Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754419AbcJEAeu (ORCPT ); Tue, 4 Oct 2016 20:34:50 -0400 Received: from shelob.surriel.com ([74.92.59.67]:53788 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751856AbcJEAep (ORCPT ); Tue, 4 Oct 2016 20:34:45 -0400 From: riel@redhat.com To: linux-kernel@vger.kernel.org Cc: dave.hansen@linux.intel.com, x86@kernel.org, tglx@linutronix.de, pbonzini@redhat.com, mingo@redhat.com, luto@kernel.org, pa@zytor.com, bp@suse.de Subject: [PATCH 7/9] x86/fpu: rename lazy restore functions to "register state valid" Date: Tue, 4 Oct 2016 20:34:36 -0400 Message-Id: <1475627678-20788-8-git-send-email-riel@redhat.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1475627678-20788-1-git-send-email-riel@redhat.com> References: <1475627678-20788-1-git-send-email-riel@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3635 Lines: 101 From: Rik van Riel Name the functions after the state they track, rather than the function they currently enable. This should make it more obvious when we use the fpu_register_state_valid function for something else in the future. Signed-off-by: Rik van Riel --- arch/x86/include/asm/fpu/internal.h | 26 ++++++++++++++++++++------ arch/x86/kernel/fpu/core.c | 4 ++-- arch/x86/kernel/smpboot.c | 2 +- 3 files changed, 23 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 499d6ed0e376..d2cfe16dd9fa 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -479,18 +479,32 @@ extern int copy_fpstate_to_sigframe(void __user *buf, void __user *fp, int size) DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx); /* + * The in-register FPU state for an FPU context on a CPU is assumed to be + * valid if the fpu->last_cpu matches the CPU, and the fpu_fpregs_owner_ctx + * matches the FPU. + * + * If the FPU register state is valid, the kernel can skip restoring the + * FPU state from memory. + * + * Any code that clobbers the FPU registers or updates the in-memory + * FPU state for a task MUST let the rest of the kernel know that the + * FPU registers are no longer valid for this task. Calling either of + * these two invalidate functions is enough, use whichever is convenient. + * * Must be run with preemption disabled: this clears the fpu_fpregs_owner_ctx, * on this CPU. - * - * This will disable any lazy FPU state restore of the current FPU state, - * but if the current thread owns the FPU, it will still be saved by. */ -static inline void __cpu_disable_lazy_restore(unsigned int cpu) +static inline void __cpu_invalidate_fpregs_state(unsigned int cpu) { per_cpu(fpu_fpregs_owner_ctx, cpu) = NULL; } -static inline int fpu_want_lazy_restore(struct fpu *fpu, unsigned int cpu) +static inline void __fpu_invalidate_fpregs_state(struct fpu *fpu) +{ + fpu->last_cpu = -1; +} + +static inline int fpregs_state_valid(struct fpu *fpu, unsigned int cpu) { return fpu == this_cpu_read_stable(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu; } @@ -588,7 +602,7 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu) } else { old_fpu->last_cpu = -1; if (fpu.preload) { - if (fpu_want_lazy_restore(new_fpu, cpu)) + if (fpregs_state_valid(new_fpu, cpu)) fpu.preload = 0; else prefetch(&new_fpu->state); diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 6a37d525bdbe..25a45ddfdbcf 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -336,7 +336,7 @@ void fpu__activate_fpstate_write(struct fpu *fpu) if (fpu->fpstate_active) { /* Invalidate any lazy state: */ - fpu->last_cpu = -1; + __fpu_invalidate_fpregs_state(fpu); } else { fpstate_init(&fpu->state); trace_x86_fpu_init_state(fpu); @@ -379,7 +379,7 @@ void fpu__current_fpstate_write_begin(void) * ensures we will not be lazy and skip a XRSTOR in the * future. */ - fpu->last_cpu = -1; + __fpu_invalidate_fpregs_state(fpu); } /* diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 42a93621f5b0..ca4c4ca2f6af 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1111,7 +1111,7 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle) return err; /* the FPU context is blank, nobody can own it */ - __cpu_disable_lazy_restore(cpu); + __cpu_invalidate_fpregs_state(cpu); common_cpu_up(cpu, tidle); -- 2.7.4