From patchwork Tue Oct 5 10:58:50 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marco Elver X-Patchwork-Id: 12536219 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F047AC433FE for ; Tue, 5 Oct 2021 11:00:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC0C461526 for ; Tue, 5 Oct 2021 11:00:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234326AbhJELCT (ORCPT ); Tue, 5 Oct 2021 07:02:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234343AbhJELBy (ORCPT ); Tue, 5 Oct 2021 07:01:54 -0400 Received: from mail-wr1-x449.google.com (mail-wr1-x449.google.com [IPv6:2a00:1450:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72252C061768 for ; Tue, 5 Oct 2021 04:00:03 -0700 (PDT) Received: by mail-wr1-x449.google.com with SMTP id r25-20020adfab59000000b001609ddd5579so2568009wrc.21 for ; Tue, 05 Oct 2021 04:00:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=xsbn5DHOInVTvHdCjIbH8F7lYj2M2KByY98qL4y3tHQ=; b=GzYNn8BbV6HkxgVdAh/WhkAVRVFifsX3fAkp8fuVoAbra5X82gtJ5hOoDMKsnHhLwC mnx7wKKhxnC9J06fLnhTs/xSclQNx4hwLNnYCZymjlGPonilYIh7ZmRmdGaX29tLzIRe M/j6QrWCMbfWV4Uu86XFyHKI9s9H6sXo+yJKUz1mUCWwgwYOJGiFIolnc4BC6eKk7wcc 6o3T4EGFdqZ5IxBb7RCK1gZZcmJPDF/AUCprOJ4NoNdyrcmFb3fuHUWzHWh165fY7Y+9 yWwiA81IolLhAEqe9OyucVzO5vf2e4p0TazEtV3o/92kFxe0WM8a08FV6GXuJapgpPZu qmdA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=xsbn5DHOInVTvHdCjIbH8F7lYj2M2KByY98qL4y3tHQ=; b=GAY9md3q2jaKTiqDWohuCt8EsqMhqBx/ZsgvjB4V0dV71t2S4AD6P++7UTt84erl/C R88D4/uAwrv25D4LIXLG3vCgojDuhzs8SCFHlJfH1NzP7AROVH9fKpuPx6aCXE2D2wpu IHF5fNkzzeq6qRypkaSdfNMqpEMKq4k0dUs/Sg37/mo+P6mdX9IULO6jjSiMYoU9znkt E0s+ezApY99mtgvtBq1jcLnhe16kTC093m2QkwP/aBO/QTTl+xIOFEOT0w3et63q7AEg gmlKNM021rVYBR//FfJX62VaRhVLkRCYzwrNb/DPw5tu2+Cp3E25w07o59OdK6eKIJhj mhcQ== X-Gm-Message-State: AOAM532DksDKNsHcW2S9YKemGjlUxWXPh5O0OWfFtOyzAMwdixSUPlfQ FFLSd8YG0ZjwQS3t/8CVIlm+s2B2SA== X-Google-Smtp-Source: ABdhPJyQ9+XR3YU56FBJU8DeE3vu/iZuM2wNV7QdNqbMLHMu3vYpUyN6kv4zopypBzI8an4m0Im5e2ujqw== X-Received: from elver.muc.corp.google.com ([2a00:79e0:15:13:e44f:5054:55f8:fcb8]) (user=elver job=sendgmr) by 2002:adf:a35d:: with SMTP id d29mr20140800wrb.318.1633431601839; Tue, 05 Oct 2021 04:00:01 -0700 (PDT) Date: Tue, 5 Oct 2021 12:58:50 +0200 In-Reply-To: <20211005105905.1994700-1-elver@google.com> Message-Id: <20211005105905.1994700-9-elver@google.com> Mime-Version: 1.0 References: <20211005105905.1994700-1-elver@google.com> X-Mailer: git-send-email 2.33.0.800.g4c38ced690-goog Subject: [PATCH -rcu/kcsan 08/23] kcsan: Show location access was reordered to From: Marco Elver To: elver@google.com, "Paul E . McKenney" Cc: Alexander Potapenko , Boqun Feng , Borislav Petkov , Dmitry Vyukov , Ingo Molnar , Josh Poimboeuf , Mark Rutland , Peter Zijlstra , Thomas Gleixner , Waiman Long , Will Deacon , kasan-dev@googlegroups.com, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org Also show the location the access was reordered to. An example report: | ================================================================== | BUG: KCSAN: data-race in test_kernel_wrong_memorder / test_kernel_wrong_memorder | | read-write to 0xffffffffc01e61a8 of 8 bytes by task 2311 on cpu 5: | test_kernel_wrong_memorder+0x57/0x90 | access_thread+0x99/0xe0 | kthread+0x2ba/0x2f0 | ret_from_fork+0x22/0x30 | | read-write (reordered) to 0xffffffffc01e61a8 of 8 bytes by task 2310 on cpu 7: | test_kernel_wrong_memorder+0x57/0x90 | access_thread+0x99/0xe0 | kthread+0x2ba/0x2f0 | ret_from_fork+0x22/0x30 | | | +-> reordered to: test_kernel_wrong_memorder+0x80/0x90 | | Reported by Kernel Concurrency Sanitizer on: | CPU: 7 PID: 2310 Comm: access_thread Not tainted 5.14.0-rc1+ #18 | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 | ================================================================== Signed-off-by: Marco Elver --- kernel/kcsan/report.c | 35 +++++++++++++++++++++++------------ 