diff options
| -rw-r--r-- | tools/bpf/bpftool/Documentation/bpftool-gen.rst | 58 | ||||
| -rw-r--r-- | tools/bpf/bpftool/gen.c | 237 | ||||
| -rw-r--r-- | tools/lib/bpf/libbpf.c | 45 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c | 11 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h | 8 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c | 19 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/struct_ops_module.c | 8 |
7 files changed, 372 insertions, 14 deletions
diff --git a/tools/bpf/bpftool/Documentation/bpftool-gen.rst b/tools/bpf/bpftool/Documentation/bpftool-gen.rst index 5006e724d1bc..5e60825818dd 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-gen.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-gen.rst @@ -257,18 +257,48 @@ EXAMPLES return 0; } -This is example BPF application with two BPF programs and a mix of BPF maps -and global variables. Source code is split across two source code files. +**$ cat example3.bpf.c** + +:: + + #include <linux/ptrace.h> + #include <linux/bpf.h> + #include <bpf/bpf_helpers.h> + /* This header file is provided by the bpf_testmod module. */ + #include "bpf_testmod.h" + + int test_2_result = 0; + + /* bpf_Testmod.ko calls this function, passing a "4" + * and testmod_map->data. + */ + SEC("struct_ops/test_2") + void BPF_PROG(test_2, int a, int b) + { + test_2_result = a + b; + } + + SEC(".struct_ops") + struct bpf_testmod_ops testmod_map = { + .test_2 = (void *)test_2, + .data = 0x1, + }; + +This is example BPF application with three BPF programs and a mix of BPF +maps and global variables. Source code is split across three source code +files. **$ clang --target=bpf -g example1.bpf.c -o example1.bpf.o** **$ clang --target=bpf -g example2.bpf.c -o example2.bpf.o** -**$ bpftool gen object example.bpf.o example1.bpf.o example2.bpf.o** +**$ clang --target=bpf -g example3.bpf.c -o example3.bpf.o** + +**$ bpftool gen object example.bpf.o example1.bpf.o example2.bpf.o example3.bpf.o** -This set of commands compiles *example1.bpf.c* and *example2.bpf.c* -individually and then statically links respective object files into the final -BPF ELF object file *example.bpf.o*. +This set of commands compiles *example1.bpf.c*, *example2.bpf.c* and +*example3.bpf.c* individually and then statically links respective object +files into the final BPF ELF object file *example.bpf.o*. **$ bpftool gen skeleton example.bpf.o name example | tee example.skel.h** @@ -291,7 +321,15 @@ BPF ELF object file *example.bpf.o*. struct bpf_map *data; struct bpf_map *bss; struct bpf_map *my_map; + struct bpf_map *testmod_map; } maps; + struct { + struct example__testmod_map__bpf_testmod_ops { + const struct bpf_program *test_1; + const struct bpf_program *test_2; + int data; + } *testmod_map; + } struct_ops; struct { struct bpf_program *handle_sys_enter; struct bpf_program *handle_sys_exit; @@ -304,6 +342,7 @@ BPF ELF object file *example.bpf.o*. struct { int x; } data; + int test_2_result; } *bss; struct example__data { _Bool global_flag; @@ -342,10 +381,16 @@ BPF ELF object file *example.bpf.o*. skel->rodata->param1 = 128; + /* Change the value through the pointer of shadow type */ + skel->struct_ops.testmod_map->data = 13; + err = example__load(skel); if (err) goto cleanup; + /* The result of the function test_2() */ + printf("test_2_result: %d\n", skel->bss->test_2_result); + err = example__attach(skel); if (err) goto cleanup; @@ -372,6 +417,7 @@ BPF ELF object file *example.bpf.o*. :: + test_2_result: 17 my_map name: my_map sys_enter prog FD: 8 my_static_var: 7 diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index a9334c57e859..1f579eacd9d4 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -55,6 +55,20 @@ static bool str_has_suffix(const char *str, const char *suffix) return true; } +static const struct btf_type * +resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id) +{ + const struct btf_type *t; + + t = skip_mods_and_typedefs(btf, id, NULL); + if (!btf_is_ptr(t)) + return NULL; + + t = skip_mods_and_typedefs(btf, t->type, res_id); + + return btf_is_func_proto(t) ? t : NULL; +} + static void get_obj_name(char *name, const char *file) { char file_copy[PATH_MAX]; @@ -909,6 +923,207 @@ codegen_progs_skeleton(struct bpf_object *obj, size_t prog_cnt, bool populate_li } } +static int walk_st_ops_shadow_vars(struct