From 81bfdd087bf31a87c5ff25cc7004d5308954a35c Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 18 Dec 2019 16:28:34 -0800 Subject: [PATCH] libbpf: Put Kconfig externs into .kconfig section Move Kconfig-provided externs into custom .kconfig section. Add __kconfig into bpf_helpers.h for user convenience. Update selftests accordingly. Suggested-by: Daniel Borkmann Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20191219002837.3074619-2-andriin@fb.com --- tools/bpf/bpftool/gen.c | 8 +-- tools/lib/bpf/bpf_helpers.h | 2 + tools/lib/bpf/libbpf.c | 58 +++++++++++-------- .../selftests/bpf/prog_tests/skeleton.c | 16 +++-- .../selftests/bpf/progs/test_core_extern.c | 20 +++---- .../selftests/bpf/progs/test_skeleton.c | 4 +- 6 files changed, 60 insertions(+), 48 deletions(-) diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index 851c465f99dc..a14d8bc5d31d 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -83,8 +83,8 @@ static const char *get_map_ident(const struct bpf_map *map) return "rodata"; else if (str_has_suffix(name, ".bss")) return "bss"; - else if (str_has_suffix(name, ".extern")) - return "externs"; /* extern is a C keyword */ + else if (str_has_suffix(name, ".kconfig")) + return "kconfig"; else return NULL; } @@ -112,8 +112,8 @@ static int codegen_datasec_def(struct bpf_object *obj, sec_ident = "bss"; else if (strcmp(sec_name, ".rodata") == 0) sec_ident = "rodata"; - else if (strcmp(sec_name, ".extern") == 0) - sec_ident = "externs"; /* extern is a C keyword */ + else if (strcmp(sec_name, ".kconfig") == 0) + sec_ident = "kconfig"; else return 0; diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h index aa46700075e1..f69cc208778a 100644 --- a/tools/lib/bpf/bpf_helpers.h +++ b/tools/lib/bpf/bpf_helpers.h @@ -53,4 +53,6 @@ enum libbpf_tristate { TRI_MODULE = 2, }; +#define __kconfig __attribute__((section(".kconfig"))) + #endif diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 2a341a5b9f63..0772eb3254e2 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -231,21 +231,21 @@ struct bpf_program { #define DATA_SEC ".data" #define BSS_SEC ".bss" #define RODATA_SEC ".rodata" -#define EXTERN_SEC ".extern" +#define KCONFIG_SEC ".kconfig" enum libbpf_map_type { LIBBPF_MAP_UNSPEC, LIBBPF_MAP_DATA, LIBBPF_MAP_BSS, LIBBPF_MAP_RODATA, - LIBBPF_MAP_EXTERN, + LIBBPF_MAP_KCONFIG, }; static const char * const libbpf_type_to_btf_name[] = { [LIBBPF_MAP_DATA] = DATA_SEC, [LIBBPF_MAP_BSS] = BSS_SEC, [LIBBPF_MAP_RODATA] = RODATA_SEC, - [LIBBPF_MAP_EXTERN] = EXTERN_SEC, + [LIBBPF_MAP_KCONFIG] = KCONFIG_SEC, }; struct bpf_map { @@ -305,7 +305,7 @@ struct bpf_object { char *kconfig_path; struct extern_desc *externs; int nr_extern; - int extern_map_idx; + int kconfig_map_idx; bool loaded; bool has_pseudo_calls; @@ -606,7 +606,7 @@ static struct bpf_object *bpf_object__new(const char *path, obj->efile.data_shndx = -1; obj->efile.rodata_shndx = -1; obj->efile.bss_shndx = -1; - obj->extern_map_idx = -1; + obj->kconfig_map_idx = -1; obj->kern_version = get_kernel_version(); obj->loaded = false; @@ -902,11 +902,25 @@ static size_t bpf_map_mmap_sz(const struct bpf_map *map) return map_sz; } +static char *internal_map_name(struct bpf_object *obj, + enum libbpf_map_type type) +{ + char map_name[BPF_OBJ_NAME_LEN]; + const char *sfx = libbpf_type_to_btf_name[type]; + int sfx_len = max((size_t)7, strlen(sfx)); + int pfx_len = min((size_t)BPF_OBJ_NAME_LEN - sfx_len - 1, + strlen(obj->name)); + + snprintf(map_name, sizeof(map_name), "%.*s%.