1 file changed, 23 insertions(+), 12 deletions(-) diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c index 1b0e050bdf6a..67794404042a 100644 --- a/kernel/kcsan/report.c +++ b/kernel/kcsan/report.c @@ -308,10 +308,12 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries /* * Skips to the first entry that matches the function of @ip, and then replaces - * that entry with @ip, returning the entries to skip. + * that entry with @ip, returning the entries to skip with @replaced containing + * the replaced entry. */ static int -replace_stack_entry(unsigned long stack_entries[], int num_entries, unsigned long ip) +replace_stack_entry(unsigned long stack_entries[], int num_entries, unsigned long ip, + unsigned long *replaced) { unsigned long symbolsize, offset; unsigned long target_func; @@ -330,6 +332,7 @@ replace_stack_entry(unsigned long stack_entries[], int num_entries, unsigned lon func -= offset; if (func == target_func) { + *replaced = stack_entries[skip]; stack_entries[skip] = ip; return skip; } @@ -342,9 +345,10 @@ replace_stack_entry(unsigned long stack_entries[], int num_entries, unsigned lon } static int -sanitize_stack_entries(unsigned long stack_entries[], int num_entries, unsigned long ip) +sanitize_stack_entries(unsigned long stack_entries[], int num_entries, unsigned long ip, + unsigned long *replaced) { - return ip ? replace_stack_entry(stack_entries, num_entries, ip) : + return ip ? replace_stack_entry(stack_entries, num_entries, ip, replaced) : get_stack_skipnr(stack_entries, num_entries); } @@ -360,6 +364,14 @@ static int sym_strcmp(void *addr1, void *addr2) return strncmp(buf1, buf2, sizeof(buf1)); } +static void +print_stack_trace(unsigned long stack_entries[], int num_entries, unsigned long reordered_to) +{ + stack_trace_print(stack_entries, num_entries, 0); + if (reordered_to) + pr_err(" |\n +-> reordered to: %pS\n", (void *)reordered_to); +} + static void print_verbose_info(struct task_struct *task) { if (!task) @@ -378,10 +390,12 @@ static void print_report(enum kcsan_value_change value_change, struct other_info *other_info, u64 old, u64 new, u64 mask) { + unsigned long reordered_to = 0; unsigned long stack_entries[NUM_STACK_ENTRIES] = { 0 }; int num_stack_entries = stack_trace_save(stack_entries, NUM_STACK_ENTRIES, 1); - int skipnr = sanitize_stack_entries(stack_entries, num_stack_entries, ai->ip); + int skipnr = sanitize_stack_entries(stack_entries, num_stack_entries, ai->ip, &reordered_to); unsigned long this_frame = stack_entries[skipnr]; + unsigned long other_reordered_to = 0; unsigned long other_frame = 0; int other_skipnr = 0; /* silence uninit warnings */ @@ -394,7 +408,7 @@ static void print_report(enum kcsan_value_change value_change, if (other_info) { other_skipnr = sanitize_stack_entries(other_info->stack_entries, other_info->num_stack_entries, - other_info->ai.ip); + other_info->ai.ip, &other_reordered_to); other_frame = other_info->stack_entries[other_skipnr]; /* @value_change is only known for the other thread */ @@ -434,10 +448,9 @@ static void print_report(enum kcsan_value_change value_change, other_info->ai.cpu_id); /* Print the other thread's stack trace. */ - stack_trace_print(other_info->stack_entries + other_skipnr, + print_stack_trace(other_info->stack_entries + other_skipnr, other_info->num_stack_entries - other_skipnr, - 0); - + other_reordered_to); if (IS_ENABLED(CONFIG_KCSAN_VERBOSE)) print_verbose_info(other_info->task); @@ -451,9 +464,7 @@ static void print_report(enum kcsan_value_change value_change, get_thread_desc(ai->task_pid), ai->cpu_id); } /* Print stack trace of this thread. */ - stack_trace_print(stack_entries + skipnr, num_stack_entries - skipnr, - 0); - + print_stack_trace(stack_entries + skipnr, num_stack_entries - skipnr, reordered_to); if (IS_ENABLED(CONFIG_KCSAN_VERBOSE)) print_verbose_info(current);