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[23.128.96.18]) by mx.google.com with ESMTP id 18si136890ejy.624.2021.09.15.07.33.19; Wed, 15 Sep 2021 07:33:45 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@mail.ustc.edu.cn header.s=dkim header.b="SkeyUn/g"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=mail.ustc.edu.cn Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237745AbhIOOcv (ORCPT + 99 others); Wed, 15 Sep 2021 10:32:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60450 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233771AbhIOOcu (ORCPT ); Wed, 15 Sep 2021 10:32:50 -0400 Received: from ustc.edu.cn (email6.ustc.edu.cn [IPv6:2001:da8:d800::8]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 93CECC061574 for ; Wed, 15 Sep 2021 07:31:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mail.ustc.edu.cn; s=dkim; h=Received:Date:From:To:Cc:Subject: Message-ID:In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=klzs1tYjzupJFTbvmrtRCSiuF++kdvsrPO lrBmiB/64=; b=SkeyUn/gti302b1GIWy5aWgXIHOPHX+oEgUz4hOj/wokCIcd4y rPKN3RczNIreqog6hRSU1Y3NEarX5ycf8W2czyBh7wWdWc9T56if1qbjFaBJxv8l 6a7m6ThnVvyslGQTKD6z8b5rdM0CNF7In9yqnGq1/umTpPsJLCBq42/kk= Received: from xhacker (unknown [101.86.20.138]) by newmailweb.ustc.edu.cn (Coremail) with SMTP id LkAmygC38qm7A0JhjssBAA--.1007S2; Wed, 15 Sep 2021 22:31:23 +0800 (CST) Date: Wed, 15 Sep 2021 22:24:56 +0800 From: Jisheng Zhang To: Greentime Hu Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, aou@eecs.berkeley.edu, palmer@dabbelt.com, paul.walmsley@sifive.com, vincent.chen@sifive.com Subject: Re: [RFC PATCH v8 21/21] riscv: Turn has_vector into a static key if VECTOR=y Message-ID: <20210915222456.1de541df@xhacker> In-Reply-To: <56e2328d133045c79b420ecbcaf37cf9d0b2248c.1631121222.git.greentime.hu@sifive.com> References: <56e2328d133045c79b420ecbcaf37cf9d0b2248c.1631121222.git.greentime.hu@sifive.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-CM-TRANSID: LkAmygC38qm7A0JhjssBAA--.1007S2 X-Coremail-Antispam: 1UD129KBjvJXoWxtF48Jr1fAFyfJFyfKrykZrb_yoWxGr47pr WqkFnxXrWUArs2ga43Janrur45J3s7Ww13Krn8Ja4rCrWrKr98J3WkXryjvF45WF1F9w1f CasFkr1Skw47JFJanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUyIb7Iv0xC_KF4lb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I2 0VC2zVCF04k26cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rw A2F7IY1VAKz4vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xII jxv20xvEc7CjxVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I 8E87Iv6xkF7I0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI 64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8Jw Am72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IY64vIr41l42xK82IYc2Ij64vIr41l4I8I3I0E 4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGV WUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_ Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rV WrJr0_WFyUJwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j 6r4UJbIYCTnIWIevJa73UjIFyTuYvjxU7eOJUUUUU X-CM-SenderInfo: xmv2xttqjtqzxdloh3xvwfhvlgxou0/ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 9 Sep 2021 01:45:33 +0800 Greentime Hu wrote: > Just like fpu, we can use static key for has_vector. > The has_vector check sits at hot code path: switch_to(). Currently, > has_vector is a bool variable if VECTOR=y, switch_to() checks it each time, > we can optimize out this check by turning the has_vector into a static key. > has_vector is newly introduced in this patch set so I believe this patch can be folded into has_vector introducing patch, I.E patch 6 > Signed-off-by: Greentime Hu > --- > arch/riscv/include/asm/switch_to.h | 10 +++++++--- > arch/riscv/kernel/cpufeature.c | 4 ++-- > arch/riscv/kernel/kernel_mode_vector.c | 4 ++-- > arch/riscv/kernel/process.c | 8 ++++---- > arch/riscv/kernel/signal.c | 6 +++--- > 5 files changed, 18 insertions(+), 14 deletions(-) > > diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h > index b48c9c974564..576204217e0f 100644 > --- a/arch/riscv/include/asm/switch_to.h > +++ b/arch/riscv/include/asm/switch_to.h > @@ -71,7 +71,11 @@ static __always_inline bool has_fpu(void) { return false; } > #endif > > #ifdef CONFIG_VECTOR > -extern bool has_vector; > +extern struct static_key_false cpu_hwcap_vector; > +static __always_inline bool has_vector(void) > +{ > + return static_branch_likely(&cpu_hwcap_vector); > +} > extern unsigned long riscv_vsize; > extern