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Tue, 13 Aug 2024 00:29:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1723508992; bh=avz7wz2KTZz1lZ8tpXBxD2kwVdHJhhzASQO4Ib+3tWM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kWmKvvbgOxSygVyyz6LOLRs1rQDdRzkKiw/2pGgzmwGIXdoM68F1FuwTrxVGijkwC Bn0c4fYPsLY7fqUD2KQJyjrGnuMMt+JFTRyiJvvwQTO/Buc6qptLTOo7XhNDfOfZzs J10bg3fkNHIXggVRwTGuYRSJdWWuNDd4IMGLHurhWDDbdgb6t2fA3LB6eGvwYXuIG+ dfY7ph7jLPD6EQcveh4BQyHaoSHTmPLpN8NxiJcljt7UOhuU3aVhpLNzr1EMvrlr7Q mRWID2bIRNPpq7Q1AOqcmjrTlfgScdIIp2434KXjrRekbpEvWtX7XKOlK5+kF3veuW iDGKZ4fUvCmnA== From: Andrii Nakryiko To: bpf@vger.kernel.org Cc: linux-mm@kvack.org, akpm@linux-foundation.org, adobriyan@gmail.com, shakeel.butt@linux.dev, hannes@cmpxchg.org, ak@linux.intel.com, osandov@osandov.com, song@kernel.org, jannh@google.com, linux-fsdevel@vger.kernel.org, willy@infradead.org, Andrii Nakryiko Subject: [PATCH v5 bpf-next 05/10] lib/buildid: rename build_id_parse() into build_id_parse_nofault() Date: Mon, 12 Aug 2024 17:29:27 -0700 Message-ID: <20240813002932.3373935-6-andrii@kernel.org> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20240813002932.3373935-1-andrii@kernel.org> References: <20240813002932.3373935-1-andrii@kernel.org> MIME-Version: 1.0 X-Stat-Signature: wxcwuj9mr55n9kgrz8bi93fyyy8uwwqy X-Rspamd-Queue-Id: 54A69A000E X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1723508993-350988 X-HE-Meta: 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 kPuShSYa dk2+lPVg9BTIyZiuyDTgMKz0/bxJQv7YT6YxBZgOxHYMpRpiZE7jchW6mnt5U0cHu9Ys8DTPduGEUAhS6Jy75BW5NOOgKTrx4dtkHGC4K7tvaj97Bt/nXOa2jiF0G7WEBxL7T7DVTCKS8UICKPPEBisnL/mwyb8v0GxaEFysPdG6gCGFIYkrGWMOhTYpy2Qe9+saw3PBDmplTlqv9cxE1XbE7ML4l0/4lRuRzGVGC1VaBowzzXRCtl7UYVh8bii7lCGl6u/lkRsNrr3X4pi7EPG7eMtV9nmhR6tLU X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. Signed-off-by: Andrii Nakryiko --- include/linux/buildid.h | 4 ++-- kernel/bpf/stackmap.c | 2 +- kernel/events/core.c | 2 +- lib/buildid.c | 25 ++++++++++++++++++++++--- 4 files changed, 26 insertions(+), 7 deletions(-) diff --git a/include/linux/buildid.h b/include/linux/buildid.h index 20aa3c2d89f7..014a88c41073 100644 --- a/include/linux/buildid.h +++ b/include/linux/buildid.h @@ -7,8 +7,8 @@ #define BUILD_ID_SIZE_MAX 20 struct vm_area_struct; -int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, - __u32 *size); +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_VMCORE_INFO) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index c99f8e5234ac..770ae8e88016 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 aa3450bdc227..c263a8b0ce54 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8851,7 +8851,7 @@ 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 8296428ff82f..b33d960f085d 100644 --- a/lib/buildid.c +++ b/lib/buildid.c @@ -293,10 +293,12 @@ static int get_build_id_64(struct freader *r, unsigned char *build_id, __u32 *si * @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) { const Elf32_Ehdr *ehdr; struct freader r; @@ -335,6 +337,23 @@ 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