From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Martin Subject: [PATCH v7 05/16] arm64: fpsimd: Generalise context saving for non-task contexts Date: Wed, 9 May 2018 17:12:54 +0100 Message-ID: <1525882385-29181-6-git-send-email-Dave.Martin@arm.com> References: <1525882385-29181-1-git-send-email-Dave.Martin@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8FB9A4A0D1 for ; Wed, 9 May 2018 12:04:20 -0400 (EDT) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id j-JiS6-meVWY for ; Wed, 9 May 2018 12:03:57 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8459B4A0CA for ; Wed, 9 May 2018 12:03:57 -0400 (EDT) In-Reply-To: <1525882385-29181-1-git-send-email-Dave.Martin@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: kvmarm@lists.cs.columbia.edu Cc: Marc Zyngier , Catalin Marinas , Christoffer Dall , linux-arm-kernel@lists.infradead.org, Ard Biesheuvel List-Id: kvmarm@lists.cs.columbia.edu In preparation for allowing non-task (i.e., KVM vcpu) FPSIMD contexts to be handled by the fpsimd common code, this patch adapts task_fpsimd_save() to save back the currently loaded context, removing the explicit dependency on current. The relevant storage to write back to in memory is now found by examining the fpsimd_last_state percpu struct. fpsimd_save() does nothing unless TIF_FOREIGN_FPSTATE is clear, and fpsimd_last_state is updated under local_bh_disable() or local_irq_disable() everywhere that TIF_FOREIGN_FPSTATE is cleared: thus, fpsimd_save() will write back to the correct storage for the loaded context. No functional change. Signed-off-by: Dave Martin Acked-by: Marc Zyngier --- arch/arm64/kernel/fpsimd.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 0c4e7e0..5fc0595 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -270,13 +270,15 @@ static void task_fpsimd_load(void) } /* - * Ensure current's FPSIMD/SVE storage in thread_struct is up to date - * with respect to the CPU registers. + * Ensure FPSIMD/SVE storage in memory for the loaded context is up to + * date with respect to the CPU registers. * * Softirqs (and preemption) must be disabled. */ -static void task_fpsimd_save(void) +static void fpsimd_save(void) { + struct user_fpsimd_state *st = __this_cpu_read(fpsimd_last_state.st); + WARN_ON(!in_softirq() && !irqs_disabled()); if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) { @@ -291,10 +293,9 @@ static void task_fpsimd_save(void) return; } - sve_save_state(sve_pffr(current), - ¤t->thread.uw.fpsimd_state.fpsr); + sve_save_state(sve_pffr(current), &st->fpsr); } else - fpsimd_save_state(¤t->thread.uw.fpsimd_state); + fpsimd_save_state(st); } } @@ -598,7 +599,7 @@ int sve_set_vector_length(struct task_struct *task, if (task == current) { local_bh_disable(); - task_fpsimd_save(); + fpsimd_save(); set_thread_flag(TIF_FOREIGN_FPSTATE); } @@ -837,7 +838,7 @@ asmlinkage void do_sve_acc(unsigned int esr, struct pt_regs *regs) local_bh_disable(); - task_fpsimd_save(); + fpsimd_save(); fpsimd_to_sve(current); /* Force ret_to_user to reload the registers: */ @@ -898,7 +899,7 @@ void fpsimd_thread_switch(struct task_struct *next) * 'current'. */ if (current->mm) - task_fpsimd_save(); + fpsimd_save(); if (next->mm) /* @@ -977,7 +978,7 @@ void fpsimd_preserve_current_state(void) return; local_bh_disable(); - task_fpsimd_save(); + fpsimd_save(); local_bh_enable(); } @@ -1117,7 +1118,7 @@ void kernel_neon_begin(void) /* Save unsaved task fpsimd state, if any: */ if (current->mm) { - task_fpsimd_save(); + fpsimd_save(); set_thread_flag(TIF_FOREIGN_FPSTATE); } @@ -1242,7 +1243,7 @@ static int fpsimd_cpu_pm_notifier(struct notifier_block *self, switch (cmd) { case CPU_PM_ENTER: if (current->mm) - task_fpsimd_save(); + fpsimd_save(); fpsimd_flush_cpu_state(); break; case CPU_PM_EXIT: -- 2.1.4