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libbpf: Add per-file linker opts

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For better future extensibility add per-file linker options. Currently
the set of available options is empty. This changes bpf_linker__add_file()
API, but it's not a breaking change as bpf_linker APIs hasn't been released
yet.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210507054119.270888-3-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2021-05-06 22:41:14 -07:00 committed by Alexei Starovoitov
parent 37f05601ea
commit fdbf5ddeb8
3 changed files with 22 additions and 6 deletions
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2
tools/bpf/bpftool/gen.c
View File

@ -638,7 +638,7 @@ static int do_object(int argc, char **argv)
while (argc) {
file = GET_ARG();
err = bpf_linker__add_file(linker, file);
err = bpf_linker__add_file(linker, file, NULL);
if (err) {
p_err("failed to link '%s': %s (%d)", file, strerror(err), err);
goto out;

10
tools/lib/bpf/libbpf.h
View File

@ -768,10 +768,18 @@ struct bpf_linker_opts {
};
#define bpf_linker_opts__last_field sz
struct bpf_linker_file_opts {
/* size of this struct, for forward/backward compatiblity */
size_t sz;
};
#define bpf_linker_file_opts__last_field sz
struct bpf_linker;
LIBBPF_API struct bpf_linker *bpf_linker__new(const char *filename, struct bpf_linker_opts *opts);
LIBBPF_API int bpf_linker__add_file(struct bpf_linker *linker, const char *filename);
LIBBPF_API int bpf_linker__add_file(struct bpf_linker *linker,
const char *filename,
const struct bpf_linker_file_opts *opts);
LIBBPF_API int bpf_linker__finalize(struct bpf_linker *linker);
LIBBPF_API void bpf_linker__free(struct bpf_linker *linker);

16
tools/lib/bpf/linker.c
View File

@ -158,7 +158,9 @@ struct bpf_linker {
static int init_output_elf(struct bpf_linker *linker, const char *file);
static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, struct src_obj *obj);
static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
const struct bpf_linker_file_opts *opts,
struct src_obj *obj);
static int linker_sanity_check_elf(struct src_obj *obj);
static int linker_sanity_check_elf_symtab(struct src_obj *obj, struct src_sec *sec);
static int linker_sanity_check_elf_relos(struct src_obj *obj, struct src_sec *sec);
@ -435,15 +437,19 @@ static int init_output_elf(struct bpf_linker *linker, const char *file)
return 0;
}
int bpf_linker__add_file(struct bpf_linker *linker, const char *filename)
int bpf_linker__add_file(struct bpf_linker *linker, const char *filename,
const struct bpf_linker_file_opts *opts)
{
struct src_obj obj = {};
int err = 0;
if (!OPTS_VALID(opts, bpf_linker_file_opts))
return -EINVAL;
if (!linker->elf)
return -EINVAL;
err = err ?: linker_load_obj_file(linker, filename, &obj);
err = err ?: linker_load_obj_file(linker, filename, opts, &obj);
err = err ?: linker_append_sec_data(linker, &obj);
err = err ?: linker_append_elf_syms(linker, &obj);
err = err ?: linker_append_elf_relos(linker, &obj);
@ -529,7 +535,9 @@ static struct src_sec *add_src_sec(struct src_obj *obj, const char *sec_name)
return sec;
}
static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, struct src_obj *obj)
static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
const struct bpf_linker_file_opts *opts,
struct src_obj *obj)
{
#if __BYTE_ORDER == __LITTLE_ENDIAN
const int host_endianness = ELFDATA2LSB;