From: Andrii Nakryiko <andriin@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
<daniel@iogearbox.net>
Cc: <andrii.nakryiko@gmail.com>, <kernel-team@fb.com>,
Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH v2 bpf-next 01/14] libbpf: ensure ELF symbols table is found before further ELF processing
Date: Mon, 31 Aug 2020 18:49:50 -0700 [thread overview]
Message-ID: <20200901015003.2871861-2-andriin@fb.com> (raw)
In-Reply-To: <20200901015003.2871861-1-andriin@fb.com>
libbpf ELF parsing logic might need symbols available before ELF parsing is
completed, so we need to make sure that symbols table section is found in
a separate pass before all the subsequent sections are processed.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
tools/lib/bpf/libbpf.c | 40 +++++++++++++++++++++++++++++-----------
1 file changed, 29 insertions(+), 11 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b688aadf09c5..ac56d4db6d3e 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2720,14 +2720,38 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
Elf *elf = obj->efile.elf;
Elf_Data *btf_ext_data = NULL;
Elf_Data *btf_data = NULL;
- Elf_Scn *scn = NULL;
int idx = 0, err = 0;
+ const char *name;
+ Elf_Data *data;
+ Elf_Scn *scn;
+ GElf_Shdr sh;
+ /* a bunch of ELF parsing functionality depends on processing symbols,
+ * so do the first pass and find the symbol table
+ */
+ scn = NULL;
while ((scn = elf_nextscn(elf, scn)) != NULL) {
- const char *name;
- GElf_Shdr sh;
- Elf_Data *data;
+ if (elf_sec_hdr(obj, scn, &sh))
+ return -LIBBPF_ERRNO__FORMAT;
+
+ if (sh.sh_type == SHT_SYMTAB) {
+ if (obj->efile.symbols) {
+ pr_warn("elf: multiple symbol tables in %s\n", obj->path);
+ return -LIBBPF_ERRNO__FORMAT;
+ }
+ data = elf_sec_data(obj, scn);
+ if (!data)
+ return -LIBBPF_ERRNO__FORMAT;
+
+ obj->efile.symbols = data;
+ obj->efile.symbols_shndx = elf_ndxscn(scn);
+ obj->efile.strtabidx = sh.sh_link;
+ }
+ }
+
+ scn = NULL;
+ while ((scn = elf_nextscn(elf, scn)) != NULL) {
idx++;
if (elf_sec_hdr(obj, scn, &sh))
@@ -2766,13 +2790,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
btf_ext_data = data;
} else if (sh.sh_type == SHT_SYMTAB) {
- if (obj->efile.symbols) {
- pr_warn("elf: multiple symbol tables in %s\n", obj->path);
- return -LIBBPF_ERRNO__FORMAT;
- }
- obj->efile.symbols = data;
- obj->efile.symbols_shndx = idx;
- obj->efile.strtabidx = sh.sh_link;
+ /* already processed during the first pass above */
} else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) {
if (sh.sh_flags & SHF_EXECINSTR) {
if (strcmp(name, ".text") == 0)
--
2.24.1
next prev parent reply other threads:[~2020-09-01 1:50 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 1:49 [PATCH v2 bpf-next 00/14] Add libbpf full support for BPF-to-BPF calls Andrii Nakryiko
2020-09-01 1:49 ` Andrii Nakryiko [this message]
2020-09-02 5:43 ` [PATCH v2 bpf-next 01/14] libbpf: ensure ELF symbols table is found before further ELF processing John Fastabend
2020-09-01 1:49 ` [PATCH v2 bpf-next 02/14] libbpf: parse multi-function sections into multiple BPF programs Andrii Nakryiko
2020-09-02 6:08 ` John Fastabend
2020-09-01 1:49 ` [PATCH v2 bpf-next 03/14] libbpf: support CO-RE relocations for multi-prog sections Andrii Nakryiko
2020-09-02 6:14 ` John Fastabend
2020-09-01 1:49 ` [PATCH v2 bpf-next 04/14] libbpf: make RELO_CALL work for multi-prog sections and sub-program calls Andrii Nakryiko
2020-09-02 5:36 ` Alexei Starovoitov
2020-09-02 19:52 ` Andrii Nakryiko
2020-09-01 1:49 ` [PATCH v2 bpf-next 05/14] libbpf: implement generalized .BTF.ext func/line info adjustment Andrii Nakryiko
2020-09-01 1:49 ` [PATCH v2 bpf-next 06/14] libbpf: add multi-prog section support for struct_ops Andrii Nakryiko
2020-09-01 1:49 ` [PATCH v2 bpf-next 07/14] selftests/bpf: add selftest for multi-prog sections and bpf-to-bpf calls Andrii Nakryiko
2020-09-02 5:41 ` Alexei Starovoitov
2020-09-02 19:57 ` Andrii Nakryiko
2020-09-01 1:49 ` [PATCH v2 bpf-next 08/14] tools/bpftool: replace bpf_program__title() with bpf_program__section_name() Andrii Nakryiko
2020-09-01 1:49 ` [PATCH v2 bpf-next 09/14] selftests/bpf: don't use deprecated libbpf APIs Andrii Nakryiko
2020-09-01 1:49 ` [PATCH v2 bpf-next 10/14] libbpf: deprecate notion of BPF program "title" in favor of "section name" Andrii Nakryiko
2020-09-01 1:50 ` [PATCH v2 bpf-next 11/14] selftests/bpf: turn fexit_bpf2bpf into test with subtests Andrii Nakryiko
2020-09-01 1:50 ` [PATCH v2 bpf-next 12/14] selftests/bpf: convert pyperf, strobemeta, and l4lb_noinline to __noinline Andrii Nakryiko
2020-09-02 5:45 ` Alexei Starovoitov
2020-09-02 19:58 ` Andrii Nakryiko
2020-09-01 1:50 ` [PATCH v2 bpf-next 13/14] selftests/bpf: modernize xdp_noinline test w/ skeleton and __noinline Andrii Nakryiko
2020-09-01 1:50 ` [PATCH v2 bpf-next 14/14] selftests/bpf: convert cls_redirect selftest to use __noinline Andrii Nakryiko
2020-09-02 5:46 ` Alexei Starovoitov
2020-09-02 19:58 ` Andrii Nakryiko
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