From patchwork Mon Mar 27 11:56:42 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yunhui Cui X-Patchwork-Id: 13189103 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 672FCC76195 for ; Mon, 27 Mar 2023 11:58:46 +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:MIME-Version:Message-Id:Date:Subject:To :From:Reply-To:Cc:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=FgJ+uW5XtyAZWGHLp9h+oG7q0UUtGGxwsY80Q7+3JCQ=; b=qY4n2hIosEmG+z 75ICcZueYEWUVG/C5qBgz+2eljAUs/3ZscMZOnpvVoHMU2xo10YtPb7vCOk7TM2/16mJ65PJKH6BF iwurCxd78KlPtdlBUd3NBCWtEvofaUV64q079qoHlD5HWeyqo8GOaaYoQMFJUTMtG4WSbDp5FxBzE GzdYwkfGQIM+iGYb+3NQNP+vcp+IONuBHcxsgBtDtwsD+BuRsjD/pmrK6mzxt8axaZp3Mrfa3AaWd i1tu13Mn2FM1yH9FdlVWjS36kxvxakF1DLJVpzPJTdSBhInfJi0ATE0I6uqGvlPyAfOIi+ZkoEm2e Bs/2R0Ej1EFyMZM0WI9w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1pglUk-00AoEa-1m; Mon, 27 Mar 2023 11:58:38 +0000 Received: from mail-pj1-x1031.google.com ([2607:f8b0:4864:20::1031]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1pglUh-00AoDN-1J for linux-riscv@lists.infradead.org; Mon, 27 Mar 2023 11:58:37 +0000 Received: by mail-pj1-x1031.google.com with SMTP id j13so7449236pjd.1 for ; Mon, 27 Mar 2023 04:58:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1679918310; h=content-transfer-encoding:mime-version:message-id:date:subject:to :from:from:to:cc:subject:date:message-id:reply-to; bh=LV9la5f2Alty6EKhNfpDearvf5tbwwgFKDMkwlyKPtE=; b=GiLwRJUOrKqj5W/x6KqK8UEqfjHXn/4U7CcAA3l7VEKUrLnhhrYxJXxqRd0Ub583gH wldPDbWqqe15vuPBf/SoYxURgxtdxIVl1avGkwN9PMj+vGfEEBuEV7Ev7OBIKR+ITanF PGto16BPPgcDSUjFniOtA94AjsxPmRGxlAR/i8AD8sYIbZseVkQYk1236f3wQZQx3Qov tlH6cXS3OZqXjXwSqKzK39kWqryHCFK43SxGiOYylmXfcSxB0zLgyhbM0dJHLO5Jb0AK f1N0nLfDLq1++CnyON6lKm4PmB1NGt4CSRJfpvCevoYgDONvfCRW9Sj1VAYrzljj6Wsr /SfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679918310; h=content-transfer-encoding:mime-version:message-id:date:subject:to :from:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=LV9la5f2Alty6EKhNfpDearvf5tbwwgFKDMkwlyKPtE=; b=sC9zlk5nW7Aa+DypUmH5URUieU7tAnbAnzXjDiM4vDPhSjtdT8LV+Xv2WQVa7VkcEM nD02Mn+zuxr6OwjFolOXIaE++9momrwZb7mLa0qeNcfuRj4ufjHiw4/t0xngaJEkotyS 1MncXzsCOLB5Lm4O/Yw3eCha/Ltt7YBp6IxqKzooXHKyiCeCg7YHA2hpEpvZHKCDnPdK mVJChmTk0PELwijK+uY4o07DKEnonn5d+xe5BH25yKewhPBm6CNCBlNmJVXd8LNG6NyF 4GMGaDC1pFL/5vFPecNPrGciRUURgo329RGwTWHn4/uNgRcsvdhjJFyHqhUYoz2R8ra7 B1Ww== X-Gm-Message-State: AAQBX9d4sQsw2G3MM/8bFm+JBn/Ptdcg14Lwj7m3xpfmRjLaIF35UCqn V7PZOdpQZHMSkMsfukpOnCuSTA== X-Google-Smtp-Source: AKy350Zva3pWuTyJ13bSraEd0rO2c/BK8g8uliYwap6yoKykNA2lwCZFLn8j/hfhi+yYc+1RHoFB8w== X-Received: by 2002:a17:90b:38d2:b0:234:dc4:2006 with SMTP id nn18-20020a17090b38d200b002340dc42006mr13442400pjb.4.1679918310187; Mon, 27 Mar 2023 04:58:30 -0700 (PDT) Received: from PF2E59YH-BKX.inc.bytedance.com ([2408:8606:1800:501::2:2]) by smtp.gmail.com with ESMTPSA id t8-20020a63dd08000000b00502ecb91940sm17959536pgg.55.2023.03.27.04.58.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Mar 2023 04:58:29 -0700 (PDT) From: Yunhui Cui To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, cuiyunhui@bytedance.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] riscv/fault: Dump user opcode bytes on fatal faults Date: Mon, 27 Mar 2023 19:56:42 +0800 Message-Id: <20230327115642.1610-1-cuiyunhui@bytedance.com> X-Mailer: git-send-email 2.37.3.windows.