[RFC PATCH 07/22] perf bpf: iterater over elf sections to collect information.

Wang Nan
2015-04-30T11:01:59Z

bpf_obj_elf_collect() is introduced to iterate over each elf sections
to collection informations in eBPF object files. This function will
futher enhanced to collect license, kernel version, programs, configs
and map information.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
tools/perf/util/bpf-loader.c | 54 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 54 insertions(+)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 14d76f6..9c077dd 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -157,6 +157,58 @@ bpf_obj_swap_init(struct bpf_obj *obj)
}
}

+static int bpf_obj_elf_collect(struct bpf_obj *obj)
+{
+ Elf *elf = obj->elf.elf;
+ GElf_Ehdr *ep = &obj->elf.ehdr;
+ Elf_Scn *scn = NULL;
+ int idx = 0, err = 0;
+
+ /* Elf is corrupted/truncated, avoid calling elf_strptr. */
+ if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) {
+ pr_err("bpf: failed to get e_shstrndx from %s\n",
+ obj->path);
+ return -EINVAL;
+ }
+
+ while ((scn = elf_nextscn(elf, scn)) != NULL) {
+ char *name;
+ GElf_Shdr sh;
+ Elf_Data *data;
+
+ idx++;
+ if (gelf_getshdr(scn, &sh) != &sh) {
+ pr_err("bpf: failed to get section header"
+ " from %s\n", obj->path);
+ err = -EINVAL;
+ goto out;
+ }
+
+ name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
+ if (!name) {
+ pr_err("bpf: failed to get section name "
+ "from %s\n", obj->path);
+ err = -EINVAL;
+ goto out;
+ }
+
+ data = elf_getdata(scn, 0);
+ if (!data) {
+ pr_err("bpf: failed to get section data "
+ "from %s(%s)\n", name, obj->path);
+ err = -EINVAL;
+ goto out;
+ }
+ pr_debug("bpf: section %s, size %ld, link %d, flags %lx, type=%d\n",
+ name,(unsigned long)data->d_size,
+ (int)sh.sh_link,
+ (unsigned long)sh.sh_flags,
+ (int)sh.sh_type);
+ }
+out:
+ return err;
+}
+
int bpf__load(const char *path)
{
struct bpf_obj *obj;
@@ -179,6 +231,8 @@ int bpf__load(const char *path)
goto out;
if ((err = bpf_obj_swap_init(obj)))
goto out;
+ if ((err = bpf_obj_elf_collect(obj)))
+ goto out;

list_add(&obj->list, &bpf_obj_list);
return 0;
--
1.8.3.4