diff options
Diffstat (limited to 'arch/x86/kernel/fpu/regset.c')
| -rw-r--r-- | arch/x86/kernel/fpu/regset.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c index 937adf702b37..ddc290d9bf8e 100644 --- a/arch/x86/kernel/fpu/regset.c +++ b/arch/x86/kernel/fpu/regset.c @@ -44,6 +44,25 @@ static void sync_fpstate(struct fpu *fpu) fpu__save(fpu); } +/* + * Invalidate cached FPU registers before modifying the stopped target + * task's fpstate. + * + * This forces the target task on resume to restore the FPU registers from + * modified fpstate. Otherwise the task might skip the restore and operate + * with the cached FPU registers which discards the modifications. + */ +static void fpu_force_restore(struct fpu *fpu) +{ + /* + * Only stopped child tasks can be used to modify the FPU + * state in the fpstate buffer: + */ + WARN_ON_FPU(fpu == ¤t->thread.fpu); + + __fpu_invalidate_fpregs_state(fpu); +} + int xfpregs_get(struct task_struct *target, const struct user_regset *regset, struct membuf to) { @@ -88,7 +107,7 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset, if (newstate.mxcsr & ~mxcsr_feature_mask) return -EINVAL; - fpu__prepare_write(fpu); + fpu_force_restore(fpu); /* Copy the state */ memcpy(&fpu->state.fxsave, &newstate, sizeof(newstate)); @@ -146,7 +165,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset, } } - fpu__prepare_write(fpu); + fpu_force_restore(fpu); ret = copy_kernel_to_xstate(&fpu->state.xsave, kbuf ?: tmpbuf); out: @@ -346,7 +365,7 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset, if (ret) return ret; - fpu__prepare_write(fpu); + fpu_force_restore(fpu); if (cpu_feature_enabled(X86_FEATURE_FXSR)) convert_to_fxsr(&fpu->state.fxsave, &env); |