diff options
| author | Andrii Nakryiko <andriin@fb.com> | 2019-11-17 09:28:05 -0800 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-11-18 11:41:59 +0100 |
| commit | 7fe74b436236b17ac57e46527166d22bcc230175 (patch) | |
| tree | 7caa1d7e4c28ee1b925410be13da037eaee7d902 /tools | |
| parent | fc9702273e2edb90400a34b3be76f7b08fa3344b (diff) | |
| download | linux-7fe74b436236b17ac57e46527166d22bcc230175.tar.bz2 | |
libbpf: Make global data internal arrays mmap()-able, if possible
Add detection of BPF_F_MMAPABLE flag support for arrays and add it as an extra
flag to internal global data maps, if supported by kernel. This allows users
to memory-map global data and use it without BPF map operations, greatly
simplifying user experience.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20191117172806.2195367-5-andriin@fb.com
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/lib/bpf/libbpf.c | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 7132c6bdec02..15e91a1d6c11 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -142,6 +142,8 @@ struct bpf_capabilities { __u32 btf_func:1; /* BTF_KIND_VAR and BTF_KIND_DATASEC support */ __u32 btf_datasec:1; + /* BPF_F_MMAPABLE is supported for arrays */ + __u32 array_mmap:1; }; /* @@ -857,8 +859,6 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type, pr_warn("failed to alloc map name\n"); return -ENOMEM; } - pr_debug("map '%s' (global data): at sec_idx %d, offset %zu.\n", - map_name, map->sec_idx, map->sec_offset); def = &map->def; def->type = BPF_MAP_TYPE_ARRAY; @@ -866,6 +866,12 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type, def->value_size = data->d_size; def->max_entries = 1; def->map_flags = type == LIBBPF_MAP_RODATA ? BPF_F_RDONLY_PROG : 0; + if (obj->caps.array_mmap) + def->map_flags |= BPF_F_MMAPABLE; + + 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); + if (data_buff) { *data_buff = malloc(data->d_size); if (!*data_buff) { @@ -2161,6 +2167,27 @@ static int bpf_object__probe_btf_datasec(struct bpf_object *obj) return 0; } +static int bpf_object__probe_array_mmap(struct bpf_object *obj) +{ + struct bpf_create_map_attr attr = { + .map_type = BPF_MAP_TYPE_ARRAY, + .map_flags = BPF_F_MMAPABLE, + .key_size = sizeof(int), + .value_size = sizeof(int), + .max_entries = 1, + }; + int fd; + + fd = bpf_create_map_xattr(&attr); + if (fd >= 0) { + obj->caps.array_mmap = 1; + close(fd); + return 1; + } + + return 0; +} + static int bpf_object__probe_caps(struct bpf_object *obj) { @@ -2169,6 +2196,7 @@ bpf_object__probe_caps(struct bpf_object *obj) bpf_object__probe_global_data, bpf_object__probe_btf_func, bpf_object__probe_btf_datasec, + bpf_object__probe_array_mmap, }; int i, ret; |