From patchwork Thu Aug 11 07:41:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xianting Tian X-Patchwork-Id: 12941214 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 5696EC19F2D for ; Thu, 11 Aug 2022 07:42:37 +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:MIME-Version:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=HVId7UjVYm8IdET0QjksmEzu6gmbejy2ysrRfWkarw8=; b=v9f+nwIKKiR81L Ahu42KL0IzvUAlhipfBhk8dhyXy63oglC3iXDGuRCMQLVTBgSTTbZoTjUcT3euO+5YiZ5EJZVeQo2 dl1I6Jtykxv8kk/0RTskr2z8kaQwBwAHqmaqt2rDZlqSwoRYB8g8BaAbipCWqF/+AY8N1mykK7jzy uRbiWFNSBzqhkf9MZyXeITCcg399qmpXnVidHQrrsNz9U2wb7JeZNRKDxa8H3VmUDktpjQluGEEa/ +Z9YdZHF2JY+1uwcr0M49ytXu1nkgaFrAbSMFfTuTNX2Ymp2wlcVFBMx9MrE3MAaLvHqYfomTmbmd 27nJnIm8wOtAlg6kTQOw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oM2pj-009mEP-MZ; Thu, 11 Aug 2022 07:42:23 +0000 Received: from out199-10.us.a.mail.aliyun.com ([47.90.199.10]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oM2pP-009lfV-9a; Thu, 11 Aug 2022 07:42:05 +0000 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R501e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046051;MF=xianting.tian@linux.alibaba.com;NM=1;PH=DS;RN=23;SR=0;TI=SMTPD_---0VLyDALP_1660203715; Received: from localhost(mailfrom:xianting.tian@linux.alibaba.com fp:SMTPD_---0VLyDALP_1660203715) by smtp.aliyun-inc.com; Thu, 11 Aug 2022 15:41:56 +0800 From: Xianting Tian To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, anup@brainfault.org, heiko@sntech.de, guoren@kernel.org, mick@ics.forth.gr, alexandre.ghiti@canonical.com, bhe@redhat.com, vgoyal@redhat.com, dyoung@redhat.com, corbet@lwn.net, Conor.Dooley@microchip.com Cc: kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, crash-utility@redhat.com, heinrich.schuchardt@canonical.com, k-hagio-ab@nec.com, hschauhan@nulltrace.org, yixun.lan@gmail.com, Xianting Tian Subject: [PATCH V6 2/6] RISC-V: Fixup get incorrect user mode PC for kernel mode regs Date: Thu, 11 Aug 2022 15:41:46 +0800 Message-Id: <20220811074150.3020189-3-xianting.tian@linux.alibaba.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220811074150.3020189-1-xianting.tian@linux.alibaba.com> References: <20220811074150.3020189-1-xianting.tian@linux.alibaba.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220811_004203_632421_88C5EFE2 X-CRM114-Status: UNSURE ( 8.94 ) X-CRM114-Notice: Please train this message. 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: , MIME-Version: 1.0 Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org When use 'echo c > /proc/sysrq-trigger' to trigger kdump, riscv_crash_save_regs() will be called to save regs for vmcore, we found "epc" value 00ffffffa5537400 is not a valid kernel virtual address, but is a user virtual address. Other regs(eg, ra, sp, gp...) are correct kernel virtual address. Actually 0x00ffffffb0dd9400 is the user mode PC of 'PID: 113 Comm: sh', which is saved in the task's stack. [ 21.201701] CPU: 0 PID: 113 Comm: sh Kdump: loaded Not tainted 5.18.9 #45 [ 21.201979] Hardware name: riscv-virtio,qemu (DT) [ 21.202160] epc : 00ffffffa5537400 ra : ffffffff80088640 sp : ff20000010333b90 [ 21.202435] gp : ffffffff810dde38 tp : ff6000000226c200 t0 : ffffffff8032be7c [ 21.202707] t1 : 0720072007200720 t2 : 30203a7375746174 s0 : ff20000010333cf0 [ 21.202973] s1 : 0000000000000000 a0 : ff20000010333b98 a1 : 0000000000000001 [ 21.203243] a2 : 0000000000000010 a3 : 0000000000000000 a4 : 28c8f0aeffea4e00 [ 21.203519] a5 : 28c8f0aeffea4e00 a6 : 0000000000000009 a7 : ffffffff8035c9b8 [ 21.203794] s2 : ffffffff810df0a8 s3 : ffffffff810df718 s4 : ff20000010333b98 [ 21.204062] s5 : 0000000000000000 s6 : 0000000000000007 s7 : ffffffff80c4a468 [ 21.204331] s8 : 00ffffffef451410 s9 : 0000000000000007 s10: 00aaaaaac0510700 [ 21.204606] s11: 0000000000000001 t3 : ff60000001218f00 t4 : ff60000001218f00 [ 21.204876] t5 : ff60000001218000 t6 : ff200000103338b8 [ 21.205079] status: 0000000200000020 badaddr: 0000000000000000 cause: 0000000000000008 With the incorrect PC, the backtrace showed by crash tool as below, the first stack frame is abnormal, crash> bt PID: 113 TASK: ff60000002269600 CPU: 0 COMMAND: "sh" #0 [ff2000001039bb90] __efistub_.Ldebug_info0 at 00ffffffa5537400 <-- Abnormal #1 [ff2000001039bcf0] panic at ffffffff806578ba #2 [ff2000001039bd50] sysrq_reset_seq_param_set at ffffffff8038c030 #3 [ff2000001039bda0] __handle_sysrq at ffffffff8038c5f8 #4 [ff2000001039be00] write_sysrq_trigger at ffffffff8038cad8 #5 [ff2000001039be20] proc_reg_write at ffffffff801b7edc #6 [ff2000001039be40] vfs_write at ffffffff80152ba6 #7 [ff2000001039be80] ksys_write at ffffffff80152ece #8 [ff2000001039bed0] sys_write at ffffffff80152f46 With the patch, we can get current kernel mode PC, the output as below, [ 17.607658] CPU: 0 PID: 113 Comm: sh Kdump: loaded Not tainted 5.18.9 #42 [ 17.607937] Hardware name: riscv-virtio,qemu (DT) [ 17.608150] epc : ffffffff800078f8 ra : ffffffff8008862c sp : ff20000010333b90 [ 17.608441] gp : ffffffff810dde38 tp : ff6000000226c200 t0 : ffffffff8032be68 [ 17.608741] t1 : 0720072007200720 t2 : 666666666666663c s0 : ff20000010333cf0 [ 17.609025] s1 : 0000000000000000 a0 : ff20000010333b98 a1 : 0000000000000001 [ 17.609320] a2 : 0000000000000010 a3 : 0000000000000000 a4 : 0000000000000000 [ 17.609601] a5 : ff60000001c78000 a6 : 000000000000003c a7 : ffffffff8035c9a4 [ 17.609894] s2 : ffffffff810df0a8 s3 : ffffffff810df718 s4 : ff20000010333b98 [ 17.610186] s5 : 0000000000000000 s6 : 0000000000000007 s7 : ffffffff80c4a468 [ 17.610469] s8 : 00ffffffca281410 s9 : 0000000000000007 s10: 00aaaaaab5bb6700 [ 17.610755] s11: 0000000000000001 t3 : ff60000001218f00 t4 : ff60000001218f00 [ 17.611041] t5 : ff60000001218000 t6 : ff20000010333988 [ 17.611255] status: 0000000200000020 badaddr: 0000000000000000 cause: 0000000000000008 With the correct PC, the backtrace showed by crash tool as below, crash> bt PID: 113 TASK: ff6000000226c200 CPU: 0 COMMAND: "sh" #0 [ff20000010333b90] riscv_crash_save_regs at ffffffff800078f8 <--- Normal #1 [ff20000010333cf0] panic at ffffffff806578c6 #2 [ff20000010333d50] sysrq_reset_seq_param_set at ffffffff8038c03c #3 [ff20000010333da0] __handle_sysrq at ffffffff8038c604 #4 [ff20000010333e00] write_sysrq_trigger at ffffffff8038cae4 #5 [ff20000010333e20] proc_reg_write at ffffffff801b7ee8 #6 [ff20000010333e40] vfs_write at ffffffff80152bb2 #7 [ff20000010333e80] ksys_write at ffffffff80152eda #8 [ff20000010333ed0] sys_write at ffffffff80152f52 Fixes: e53d28180d4d ("RISC-V: Add kdump support") Co-developed-by: Guo Ren Signed-off-by: Xianting Tian --- arch/riscv/kernel/crash_save_regs.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/riscv/kernel/crash_save_regs.S b/arch/riscv/kernel/crash_save_regs.S index 7832fb763aba..b2a1908c0463 100644 --- a/arch/riscv/kernel/crash_save_regs.S +++ b/arch/riscv/kernel/crash_save_regs.S @@ -44,7 +44,7 @@ SYM_CODE_START(riscv_crash_save_regs) REG_S t6, PT_T6(a0) /* x31 */ csrr t1, CSR_STATUS - csrr t2, CSR_EPC + auipc t2, 0x0 csrr t3, CSR_TVAL csrr t4, CSR_CAUSE