[RFC PATCH v7 09/37] bpf tools: Collect map definitions from 'maps' section

Wang Nan
2015-06-12T05:36:32Z

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>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
---
tools/lib/bpf/libbpf.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3bd183c..3315f00 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -81,6 +81,9 @@ void libbpf_set_print(libbpf_print_fn_t warn,
struct bpf_object {
char license[64];
u32 kern_version;
+ void *maps_buf;
+ size_t maps_buf_sz;
+
/*
* Information when doing elf related work. Only valid if fd
* is valid.
@@ -249,6 +252,28 @@ bpf_object__init_kversion(struct bpf_object *obj,
return 0;
}

+static int
+bpf_object__init_maps(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_object__elf_collect(struct bpf_object *obj)
{
Elf *elf = obj->efile.elf;
@@ -304,6 +329,9 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
err = bpf_object__init_kversion(obj,
data->d_buf,
data->d_size);
+ else if (strcmp(name, "maps") == 0)
+ err = bpf_object__init_maps(obj, data->d_buf,
+ data->d_size);
if (err)
goto out;
}
@@ -381,5 +409,6 @@ void bpf_object__close(struct bpf_object *obj)

bpf_object__elf_finish(obj);

+ zfree(&obj->maps_buf);
free(obj);
}
--
1.8.3.4