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tools lib bpf: Collect map definition in bpf_object
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This patch collects more information from maps sections in BPF object
files into 'struct bpf_object', enables later patches access those
information (such as the type and size of the map).

In this patch, a new handler 'struct bpf_map' is extracted in parallel
with bpf_object and bpf_program. Its iterator and accessor is also
created.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1448614067-197576-2-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Wang Nan authored and Arnaldo Carvalho de Melo committed Nov 28, 2015
1 parent 0390504 commit 9d759a9
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Showing 2 changed files with 148 additions and 60 deletions.
187 changes: 127 additions & 60 deletions tools/lib/bpf/libbpf.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -163,22 +163,24 @@ struct bpf_program {
bpf_program_clear_priv_t clear_priv;
};

struct bpf_map {
int fd;
struct bpf_map_def def;
void *priv;
bpf_map_clear_priv_t clear_priv;
};

static LIST_HEAD(bpf_objects_list);

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;
int *map_fds;
/*
* This field is required because maps_buf will be freed and
* maps_buf_sz will be set to 0 after loaded.
*/
size_t nr_map_fds;
struct bpf_map *maps;
size_t nr_maps;

bool loaded;

/*
Expand Down Expand Up @@ -489,21 +491,38 @@ static int
bpf_object__init_maps(struct bpf_object *obj, void *data,
size_t size)
{
if (size == 0) {
size_t nr_maps;
int i;

nr_maps = size / sizeof(struct bpf_map_def);
if (!data || !nr_maps) {
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);
pr_debug("maps in %s: %zd bytes\n", obj->path, size);

obj->maps = calloc(nr_maps, sizeof(obj->maps[0]));
if (!obj->maps) {
pr_warning("alloc maps for object failed\n");
return -ENOMEM;
}
obj->nr_maps = nr_maps;

for (i = 0; i < nr_maps; i++) {
struct bpf_map_def *def = &obj->maps[i].def;

obj->maps_buf_sz = size;
memcpy(obj->maps_buf, data, size);
pr_debug("maps in %s: %ld bytes\n", obj->path, (long)size);
/*
* fill all fd with -1 so won't close incorrect
* fd (fd=0 is stdin) when failure (zclose won't close
* negative fd)).
*/
obj->maps[i].fd = -1;

/* Save map definition into obj->maps */
*def = ((struct bpf_map_def *)data)[i];
}
return 0;
}

Expand Down Expand Up @@ -688,60 +707,33 @@ static int
bpf_object__create_maps(struct bpf_object *obj)
{
unsigned int i;
size_t nr_maps;
int *pfd;

nr_maps = obj->maps_buf_sz / sizeof(struct bpf_map_def);
if (!obj->maps_buf || !nr_maps) {
pr_debug("don't need create maps for %s\n",
obj->path);
return 0;
}

obj->map_fds = malloc(sizeof(int) * nr_maps);
if (!obj->map_fds) {
pr_warning("realloc perf_bpf_map_fds failed\n");
return -ENOMEM;
}
obj->nr_map_fds = nr_maps;

/* fill all fd with -1 */
memset(obj->map_fds, -1, sizeof(int) * nr_maps);
for (i = 0; i < obj->nr_maps; i++) {
struct bpf_map_def *def = &obj->maps[i].def;
int *pfd = &obj->maps[i].fd;

pfd = obj->map_fds;
for (i = 0; i < nr_maps; i++) {
struct bpf_map_def def;

def = *(struct bpf_map_def *)(obj->maps_buf +
i * sizeof(struct bpf_map_def));

*pfd = bpf_create_map(def.type,
def.key_size,
def.value_size,
def.max_entries);
*pfd = bpf_create_map(def->type,
def->key_size,
def->value_size,
def->max_entries);
if (*pfd < 0) {
size_t j;
int err = *pfd;

pr_warning("failed to create map: %s\n",
strerror(errno));
for (j = 0; j < i; j++)
zclose(obj->map_fds[j]);
obj->nr_map_fds = 0;
zfree(&obj->map_fds);
zclose(obj->maps[j].fd);
return err;
}
pr_debug("create map: fd=%d\n", *pfd);
pfd++;
}

zfree(&obj->maps_buf);
obj->maps_buf_sz = 0;
return 0;
}

static int
bpf_program__relocate(struct bpf_program *prog, int *map_fds)
bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
{
int i;

