Instead of all or nothing approach of overriding Kconfig file location, allow to extend it with extra values and override chosen subset of values though optional user-provided extra config, passed as a string through open options' .kconfig option. If same config key is present in both user-supplied config and Kconfig, user-supplied one wins. This allows applications to more easily test various conditions despite host kernel's real configuration. If all of BPF object's __kconfig externs are satisfied from user-supplied config, system Kconfig won't be read at all. Simplify selftests by not needing to create temporary Kconfig files. Suggested-by: Alexei Starovoitov <ast@xxxxxx> Signed-off-by: Andrii Nakryiko <andriin@xxxxxx> --- tools/lib/bpf/libbpf.c | 204 +++++++++++------- tools/lib/bpf/libbpf.h | 8 +- .../selftests/bpf/prog_tests/core_extern.c | 32 +-- 3 files changed, 132 insertions(+), 112 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index ed54a6a7f6f2..f90db2b18e4b 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -302,7 +302,7 @@ struct bpf_object { size_t nr_maps; size_t maps_cap; - char *kconfig_path; + char *kconfig; struct extern_desc *externs; int nr_extern; int kconfig_map_idx; @@ -1149,98 +1149,129 @@ static int set_ext_value_num(struct extern_desc *ext, void *ext_val, return 0; } -static int bpf_object__read_kernel_config(struct bpf_object *obj, - const char *config_path, - void *data) +static int bpf_object__process_kconfig_line(struct bpf_object *obj, + char *buf, void *data) { - char buf[PATH_MAX], *sep, *value; struct extern_desc *ext; + char *sep, *value; int len, err = 0; void *ext_val; __u64 num; - gzFile file; - if (config_path) { - file = gzopen(config_path, "r"); - } else { - struct utsname uts; + if (strncmp(buf, "CONFIG_", 7)) + return 0; - uname(&uts); - len = snprintf(buf, PATH_MAX, "/boot/config-%s", uts.release); - if (len < 0) - return -EINVAL; - else if (len >= PATH_MAX) - return -ENAMETOOLONG; - /* gzopen also accepts uncompressed files. */ - file = gzopen(buf, "r"); - if (!file) - file = gzopen("/proc/config.gz", "r"); + sep = strchr(buf, '='); + if (!sep) { + pr_warn("failed to parse '%s': no separator\n", buf); + return -EINVAL; + } + + /* Trim ending '\n' */ + len = strlen(buf); + if (buf[len - 1] == '\n') + buf[len - 1] = '\0'; + /* Split on '=' and ensure that a value is present. */ + *sep = '\0'; + if (!sep[1]) { + *sep = '='; + pr_warn("failed to parse '%s': no value\n", buf); + return -EINVAL; + } + + ext = find_extern_by_name(obj, buf); + if (!ext || ext->is_set) + return 0; + + ext_val = data + ext->data_off; + value = sep + 1; + + switch (*value) { + case 'y': case 'n': case 'm': + err = set_ext_value_tri(ext, ext_val, *value); + break; + case '"': + err = set_ext_value_str(ext, ext_val, value); + break; + default: + /* assume integer */ + err = parse_u64(value, &num); + if (err) { + pr_warn("extern %s=%s should be integer\n", + ext->name, value); + return err; + } + err = set_ext_value_num(ext, ext_val, num); + break; } + if (err) + return err; + pr_debug("extern %s=%s\n", ext->name, value); + return 0; +} + +static int bpf_object__read_kconfig_file(struct bpf_object *obj, void *data) +{ + char buf[PATH_MAX]; + struct utsname uts; + int len, err = 0; + gzFile file; + + uname(&uts); + len = snprintf(buf, PATH_MAX, "/boot/config-%s", uts.release); + if (len < 0) + return -EINVAL; + else if (len >= PATH_MAX) + return -ENAMETOOLONG; + + /* gzopen also accepts uncompressed files. */ + file = gzopen(buf, "r"); + if (!file) + file = gzopen("/proc/config.gz", "r"); + if (!file) { - pr_warn("failed to read kernel config at '%s'\n", config_path); + pr_warn("failed to open system Kconfig\n"); return -ENOENT; } while (gzgets(file, buf, sizeof(buf))) { - if (strncmp(buf, "CONFIG_", 7)) - continue; - - sep = strchr(buf, '='); - if (!sep) { - err = -EINVAL; - pr_warn("failed to parse '%s': no separator\n", buf); - goto out; - } - /* Trim ending '\n' */ - len = strlen(buf); - if (buf[len - 1] == '\n') - buf[len - 1] = '\0'; - /* Split on '=' and ensure that a value is present. */ - *sep = '\0'; - if (!sep[1]) { - err = -EINVAL; - *sep = '='; - pr_warn("failed to parse '%s': no value\n", buf); + err = bpf_object__process_kconfig_line(obj, buf, data); + if (err) { + pr_warn("error parsing system Kconfig line '%s': %d\n", + buf, err); goto out; } + } - ext = find_extern_by_name(obj, buf); - if (!ext) - continue; - if (ext->is_set) { - err = -EINVAL; - pr_warn("re-defining extern '%s' not allowed\n", buf); - goto out; - } +out: + gzclose(file); + return err; +} - ext_val = data + ext->data_off; - value = sep + 1; +static int bpf_object__read_kconfig_mem(struct bpf_object *obj, + const char *config, void *data) +{ + char buf[PATH_MAX]; + int err = 0; + FILE *file; - switch (*value) { - case 'y': case 'n': case 'm': - err = set_ext_value_tri(ext, ext_val, *value); - break; - case '"': - err = set_ext_value_str(ext, ext_val, value); - break; - default: - /* assume integer */ - err = parse_u64(value, &num); - if (err) { - pr_warn("extern %s=%s should be integer\n", - ext->name, value); - goto out; - } - err = set_ext_value_num(ext, ext_val, num); + file = fmemopen((void *)config, strlen(config), "r"); + if (!file) { + err = -errno; + pr_warn("failed to open in-memory Kconfig: %d\n", err); + return err; + } + + while (fgets(buf, sizeof(buf), file)) { + err = bpf_object__process_kconfig_line(obj, buf, data); + if (err) { + pr_warn("error parsing in-memory Kconfig line '%s': %d\n", + buf, err); break; } - if (err) - goto out; - pr_debug("extern %s=%s\n", ext->name, value); } -out: - gzclose(file); + fclose(file); return err; } @@ -4567,7 +4598,7 @@ static struct bpf_object * __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, const struct bpf_object_open_opts *opts) { - const char *obj_name, *kconfig_path; + const char *obj_name, *kconfig; struct bpf_program *prog; struct bpf_object *obj; char tmp_name[64]; @@ -4599,10 +4630,10 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, return obj; obj->relaxed_core_relocs = OPTS_GET(opts, relaxed_core_relocs, false); - kconfig_path = OPTS_GET(opts, kconfig_path, NULL); - if (kconfig_path) { - obj->kconfig_path = strdup(kconfig_path); - if (!obj->kconfig_path) + kconfig = OPTS_GET(opts, kconfig, NULL); + if (kconfig) { + obj->kconfig = strdup(kconfig); + if (!obj->kconfig) return ERR_PTR(-ENOMEM); } @@ -4745,7 +4776,7 @@ static int bpf_object__sanitize_maps(struct bpf_object *obj) } static int bpf_object__resolve_externs(struct bpf_object *obj, - const char *config_path) + const char *extra_kconfig) { bool need_config = false; struct extern_desc *ext; @@ -4779,8 +4810,21 @@ static int bpf_object__resolve_externs(struct bpf_object *obj, return -EINVAL; } } + if (need_config && extra_kconfig) { + err = bpf_object__read_kconfig_mem(obj, extra_kconfig, data); + if (err) + return -EINVAL; + need_config = false; + for (i = 0; i < obj->nr_extern; i++) { + ext = &obj->externs[i]; + if (!ext->is_set) { + need_config = true; + break; + } + } + } if (need_config) { - err = bpf_object__read_kernel_config(obj, config_path, data); + err = bpf_object__read_kconfig_file(obj, data); if (err) return -EINVAL; } @@ -4818,7 +4862,7 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr) obj->loaded = true; err = bpf_object__probe_caps(obj); - err = err ? : bpf_object__resolve_externs(obj, obj->kconfig_path); + err = err ? : bpf_object__resolve_externs(obj, obj->kconfig); err = err ? : bpf_object__sanitize_and_load_btf(obj); err = err ? : bpf_object__sanitize_maps(obj); err = err ? : bpf_object__create_maps(obj); @@ -5412,7 +5456,7 @@ void bpf_object__close(struct bpf_object *obj) zfree(&map->pin_path); } - zfree(&obj->kconfig_path); + zfree(&obj->kconfig); zfree(&obj->externs); obj->nr_extern = 0; diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index f7084235bae9..ffe62e3baffd 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -85,12 +85,12 @@ struct bpf_object_open_opts { */ const char *pin_root_path; __u32 attach_prog_fd; - /* kernel config file path override (for CONFIG_ externs); can point - * to either uncompressed text file or .gz file + /* Additional kernel config content that augments and overrides + * system Kconfig for CONFIG_xxx externs. */ - const char *kconfig_path; + const char *kconfig; }; -#define bpf_object_open_opts__last_field kconfig_path +#define bpf_object_open_opts__last_field kconfig LIBBPF_API struct bpf_object *bpf_object__open(const char *path); LIBBPF_API struct bpf_object * diff --git a/tools/testing/selftests/bpf/prog_tests/core_extern.c b/tools/testing/selftests/bpf/prog_tests/core_extern.c index 5f03dc1de29e..b093787e9448 100644 --- a/tools/testing/selftests/bpf/prog_tests/core_extern.c +++ b/tools/testing/selftests/bpf/prog_tests/core_extern.c @@ -23,19 +23,13 @@ static uint32_t get_kernel_version(void) static struct test_case { const char *name; const char *cfg; - const char *cfg_path; bool fails; struct test_core_extern__data data; } test_cases[] = { - { .name = "default search path", .cfg_path = NULL, - .data = { .bpf_syscall = true } }, - { .name = "/proc/config.gz", .cfg_path = "/proc/config.gz", - .data = { .bpf_syscall = true } }, - { .name = "missing config", .fails = true, - .cfg_path = "/proc/invalid-config.gz" }, + { .name = "default search path", .data = { .bpf_syscall = true } }, { .name = "custom values", - .cfg = "CONFIG_BPF_SYSCALL=y\n" + .cfg = "CONFIG_BPF_SYSCALL=n\n" "CONFIG_TRISTATE=m\n" "CONFIG_BOOL=y\n" "CONFIG_CHAR=100\n" @@ -45,7 +39,7 @@ static struct test_case { "CONFIG_STR=\"abracad\"\n" "CONFIG_MISSING=0", .data = { - .bpf_syscall = true, + .bpf_syscall = false, .tristate_val = TRI_MODULE, .bool_val = true, .char_val = 100, @@ -133,30 +127,14 @@ void test_core_extern(void) int n = sizeof(*skel->data) / sizeof(uint64_t); for (i = 0; i < ARRAY_SIZE(test_cases); i++) { - char tmp_cfg_path[] = "/tmp/test_core_extern_cfg.XXXXXX"; struct test_case *t = &test_cases[i]; DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts, - .kconfig_path = t->cfg_path, + .kconfig = t->cfg, ); if (!test__start_subtest(t->name)) continue; - if (t->cfg) { - size_t n = strlen(t->cfg) + 1; - int fd = mkstemp(tmp_cfg_path); - int written; - - if (CHECK(fd < 0, "mkstemp", "errno: %d\n", errno)) - continue; - printf("using '%s' as config file\n", tmp_cfg_path); - written = write(fd, t->cfg, n); - close(fd); - if (CHECK_FAIL(written != n)) - goto cleanup; - opts.kconfig_path = tmp_cfg_path; - } - skel = test_core_extern__open_opts(&opts); if (CHECK(!skel, "skel_open", "skeleton open failed\n")) goto cleanup; @@ -185,8 +163,6 @@ void test_core_extern(void) j, exp[j], got[j]); } cleanup: - if (t->cfg) - unlink(tmp_cfg_path); test_core_extern__destroy(skel); skel = NULL; } -- 2.17.1