[RFC PATCH v3 13/37] bpf tools: Collect map definitions from 'maps' section

Wang Nan
2015-05-17T11:04:15Z

If maps are used by eBPF programs, corresponding object file(s) should
contain a section named 'map'. Which contains map definitions. This
patch copies the data of the whole section. Map data parsing should be
acted just before map loading.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
tools/lib/bpf/libbpf.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b26f1ee..6ee5f3c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -82,6 +82,8 @@ struct bpf_object {
bool needs_swap;
char license[64];
u32 kern_version;
+ void *maps_buf;
+ size_t maps_buf_sz;

/*
* Information when doing elf related work. Only valid if fd
@@ -244,6 +246,27 @@ static int bpf_obj_kver_init(struct bpf_object *obj,
return 0;
}

+static int bpf_obj_maps_init(struct bpf_object *obj, void *data,
+ size_t size)
+{
+ if (size == 0) {
+ pr_debug("%s doesn't need map definition\n",
+ obj->path);
+ return 0;
+ }
+
+ obj->maps_buf = malloc(size);
+ if (!obj->maps_buf) {
+ pr_warning("malloc maps failed: %s\n", obj->path);
+ return -ENOMEM;
+ }
+
+ obj->maps_buf_sz = size;
+ memcpy(obj->maps_buf, data, size);
+ pr_debug("maps in %s: %ld bytes\n", obj->path, (long)size);
+ return 0;
+}
+
static int bpf_obj_elf_collect(struct bpf_object *obj)
{
Elf *elf = obj->elf.elf;
@@ -298,6 +321,9 @@ static int bpf_obj_elf_collect(struct bpf_object *obj)
else if (strcmp(name, "version") == 0)
err = bpf_obj_kver_init(obj, data->d_buf,
data->d_size);
+ else if (strcmp(name, "maps") == 0)
+ err = bpf_obj_maps_init(obj, data->d_buf,
+ data->d_size);
if (err)
goto out;
}
@@ -359,5 +385,7 @@ void bpf_close_object(struct bpf_object *obj)

if (obj->path)
free(obj->path);
+ if (obj->maps_buf)
+ free(obj->maps_buf);
free(obj);
}
--
1.8.3.4