From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF27755C1C3 for ; Tue, 8 Sep 2026 13:32:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788874382; cv=none; b=JC213Vekk/Xn4QgkEUH+XldYrUV/T6jhNmo4tn0K2Hj/3lm4bWJQQ/evA4AgGAUD0TQzGrqty8s8IoyQv9c55xLAOKExCwiBeEdZnVvSeTJFxYdwLBe3d0GisyLuNj+wq7mOHgpDL+axGDuyMcz/w67s6QdOv/6vJ4jwNdBMr0A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788874382; c=relaxed/simple; bh=MVZ70RQ24F31QhDE7yJpDyxkuMYnAD2HpDHVC8piyFk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ehMCc7WEVUzjgOv4flO/xItroO3XFY8j8Pddt/ERU3sTVJN22C1nWGbuCZQdIlL6JGb8pCVyuwBEjopFVW+Cj0FA4Hf2/Tz0xmtIgUyu5Nxt3bS693Wrs/5BM2kjzpJChX5FJddKsqmBL0AFUD4Hs+QBGZN4TAafuC/282Ia7ss= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 Received: by smtp.kernel.org (Postfix) with ESMTPSA id A5F4E1F00A3E; Tue, 8 Sep 2026 13:32:53 +0000 (UTC) From: Sasha Levin To: stable@vger.kernel.org Cc: Andrii Nakryiko , Eduard Zingerman , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.6.y 1/3] lib/buildid: rename build_id_parse() into build_id_parse_nofault() Date: Tue, 8 Sep 2026 09:32:49 -0400 Message-ID: <20260908133251.2324526-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090326-saturate-wobbling-7457@gregkh> References: <2026090326-saturate-wobbling-7457@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Andrii Nakryiko [ Upstream commit 45b8fc3096542a53bfd245a9ad8ef870384b4897 ] Make it clear that build_id_parse() assumes that it can take no page fault by renaming it and current few users to build_id_parse_nofault(). Also add build_id_parse() stub which for now falls back to non-sleepable implementation, but will be changed in subsequent patches to take advantage of sleepable context. PROCMAP_QUERY ioctl() on /proc//maps file is using build_id_parse() and will automatically take advantage of more reliable sleepable context implementation. Reviewed-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240829174232.3133883-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov Stable-dep-of: b1a47b2708d4 ("bpf: Disable preemption in __bpf_get_stack") Signed-off-by: Sasha Levin --- include/linux/buildid.h | 2 ++ kernel/bpf/stackmap.c | 2 +- kernel/events/core.c | 2 +- lib/buildid.c | 25 ++++++++++++++++++++++--- 4 files changed, 26 insertions(+), 5 deletions(-) diff --git a/include/linux/buildid.h b/include/linux/buildid.h index 3b7a0ff4642fd..7b645d032875d 100644 --- a/include/linux/buildid.h +++ b/include/linux/buildid.h @@ -8,6 +8,8 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size); +int build_id_parse_nofault(struct vm_area_struct *vma, + unsigned char *build_id, __u32 *size); int build_id_parse_buf(const void *buf, unsigned char *build_id, u32 buf_size); #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) || IS_ENABLED(CONFIG_CRASH_CORE) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index a330f38ae7335..0ed48217b2089 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -156,7 +156,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, goto build_id_valid; } vma = find_vma(current->mm, ips[i]); - if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) { + if (!vma || build_id_parse_nofault(vma, id_offs[i].build_id, NULL)) { /* per entry fall back to ips */ id_offs[i].status = BPF_STACK_BUILD_ID_IP; id_offs[i].ip = ips[i]; diff --git a/kernel/events/core.c b/kernel/events/core.c index 95743e6c5b0cb..7b16033510a18 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8903,7 +8903,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size; if (atomic_read(&nr_build_id_events)) - build_id_parse(vma, mmap_event->build_id, &mmap_event->build_id_size); + build_id_parse_nofault(vma, mmap_event->build_id, &mmap_event->build_id_size); perf_iterate_sb(perf_event_mmap_output, mmap_event, diff --git a/lib/buildid.c b/lib/buildid.c index 8d839ff5548ea..6ce6cb6e26fb3 100644 --- a/lib/buildid.c +++ b/lib/buildid.c @@ -144,10 +144,12 @@ static int get_build_id_64(const void *page_addr, unsigned char *build_id, * @build_id: buffer to store build id, at least BUILD_ID_SIZE long * @size: returns actual build id size in case of success * - * Return: 0 on success, -EINVAL otherwise + * Assumes no page fault can be taken, so if relevant portions of ELF file are + * not already paged in, fetching of build ID fails. + * + * Return: 0 on success; negative error, otherwise */ -int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, - __u32 *size) +int build_id_parse_nofault(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size) { Elf32_Ehdr *ehdr; struct page *page; @@ -192,6 +194,23 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, return ret; } +/* + * Parse build ID of ELF file mapped to VMA + * @vma: vma object + * @build_id: buffer to store build id, at least BUILD_ID_SIZE long + * @size: returns actual build id size in case of success + * + * Assumes faultable context and can cause page faults to bring in file data + * into page cache. + * + * Return: 0 on success; negative error, otherwise + */ +int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size) +{ + /* fallback to non-faultable version for now */ + return build_id_parse_nofault(vma, build_id, size); +} + /** * build_id_parse_buf - Get build ID from a buffer * @buf: ELF note section(s) to parse -- 2.53.0