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libbpf: Add support for bpf_arena.

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mmap() bpf_arena right after creation, since the kernel needs to
remember the address returned from mmap. This is user_vm_start.
LLVM will generate bpf_arena_cast_user() instructions where
necessary and JIT will add upper 32-bit of user_vm_start
to such pointers.

Fix up bpf_map_mmap_sz() to compute mmap size as
map->value_size * map->max_entries for arrays and
PAGE_SIZE * map->max_entries for arena.

Don't set BTF at arena creation time, since it doesn't support it.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240308010812.89848-9-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2024-03-07 17:08:06 -08:00 committed by Andrii Nakryiko
parent 4d2b56081c
commit 79ff13e991
2 changed files with 46 additions and 8 deletions
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47
tools/lib/bpf/libbpf.c
View File

@ -185,6 +185,7 @@ static const char * const map_type_name[] = {
[BPF_MAP_TYPE_BLOOM_FILTER] = "bloom_filter",
[BPF_MAP_TYPE_USER_RINGBUF] = "user_ringbuf",
[BPF_MAP_TYPE_CGRP_STORAGE] = "cgrp_storage",
[BPF_MAP_TYPE_ARENA] = "arena",
};
static const char * const prog_type_name[] = {
@ -1684,7 +1685,7 @@ static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
return map;
}
static size_t bpf_map_mmap_sz(unsigned int value_sz, unsigned int max_entries)
static size_t array_map_mmap_sz(unsigned int value_sz, unsigned int max_entries)
{
const long page_sz = sysconf(_SC_PAGE_SIZE);
size_t map_sz;
@ -1694,6 +1695,20 @@ static size_t bpf_map_mmap_sz(unsigned int value_sz, unsigned int max_entries)
return map_sz;
}
static size_t bpf_map_mmap_sz(const struct bpf_map *map)
{
const long page_sz = sysconf(_SC_PAGE_SIZE);
switch (map->def.type) {
case BPF_MAP_TYPE_ARRAY:
return array_map_mmap_sz(map->def.value_size, map->def.max_entries);
case BPF_MAP_TYPE_ARENA:
return page_sz * map->def.max_entries;
default:
return 0; /* not supported */
}
}
static int bpf_map_mmap_resize(struct bpf_map *map, size_t old_sz, size_t new_sz)
{
void *mmaped;
@ -1847,7 +1862,7 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %x.\n",
map->name, map->sec_idx, map->sec_offset, def->map_flags);
mmap_sz = bpf_map_mmap_sz(map->def.value_size, map->def.max_entries);
mmap_sz = bpf_map_mmap_sz(map);
map->mmaped = mmap(NULL, mmap_sz, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (map->mmaped == MAP_FAILED) {
@ -5017,6 +5032,7 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
case BPF_MAP_TYPE_SOCKHASH:
case BPF_MAP_TYPE_QUEUE:
case BPF_MAP_TYPE_STACK:
case BPF_MAP_TYPE_ARENA:
create_attr.btf_fd = 0;
create_attr.btf_key_type_id = 0;
create_attr.btf_value_type_id = 0;
@ -5261,7 +5277,19 @@ retry:
if (err < 0)
goto err_out;
}
if (map->def.type == BPF_MAP_TYPE_ARENA) {
map->mmaped = mmap((void *)map->map_extra, bpf_map_mmap_sz(map),
PROT_READ | PROT_WRITE,
map->map_extra ? MAP_SHARED | MAP_FIXED : MAP_SHARED,
map->fd, 0);
if (map->mmaped == MAP_FAILED) {
err = -errno;
map->mmaped = NULL;
pr_warn("map '%s': failed to mmap arena: %d\n",
map->name, err);
return err;
}
}
if (map->init_slots_sz && map->def.type != BPF_MAP_TYPE_PROG_ARRAY) {
err = init_map_in_map_slots(obj, map);
if (err < 0)
@ -8761,7 +8789,7 @@ static void bpf_map__destroy(struct bpf_map *map)
if (map->mmaped) {
size_t mmap_sz;
mmap_sz = bpf_map_mmap_sz(map->def.value_size, map->def.max_entries);
mmap_sz = bpf_map_mmap_sz(map);
munmap(map->mmaped, mmap_sz);
map->mmaped = NULL;
}
@ -9995,11 +10023,14 @@ int bpf_map__set_value_size(struct bpf_map *map, __u32 size)
return libbpf_err(-EBUSY);
if (map->mmaped) {
int err;
size_t mmap_old_sz, mmap_new_sz;
int err;
mmap_old_sz = bpf_map_mmap_sz(map->def.value_size, map->def.max_entries);
mmap_new_sz = bpf_map_mmap_sz(size, map->def.max_entries);
if (map->def.type != BPF_MAP_TYPE_ARRAY)
return -EOPNOTSUPP;
mmap_old_sz = bpf_map_mmap_sz(map);
mmap_new_sz = array_map_mmap_sz(size, map->def.max_entries);
err = bpf_map_mmap_resize(map, mmap_old_sz, mmap_new_sz);
if (err) {
pr_warn("map '%s': failed to resize memory-mapped region: %d\n",
@ -13530,7 +13561,7 @@ int bpf_object__load_skeleton(struct bpf_object_skeleton *s)
for (i = 0; i < s->map_cnt; i++) {
struct bpf_map *map = *s->maps[i].map;
size_t mmap_sz = bpf_map_mmap_sz(map->def.value_size, map->def.max_entries);
size_t mmap_sz = bpf_map_mmap_sz(map);
int prot, map_fd = map->fd;
void **mmaped = s->maps[i].mmaped;

7
tools/lib/bpf/libbpf_probes.c
View File

@ -338,6 +338,13 @@ static int probe_map_create(enum bpf_map_type map_type)
key_size = 0;
max_entries = 1;
break;
case BPF_MAP_TYPE_ARENA:
key_size = 0;
value_size = 0;
max_entries = 1; /* one page */
opts.map_extra = 0; /* can mmap() at any address */
opts.map_flags = BPF_F_MMAPABLE;
break;
case BPF_MAP_TYPE_HASH:
case BPF_MAP_TYPE_ARRAY:
case BPF_MAP_TYPE_PROG_ARRAY: