From nobody Tue Apr 28 05:05:51 2026 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 169F8C433EF for ; Mon, 6 Jun 2022 08:23:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231706AbiFFIXW (ORCPT ); Mon, 6 Jun 2022 04:23:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40988 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231653AbiFFIXS (ORCPT ); Mon, 6 Jun 2022 04:23:18 -0400 Received: from out30-57.freemail.mail.aliyun.com (out30-57.freemail.mail.aliyun.com [115.124.30.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 26E6110C8 for ; Mon, 6 Jun 2022 01:23:15 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=alimailimapcm10staff010182156082;MF=xianting.tian@linux.alibaba.com;NM=1;PH=DS;RN=13;SR=0;TI=SMTPD_---0VFUVkL4_1654503791; Received: from localhost(mailfrom:xianting.tian@linux.alibaba.com fp:SMTPD_---0VFUVkL4_1654503791) by smtp.aliyun-inc.com(127.0.0.1); Mon, 06 Jun 2022 16:23:12 +0800 From: Xianting Tian To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, wangkefeng.wang@huawei.com, philipp.tomsich@vrull.eu, ebiederm@xmission.com, heiko@sntech.de, vitaly.wool@konsulko.com, tongtiangen@huawei.com, guoren@kernel.org Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Xianting Tian Subject: [RESEND PATCH v2] RISC-V: Add fast call path of crash_kexec() Date: Mon, 6 Jun 2022 16:23:08 +0800 Message-Id: <20220606082308.2883458-1-xianting.tian@linux.alibaba.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Currently, almost all archs (x86, arm64, mips...) support fast call of crash_kexec() when "regs && kexec_should_crash()" is true. But RISC-V not, it can only enter crash system via panic(). However panic() doesn't pass the regs of the real accident scene to crash_kexec(), it caused we can't get accurate backtrace via gdb, $ riscv64-linux-gnu-gdb vmlinux vmcore Reading symbols from vmlinux... [New LWP 95] #0 console_unlock () at kernel/printk/printk.c:2557 2557 if (do_cond_resched) (gdb) bt #0 console_unlock () at kernel/printk/printk.c:2557 #1 0x0000000000000000 in ?? () With the patch we can get the accurate backtrace, $ riscv64-linux-gnu-gdb vmlinux vmcore Reading symbols from vmlinux... [New LWP 95] #0 0xffffffe00063a4e0 in test_thread (data=3D) at drivers/= test_crash.c:81 81 *(int *)p =3D 0xdead; (gdb) (gdb) bt #0 0xffffffe00064d5c0 in test_thread (data=3D) at drivers/= test_crash.c:81 #1 0x0000000000000000 in ?? () Test code to produce NULL address dereference in test_crash.c, void *p =3D NULL; *(int *)p =3D 0xdead; Reviewed-by: Guo Ren Tested-by: Xianting Tian Signed-off-by: Xianting Tian --- Changes from v1: - simplify the commit message --- arch/riscv/kernel/traps.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index fe92e119e6a3..e666ebfa2a64 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -16,6 +16,7 @@ #include #include #include +#include =20 #include #include @@ -44,6 +45,9 @@ void die(struct pt_regs *regs, const char *str) =20 ret =3D notify_die(DIE_OOPS, str, regs, 0, regs->cause, SIGSEGV); =20 + if (regs && kexec_should_crash(current)) + crash_kexec(regs); + bust_spinlocks(0); add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); spin_unlock_irq(&die_lock); --=20 2.17.1