diff options
| -rw-r--r-- | tools/bpf/bpftool/gen.c | 127 |
1 files changed, 105 insertions, 22 deletions
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index f8c1413523a3..145734b4fe41 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -209,15 +209,36 @@ static int codegen_datasec_def(struct bpf_object *obj, return 0; } +static const struct btf_type *find_type_for_map(struct btf *btf, const char *map_ident) +{ + int n = btf__type_cnt(btf), i; + char sec_ident[256]; + + for (i = 1; i < n; i++) { + const struct btf_type *t = btf__type_by_id(btf, i); + const char *name; + + if (!btf_is_datasec(t)) + continue; + + name = btf__str_by_offset(btf, t->name_off); + if (!get_datasec_ident(name, sec_ident, sizeof(sec_ident))) + continue; + + if (strcmp(sec_ident, map_ident) == 0) + return t; + } + return NULL; +} + static int codegen_datasecs(struct bpf_object *obj, const char *obj_name) { struct btf *btf = bpf_object__btf(obj); - int n = btf__type_cnt(btf); struct btf_dump *d; struct bpf_map *map; const struct btf_type *sec; - char sec_ident[256], map_ident[256]; - int i, err = 0; + char map_ident[256]; + int err = 0; d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL); err = libbpf_get_error(d); @@ -234,23 +255,7 @@ static int codegen_datasecs(struct bpf_object *obj, const char *obj_name) if (!get_map_ident(map, map_ident, sizeof(map_ident))) continue; - sec = NULL; - for (i = 1; i < n; i++) { - const struct btf_type *t = btf__type_by_id(btf, i); - const char *name; - - if (!btf_is_datasec(t)) - continue; - - name = btf__str_by_offset(btf, t->name_off); - if (!get_datasec_ident(name, sec_ident, sizeof(sec_ident))) - continue; - - if (strcmp(sec_ident, map_ident) == 0) { - sec = t; - break; - } - } + sec = find_type_for_map(btf, map_ident); /* In some cases (e.g., sections like .rodata.cst16 containing * compiler allocated string constants only) there will be @@ -363,6 +368,73 @@ static size_t bpf_map_mmap_sz(const struct bpf_map *map) return map_sz; } +/* Emit type size asserts for all top-level fields in memory-mapped internal maps. */ +static void codegen_asserts(struct bpf_object *obj, const char *obj_name) +{ + struct btf *btf = bpf_object__btf(obj); + struct bpf_map *map; + struct btf_var_secinfo *sec_var; + int i, vlen; + const struct btf_type *sec; + char map_ident[256], var_ident[256]; + + codegen("\ + \n\ + __attribute__((unused)) static void \n\ + %1$s__assert(struct %1$s *s) \n\ + { \n\ + #ifdef __cplusplus \n\ + #define _Static_assert static_assert \n\ + #endif \n\ + ", obj_name); + + bpf_object__for_each_map(map, obj) { + if (!bpf_map__is_internal(map)) + continue; + if (!(bpf_map__map_flags(map) & BPF_F_MMAPABLE)) + continue; + if (!get_map_ident(map, map_ident, sizeof(map_ident))) + continue; + + sec = find_type_for_map(btf, map_ident); + if (!sec) { + /* best effort, couldn't find the type for this map */ + continue; + } + + sec_var = btf_var_secinfos(sec); + vlen = btf_vlen(sec); + + for (i = 0; i < vlen; i++, sec_var++) { + const struct btf_type *var = btf__type_by_id(btf, sec_var->type); + const char *var_name = btf__name_by_offset(btf, var->name_off); + long var_size; + + /* static variables are not exposed through BPF skeleton */ + if (btf_var(var)->linkage == BTF_VAR_STATIC) + continue; + + var_size = btf__resolve_size(btf, var->type); + if (var_size < 0) + continue; + + var_ident[0] = '\0'; + strncat(var_ident, var_name, sizeof(var_ident) - 1); + sanitize_identifier(var_ident); + + printf("\t_Static_assert(sizeof(s->%s->%s) == %ld, \"unexpected size of '%s'\");\n", + map_ident, var_ident, var_size, var_ident); + } + } + codegen("\ + \n\ + #ifdef __cplusplus \n\ + #undef _Static_assert \n\ + #endif \n\ + } \n\ + "); +} + static void codegen_attach_detach(struct bpf_object *obj, const char *obj_name) { struct bpf_program *prog; @@ -639,8 +711,11 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h } \n\ return skel; \n\ } \n\ + \n\ ", obj_name); + codegen_asserts(obj, obj_name); + codegen("\ \n\ \n\ @@ -1046,9 +1121,17 @@ static int do_skeleton(int argc, char **argv) const void *%1$s::elf_bytes(size_t *sz) { return %1$s__elf_bytes(sz); } \n\ #endif /* __cplusplus */ \n\ \n\ - #endif /* %2$s */ \n\ ", - obj_name, header_guard); + obj_name); + + codegen_asserts(obj, obj_name); + + codegen("\ + \n\ + \n\ + #endif /* %1$s */ \n\ + ", + header_guard); err = 0; out: bpf_object__close(obj); |