From patchwork Wed Aug 14 08:23:52 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Chen X-Patchwork-Id: 11093493 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D211F14DB for ; Wed, 14 Aug 2019 08:24:06 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BDB46287AB for ; Wed, 14 Aug 2019 08:24:06 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B1B72287AF; Wed, 14 Aug 2019 08:24:06 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 47E68287B3 for ; Wed, 14 Aug 2019 08:24:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=op08/G9b27Gp3hFF6bo/y9wujmIHCoHnhNNDJFNtqG8=; b=U24ysNTFdbt5UO4tltOwuSxDKm K/aaUUL9aotlJlubOSNR8XMhZV33eO4v8urV60DbNckWRY0ROOdxlFyYLg+M6lktee7BzMeOYMFmD Ocvv+BG9V7kBhfCU8F8KdNzErxpZxCJk5/goQDJZKjE9wCycyClG1vUbSaLNTONhPLSKRbzZ9HQzF DDolwE5QHgXTBmDNpFZeKVkuR5+QD7XMzDBaRIfp65CGR6KbWSAWeLII2FHcgJtKAbv3fXfnfrnfX WR8hnZjnH5hs1R265fnD1DZNz2pwwwwwGhvzn57ADEXTr2lao8aM/gqBy0QkxRyLupTQv+eilR6eB h1gqGbPQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hxoZe-0002KG-9o; Wed, 14 Aug 2019 08:24:02 +0000 Received: from mail-pg1-x541.google.com ([2607:f8b0:4864:20::541]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hxoZb-0002Hh-Pm for linux-riscv@lists.infradead.org; Wed, 14 Aug 2019 08:24:01 +0000 Received: by mail-pg1-x541.google.com with SMTP id i18so52714362pgl.11 for ; Wed, 14 Aug 2019 01:23:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sifive.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=355/fM8G6OID12UiIjtTxx4G3WOw7wrHVjqcAOVdVjM=; b=ZfvFzV82vpyyn+70V/08TU9H+meQN6zQkx8KP1zphiFbhxeeSxdBYZf8SGiM2El89/ VaGw1EczgJ2KWru4TAyQEKsc6cCufq6NsaqtrZAkXM10TrzDPzz2TxDee6VQI+sRB99/ 1Rp5NtJyscgRoFzyuFG+ujdvNWzsKUyXGQlWT5FyX/L31Yu4Zj3g/4UyObiOlVkijRen lCragje8ySbRcq/IRtDGeEiWQ+c1A2QEspRdnzkB5iyrqx5MBV6JXnR+8/zWbaQt0r0R 2ROiYSEovMAVEYGeYf69soEIq5t5rorhMUenmWnDQjyRHcvzW2HAkW4zNPXzMTRz96B6 HhPw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=355/fM8G6OID12UiIjtTxx4G3WOw7wrHVjqcAOVdVjM=; b=nJzXMolW1LWK73l538A3FlhtBoJAJMV+xPLmT3VLF3DTm0BaVsAsi80m6x9txItViM I4z3wUUndmwBjJ3Ra2KZZDvUT/+88ujdHTsABUOEfFoNmuN6ePvPkK5xtofaOUlSmghk 4SG6QBfxb8bdCSwjv4ngMBugPTkaeE172KtyaLFba6p0oRfHBtHJzAvrVkmeExVs8fDU OaFi4+X7vqfz8UpTXnk9gRU0sb51RyZkeyWCuvDYcwMVDL1/JPGKe04Lv++fHO7o+Nvo 2Zh2VCh3srPmTA2R1zXVfxlFIVZ0Sb55izx8omD4ZI0KMpiNZin9JPQrsGJW20wDbL32 3JeA== X-Gm-Message-State: APjAAAVFe9fCfS0WrrdxtkKBlFYJzYbRNROGgWI95uCIU5TXEP1WnvSo nlPbOrcejcD4Ka34QynRlGUIkg== X-Google-Smtp-Source: APXvYqywRx18R0hMG2RnROTtsgpH40TUafc/j8X3By4v7TBusOlcABsMHZE9qz0KUcqdzr7Mh5i54w== X-Received: by 2002:a63:61cd:: with SMTP id v196mr38524614pgb.263.1565771039143; Wed, 14 Aug 2019 01:23:59 -0700 (PDT) Received: from localhost.localdomain (220-132-236-182.HINET-IP.hinet.net. [220.132.236.182]) by smtp.gmail.com with ESMTPSA id f205sm12359152pfa.161.2019.08.14.01.23.57 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 14 Aug 2019 01:23:58 -0700 (PDT) From: Vincent Chen To: Paul Walmsley , Palmer Dabbelt Subject: [PATCH v2 1/2] riscv: Correct the initialized flow of FP register Date: Wed, 14 Aug 2019 16:23:52 +0800 Message-Id: <1565771033-1831-2-git-send-email-vincent.chen@sifive.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1565771033-1831-1-git-send-email-vincent.chen@sifive.com> References: <1565771033-1831-1-git-send-email-vincent.chen@sifive.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190814_012359_858674_6C718DC0 X-CRM114-Status: GOOD ( 12.80 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Vincent Chen , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org MIME-Version: 1.0 Sender: "linux-riscv" Errors-To: linux-riscv-bounces+patchwork-linux-riscv=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP The following two reasons cause FP registers are sometimes not initialized before starting the user program. 1. Currently, the FP context is initialized in flush_thread() function and we expect these initial values to be restored to FP register when doing FP context switch. However, the FP context switch only occurs in switch_to function. Hence, if this process does not be scheduled out and scheduled in before entering the user space, the FP registers have no chance to initialize. 