Commit 6c956392 authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo

bpf tools: Read eBPF object from buffer

To support dynamic compiling, this patch allows caller to pass a
in-memory buffer to libbpf by bpf_object__open_buffer(). libbpf calls
elf_memory() to open it as ELF object file.

Because __bpf_object__open() collects all required data and won't need
that buffer anymore, libbpf uses that buffer directly instead of clone a
new buffer. Caller of libbpf can free that buffer or use it do other
things after bpf_object__open_buffer() return.
Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Acked-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1435716878-189507-7-git-send-email-wangnan0@huawei.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 1a5e3fb1
......@@ -84,6 +84,8 @@ struct bpf_object {
*/
struct {
int fd;
void *obj_buf;
size_t obj_buf_sz;
Elf *elf;
GElf_Ehdr ehdr;
} efile;
......@@ -91,7 +93,9 @@ struct bpf_object {
};
#define obj_elf_valid(o) ((o)->efile.elf)
static struct bpf_object *bpf_object__new(const char *path)
static struct bpf_object *bpf_object__new(const char *path,
void *obj_buf,
size_t obj_buf_sz)
{
struct bpf_object *obj;
......@@ -103,6 +107,16 @@ static struct bpf_object *bpf_object__new(const char *path)
strcpy(obj->path, path);
obj->efile.fd = -1;
/*
* Caller of this function should also calls
* bpf_object__elf_finish() after data collection to return
* obj_buf to user. If not, we should duplicate the buffer to
* avoid user freeing them before elf finish.
*/
obj->efile.obj_buf = obj_buf;
obj->efile.obj_buf_sz = obj_buf_sz;
return obj;
}
......@@ -116,6 +130,8 @@ static void bpf_object__elf_finish(struct bpf_object *obj)
obj->efile.elf = NULL;
}
zclose(obj->efile.fd);
obj->efile.obj_buf = NULL;
obj->efile.obj_buf_sz = 0;
}
static int bpf_object__elf_init(struct bpf_object *obj)
......@@ -128,16 +144,26 @@ static int bpf_object__elf_init(struct bpf_object *obj)
return -EEXIST;
}
obj->efile.fd = open(obj->path, O_RDONLY);
if (obj->efile.fd < 0) {
pr_warning("failed to open %s: %s\n", obj->path,
strerror(errno));
return -errno;
if (obj->efile.obj_buf_sz > 0) {
/*
* obj_buf should have been validated by
* bpf_object__open_buffer().
*/
obj->efile.elf = elf_memory(obj->efile.obj_buf,
obj->efile.obj_buf_sz);
} else {
obj->efile.fd = open(obj->path, O_RDONLY);
if (obj->efile.fd < 0) {
pr_warning("failed to open %s: %s\n", obj->path,
strerror(errno));
return -errno;
}
obj->efile.elf = elf_begin(obj->efile.fd,
LIBBPF_ELF_C_READ_MMAP,
NULL);
}
obj->efile.elf = elf_begin(obj->efile.fd,
LIBBPF_ELF_C_READ_MMAP,
NULL);
if (!obj->efile.elf) {
pr_warning("failed to open %s as ELF file\n",
obj->path);
......@@ -167,7 +193,7 @@ static int bpf_object__elf_init(struct bpf_object *obj)
}
static struct bpf_object *
__bpf_object__open(const char *path)
__bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz)
{
struct bpf_object *obj;
......@@ -176,7 +202,7 @@ __bpf_object__open(const char *path)
return NULL;
}
obj = bpf_object__new(path);
obj = bpf_object__new(path, obj_buf, obj_buf_sz);
if (!obj)
return NULL;
......@@ -198,7 +224,19 @@ struct bpf_object *bpf_object__open(const char *path)
pr_debug("loading %s\n", path);
return __bpf_object__open(path);
return __bpf_object__open(path, NULL, 0);
}
struct bpf_object *bpf_object__open_buffer(void *obj_buf,
size_t obj_buf_sz)
{
/* param validation */
if (!obj_buf || obj_buf_sz <= 0)
return NULL;
pr_debug("loading object from buffer\n");
return __bpf_object__open("[buffer]", obj_buf, obj_buf_sz);
}
void bpf_object__close(struct bpf_object *obj)
......
......@@ -26,6 +26,8 @@ void libbpf_set_print(libbpf_print_fn_t warn,
struct bpf_object;
struct bpf_object *bpf_object__open(const char *path);
struct bpf_object *bpf_object__open_buffer(void *obj_buf,
size_t obj_buf_sz);
void bpf_object__close(struct bpf_object *object);
#endif
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