From: Alexei Starovoitov <ast@xxxxxxxxxx>
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@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 43 ++++++++++++++++++++++++++++++-----
tools/lib/bpf/libbpf_probes.c | 7 ++++++
2 files changed, 44 insertions(+), 6 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 01f407591a92..4880d623098d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -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[] = {
@@ -1577,7 +1578,7 @@ 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 __bpf_map_mmap_sz(unsigned int value_sz, unsigned int max_entries)
{
const long page_sz = sysconf(_SC_PAGE_SIZE);
size_t map_sz;
@@ -1587,6 +1588,20 @@ 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 __bpf_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;
@@ -1740,7 +1755,7 @@ 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) {
@@ -4852,6 +4867,7 @@ 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;
@@ -4908,6 +4924,21 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
if (map->fd == map_fd)
return 0;
+ if (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;
+ close(map_fd);
+ pr_warn("map '%s': failed to mmap bpf_arena: %d\n",
+ bpf_map__name(map), err);
+ return err;
+ }
+ }
+
/* Keep placeholder FD value but now point it to the BPF map object.
* This way everything that relied on this map's FD (e.g., relocated
* ldimm64 instructions) will stay valid and won't need adjustments.
@@ -8582,7 +8613,7 @@ 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;
}
@@ -9830,8 +9861,8 @@ int bpf_map__set_value_size(struct bpf_map *map, __u32 size)
int err;
size_t mmap_old_sz, mmap_new_sz;
- 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);
+ mmap_old_sz = bpf_map_mmap_sz(map);
+ mmap_new_sz = __bpf_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",
@@ -13356,7 +13387,7 @@ 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;
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index ee9b1dbea9eb..302188122439 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -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:
--
2.34.1
