From patchwork Thu Mar 20 17:29:22 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Charlie Jenkins X-Patchwork-Id: 14024195 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EB6F4C35FFF for ; Thu, 20 Mar 2025 17:31:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References:Message-Id :MIME-Version:Subject:Date:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=krkUCHe7704INogIR8lX67ywhTCuyxYoBPIkDzaVNvo=; b=IkLORvyWfmufnz StxqDkwppsUXfx4fxLY0xN1UvByvuRngrn434a0D+yOYOFWyU9o/42gs9SARePj2NJNIcTJ78DgIn JicVbPNoYN8xQpwDxReB+R+VAfSCgon+rL0KySIXZX5c9qUEA5n6Y06VcPPvR9D/BZ5/yZ3RSf093 L8PP30pWG7bOBQh4bmG7krQLgKT000kn0Rw5w06IVVmWhIx794+sxOqoqv+zOc7Z0I4gkGK5wHGQB hylH1l9p7WKV9CAuP6ZZsrOjYUWWbLolIpVYT6Qdyyi7SS42hasFi+UagZufft1m+qBk4hMNLEoby SNM1SxdSMHBv+JY7vMMQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tvJjg-0000000CoGH-3YtU; Thu, 20 Mar 2025 17:31:16 +0000 Received: from mail-pl1-x633.google.com ([2607:f8b0:4864:20::633]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tvJi6-0000000Cnz4-0tJA for linux-riscv@lists.infradead.org; Thu, 20 Mar 2025 17:29:39 +0000 Received: by mail-pl1-x633.google.com with SMTP id d9443c01a7336-224100e9a5cso21626765ad.2 for ; Thu, 20 Mar 2025 10:29:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20230601.gappssmtp.com; s=20230601; t=1742491777; x=1743096577; darn=lists.infradead.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=ehMUm3J1yyvZGiQlan49h9651rjeLktXjDjteQa4YzI=; b=KPa6t8zcmg+lE6rXNQ3auWt8vchhGgntrAfftJUnOmBoaahpNRajiRzJEx8gncExzu k4vyGd1xNOBV9zbpp5hGiFrMY3j0xd1lHh1qZ9tjWPoGIfvJmhjJJEXxNfKsifku9Fzw f2oVzP9izhYXP7GM35jJpI/pP4MvYF1zp4yZ89dDl15hhIgT6enAkr5Jp/mespV5lw0z gDpyN1qXiWyX62n2b+t2p0izzfRhZLM96JPXTLHZraR1LQCzVtBEft6bYNlDJb7i+B+V hLnBYjGuzmz8yrfgR4zRqPWoFW0B54sZhRQ8g7XRP7ZPr/Cg1/aUne2MrJG7gm+oLXUv yd1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1742491777; x=1743096577; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ehMUm3J1yyvZGiQlan49h9651rjeLktXjDjteQa4YzI=; b=XXDktKjTnu4z3msI5wuZboQHUKtCmcjMmD31myeb2T3Lc0x4P0lm51zlFesB5gf0oK c9Rw/pD7gxTd6Vh5jZjEIx17MzyWVBEkyDJbqHYRqG1KBvjOTO7uV/46rgUllL9cuh7b BwBx+Anmn2E+iAhAOKvqTCiEoAlhR3oN9NWiOR5IPLztUZfJ1lzG2tzY/WefkdSrHman JaSCGMIL7gdsi70zs2xMXBznGMyOJHTtdJv77nXt7rNj+D9pNS1Tuj/qbi58mUiymh2d TfrWOTLsHS7sUsoBVmGZZEzRpZTCWoYhS7pL/2KA8+IsZu2HsS2WYpJi+neCSi//wjLH uZOA== X-Gm-Message-State: AOJu0YxXStjJM380w1exKpUtSA0xXy3oQXebcJbHs7QdHiMxBjS+U5/F fIt9pWu17RCriveGRhmWYD4HjI4S2JKUWdhfud04CprI92cQU7XVy1X7iWePJqo= X-Gm-Gg: ASbGncuRgOS8y+nNZnXfccoA6wcKNzq11tpdBU700B5lbK3HeI7YrGhj5YdJffyDz92 EocdQcImP+JIRQoh/8sH+doZ2qb+xcuCxd9RNWBVu+3plWTKpc04VUuHMmC6966S0yU51o9lmfb IfnrGB6Wf1mLf37pktf5Bl/xaJBluUabURuroEh4w8emKhyoqbOp6qJ6QDBCvPDpLOh7U+TNMbQ 3hF96aT0hLOSS1OrDoUpHMQQbQG/fBqeQ/6wCSZv2rj4NukmuRHLI+Cu7RVvIlfldN9qRtxJ/sn Q7Wp2/DA5l/MvORQn6yx53Ym0ExdcR0+LVN8uIkiqWNBY+zpzVvBuPnCVlId X-Google-Smtp-Source: AGHT+IHosJQQFvVMIroy5HqFrhcvWEZzb29pVdZNHAFlNJkZE8gGcxmxyZzEuwUqug8vYxa+GU6q9w== X-Received: by 2002:a17:902:d4c5:b0:221:7e36:b13e with SMTP id d9443c01a7336-22780c7a32dmr3719635ad.12.1742491777384; Thu, 20 Mar 2025 10:29:37 -0700 (PDT) Received: from charlie.