From: Jiri Olsa <jolsa@kernel.org>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>
Subject: [PATCHv4 bpf-next 2/3] selftests/bpf: Add read_build_id function
Date: Fri, 31 Mar 2023 11:31:56 +0200 [thread overview]
Message-ID: <20230331093157.1749137-3-jolsa@kernel.org> (raw)
In-Reply-To: <20230331093157.1749137-1-jolsa@kernel.org>
Adding read_build_id function that parses out build id from
specified binary.
It will replace extract_build_id and also be used in following
changes.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/testing/selftests/bpf/trace_helpers.c | 82 +++++++++++++++++++++
tools/testing/selftests/bpf/trace_helpers.h | 5 ++
2 files changed, 87 insertions(+)
diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index 934bf28fc888..9b070cdf44ac 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -11,6 +11,9 @@
#include <linux/perf_event.h>
#include <sys/mman.h>
#include "trace_helpers.h"
+#include <linux/limits.h>
+#include <libelf.h>
+#include <gelf.h>
#define TRACEFS_PIPE "/sys/kernel/tracing/trace_pipe"
#define DEBUGFS_PIPE "/sys/kernel/debug/tracing/trace_pipe"
@@ -234,3 +237,82 @@ ssize_t get_rel_offset(uintptr_t addr)
fclose(f);
return -EINVAL;
}
+
+static int
+parse_build_id_buf(const void *note_start, Elf32_Word note_size, char *build_id)
+{
+ Elf32_Word note_offs = 0;
+
+ while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
+ Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs);
+
+ if (nhdr->n_type == 3 && nhdr->n_namesz == sizeof("GNU") &&
+ !strcmp((char *)(nhdr + 1), "GNU") && nhdr->n_descsz > 0 &&
+ nhdr->n_descsz <= BPF_BUILD_ID_SIZE) {
+ memcpy(build_id, note_start + note_offs +
+ ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), nhdr->n_descsz);
+ memset(build_id + nhdr->n_descsz, 0, BPF_BUILD_ID_SIZE - nhdr->n_descsz);
+ return (int) nhdr->n_descsz;
+ }
+
+ note_offs = note_offs + sizeof(Elf32_Nhdr) +
+ ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4);
+ }
+
+ return -ENOENT;
+}
+
+/* Reads binary from *path* file and returns it in the *build_id* buffer
+ * with *size* which is expected to be at least BPF_BUILD_ID_SIZE bytes.
+ * Returns size of build id on success. On error the error value is
+ * returned.
+ */
+int read_build_id(const char *path, char *build_id, size_t size)
+{
+ int fd, err = -EINVAL;
+ Elf *elf = NULL;
+ GElf_Ehdr ehdr;
+ size_t max, i;
+
+ if (size < BPF_BUILD_ID_SIZE)
+ return -EINVAL;
+
+ fd = open(path, O_RDONLY | O_CLOEXEC);
+ if (fd < 0)
+ return -errno;
+
+ (void)elf_version(EV_CURRENT);
+
+ elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+ if (!elf)
+ goto out;
+ if (elf_kind(elf) != ELF_K_ELF)
+ goto out;
+ if (!gelf_getehdr(elf, &ehdr))
+ goto out;
+
+ for (i = 0; i < ehdr.e_phnum; i++) {
+ GElf_Phdr mem, *phdr;
+ char *data;
+
+ phdr = gelf_getphdr(elf, i, &mem);
+ if (!phdr)
+ goto out;
+ if (phdr->p_type != PT_NOTE)
+ continue;
+ data = elf_rawfile(elf, &max);
+ if (!data)
+ goto out;
+ if (phdr->p_offset + phdr->p_memsz > max)
+ goto out;
+ err = parse_build_id_buf(data + phdr->p_offset, phdr->p_memsz, build_id);
+ if (err > 0)
+ break;
+ }
+
+out:
+ if (elf)
+ elf_end(elf);
+ close(fd);
+ return err;
+}
diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h
index 53efde0e2998..876f3e711df6 100644
--- a/tools/testing/selftests/bpf/trace_helpers.h
+++ b/tools/testing/selftests/bpf/trace_helpers.h
@@ -4,6 +4,9 @@
#include <bpf/libbpf.h>
+#define __ALIGN_MASK(x, mask) (((x)+(mask))&~(mask))
+#define ALIGN(x, a) __ALIGN_MASK(x, (typeof(x))(a)-1)
+
struct ksym {
long addr;
char *name;
@@ -23,4 +26,6 @@ void read_trace_pipe(void);
ssize_t get_uprobe_offset(const void *addr);
ssize_t get_rel_offset(uintptr_t addr);
+int read_build_id(const char *path, char *build_id, size_t size);
+
#endif
--
2.39.2
next prev parent reply other threads:[~2023-03-31 9:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-31 9:31 [PATCHv4 bpf-next 0/3] selftests/bpf: Add read_build_id function Jiri Olsa
2023-03-31 9:31 ` [PATCHv4 bpf-next 1/3] selftests/bpf: Add err.h header Jiri Olsa
2023-03-31 9:31 ` Jiri Olsa [this message]
2023-03-31 9:31 ` [PATCHv4 bpf-next 3/3] selftests/bpf: Replace extract_build_id with read_build_id Jiri Olsa
2023-03-31 16:50 ` [PATCHv4 bpf-next 0/3] selftests/bpf: Add read_build_id function patchwork-bot+netdevbpf
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