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.
Use traditional map->value_size * map->max_entries to calculate mmap sz,
though it's not the best fit.
Also don't set BTF at bpf_arena creation time, since it doesn't support it.
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 18 ++++++++++++++++++
tools/lib/bpf/libbpf_probes.c | 6 ++++++
2 files changed, 24 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 01f407591a92..c5ce5946dc6d 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[] = {
@@ -4852,6 +4853,7 @@ 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 +4910,22 @@ 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) {
+ size_t mmap_sz;
+
+ mmap_sz = bpf_map_mmap_sz(def->value_size, def->max_entries);
+ map->mmaped = mmap((void *)map->map_extra, mmap_sz, 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 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.
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index ee9b1dbea9eb..cbc7f4c09060 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -338,6 +338,12 @@ 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 = sizeof(__u64);
+ value_size = sizeof(__u64);
+ 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