Expand All @@ -761,7 +753,7 @@ bpf_program__relocate(struct bpf_program *prog, int *map_fds)
return -LIBBPF_ERRNO__RELOC;
}
insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
insns[insn_idx].imm = map_fds[map_idx];
insns[insn_idx].imm = obj->maps[map_idx].fd;
}

zfree(&prog->reloc_desc);
Expand All @@ -780,7 +772,7 @@ bpf_object__relocate(struct bpf_object *obj)
for (i = 0; i < obj->nr_programs; i++) {
prog = &obj->programs[i];

err = bpf_program__relocate(prog, obj->map_fds);
err = bpf_program__relocate(prog, obj);
if (err) {
pr_warning("failed to relocate '%s'\n",
prog->section_name);
Expand All @@ -804,8 +796,7 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
Elf_Data *data = obj->efile.reloc[i].data;
int idx = shdr->sh_info;
struct bpf_program *prog;
size_t nr_maps = obj->maps_buf_sz /
sizeof(struct bpf_map_def);
size_t nr_maps = obj->nr_maps;

if (shdr->sh_type != SHT_REL) {
pr_warning("internal error at %d\n", __LINE__);
Expand Down Expand Up @@ -1050,10 +1041,8 @@ int bpf_object__unload(struct bpf_object *obj)
if (!obj)
return -EINVAL;

for (i = 0; i < obj->nr_map_fds; i++)
zclose(obj->map_fds[i]);
zfree(&obj->map_fds);
obj->nr_map_fds = 0;
for (i = 0; i < obj->nr_maps; i++)
zclose(obj->maps[i].fd);

for (i = 0; i < obj->nr_programs; i++)
bpf_program__unload(&obj->programs[i]);
Expand Down Expand Up @@ -1096,7 +1085,15 @@ void bpf_object__close(struct bpf_object *obj)
bpf_object__elf_finish(obj);
bpf_object__unload(obj);

zfree(&obj->maps_buf);
for (i = 0; i < obj->nr_maps; i++) {
if (obj->maps[i].clear_priv)
obj->maps[i].clear_priv(&obj->maps[i],
obj->maps[i].priv);
obj->maps[i].priv = NULL;
obj->maps[i].clear_priv = NULL;
}
zfree(&obj->maps);
obj->nr_maps = 0;

if (obj->programs && obj->nr_programs) {
for (i = 0; i < obj->nr_programs; i++)
Expand Down Expand Up @@ -1251,3 +1248,73 @@ int bpf_program__nth_fd(struct bpf_program *prog, int n)

return fd;
}

int bpf_map__get_fd(struct bpf_map *map)
{
if (!map)
return -EINVAL;

return map->fd;
}

int bpf_map__get_def(struct bpf_map *map, struct bpf_map_def *pdef)
{
if (!map || !pdef)
return -EINVAL;

*pdef = map->def;
return 0;
}

int bpf_map__set_private(struct bpf_map *map, void *priv,
bpf_map_clear_priv_t clear_priv)
{
if (!map)
return -EINVAL;

if (map->priv) {
if (map->clear_priv)
map->clear_priv(map, map->priv);
}

map->priv = priv;
map->clear_priv = clear_priv;
return 0;
}

int bpf_map__get_private(struct bpf_map *map, void **ppriv)
{
if (!map)
return -EINVAL;

if (ppriv)
*ppriv = map->priv;
return 0;
}

struct bpf_map *
bpf_map__next(struct bpf_map *prev, struct bpf_object *obj)
{
size_t idx;
struct bpf_map *s, *e;

if (!obj || !obj->maps)
return NULL;

s = obj->maps;
e = obj->maps + obj->nr_maps;

if (prev == NULL)
return s;

if ((prev < s) || (prev >= e)) {
pr_warning("error in %s: map handler doesn't belong to object\n",
__func__);
return NULL;
}

idx = (prev - obj->maps) + 1;
if (idx >= obj->nr_maps)
return NULL;
return &obj->maps[idx];
}
21 changes: 21 additions & 0 deletions tools/lib/bpf/libbpf.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -165,4 +165,25 @@ struct bpf_map_def {
unsigned int max_entries;
};

/*
* There is another 'struct bpf_map' in include/linux/map.h. However,
* it is not a uapi header so no need to consider name clash.
*/
struct bpf_map;

struct bpf_map *
bpf_map__next(struct bpf_map *map, struct bpf_object *obj);
#define bpf_map__for_each(pos, obj) \
for ((pos) = bpf_map__next(NULL, (obj)); \
(pos) != NULL; \
(pos) = bpf_map__next((pos), (obj)))

int bpf_map__get_fd(struct bpf_map *map);
int bpf_map__get_def(struct bpf_map *map, struct bpf_map_def *pdef);

typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);
int bpf_map__set_private(struct bpf_map *map, void *priv,
bpf_map_clear_priv_t clear_priv);
int bpf_map__get_private(struct bpf_map *map, void **ppriv);

#endif

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