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22780f45994sm554075ad.81.2025.03.20.10.29.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Mar 2025 10:29:36 -0700 (PDT) From: Charlie Jenkins Date: Thu, 20 Mar 2025 10:29:22 -0700 Subject: [PATCH v6 2/4] riscv: entry: Split ret_from_fork() into user and kernel MIME-Version: 1.0 Message-Id: <20250320-riscv_optimize_entry-v6-2-63e187e26041@rivosinc.com> References: <20250320-riscv_optimize_entry-v6-0-63e187e26041@rivosinc.com> In-Reply-To: <20250320-riscv_optimize_entry-v6-0-63e187e26041@rivosinc.com> To: Paul Walmsley , Palmer Dabbelt , Huacai Chen , WANG Xuerui , Thomas Gleixner , Peter Zijlstra , Andy Lutomirski , Alexandre Ghiti , Arnd Bergmann , Albert Ou , Alexandre Ghiti Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, Charlie Jenkins X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=4464; i=charlie@rivosinc.com; h=from:subject:message-id; bh=LoTSopBOka5A9kpDiPFFurbF+1mjOb81UBycxnBlNbA=; b=owGbwMvMwCXWx5hUnlvL8Y3xtFoSQ/qdgKoixkOt4od/iEifL9zYlhO5zOWE7Vw5m4ApZ998y O14lMvdUcrCIMbFICumyMJzrYG59Y5+2VHRsgkwc1iZQIYwcHEKwEQ2pDL8d4p6u1r9XZ/p36Ph jJrvuJPnX6/4mvmoWWO2f7i9ULmTNcNfuVlX/l06sK2ofs2Kdtmgf/l/nq4y9epjOXvN4/StFeu UuAA= X-Developer-Key: i=charlie@rivosinc.com; a=openpgp; fpr=7D834FF11B1D8387E61C776FFB10D1F27D6B1354 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250320_102938_248451_6F411763 X-CRM114-Status: GOOD ( 13.31 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org This function was unified into a single function in commit ab9164dae273 ("riscv: entry: Consolidate ret_from_kernel_thread into ret_from_fork"). However that imposed a performance degradation. Partially reverting this commit to have ret_from_fork() split again results in a 1% increase on the number of times fork is able to be called per second. Signed-off-by: Charlie Jenkins Acked-by: Alexandre Ghiti --- arch/riscv/include/asm/asm-prototypes.h | 3 ++- arch/riscv/kernel/entry.S | 13 ++++++++++--- arch/riscv/kernel/process.c | 17 +++++++++++------ 3 files changed, 23 insertions(+), 10 deletions(-) diff --git a/arch/riscv/include/asm/asm-prototypes.h b/arch/riscv/include/asm/asm-prototypes.h index 733ff609778797001006c33bba9e3cc5b1f15387..bfc8ea5f9319b19449ec59493b45b926df888832 100644 --- a/arch/riscv/include/asm/asm-prototypes.h +++ b/arch/riscv/include/asm/asm-prototypes.h @@ -52,7 +52,8 @@ DECLARE_DO_ERROR_INFO(do_trap_ecall_s); DECLARE_DO_ERROR_INFO(do_trap_ecall_m); DECLARE_DO_ERROR_INFO(do_trap_break); -asmlinkage void ret_from_fork(void *fn_arg, int (*fn)(void *), struct pt_regs *regs); +asmlinkage void ret_from_fork_kernel(void *fn_arg, int (*fn)(void *), struct pt_regs *regs); +asmlinkage void ret_from_fork_user(struct pt_regs *regs); asmlinkage void handle_bad_stack(struct pt_regs *regs); asmlinkage void do_page_fault(struct pt_regs *regs); asmlinkage void do_irq(struct pt_regs *regs); diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index b2dc5e7c7b3a843fa4aa02eba2a911eb3ce31d1f..0fb338000c6dc0358742cd03497fa54b9e9d1aec 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -319,14 +319,21 @@ SYM_CODE_END(handle_kernel_stack_overflow) ASM_NOKPROBE(handle_kernel_stack_overflow) #endif -SYM_CODE_START(ret_from_fork_asm) +SYM_CODE_START(ret_from_fork_kernel_asm) call schedule_tail move a0, s1 /* fn_arg */ move a1, s0 /* fn */ move a2, sp /* pt_regs */ - call ret_from_fork + call ret_from_fork_kernel j ret_from_exception -SYM_CODE_END(ret_from_fork_asm) +SYM_CODE_END(ret_from_fork_kernel_asm) + +SYM_CODE_START(ret_from_fork_user_asm) + call schedule_tail + move a0, sp /* pt_regs */ + call ret_from_fork_user + j ret_from_exception +SYM_CODE_END(ret_from_fork_user_asm) #ifdef CONFIG_IRQ_STACKS /* diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 7b0a0bfe29aec896c2bdd8976d855dd390de88d7..485ec7a80a56097e8905cd6395af29633846b5c8 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -38,7 +38,8 @@ unsigned long __stack_chk_guard __read_mostly; EXPORT_SYMBOL(__stack_chk_guard); #endif -extern asmlinkage void ret_from_fork_asm(void); +extern asmlinkage void ret_from_fork_kernel_asm(void); +extern asmlinkage void ret_from_fork_user_asm(void); void noinstr arch_cpu_idle(void) { @@ -208,14 +209,18 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) return 0; } -asmlinkage void ret_from_fork(void *fn_arg, int (*fn)(void *), struct pt_regs *regs) +asmlinkage void ret_from_fork_kernel(void *fn_arg, int (*fn)(void *), struct pt_regs *regs) { - if (unlikely(fn)) - fn(fn_arg); + fn(fn_arg); syscall_exit_to_user_mode(regs); } +asmlinkage void ret_from_fork_user(struct pt_regs *regs) +{ + syscall_exit_to_user_mode(regs); +} + int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) { unsigned long clone_flags = args->flags; @@ -238,6 +243,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.s[0] = (unsigned long)args->fn; p->thread.s[1] = (unsigned long)args->fn_arg; + p->thread.ra = (unsigned long)ret_from_fork_kernel_asm; } else { *childregs = *(current_pt_regs()); /* Turn off status.VS */ @@ -247,12 +253,11 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) if (clone_flags & CLONE_SETTLS) childregs->tp = tls; childregs->a0 = 0; /* Return value of fork() */ - p->thread.s[0] = 0; + p->thread.ra = (unsigned long)ret_from_fork_user_asm; } p->thread.riscv_v_flags = 0; if (has_vector() || has_xtheadvector()) riscv_v_thread_alloc(p); - p->thread.ra = (unsigned long)ret_from_fork_asm; p->thread.sp = (unsigned long)childregs; /* kernel sp */ return 0; }