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Tue, 30 Jul 2024 20:39:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722371974; bh=aAQDsE7GDxJhm+wL9UOlgeKFBMIyy3lwjoQ7+lNWLG8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GXTKL8FwKOoOm71IhW1FyHalGRRuOZmfTPOquyCKYTY2T9UguVxHdnJ2kE8t6vvcq HNpPIuSOEHkVVRJNvrgifTT+eguuUiCTQIA+kzynaaJj6Ga2EYaJxRmBljOC6lYzmd DcJknR+8PpuZNYHjrEiFTViclfvXOy9ezaT3gcaMZyvPRRuS5vmJ+AI8pSAFVGrTY0 pd3mKEsEfcEOyQpyu4RtjN0SvOgYlJcyyGyapucVs5Mo1kU++zh9AZYp6s6cEURr4P uu3MRp7y2+tiKzk0NnJ5OcCm1wWNNJyl4yq7QXyRv9hkyDC84Xx6T4G3bWH6QC1U4y M9F27worVIM/A== 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, Andrii Nakryiko Subject: [PATCH v3 bpf-next 05/10] lib/buildid: rename build_id_parse() into build_id_parse_nofault() Date: Tue, 30 Jul 2024 13:39:09 -0700 Message-ID: <20240730203914.1182569-6-andrii@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240730203914.1182569-1-andrii@kernel.org> References: <20240730203914.1182569-1-andrii@kernel.org> MIME-Version: 1.0 X-Rspamd-Queue-Id: 683421C002B X-Stat-Signature: 6bojz1xmh3gegwduye4ihfa5qgo3fiu4 X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1722371977-768982 X-HE-Meta: U2FsdGVkX18zPoH+B/kgs1WANmS//mjtrXL/5NjuZC+DZLjtZu6eXDFsDKNAlZonni3t+t4zVhuV5I/VCoabfuYRelG5p+rVJPTSL7TiJd01CHH8SJV/ZB1ZEvlGNo+8RL7G6LQUvQF/SR++uwkZfRfqsfLAW9O6+bb/T6votK5q6T9DegANG2FqBjmvHVTye2LpdlhWUEV1YtSkl77hgY4WlmCquu7uQID4sJN+XPfRYvEzUrhalM1mloWstAXISpDVpptU7P6Ng1mcaSdQPzAT9Kkhin+FxiZKlQMuU0dr5aXatbFWA59CFdOrwncgyxt26mvdUSVfC05eS3CQryehGUBUYoJs666+lShJhbPIbicSYyqpntTO/pMYbX5GGCBPE7zKOtqIRVmjS/XJhKEqfYUXoQp23WfFJATvVyPlzQiZy8kSe4nlifimn0X1GwS/32S/gExIv82oavuK2PcEYLBXYaVuYb2MhNUM+FLrJrK00hQ+DtPk+8hOw8urC4RrHL1BUolTPOKQeOvzw0hv9/fysTU2OQ8OTN5jAPtxHpOcfob6cet0ibRKKykHJDFzgc/7fodCKKdeUoZDSpNczU8n8jihUU9kt8MjBMmQokap/HAzKZb1qkfxsmmDifOtQPNAxilL0lDSL1x/pvOSwDRNDYt+8u7z6sSYQbE9FDoz4QYmPdje9CVvkFtyAuWzgMUQU7VPj8J3pUxmJBdOo0CpzdqDFwYrEDCjHI4d3B2tDsb7RQby0EfcPJik6BLx4ir37nyvwgQIagxsrEiNGNJVXWGjKiy2LhQYmIdsGcJDrLj9R9Q39FjkW/VxGvuvnRSZz+LqDu9kN+vPzoXN9NtZW4eE37VvyxwQfs75CfIOKEPnMQE0uwa4dX9gY4nLIpnDNUibokD0IvnuMn8EEgdgH48Yj7FIF69dSFov/b4KCTjMPYsAQJ9GCZbLpjkUaefarGU3O7dphPF ypHoAstg w8eZo1Iet4vDtdizPnri7R/afpBg7A5tp99FK65yT0Lz5TmuL0YOqkpwsUXst1HTcwhkJnN+QV2rmatwb7M3xuQ3EvftbJZKzup8v8QrIz0o66BroX5gitY2S5VN5hu5iw2v0QLIT6XCIrjbf4pv3E31XNTuwhOrDKmHAXdjyLKeQH2dfAkSzQi4TUW9lt5Gz9bwIK+/wcEuMMF11Tgc2aeVIrJJfGw/DfmnwbgV8xYn7kkRnXIj7M5PeW3AZhpYuNI5kFBhr42FJvssVAtfk2Dut6uNW2XBOYWu7 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 095e79158b85..5c869a2a30ab 100644 --- a/lib/buildid.c +++ b/lib/buildid.c @@ -279,10 +279,12 @@ 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; @@ -321,6 +323,23 @@ 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