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 6348FC2FC2D for ; Thu, 17 Aug 2023 13:27:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351474AbjHQN1c (ORCPT ); Thu, 17 Aug 2023 09:27:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351453AbjHQN1S (ORCPT ); Thu, 17 Aug 2023 09:27:18 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B9BE0211E for ; Thu, 17 Aug 2023 06:27:17 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 567FF6390B for ; Thu, 17 Aug 2023 13:27:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C4C9C433C9; Thu, 17 Aug 2023 13:27:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1692278836; bh=N7FOBKn6lVaujIc2fp+E6e+ga7diecnqFscfWVPh/C8=; h=From:To:Subject:In-Reply-To:References:Date:From; b=tRn4KRnriHXnC/fn1AMuvXbbTYhmGvx/qn58YB0AL7kg9FZnQIl0zZ6HBu2aSJKj2 ytNC4XhS+8ptKqzIzPae5q9fHmYKsWsozd5BTG3AtllOSvlXRFQUzVCukP1GSuKz+I aP899IJXsajbULeBYxvhQTgKWQlfP4fxk6yQRZMNGXAVsDoeE92DzjXp09tuVOLumn xdQ/UgfW+UU3oIxAHQjaEBrLkqwawRqQ5e9zJHFdJ0tCxpIfieI0zzrCNxgVrZ+1Wb F2SSVwRooyzzHKJgo/kXohULYbKgJ4hu3CsB4z0bwWHu2JxkQ4stPD9FnFttCqxHHd Zwrq/qfowY0jw== From: =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= To: Yunhui Cui , paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, guoren@kernel.org, bjorn@rivosinc.com, conor.dooley@microchip.com, jszhang@kernel.org, andy.chiu@sifive.com, cuiyunhui@bytedance.com, dave.hansen@linux.intel.com, elver@google.com, glider@google.com, cyphar@cyphar.com, kirill.shutemov@linux.intel.com, keescook@chromium.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] riscv: add userland instruction dump to RISC-V splats In-Reply-To: <20230817114130.24662-1-cuiyunhui@bytedance.com> References: <20230817114130.24662-1-cuiyunhui@bytedance.com> Date: Thu, 17 Aug 2023 15:27:14 +0200 Message-ID: <87msyphk99.fsf@all.your.base.are.belong.to.us> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yunhui Cui writes: > Added userland instruction dump in dump_kernel_instr(). > > An example: > [ 0.822439] Freeing unused kernel image (initmem) memory: 6916K > [ 0.823817] Run /init as init process > [ 0.839411] init[1]: unhandled signal 4 code 0x1 at 0x000000000005be18= in bb[10000+5fb000] > [ 0.840751] CPU: 0 PID: 1 Comm: init Not tainted 5.14.0-rc4-00049-gbd6= 44290aa72-dirty #187 > [ 0.841373] Hardware name: , BIOS > [ 0.841743] epc : 000000000005be18 ra : 0000000000079e74 sp : 0000003f= ffcafda0 > [ 0.842271] gp : ffffffff816e9dc8 tp : 0000000000000000 t0 : 00000000= 00000000 > [ 0.842947] t1 : 0000003fffc9fdf0 t2 : 0000000000000000 s0 : 00000000= 00000000 > [ 0.843434] s1 : 0000000000000000 a0 : 0000003fffca0190 a1 : 0000003f= ffcafe18 > [ 0.843891] a2 : 0000000000000000 a3 : 0000000000000000 a4 : 00000000= 00000000 > [ 0.844357] a5 : 0000000000000000 a6 : 0000000000000000 a7 : 00000000= 00000000 > [ 0.844803] s2 : 0000000000000000 s3 : 0000000000000000 s4 : 00000000= 00000000 > [ 0.845253] s5 : 0000000000000000 s6 : 0000000000000000 s7 : 00000000= 00000000 > [ 0.845722] s8 : 0000000000000000 s9 : 0000000000000000 s10: 00000000= 00000000 > [ 0.846180] s11: 0000000000d144e0 t3 : 0000000000000000 t4 : 00000000= 00000000 > [ 0.846616] t5 : 0000000000000000 t6 : 0000000000000000 > [ 0.847204] status: 0000000200000020 badaddr: 00000000f0028053 cause: = 0000000000000002 > [ 0.848219] Code: f06f ff5f 3823 fa11 0113 fb01 2e23 0201 0293 0000 (8= 053) f002 > [ 0.851016] Kernel panic - not syncing: Attempted to kill init! exitco= de=3D0x00000004 > > Signed-off-by: Yunhui Cui > --- > arch/riscv/kernel/traps.c | 10 +++++++--- > include/linux/uaccess.h | 5 +++++ > 2 files changed, 12 insertions(+), 3 deletions(-) > > diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c > index f910dfccbf5d..a6a850e42d59 100644 > --- a/arch/riscv/kernel/traps.c > +++ b/arch/riscv/kernel/traps.c > @@ -33,7 +33,7 @@ int show_unhandled_signals =3D 1; >=20=20 > static DEFINE_SPINLOCK(die_lock); >=20=20 > -static void dump_kernel_instr(const char *loglvl, struct pt_regs *regs) > +static void dump_instr(const char *loglvl, struct pt_regs *regs) > { > char str[sizeof("0000 ") * 12 + 2 + 1], *p =3D str; > const u16 *insns =3D (u16 *)instruction_pointer(regs); > @@ -42,7 +42,10 @@ static void dump_kernel_instr(const char *loglvl, stru= ct pt_regs *regs) > int i; >=20=20 > for (i =3D -10; i < 2; i++) { > - bad =3D get_kernel_nofault(val, &insns[i]); > + if (user_mode(regs)) > + bad =3D get_user_nofault(val, &insns[i]); > + else > + bad =3D get_kernel_nofault(val, &insns[i]); > if (!bad) { > p +=3D sprintf(p, i =3D=3D 0 ? "(%04hx) " : "%04hx ", val); > } else { > @@ -71,7 +74,7 @@ void die(struct pt_regs *regs, const char *str) > print_modules(); > if (regs) { > show_regs(regs); > - dump_kernel_instr(KERN_EMERG, regs); > + dump_instr(KERN_EMERG, regs); > } >=20=20 > cause =3D regs ? regs->cause : -1; > @@ -104,6 +107,7 @@ void do_trap(struct pt_regs *regs, int signo, int cod= e, unsigned long addr) > print_vma_addr(KERN_CONT " in ", instruction_pointer(regs)); > pr_cont("\n"); > __show_regs(regs); > + dump_instr(KERN_EMERG, regs); > } >=20=20 > force_sig_fault(signo, code, (void __user *)addr); > diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h > index 3064314f4832..ba8cb37a7241 100644 > --- a/include/linux/uaccess.h > +++ b/include/linux/uaccess.h > @@ -385,6 +385,11 @@ long strncpy_from_user_nofault(char *dst, const void= __user *unsafe_addr, > long count); > long strnlen_user_nofault(const void __user *unsafe_addr, long count); >=20=20 > +#define get_user_nofault(val, ptr) ({ \ > + const typeof(val) *__gk_ptr =3D (ptr); \ > + copy_from_user_nofault(&(val), __gk_ptr, sizeof(val));\ > +}) > + Your previous version had a check: | /* The user space code from other tasks cannot be accessed. */ | if (regs !=3D task_pt_regs(current)) | return -EPERM; Why was that left out? Is it not needed? Your get_user_nofault is only used in this file, so maybe it's better to do what x86 does, and introduce a static "copy_code()" that deals with the user/kernel checks/copy? Bj=C3=B6rn