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230327_045835_733183_B4DF7F12 X-CRM114-Status: GOOD ( 11.53 ) 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 We encountered such a problem(logs are below). We are more curious about which instruction execution caused the exception. After dumping it through show_opcodes(), we found that it was caused by a floating-point instruction. In this way, we found the problem: in the system bringup , it is precisely that we have not enabled the floating point function. So when an exception occurs, it is necessary to dump the instruction that caused the exception, like x86/fault (ba54d856a9d8). Logs: [ 0.822481] Run /init as init process [ 0.837569] init[1]: unhandled signal 4 code 0x1 at 0x000000000005e028 in bb[10000+5fe000] [ 0.932292] CPU: 0 PID: 1 Comm: init Not tainted 5.14.0-rc4-00048-g4a843c9043e8-dirty #138 [ 0.932949] Hardware name: , BIOS [ 0.933399] epc : 000000000005e028 ra : 000000000007c7c4 sp : 0000003fffd45da0 [ 0.933855] gp : ffffffff816ea2d8 tp : 0000000000000000 t0 : 0000000000000000 [ 0.934303] t1 : 0000003fffd35df0 t2 : 0000000000000000 s0 : 0000000000000000 [ 0.934734] s1 : 0000000000000000 a0 : 0000003fffd36190 a1 : 0000003fffd45e18 [ 0.935200] a2 : 0000000000000000 a3 : 0000000000000000 a4 : 0000000000000000 [ 0.935622] a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000000000000 [ 0.936073] s2 : 0000000000000000 s3 : 0000000000000000 s4 : 0000000000000000 [ 0.936495] s5 : 0000000000000000 s6 : 0000000000000000 s7 : 0000000000000000 [ 0.936947] s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000000000000000 [ 0.937487] s11: 0000000000d14980 t3 : 0000000000000000 t4 : 0000000000000000 [ 0.937954] t5 : 0000000000000000 t6 : 0000000000000000 [ 0.938510] status: 0000000200000020 badaddr: 00000000f0028053 cause: 0000000000000002 Signed-off-by: Yunhui Cui --- arch/riscv/include/asm/bug.h | 1 + arch/riscv/kernel/process.c | 30 ++++++++++++++++++++++++++++++ arch/riscv/kernel/traps.c | 1 + 3 files changed, 32 insertions(+) diff --git a/arch/riscv/include/asm/bug.h b/arch/riscv/include/asm/bug.h index d3804a2f9aad..77655dd10a2c 100644 --- a/arch/riscv/include/asm/bug.h +++ b/arch/riscv/include/asm/bug.h @@ -86,6 +86,7 @@ struct pt_regs; struct task_struct; void __show_regs(struct pt_regs *regs); +void show_opcodes(struct pt_regs *regs); void die(struct pt_regs *regs, const char *str); void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr); diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 03ac3aa611f5..759dc74fe160 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -83,6 +83,36 @@ void show_regs(struct pt_regs *regs) dump_backtrace(regs, NULL, KERN_DEFAULT); } +static int copy_code(struct pt_regs *regs, u8 *buf, unsigned long src, + unsigned int nbytes) +{ + if (!user_mode(regs)) + return copy_from_kernel_nofault(buf, (u8 *)src, nbytes); + + /* The user space code from other tasks cannot be accessed. */ + if (regs != task_pt_regs(current)) + return -EPERM; + + return copy_from_user_nofault(buf, (void __user *)src, nbytes); +} + +void show_opcodes(struct pt_regs *regs) +{ + u8 opcodes[4]; + + switch (copy_code(regs, opcodes, regs->epc, sizeof(opcodes))) { + case 0: + pr_info("Opcode: %4ph", opcodes); + break; + case -EPERM: + pr_err("Unable to access userspace of other tasks"); + break; + default: + pr_err("Failed to access opcode"); + break; + } +} + void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) { diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index 0a98fd0ddfe9..a6f6851e4e87 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -68,6 +68,7 @@ void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr) print_vma_addr(KERN_CONT " in ", instruction_pointer(regs)); pr_cont("\n"); __show_regs(regs); + show_opcodes(regs); } force_sig_fault(signo, code, (void __user *)addr);