diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/fpu/internal.h | 34 | ||||
| -rw-r--r-- | arch/x86/kernel/fpu/core.c | 4 | ||||
| -rw-r--r-- | arch/x86/kernel/traps.c | 2 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 2 | ||||
| -rw-r--r-- | arch/x86/mm/mpx.c | 2 |
5 files changed, 29 insertions, 15 deletions
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 89c6ec80c1ac..11055f51e67a 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -265,9 +265,15 @@ static inline void fpu_fxsave(struct fpu *fpu) /* * These must be called with preempt disabled. Returns - * 'true' if the FPU state is still intact. + * 'true' if the FPU state is still intact and we can + * keep registers active. + * + * The legacy FNSAVE instruction cleared all FPU state + * unconditionally, so registers are essentially destroyed. + * Modern FPU state can be kept in registers, if there are + * no pending FP exceptions. (Note the FIXME below.) */ -static inline int fpu_save_init(struct fpu *fpu) +static inline int copy_fpregs_to_fpstate(struct fpu *fpu) { if (use_xsave()) { xsave_state(&fpu->state->xsave); @@ -276,13 +282,16 @@ static inline int fpu_save_init(struct fpu *fpu) * xsave header may indicate the init state of the FP. */ if (!(fpu->state->xsave.header.xfeatures & XSTATE_FP)) - return 1; - } else if (use_fxsr()) { - fpu_fxsave(fpu); + goto keep_fpregs; } else { - asm volatile("fnsave %[fx]; fwait" - : [fx] "=m" (fpu->state->fsave)); - return 0; + if (use_fxsr()) { + fpu_fxsave(fpu); + } else { + /* FNSAVE always clears FPU registers: */ + asm volatile("fnsave %[fx]; fwait" + : [fx] "=m" (fpu->state->fsave)); + goto drop_fpregs; + } } /* @@ -295,9 +304,14 @@ static inline int fpu_save_init(struct fpu *fpu) */ if (unlikely(fpu->state->fxsave.swd & X87_FSW_ES)) { asm volatile("fnclex"); - return 0; + goto drop_fpregs; } + +keep_fpregs: return 1; + +drop_fpregs: + return 0; } extern void fpu__save(struct fpu *fpu); @@ -448,7 +462,7 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu) (use_eager_fpu() || new_fpu->counter > 5); if (old_fpu->fpregs_active) { - if (!fpu_save_init(old_fpu)) + if (!copy_fpregs_to_fpstate(old_fpu)) old_fpu->last_cpu = -1; else old_fpu->last_cpu = cpu; diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index b20d4ea8e132..ca88608a62a5 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -102,7 +102,7 @@ void __kernel_fpu_begin(void) kernel_fpu_disable(); if (fpu->fpregs_active) { - fpu_save_init(fpu); + copy_fpregs_to_fpstate(fpu); } else { this_cpu_write(fpu_fpregs_owner_ctx, NULL); if (!use_eager_fpu()) @@ -196,7 +196,7 @@ void fpu__save(struct fpu *fpu) if (use_eager_fpu()) { __save_fpu(fpu); } else { - fpu_save_init(fpu); + copy_fpregs_to_fpstate(fpu); fpregs_deactivate(fpu); } } diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index a65586edbb57..f028f1da3480 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -395,7 +395,7 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) * It is not directly accessible, though, so we need to * do an xsave and then pull it out of the xsave buffer. */ - fpu_save_init(&tsk->thread.fpu); + copy_fpregs_to_fpstate(&tsk->thread.fpu); xsave_buf = &(tsk->thread.fpu.state->xsave); bndcsr = get_xsave_addr(xsave_buf, XSTATE_BNDCSR); if (!bndcsr) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 0b58b9397098..d90bf4afa2b0 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7058,7 +7058,7 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu) return; vcpu->guest_fpu_loaded = 0; - fpu_save_init(&vcpu->arch.guest_fpu); + copy_fpregs_to_fpstate(&vcpu->arch.guest_fpu); __kernel_fpu_end(); ++vcpu->stat.fpu_reload; kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu); diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index 5563be313fd6..3287215be60a 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -357,7 +357,7 @@ static __user void *task_get_bounds_dir(struct task_struct *tsk) * The bounds directory pointer is stored in a register * only accessible if we first do an xsave. */ - fpu_save_init(&tsk->thread.fpu); + copy_fpregs_to_fpstate(&tsk->thread.fpu); bndcsr = get_xsave_addr(&tsk->thread.fpu.state->xsave, XSTATE_BNDCSR); if (!bndcsr) return MPX_INVALID_BOUNDS_DIR; |