*s", pfx_len, obj->name, + sfx_len, libbpf_type_to_btf_name[type]); + + return strdup(map_name); +} + static int bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type, int sec_idx, void *data, size_t data_sz) { - char map_name[BPF_OBJ_NAME_LEN]; struct bpf_map_def *def; struct bpf_map *map; int err; @@ -918,9 +932,7 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type, map->libbpf_type = type; map->sec_idx = sec_idx; map->sec_offset = 0; - snprintf(map_name, sizeof(map_name), "%.8s%.7s", obj->name, - libbpf_type_to_btf_name[type]); - map->name = strdup(map_name); + map->name = internal_map_name(obj, type); if (!map->name) { pr_warn("failed to alloc map name\n"); return -ENOMEM; @@ -931,12 +943,12 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type, def->key_size = sizeof(int); def->value_size = data_sz; def->max_entries = 1; - def->map_flags = type == LIBBPF_MAP_RODATA || type == LIBBPF_MAP_EXTERN + def->map_flags = type == LIBBPF_MAP_RODATA || type == LIBBPF_MAP_KCONFIG ? BPF_F_RDONLY_PROG : 0; 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); + map->name, map->sec_idx, map->sec_offset, def->map_flags); map->mmaped = mmap(NULL, bpf_map_mmap_sz(map), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); @@ -1232,7 +1244,7 @@ out: return err; } -static int bpf_object__init_extern_map(struct bpf_object *obj) +static int bpf_object__init_kconfig_map(struct bpf_object *obj) { struct extern_desc *last_ext; size_t map_sz; @@ -1244,13 +1256,13 @@ static int bpf_object__init_extern_map(struct bpf_object *obj) last_ext = &obj->externs[obj->nr_extern - 1]; map_sz = last_ext->data_off + last_ext->sz; - err = bpf_object__init_internal_map(obj, LIBBPF_MAP_EXTERN, + err = bpf_object__init_internal_map(obj, LIBBPF_MAP_KCONFIG, obj->efile.symbols_shndx, NULL, map_sz); if (err) return err; - obj->extern_map_idx = obj->nr_maps - 1; + obj->kconfig_map_idx = obj->nr_maps - 1; return 0; } @@ -1742,7 +1754,7 @@ static int bpf_object__init_maps(struct bpf_object *obj, err = bpf_object__init_user_maps(obj, strict); err = err ?: bpf_object__init_user_btf_maps(obj, strict, pin_root_path); err = err ?: bpf_object__init_global_data_maps(obj); - err = err ?: bpf_object__init_extern_map(obj); + err = err ?: bpf_object__init_kconfig_map(obj); if (err) return err; @@ -2269,9 +2281,9 @@ static int bpf_object__collect_externs(struct bpf_object *obj) i, ext->sym_idx, ext->data_off, ext->name); } - btf_id = btf__find_by_name(obj->btf, EXTERN_SEC); + btf_id = btf__find_by_name(obj->btf, KCONFIG_SEC); if (btf_id <= 0) { - pr_warn("no BTF info found for '%s' datasec\n", EXTERN_SEC); + pr_warn("no BTF info found for '%s' datasec\n", KCONFIG_SEC); return -ESRCH; } @@ -2361,7 +2373,7 @@ bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx) else if (shndx == obj->efile.rodata_shndx) return LIBBPF_MAP_RODATA; else if (shndx == obj->efile.symbols_shndx) - return LIBBPF_MAP_EXTERN; + return LIBBPF_MAP_KCONFIG; else return LIBBPF_MAP_UNSPEC; } @@ -2908,8 +2920,8 @@ bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map) return err; } - /* Freeze .rodata and .extern map as read-only from syscall side. */ - if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_EXTERN) { + /* Freeze .rodata and .kconfig map as read-only from syscall side. */ + if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG) { err = bpf_map_freeze(map->fd); if (err) { err = -errno; @@ -4264,7 +4276,7 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj) break; case RELO_EXTERN: insn[0].src_reg = BPF_PSEUDO_MAP_VALUE; - insn[0].imm = obj->maps[obj->extern_map_idx].fd; + insn[0].imm = obj->maps[obj->kconfig_map_idx].fd; insn[1].imm = relo->sym_off; break; case RELO_CALL: @@ -4743,7 +4755,7 @@ static int bpf_object__resolve_externs(struct bpf_object *obj, if (obj->nr_extern == 0) return 0; - data = obj->maps[obj->extern_map_idx].mmaped; + data = obj->maps[obj->kconfig_map_idx].mmaped; for (i = 0; i < obj->nr_extern; i++) { ext = &obj->externs[i]; @@ -7546,7 +7558,7 @@ int bpf_object__open_skeleton(struct bpf_object_skeleton *s, } /* externs shouldn't be pre-setup from user code */ - if (mmaped && (*map)->libbpf_type != LIBBPF_MAP_EXTERN) + if (mmaped && (*map)->libbpf_type != LIBBPF_MAP_KCONFIG) *mmaped = (*map)->mmaped; } diff --git a/tools/testing/selftests/bpf/prog_tests/skeleton.c b/tools/testing/selftests/bpf/prog_tests/skeleton.c index ec6f2aec3853..9264a2736018 100644 --- a/tools/testing/selftests/bpf/prog_tests/skeleton.c +++ b/tools/testing/selftests/bpf/prog_tests/skeleton.c @@ -15,20 +15,18 @@ void test_skeleton(void) int duration = 0, err; struct test_skeleton* skel; struct test_skeleton__bss *bss; - struct test_skeleton__externs *exts; + struct test_skeleton__kconfig *kcfg; skel = test_skeleton__open(); if (CHECK(!skel, "skel_open", "failed to open skeleton\n")) return; - printf("EXTERNS BEFORE: %p\n", skel->externs); - if (CHECK(skel->externs, "skel_externs", "externs are mmaped()!\n")) + if (CHECK(skel->kconfig, "skel_kconfig", "kconfig is mmaped()!\n")) goto cleanup; err = test_skeleton__load(skel); if (CHECK(err, "skel_load", "failed to load skeleton: %d\n", err)) goto cleanup; - printf("EXTERNS AFTER: %p\n", skel->externs); bss = skel->bss; bss->in1 = 1; @@ -37,7 +35,7 @@ void test_skeleton(void) bss->in4 = 4; bss->in5.a = 5; bss->in5.b = 6; - exts = skel->externs; + kcfg = skel->kconfig; err = test_skeleton__attach(skel); if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err)) @@ -55,10 +53,10 @@ void test_skeleton(void) CHECK(bss->handler_out5.b != 6, "res6", "got %lld != exp %d\n", bss->handler_out5.b, 6); - CHECK(bss->bpf_syscall != exts->CONFIG_BPF_SYSCALL, "ext1", - "got %d != exp %d\n", bss->bpf_syscall, exts->CONFIG_BPF_SYSCALL); - CHECK(bss->kern_ver != exts->LINUX_KERNEL_VERSION, "ext2", - "got %d != exp %d\n", bss->kern_ver, exts->LINUX_KERNEL_VERSION); + CHECK(bss->bpf_syscall != kcfg->CONFIG_BPF_SYSCALL, "ext1", + "got %d != exp %d\n", bss->bpf_syscall, kcfg->CONFIG_BPF_SYSCALL); + CHECK(bss->kern_ver != kcfg->LINUX_KERNEL_VERSION, "ext2", + "got %d != exp %d\n", bss->kern_ver, kcfg->LINUX_KERNEL_VERSION); cleanup: test_skeleton__destroy(skel); diff --git a/tools/testing/selftests/bpf/progs/test_core_extern.c b/tools/testing/selftests/bpf/progs/test_core_extern.c index e12f09f9e881..9bfc91d9d004 100644 --- a/tools/testing/selftests/bpf/progs/test_core_extern.c +++ b/tools/testing/selftests/bpf/progs/test_core_extern.c @@ -10,16 +10,16 @@ /* non-existing BPF helper, to test dead code elimination */ static int (*bpf_missing_helper)(const void *arg1, int arg2) = (void *) 999; -extern int LINUX_KERNEL_VERSION; -extern bool CONFIG_BPF_SYSCALL; /* strong */ -extern enum libbpf_tristate CONFIG_TRISTATE __weak; -extern bool CONFIG_BOOL __weak; -extern char CONFIG_CHAR __weak; -extern uint16_t CONFIG_USHORT __weak; -extern int CONFIG_INT __weak; -extern uint64_t CONFIG_ULONG __weak; -extern const char CONFIG_STR[8] __weak; -extern uint64_t CONFIG_MISSING __weak; +extern int LINUX_KERNEL_VERSION __kconfig; +extern bool CONFIG_BPF_SYSCALL __kconfig; /* strong */ +extern enum libbpf_tristate CONFIG_TRISTATE __kconfig __weak; +extern bool CONFIG_BOOL __kconfig __weak; +extern char CONFIG_CHAR __kconfig __weak; +extern uint16_t CONFIG_USHORT __kconfig __weak; +extern int CONFIG_INT __kconfig __weak; +extern uint64_t CONFIG_ULONG __kconfig __weak; +extern const char CONFIG_STR[8] __kconfig __weak; +extern uint64_t CONFIG_MISSING __kconfig __weak; uint64_t kern_ver = -1; uint64_t bpf_syscall = -1; diff --git a/tools/testing/selftests/bpf/progs/test_skeleton.c b/tools/testing/selftests/bpf/progs/test_skeleton.c index 9caa44758ea2..4f69aac5635f 100644 --- a/tools/testing/selftests/bpf/progs/test_skeleton.c +++ b/tools/testing/selftests/bpf/progs/test_skeleton.c @@ -21,8 +21,8 @@ char out3 = 0; long long out4 = 0; int out1 = 0; -extern bool CONFIG_BPF_SYSCALL; -extern int LINUX_KERNEL_VERSION; +extern bool CONFIG_BPF_SYSCALL __kconfig; +extern int LINUX_KERNEL_VERSION __kconfig; bool bpf_syscall = 0; int kern_ver = 0; -- 2.30.2