btf *btf, const char *ident, + const struct btf_type *map_type, __u32 map_type_id) +{ + LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts, .indent_level = 3); + const struct btf_type *member_type; + __u32 offset, next_offset = 0; + const struct btf_member *m; + struct btf_dump *d = NULL; + const char *member_name; + __u32 member_type_id; + int i, err = 0, n; + int size; + + d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL); + if (!d) + return -errno; + + n = btf_vlen(map_type); + for (i = 0, m = btf_members(map_type); i < n; i++, m++) { + member_type = skip_mods_and_typedefs(btf, m->type, &member_type_id); + member_name = btf__name_by_offset(btf, m->name_off); + + offset = m->offset / 8; + if (next_offset < offset) + printf("\t\t\tchar __padding_%d[%d];\n", i, offset - next_offset); + + switch (btf_kind(member_type)) { + case BTF_KIND_INT: + case BTF_KIND_FLOAT: + case BTF_KIND_ENUM: + case BTF_KIND_ENUM64: + /* scalar type */ + printf("\t\t\t"); + opts.field_name = member_name; + err = btf_dump__emit_type_decl(d, member_type_id, &opts); + if (err) { + p_err("Failed to emit type declaration for %s: %d", member_name, err); + goto out; + } + printf(";\n"); + + size = btf__resolve_size(btf, member_type_id); + if (size < 0) { + p_err("Failed to resolve size of %s: %d\n", member_name, size); + err = size; + goto out; + } + + next_offset = offset + size; + break; + + case BTF_KIND_PTR: + if (resolve_func_ptr(btf, m->type, NULL)) { + /* Function pointer */ + printf("\t\t\tstruct bpf_program *%s;\n", member_name); + + next_offset = offset + sizeof(void *); + break; + } + /* All pointer types are unsupported except for + * function pointers. + */ + fallthrough; + + default: + /* Unsupported types + * + * Types other than scalar types and function + * pointers are currently not supported in order to + * prevent conflicts in the generated code caused + * by multiple definitions. For instance, if the + * struct type FOO is used in a struct_ops map, + * bpftool has to generate definitions for FOO, + * which may result in conflicts if FOO is defined + * in different skeleton files. + */ + size = btf__resolve_size(btf, member_type_id); + if (size < 0) { + p_err("Failed to resolve size of %s: %d\n", member_name, size); + err = size; + goto out; + } + printf("\t\t\tchar __unsupported_%d[%d];\n", i, size); + + next_offset = offset + size; + break; + } + } + + /* Cannot fail since it must be a struct type */ + size = btf__resolve_size(btf, map_type_id); + if (next_offset < (__u32)size) + printf("\t\t\tchar __padding_end[%d];\n", size - next_offset); + +out: + btf_dump__free(d); + + return err; +} + +/* Generate the pointer of the shadow type for a struct_ops map. + * + * This function adds a pointer of the shadow type for a struct_ops map. + * The members of a struct_ops map can be exported through a pointer to a + * shadow type. The user can access these members through the pointer. + * + * A shadow type includes not all members, only members of some types. + * They are scalar types and function pointers. The function pointers are + * translated to the pointer of the struct bpf_program. The scalar types + * are translated to the original type without any modifiers. + * + * Unsupported types will be translated to a char array to occupy the same + * space as the original field, being renamed as __unsupported_*. The user + * should treat these fields as opaque data. + */ +static int gen_st_ops_shadow_type(const char *obj_name, struct btf *btf, const char *ident, + const struct bpf_map *map) +{ + const struct btf_type *map_type; + const char *type_name; + __u32 map_type_id; + int err; + + map_type_id = bpf_map__btf_value_type_id(map); + if (map_type_id == 0) + return -EINVAL; + map_type = btf__type_by_id(btf, map_type_id); + if (!map_type) + return -EINVAL; + + type_name = btf__name_by_offset(btf, map_type->name_off); + + printf("\t\tstruct %s__%s__%s {\n", obj_name, ident, type_name); + + err = walk_st_ops_shadow_vars(btf, ident, map_type, map_type_id); + if (err) + return err; + + printf("\t\t} *%s;\n", ident); + + return 0; +} + +static int gen_st_ops_shadow(const char *obj_name, struct btf *btf, struct bpf_object *obj) +{ + int err, st_ops_cnt = 0; + struct bpf_map *map; + char ident[256]; + + if (!btf) + return 0; + + /* Generate the pointers to shadow types of + * struct_ops maps. + */ + bpf_object__for_each_map(map, obj) { + if (bpf_map__type(map) != BPF_MAP_TYPE_STRUCT_OPS) + continue; + if (!get_map_ident(map, ident, sizeof(ident))) + continue; + + if (st_ops_cnt == 0) /* first struct_ops map */ + printf("\tstruct {\n"); + st_ops_cnt++; + + err = gen_st_ops_shadow_type(obj_name, btf, ident, map); + if (err) + return err; + } + + if (st_ops_cnt) + printf("\t} struct_ops;\n"); + + return 0; +} + +/* Generate the code to initialize the pointers of shadow types. */ +static void gen_st_ops_shadow_init(struct btf *btf, struct bpf_object *obj) +{ + struct bpf_map *map; + char ident[256]; + + if (!btf) + return; + + /* Initialize the pointers to_ops shadow types of + * struct_ops maps. + */ + bpf_object__for_each_map(map, obj) { + if (bpf_map__type(map) != BPF_MAP_TYPE_STRUCT_OPS) + continue; + if (!get_map_ident(map, ident, sizeof(ident))) + continue; + codegen("\ + \n\ + obj->struct_ops.%1$s = bpf_map__initial_value(obj->maps.%1$s, NULL);\n\ + \n\ + ", ident); + } +} + static int do_skeleton(int argc, char **argv) { char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")]; @@ -1052,6 +1267,11 @@ static int do_skeleton(int argc, char **argv) printf("\t} maps;\n"); } + btf = bpf_object__btf(obj); + err = gen_st_ops_shadow(obj_name, btf, obj); + if (err) + goto out; + if (prog_cnt) { printf("\tstruct {\n"); bpf_object__for_each_program(prog, obj) { @@ -1075,7 +1295,6 @@ static int do_skeleton(int argc, char **argv) printf("\t} links;\n"); } - btf = bpf_object__btf(obj); if (btf) { err = codegen_datasecs(obj, obj_name); if (err) @@ -1133,6 +1352,12 @@ static int do_skeleton(int argc, char **argv) if (err) \n\ goto err_out; \n\ \n\ + ", obj_name); + + gen_st_ops_shadow_init(btf, obj); + + codegen("\ + \n\ return obj; \n\ err_out: \n\ %1$s__destroy(obj); \n\ @@ -1442,6 +1667,10 @@ static int do_subskeleton(int argc, char **argv) printf("\t} maps;\n"); } + err = gen_st_ops_shadow(obj_name, btf, obj); + if (err) + goto out; + if (prog_cnt) { printf("\tstruct {\n"); bpf_object__for_each_program(prog, obj) { @@ -1553,6 +1782,12 @@ static int do_subskeleton(int argc, char **argv) if (err) \n\ goto err; \n\ \n\ + "); + + gen_st_ops_shadow_init(btf, obj); + + codegen("\ + \n\ return obj; \n\ err: \n\ %1$s__destroy(obj); \n\ diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 01f407591a92..6c2979f1b471 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -1014,6 +1014,19 @@ static bool bpf_map__is_struct_ops(const struct bpf_map *map) return map->def.type == BPF_MAP_TYPE_STRUCT_OPS; } +static bool is_valid_st_ops_program(struct bpf_object *obj, + const struct bpf_program *prog) +{ + int i; + + for (i = 0; i < obj->nr_programs; i++) { + if (&obj->programs[i] == prog) + return prog->type == BPF_PROG_TYPE_STRUCT_OPS; + } + + return false; +} + /* Init the map's fields that depend on kern_btf */ static int bpf_map__init_kern_struct_ops(struct bpf_map *map) { @@ -1102,9 +1115,16 @@ static int bpf_map__init_kern_struct_ops(struct bpf_map *map) if (btf_is_ptr(mtype)) { struct bpf_program *prog; - prog = st_ops->progs[i]; + /* Update the value from the shadow type */ + prog = *(void **)mdata; + st_ops->progs[i] = prog; if (!prog) continue; + if (!is_valid_st_ops_program(obj, prog)) { + pr_warn("struct_ops init_kern %s: member %s is not a struct_ops program\n", + map->name, mname); + return -ENOTSUP; + } kern_mtype = skip_mods_and_typedefs(kern_btf, kern_mtype->type, @@ -1229,6 +1249,7 @@ static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name, map->name = strdup(var_name); if (!map->name) return -ENOMEM; + map->btf_value_type_id = type_id; map->def.type = BPF_MAP_TYPE_STRUCT_OPS; map->def.key_size = sizeof(int); @@ -4857,6 +4878,10 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b create_attr.btf_value_type_id = 0; map->btf_key_type_id = 0; map->btf_value_type_id = 0; + break; + case BPF_MAP_TYPE_STRUCT_OPS: + create_attr.btf_value_type_id = 0; + break; default: break; } @@ -9305,7 +9330,9 @@ static struct bpf_map *find_struct_ops_map_by_offset(struct bpf_object *obj, return NULL; } -/* Collect the reloc from ELF and populate the st_ops->progs[] */ +/* Collect the reloc from ELF, populate the st_ops->progs[], and update + * st_ops->data for shadow type. + */ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj, Elf64_Shdr *shdr, Elf_Data *data) { @@ -9419,6 +9446,14 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj, } st_ops->progs[member_idx] = prog; + + /* st_ops->data will be exposed to users, being returned by + * bpf_map__initial_value() as a pointer to the shadow + * type. All function pointers in the original struct type + * should be converted to a pointer to struct bpf_program + * in the shadow type. + */ + *((struct bpf_program **)(st_ops->data + moff)) = prog; } return 0; @@ -9877,6 +9912,12 @@ int bpf_map__set_initial_value(struct bpf_map *map, void *bpf_map__initial_value(struct bpf_map *map, size_t *psize) { + if (bpf_map__is_struct_ops(map)) { + if (psize) + *psize = map->def.value_size; + return map->st_ops->data; + } + if (!map->mmaped) return NULL; *psize = map->def.value_size; diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c index 66787e99ba1b..098ddd067224 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c @@ -539,6 +539,15 @@ static int bpf_testmod_ops_init_member(const struct btf_type *t, const struct btf_member *member, void *kdata, const void *udata) { + if (member->offset == offsetof(struct bpf_testmod_ops, data) * 8) { + /* For data fields, this function has to copy it and return + * 1 to indicate that the data has been handled by the + * struct_ops type, or the verifier will reject the map if + * the value of the data field is not zero. + */ + ((struct bpf_testmod_ops *)kdata)->data = ((struct bpf_testmod_ops *)udata)->data; + return 1; + } return 0; } @@ -559,7 +568,7 @@ static int bpf_dummy_reg(void *kdata) * initialized, so we need to check for NULL. */ if (ops->test_2) - ops->test_2(4, 3); + ops->test_2(4, ops->data); return 0; } diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h index c3b0cf788f9f..971458acfac3 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h @@ -35,6 +35,14 @@ struct bpf_testmod_ops { void (*test_2)(int a, int b); /* Used to test nullable arguments. */ int (*test_maybe_null)(int dummy, struct task_struct *task); + + /* The following fields are used to test shadow copies. */ + char onebyte; + struct { + int a; + int b; + } unsupported; + int data; }; #endif /* _BPF_TESTMOD_H */ diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c index 8d833f0c7580..7d6facf46ebb 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c +++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c @@ -32,17 +32,23 @@ cleanup: static void test_struct_ops_load(void) { - DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts); struct struct_ops_module *skel; struct bpf_map_info info = {}; struct bpf_link *link; int err; u32 len; - skel = struct_ops_module__open_opts(&opts); + skel = struct_ops_module__open(); if (!ASSERT_OK_PTR(skel, "struct_ops_module_open")) return; + skel->struct_ops.testmod_1->data = 13; + skel->struct_ops.testmod_1->test_2 = skel->progs.test_3; + /* Since test_2() is not being used, it should be disabled from + * auto-loading, or it will fail to load. + */ + bpf_program__set_autoload(skel->progs.test_2, false); + err = struct_ops_module__load(skel); if (!ASSERT_OK(err, "struct_ops_module_load")) goto cleanup; @@ -56,8 +62,13 @@ static void test_struct_ops_load(void) link = bpf_map__attach_struct_ops(skel->maps.testmod_1); ASSERT_OK_PTR(link, "attach_test_mod_1"); - /* test_2() will be called from bpf_dummy_reg() in bpf_testmod.c */ - ASSERT_EQ(skel->bss->test_2_result, 7, "test_2_result"); + /* test_3() will be called from bpf_dummy_reg() in bpf_testmod.c + * + * In bpf_testmod.c it will pass 4 and 13 (the value of data) to + * .test_2. So, the value of test_2_result should be 20 (4 + 13 + + * 3). + */ + ASSERT_EQ(skel->bss->test_2_result, 20, "check_shadow_variables"); bpf_link__destroy(link); diff --git a/tools/testing/selftests/bpf/progs/struct_ops_module.c b/tools/testing/selftests/bpf/progs/struct_ops_module.c index b78746b3cef3..25952fa09348 100644 --- a/tools/testing/selftests/bpf/progs/struct_ops_module.c +++ b/tools/testing/selftests/bpf/progs/struct_ops_module.c @@ -21,9 +21,17 @@ void BPF_PROG(test_2, int a, int b) test_2_result = a + b; } +SEC("struct_ops/test_3") +int BPF_PROG(test_3, int a, int b) +{ + test_2_result = a + b + 3; + return a + b + 3; +} + SEC(".struct_ops.link") struct bpf_testmod_ops testmod_1 = { .test_1 = (void *)test_1, .test_2 = (void *)test_2, + .data = 0x1, }; |