From mboxrd@z Thu Jan 1 00:00:00 1970 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2806EC7619A for ; Mon, 27 Mar 2023 11:58:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232537AbjC0L6f (ORCPT ); Mon, 27 Mar 2023 07:58:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47628 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232464AbjC0L6d (ORCPT ); Mon, 27 Mar 2023 07:58:33 -0400 Received: from mail-pj1-x102c.google.com (mail-pj1-x102c.google.com [IPv6:2607:f8b0:4864:20::102c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A657435B5 for ; Mon, 27 Mar 2023 04:58:30 -0700 (PDT) Received: by mail-pj1-x102c.google.com with SMTP id gp15-20020a17090adf0f00b0023d1bbd9f9eso11601341pjb.0 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=EmanuUq2+YXjon8/5irAY4+Lm8ZVFRwRMv29j9nm7fOxZVq5pP5Hczh5F+bHVptas6 zQ/RU4o5mHwONGozbXTAb84zD6kKak4DuMxVqy7ZVPRWO3q53HYzTgf3uslnUrCJSqBU 1CLwkykYSyVr1M/NVbKRYLTH7qzGxw3vF/N8xQ3y/fY5MBMHezxh9Cpi9YR34C+E0/Rl 1Zj3z+2OY3trHgZhFYry5kBz24hISCmj8inppGeEivyKe+on25qroMu/ZcuIGaLffyr4 9vk0+BOFa96ZoSFo9KI76Bc3p54dWQWkSRUN2IoSeTiDtCt2vBJnVNWG3rgxQSL0CXZC jtoQ== X-Gm-Message-State: AAQBX9dZjuo77rmyCUuX0H+K+ZUgHLzBYC3bT7Hgq0v4DB1/xGQvvoSX Fh7qaULB1rWc7nbgjcXrHnHx2iqGwHxnyrw0xCzvWQ== 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 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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); -- 2.20.1