[RFC PATCH 08/22] perf bpf: collect version and license from ELF.

Wang Nan
2015-04-30T10:53:44Z

Expand bpf_obj_elf_collect() to let it collect license and kernel
version information in eBPF object files. eBPF object file should have
a section named 'license', which contains a string. It should also
have a section named 'version', contains a u32 LINUX_VERSION_CODE.

bpf_obj_validate() is introduced to validate object file after loaded.
Currently it only check existance of 'version' section.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
tools/perf/util/bpf-loader.c | 47 ++++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/bpf-loader.h | 2 ++
2 files changed, 49 insertions(+)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 9c077dd..296fb06 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -157,6 +157,32 @@ bpf_obj_swap_init(struct bpf_obj *obj)
}
}

+static int bpf_obj_license_init(struct bpf_obj *obj,
+ void *data, size_t size)
+{
+ memcpy(obj->license, data,
+ min(size, sizeof(obj->license) - 1));
+ pr_debug("bpf: license of %s is %s\n", obj->path, obj->license);
+ return 0;
+}
+
+static int bpf_obj_kver_init(struct bpf_obj *obj,
+ void *data, size_t size)
+{
+ u32 kver;
+ if (size < sizeof(kver)) {
+ pr_err("bpf: invalid kver section in %s\n", obj->path);
+ return -EINVAL;
+ }
+ memcpy(&kver, data, sizeof(kver));
+ if (obj->needs_swap)
+ kver = bswap_32(kver);
+ obj->kern_version = kver;
+ pr_debug("bpf: kernel version of %s is %x\n", obj->path,
+ obj->kern_version);
+ return 0;
+}
+
static int bpf_obj_elf_collect(struct bpf_obj *obj)
{
Elf *elf = obj->elf.elf;
@@ -204,11 +230,30 @@ static int bpf_obj_elf_collect(struct bpf_obj *obj)
(int)sh.sh_link,
(unsigned long)sh.sh_flags,
(int)sh.sh_type);
+
+ if (strcmp(name, "license") == 0)
+ err = bpf_obj_license_init(obj, data->d_buf,
+ data->d_size);
+ else if (strcmp(name, "version") == 0)
+ err = bpf_obj_kver_init(obj, data->d_buf,
+ data->d_size);
+ if (err)
+ goto out;
}
out:
return err;
}

+static int bpf_obj_validate(struct bpf_obj *obj)
+{
+ if (obj->kern_version == 0) {
+ pr_err("bpf: %s doesn't provide kernel version\n",
+ obj->path);
+ return -EINVAL;
+ }
+ return 0;
+}
+
int bpf__load(const char *path)
{
struct bpf_obj *obj;
@@ -233,6 +278,8 @@ int bpf__load(const char *path)
goto out;
if ((err = bpf_obj_elf_collect(obj)))
goto out;
+ if ((err = bpf_obj_validate(obj)))
+ goto out;

list_add(&obj->list, &bpf_obj_list);
return 0;
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index c27b0ac..e1d5c42 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -23,6 +23,8 @@ struct bpf_obj {
struct list_head list;
char *path;
bool needs_swap;
+ char license[64];
+ u32 kern_version;

/*
* Information when doing elf related work. Only valid if fd
--
1.8.3.4