[RFC PATCH 09/22] perf bpf: collect map definitions.

Wang Nan
2015-04-30T10:53:50Z

If maps are used by eBPF programs, corresponding object file(s) should
contain a section named 'map'. Which contains map definitions, one for
each map to describe its format. 'struct perf_bpf_map_def' is
introduced as part of protocol between perf and eBPF programs. All map
definitions are copied to obj->maps.

bpf.h is introduced for common bpf operations.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
tools/perf/util/bpf-loader.c | 31 +++++++++++++++++++++++++++++++
tools/perf/util/bpf-loader.h | 3 +++
2 files changed, 34 insertions(+)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 296fb06..bf3b793 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -65,6 +65,8 @@ static void bpf_obj_close(struct bpf_obj *obj)

if (obj->path)
free(obj->path);
+ if (obj->maps)
+ free(obj->maps);
free(obj);
}

@@ -183,6 +185,32 @@ static int bpf_obj_kver_init(struct bpf_obj *obj,
return 0;
}

+static int bpf_obj_maps_init(struct bpf_obj *obj, void *data,
+ size_t size)
+{
+ size_t map_def_sz = sizeof(struct bpf_map_def);
+ int nr_maps = size / map_def_sz;
+
+ if (nr_maps == 0) {
+ pr_debug("bpf: %s doesn't need map definition\n",
+ obj->path);
+ return 0;
+ }
+
+ obj->maps = malloc(nr_maps * map_def_sz);
+ if (!obj->maps) {
+ pr_err("bpf: malloc maps failed: %s\n", obj->path);
+ return -ENOMEM;
+ }
+
+ obj->nr_maps = nr_maps;
+ memcpy(obj->maps, data, nr_maps * map_def_sz);
+ pr_debug("bpf: %d map%s in %s\n", nr_maps,
+ nr_maps > 1 ? "s" : "",
+ obj->path);
+ return 0;
+}
+
static int bpf_obj_elf_collect(struct bpf_obj *obj)
{
Elf *elf = obj->elf.elf;
@@ -237,6 +265,9 @@ static int bpf_obj_elf_collect(struct bpf_obj *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;
}
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index e1d5c42..6c5c8d6 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -14,6 +14,7 @@
#include "perf.h"
#include "symbol.h"
#include "probe-event.h"
+#include "bpf.h"

int bpf__load(const char *path);
int bpf__run(void);
@@ -25,6 +26,8 @@ struct bpf_obj {
bool needs_swap;
char license[64];
u32 kern_version;
+ struct bpf_map_def *maps;
+ size_t nr_maps;

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