do_device_not_available
+        * will load the FPU context.
         *
         * We have to do all this with preemption disabled,
         * mostly because of the FNSAVE case, because in that
@@ -259,19 +267,13 @@ static void fpu_copy(struct fpu *dst_fpu, struct fpu *src_fpu)
        preempt_disable();
        if (!copy_fpregs_to_fpstate(dst_fpu)) {
                memcpy(&src_fpu->state, &dst_fpu->state, xstate_size);
-               fpregs_deactivate(src_fpu);
+
+               if (use_eager_fpu())
+                       copy_kernel_to_fpregs(&src_fpu->state);
+               else
+                       fpregs_deactivate(src_fpu);
        }
        preempt_enable();
-}
-
-int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
-{
-       dst_fpu->counter = 0;
-       dst_fpu->fpregs_active = 0;
-       dst_fpu->last_cpu = -1;
-
-       if (src_fpu->fpstate_active && cpu_has_fpu)
-               fpu_copy(dst_fpu, src_fpu);
 
        return 0;
 }
@@ -425,7 +427,7 @@ void fpu__clear(struct fpu *fpu)
 {
        WARN_ON_FPU(fpu != &current->thread.fpu); /* Almost certainly an anomaly */
 
-       if (!use_eager_fpu()) {
+       if (!use_eager_fpu() || !static_cpu_has(X86_FEATURE_FPU)) {
                /* FPU state will be reallocated lazily at the first use. */
                fpu__drop(fpu);
        } else {