2. In flush_thread(), the state of reg->sstatus.FS inherits from the parent. Hence, the state of reg->sstatus.FS may be dirty. If this process is scheduled out during flush_thread() and initializing the FP register, the fstate_save() in switch_to will corrupt the FP context which has been initialized until flush_thread(). To solve the 1st case, the initialization of the FP register will be completed in start_thread(). It makes sure all FP registers are initialized before starting the user program. For the 2nd case, the state of reg->sstatus.FS in start_thread will be set to SR_FS_OFF to prevent this process from corrupting FP context in doing context save. The FP state is set to SR_FS_INITIAL in start_trhead(). Signed-off-by: Vincent Chen Reviewed-by: Anup Patel Reviewed-by: Christoph Hellwig Signed-off-by: Vincent Chen Reviewed-by: Anup Patel Reviewed-by: Christoph Hellwig Signed-off-by: Paul Walmsley --- arch/riscv/include/asm/switch_to.h | 6 ++++++ arch/riscv/kernel/process.c | 11 +++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h index 853b65e..0575b8a 100644 --- a/arch/riscv/include/asm/switch_to.h +++ b/arch/riscv/include/asm/switch_to.h @@ -19,6 +19,12 @@ static inline void __fstate_clean(struct pt_regs *regs) regs->sstatus |= (regs->sstatus & ~(SR_FS)) | SR_FS_CLEAN; } +static inline void fstate_off(struct task_struct *task, + struct pt_regs *regs) +{ + regs->sstatus = (regs->sstatus & ~SR_FS) | SR_FS_OFF; +} + static inline void fstate_save(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index f23794b..fb3a082 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -64,8 +64,14 @@ void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) { regs->sstatus = SR_SPIE; - if (has_fpu) + if (has_fpu) { regs->sstatus |= SR_FS_INITIAL; + /* + * Restore the initial value to the FP register + * before starting the user program. + */ + fstate_restore(current, regs); + } regs->sepc = pc; regs->sp = sp; set_fs(USER_DS); @@ -75,10 +81,11 @@ void flush_thread(void) { #ifdef CONFIG_FPU /* - * Reset FPU context + * Reset FPU state and context * frm: round to nearest, ties to even (IEEE default) * fflags: accrued exceptions cleared */ + fstate_off(current, task_pt_regs(current)); memset(¤t->thread.fstate, 0, sizeof(current->thread.fstate)); #endif } From patchwork Wed Aug 14 08:23:53 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Chen X-Patchwork-Id: 11093495 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 880EC112C for ; Wed, 14 Aug 2019 08:24:08 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 733F2287AB for ; 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[220.132.236.182]) by smtp.gmail.com with ESMTPSA id f205sm12359152pfa.161.2019.08.14.01.23.59 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 14 Aug 2019 01:24:00 -0700 (PDT) From: Vincent Chen To: Paul Walmsley , Palmer Dabbelt Subject: [PATCH v2 2/2] riscv: Make __fstate_clean() work correctly. Date: Wed, 14 Aug 2019 16:23:53 +0800 Message-Id: <1565771033-1831-3-git-send-email-vincent.chen@sifive.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1565771033-1831-1-git-send-email-vincent.chen@sifive.com> References: <1565771033-1831-1-git-send-email-vincent.chen@sifive.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190814_012401_417731_60054EF1 X-CRM114-Status: GOOD ( 10.83 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Vincent Chen , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-stable MIME-Version: 1.0 Sender: "linux-riscv" Errors-To: linux-riscv-bounces+patchwork-linux-riscv=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Make the __fstate_clean() function correctly set the state of sstatus.FS in pt_regs to SR_FS_CLEAN. Fixes: 7db91e5 ("RISC-V: Task implementation") Cc: linux-stable Signed-off-by: Vincent Chen Reviewed-by: Anup Patel Reviewed-by: Christoph Hellwig Signed-off-by: Vincent Chen Reviewed-by: Anup Patel Reviewed-by: Christoph Hellwig Signed-off-by: Paul Walmsley --- arch/riscv/include/asm/switch_to.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h index 0575b8a..0aa5b94 100644 --- a/arch/riscv/include/asm/switch_to.h +++ b/arch/riscv/include/asm/switch_to.h @@ -16,7 +16,7 @@ extern void __fstate_restore(struct task_struct *restore_from); static inline void __fstate_clean(struct pt_regs *regs) { - regs->sstatus |= (regs->sstatus & ~(SR_FS)) | SR_FS_CLEAN; + regs->sstatus = (regs->sstatus & ~SR_FS) | SR_FS_CLEAN; } static inline void fstate_off(struct task_struct *task,