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Commit a5b8bd47 authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
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bpf tools: Collect eBPF programs from their own sections 



This patch collects all programs in an object file into an array of
'struct bpf_program' for further processing. That structure is for
representing each eBPF program. 'bpf_prog' should be a better name, but
it has been used by linux/filter.h. Although it is a kernel space name,
I still prefer to call it 'bpf_program' to prevent possible confusion.

bpf_object__add_program() creates a new 'struct bpf_program' object.
It first init a variable in stack using bpf_program__init(), then if
success, enlarges obj->programs array and copy the new object in.

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/1435716878-189507-13-git-send-email-wangnan0@huawei.com


[ Made bpf_object__add_program() propagate the error (-EINVAL or -ENOMEM) ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent bec7d68c

tools/lib/bpf/libbpf.c

+114 −0
Original line number Diff line number Diff line
@@ -78,12 +78,27 @@ void libbpf_set_print(libbpf_print_fn_t warn, 
# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ

#endif



/*

 * bpf_prog should be a better name but it has been used in

 * linux/filter.h.

 */

struct bpf_program {

	/* Index in elf obj file, for relocation use. */

	int idx;

	char *section_name;

	struct bpf_insn *insns;

	size_t insns_cnt;

};



struct bpf_object {

	char license[64];

	u32 kern_version;

	void *maps_buf;

	size_t maps_buf_sz;



	struct bpf_program *programs;

	size_t nr_programs;



	/*

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

	 * is valid.
@@ -100,6 +115,85 @@ struct bpf_object { 
};

#define obj_elf_valid(o)	((o)->efile.elf)



static void bpf_program__exit(struct bpf_program *prog)

{

	if (!prog)

		return;



	zfree(&prog->section_name);

	zfree(&prog->insns);

	prog->insns_cnt = 0;

	prog->idx = -1;

}



static int

bpf_program__init(void *data, size_t size, char *name, int idx,

		    struct bpf_program *prog)

{

	if (size < sizeof(struct bpf_insn)) {

		pr_warning("corrupted section '%s'\n", name);

		return -EINVAL;

	}



	bzero(prog, sizeof(*prog));



	prog->section_name = strdup(name);

	if (!prog->section_name) {

		pr_warning("failed to alloc name for prog %s\n",

			   name);

		goto errout;

	}



	prog->insns = malloc(size);

	if (!prog->insns) {

		pr_warning("failed to alloc insns for %s\n", name);

		goto errout;

	}

	prog->insns_cnt = size / sizeof(struct bpf_insn);

	memcpy(prog->insns, data,

	       prog->insns_cnt * sizeof(struct bpf_insn));

	prog->idx = idx;



	return 0;

errout:

	bpf_program__exit(prog);

	return -ENOMEM;

}



static int

bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,

			char *name, int idx)

{

	struct bpf_program prog, *progs;

	int nr_progs, err;



	err = bpf_program__init(data, size, name, idx, &prog);

	if (err)

		return err;



	progs = obj->programs;

	nr_progs = obj->nr_programs;



	progs = realloc(progs, sizeof(progs[0]) * (nr_progs + 1));

	if (!progs) {

		/*

		 * In this case the original obj->programs

		 * is still valid, so don't need special treat for

		 * bpf_close_object().

		 */

		pr_warning("failed to alloc a new program '%s'\n",

			   name);

		bpf_program__exit(&prog);

		return -ENOMEM;

	}



	pr_debug("found program %s\n", prog.section_name);

	obj->programs = progs;

	obj->nr_programs = nr_progs + 1;

	progs[nr_progs] = prog;

	return 0;

}



static struct bpf_object *bpf_object__new(const char *path,

					  void *obj_buf,

					  size_t obj_buf_sz)
@@ -342,6 +436,17 @@ static int bpf_object__elf_collect(struct bpf_object *obj) 
				err = -EEXIST;

			} else

				obj->efile.symbols = data;

		} else if ((sh.sh_type == SHT_PROGBITS) &&

			   (sh.sh_flags & SHF_EXECINSTR) &&

			   (data->d_size > 0)) {

			err = bpf_object__add_program(obj, data->d_buf,

						      data->d_size, name, idx);

			if (err) {

				char errmsg[128];

				strerror_r(-err, errmsg, sizeof(errmsg));

				pr_warning("failed to alloc program %s (%s): %s",

					   name, obj->path, errmsg);

			}

		}

		if (err)

			goto out;
@@ -415,11 +520,20 @@ struct bpf_object *bpf_object__open_buffer(void *obj_buf, 


void bpf_object__close(struct bpf_object *obj)

{

	size_t i;



	if (!obj)

		return;



	bpf_object__elf_finish(obj);



	zfree(&obj->maps_buf);



	if (obj->programs && obj->nr_programs) {

		for (i = 0; i < obj->nr_programs; i++)

			bpf_program__exit(&obj->programs[i]);

	}

	zfree(&obj->programs);



	free(obj);

}