From nobody Tue Apr 7 07:55:58 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 ADC8AC43219 for ; Wed, 12 Oct 2022 22:03:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230094AbiJLWDb (ORCPT ); Wed, 12 Oct 2022 18:03:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229947AbiJLWCZ (ORCPT ); Wed, 12 Oct 2022 18:02:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3F141125719; Wed, 12 Oct 2022 15:00:47 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1E56A61632; Wed, 12 Oct 2022 22:00:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 81D97C433B5; Wed, 12 Oct 2022 22:00:35 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1oijmW-0049Cc-0G; Wed, 12 Oct 2022 18:00:52 -0400 Message-ID: <20221012220051.926552531@goodmis.org> User-Agent: quilt/0.66 Date: Wed, 12 Oct 2022 17:59:15 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Andrew Morton , stable@vger.kernel.org, Tom Zanussi Subject: [for-linus][PATCH 4/5] tracing: Add "(fault)" name injection to kernel probes References: <20221012215911.735621065@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Steven Rostedt (Google)" Have the specific functions for kernel probes that read strings to inject the "(fault)" name directly. trace_probes.c does this too (for uprobes) but as the code to read strings are going to be used by synthetic events (and perhaps other utilities), it simplifies the code by making sure those other uses do not need to implement the "(fault)" name injection as well. Link: https://lkml.kernel.org/r/20221012104534.644803645@goodmis.org Cc: stable@vger.kernel.org Cc: Andrew Morton Cc: Tom Zanussi Acked-by: Masami Hiramatsu (Google) Reviewed-by: Tom Zanussi Fixes: bd82631d7ccdc ("tracing: Add support for dynamic strings to syntheti= c events") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_probe_kernel.h | 31 +++++++++++++++++++++++++------ 1 file changed, 25 insertions(+), 6 deletions(-) diff --git a/kernel/trace/trace_probe_kernel.h b/kernel/trace/trace_probe_k= ernel.h index 1d43df29a1f8..77dbd9ff9782 100644 --- a/kernel/trace/trace_probe_kernel.h +++ b/kernel/trace/trace_probe_kernel.h @@ -2,6 +2,8 @@ #ifndef __TRACE_PROBE_KERNEL_H_ #define __TRACE_PROBE_KERNEL_H_ =20 +#define FAULT_STRING "(fault)" + /* * This depends on trace_probe.h, but can not include it due to * the way trace_probe_tmpl.h is used by trace_kprobe.c and trace_eprobe.c. @@ -13,8 +15,16 @@ static nokprobe_inline int kern_fetch_store_strlen_user(unsigned long addr) { const void __user *uaddr =3D (__force const void __user *)addr; + int ret; =20 - return strnlen_user_nofault(uaddr, MAX_STRING_SIZE); + ret =3D strnlen_user_nofault(uaddr, MAX_STRING_SIZE); + /* + * strnlen_user_nofault returns zero on fault, insert the + * FAULT_STRING when that occurs. + */ + if (ret <=3D 0) + return strlen(FAULT_STRING) + 1; + return ret; } =20 /* Return the length of string -- including null terminal byte */ @@ -34,7 +44,18 @@ kern_fetch_store_strlen(unsigned long addr) len++; } while (c && ret =3D=3D 0 && len < MAX_STRING_SIZE); =20 - return (ret < 0) ? ret : len; + /* For faults, return enough to hold the FAULT_STRING */ + return (ret < 0) ? strlen(FAULT_STRING) + 1 : len; +} + +static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest= , void *base, int len) +{ + if (ret >=3D 0) { + *(u32 *)dest =3D make_data_loc(ret, __dest - base); + } else { + strscpy(__dest, FAULT_STRING, len); + ret =3D strlen(__dest) + 1; + } } =20 /* @@ -55,8 +76,7 @@ kern_fetch_store_string_user(unsigned long addr, void *de= st, void *base) __dest =3D get_loc_data(dest, base); =20 ret =3D strncpy_from_user_nofault(__dest, uaddr, maxlen); - if (ret >=3D 0) - *(u32 *)dest =3D make_data_loc(ret, __dest - base); + set_data_loc(ret, dest, __dest, base, maxlen); =20 return ret; } @@ -87,8 +107,7 @@ kern_fetch_store_string(unsigned long addr, void *dest, = void *base) * probing. */ ret =3D strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen); - if (ret >=3D 0) - *(u32 *)dest =3D make_data_loc(ret, __dest - base); + set_data_loc(ret, dest, __dest, base, maxlen); =20 return ret; } --=20 2.35.1