void __vstate_save(struct __riscv_v_state *save_to, void *datap); > extern void __vstate_restore(struct __riscv_v_state *restore_from, void *datap); > @@ -120,7 +124,7 @@ static inline void __switch_to_vector(struct task_struct *prev, > } > > #else > -#define has_vector false > +static __always_inline bool has_vector(void) { return false; } > #define riscv_vsize (0) > #define vstate_save(task, regs) do { } while (0) > #define vstate_restore(task, regs) do { } while (0) > @@ -136,7 +140,7 @@ do { \ > struct task_struct *__next = (next); \ > if (has_fpu()) \ > __switch_to_fpu(__prev, __next); \ > - if (has_vector) \ > + if (has_vector()) \ > __switch_to_vector(__prev, __next); \ > ((last) = __switch_to(__prev, __next)); \ > } while (0) > diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c > index af984f875f60..0139ec20adce 100644 > --- a/arch/riscv/kernel/cpufeature.c > +++ b/arch/riscv/kernel/cpufeature.c > @@ -23,7 +23,7 @@ __ro_after_init DEFINE_STATIC_KEY_FALSE(cpu_hwcap_fpu); > #endif > #ifdef CONFIG_VECTOR > #include > -bool has_vector __read_mostly; > +__ro_after_init DEFINE_STATIC_KEY_FALSE(cpu_hwcap_vector); > unsigned long riscv_vsize __read_mostly; > #endif > > @@ -157,7 +157,7 @@ void __init riscv_fill_hwcap(void) > > #ifdef CONFIG_VECTOR > if (elf_hwcap & COMPAT_HWCAP_ISA_V) { > - has_vector = true; > + static_branch_enable(&cpu_hwcap_vector); > /* There are 32 vector registers with vlenb length. */ > rvv_enable(); > riscv_vsize = csr_read(CSR_VLENB) * 32; > diff --git a/arch/riscv/kernel/kernel_mode_vector.c b/arch/riscv/kernel/kernel_mode_vector.c > index 0d990bd8b8dd..0d08954c30af 100644 > --- a/arch/riscv/kernel/kernel_mode_vector.c > +++ b/arch/riscv/kernel/kernel_mode_vector.c > @@ -110,7 +110,7 @@ static void vector_flush_cpu_state(void) > */ > void kernel_rvv_begin(void) > { > - if (WARN_ON(!has_vector)) > + if (WARN_ON(!has_vector())) > return; > > WARN_ON(!may_use_vector()); > @@ -140,7 +140,7 @@ EXPORT_SYMBOL(kernel_rvv_begin); > */ > void kernel_rvv_end(void) > { > - if (WARN_ON(!has_vector)) > + if (WARN_ON(!has_vector())) > return; > > /* Invalidate vector regs */ > diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c > index 05ff5f934e7e..62540815ba1c 100644 > --- a/arch/riscv/kernel/process.c > +++ b/arch/riscv/kernel/process.c > @@ -96,7 +96,7 @@ void start_thread(struct pt_regs *regs, unsigned long pc, > fstate_restore(current, regs); > } > > - if (has_vector) { > + if (has_vector()) { > struct __riscv_v_state *vstate = &(current->thread.vstate); > > /* Enable vector and allocate memory for vector registers. */ > @@ -141,11 +141,11 @@ void flush_thread(void) > int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) > { > fstate_save(src, task_pt_regs(src)); > - if (has_vector) > + if (has_vector()) > /* To make sure every dirty vector context is saved. */ > vstate_save(src, task_pt_regs(src)); > *dst = *src; > - if (has_vector) { > + if (has_vector()) { > /* Copy vector context to the forked task from parent. */ > if ((task_pt_regs(src)->status & SR_VS) != SR_VS_OFF) { > dst->thread.vstate.datap = kzalloc(riscv_vsize, GFP_KERNEL); > @@ -164,7 +164,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) > void arch_release_task_struct(struct task_struct *tsk) > { > /* Free the vector context of datap. */ > - if (has_vector) > + if (has_vector()) > kfree(tsk->thread.vstate.datap); > } > > diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c > index d30a3b588156..6a19b4b7b206 100644 > --- a/arch/riscv/kernel/signal.c > +++ b/arch/riscv/kernel/signal.c > @@ -192,7 +192,7 @@ static long restore_sigcontext(struct pt_regs *regs, > goto invalid; > goto done; > case RVV_MAGIC: > - if (!has_vector) > + if (!has_vector()) > goto invalid; > if (size != rvv_sc_size) > goto invalid; > @@ -221,7 +221,7 @@ static size_t cal_rt_frame_size(void) > > frame_size = sizeof(*frame); > > - if (has_vector) > + if (has_vector()) > total_context_size += rvv_sc_size; > /* Preserved a __riscv_ctx_hdr for END signal context header. */ > total_context_size += sizeof(struct __riscv_ctx_hdr); > @@ -288,7 +288,7 @@ static long setup_sigcontext(struct rt_sigframe __user *frame, > if (has_fpu()) > err |= save_fp_state(regs, &sc->sc_fpregs); > /* Save the vector state. */ > - if (has_vector) > + if (has_vector()) > err |= save_v_state(regs, &sc_reserved_free_ptr); > > /* Put END __riscv_ctx_hdr at the end. */