diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 11a65db4b93f..7e3b79d7c25f 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -44,6 +44,7 @@ #include "btf.h" #include "str_error.h" #include "libbpf_util.h" +#include "libbpf_internal.h" #ifndef EM_BPF #define EM_BPF 247 @@ -128,6 +129,10 @@ struct bpf_capabilities { __u32 name:1; /* v5.2: kernel support for global data sections. */ __u32 global_data:1; + /* BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO support */ + __u32 btf_func:1; + /* BTF_KIND_VAR and BTF_KIND_DATASEC support */ + __u32 btf_datasec:1; }; /* @@ -1021,6 +1026,74 @@ static bool section_have_execinstr(struct bpf_object *obj, int idx) return false; } +static void bpf_object__sanitize_btf(struct bpf_object *obj) +{ + bool has_datasec = obj->caps.btf_datasec; + bool has_func = obj->caps.btf_func; + struct btf *btf = obj->btf; + struct btf_type *t; + int i, j, vlen; + __u16 kind; + + if (!obj->btf || (has_func && has_datasec)) + return; + + for (i = 1; i <= btf__get_nr_types(btf); i++) { + t = (struct btf_type *)btf__type_by_id(btf, i); + kind = BTF_INFO_KIND(t->info); + + if (!has_datasec && kind == BTF_KIND_VAR) { + /* replace VAR with INT */ + t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0); + t->size = sizeof(int); + *(int *)(t+1) = BTF_INT_ENC(0, 0, 32); + } else if (!has_datasec && kind == BTF_KIND_DATASEC) { + /* replace DATASEC with STRUCT */ + struct btf_var_secinfo *v = (void *)(t + 1); + struct btf_member *m = (void *)(t + 1); + struct btf_type *vt; + char *name; + + name = (char *)btf__name_by_offset(btf, t->name_off); + while (*name) { + if (*name == '.') + *name = '_'; + name++; + } + + vlen = BTF_INFO_VLEN(t->info); + t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, vlen); + for (j = 0; j < vlen; j++, v++, m++) { + /* order of field assignments is important */ + m->offset = v->offset * 8; + m->type = v->type; + /* preserve variable name as member name */ + vt = (void *)btf__type_by_id(btf, v->type); + m->name_off = vt->name_off; + } + } else if (!has_func && kind == BTF_KIND_FUNC_PROTO) { + /* replace FUNC_PROTO with ENUM */ + vlen = BTF_INFO_VLEN(t->info); + t->info = BTF_INFO_ENC(BTF_KIND_ENUM, 0, vlen); + t->size = sizeof(__u32); /* kernel enforced */ + } else if (!has_func && kind == BTF_KIND_FUNC) { + /* replace FUNC with TYPEDEF */ + t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0); + } + } +} + +static void bpf_object__sanitize_btf_ext(struct bpf_object *obj) +{ + if (!obj->btf_ext) + return; + + if (!obj->caps.btf_func) { + btf_ext__free(obj->btf_ext); + obj->btf_ext = NULL; + } +} + static int bpf_object__elf_collect(struct bpf_object *obj, int flags) { Elf *elf = obj->efile.elf; @@ -1164,8 +1237,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) obj->btf = NULL; } else { err = btf__finalize_data(obj, obj->btf); - if (!err) + if (!err) { + bpf_object__sanitize_btf(obj); err = btf__load(obj->btf); + } if (err) { pr_warning("Error finalizing and loading %s into kernel: %d. Ignored and continue.\n", BTF_ELF_SEC, err); @@ -1187,6 +1262,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) BTF_EXT_ELF_SEC, PTR_ERR(obj->btf_ext)); obj->btf_ext = NULL; + } else { + bpf_object__sanitize_btf_ext(obj); } } } @@ -1556,12 +1633,63 @@ bpf_object__probe_global_data(struct bpf_object *obj) return 0; } +static int bpf_object__probe_btf_func(struct bpf_object *obj) +{ + const char strs[] = "\0int\0x\0a"; + /* void x(int a) {} */ + __u32 types[] = { + /* int */ + BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ + /* FUNC_PROTO */ /* [2] */ + BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0), + BTF_PARAM_ENC(7, 1), + /* FUNC x */ /* [3] */ + BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2), + }; + int res; + + res = libbpf__probe_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs)); + if (res < 0) + return res; + if (res > 0) + obj->caps.btf_func = 1; + return 0; +} + +static int bpf_object__probe_btf_datasec(struct bpf_object *obj) +{ + const char strs[] = "\0x\0.data"; + /* static int a; */ + __u32 types[] = { + /* int */ + BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ + /* VAR x */ /* [2] */ + BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1), + BTF_VAR_STATIC, + /* DATASEC val */ /* [3] */ + BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4), + BTF_VAR_SECINFO_ENC(2, 0, 4), + }; + int res; + + res = libbpf__probe_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs)); + if (res < 0) + return res; + if (res > 0) + obj->caps.btf_datasec = 1; + return 0; +} + static int bpf_object__probe_caps(struct bpf_object *obj) { int (*probe_fn[])(struct bpf_object *obj) = { bpf_object__probe_name, bpf_object__probe_global_data, + bpf_object__probe_btf_func, + bpf_object__probe_btf_datasec, }; int i, ret; diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h new file mode 100644 index 000000000000..789e435b5900 --- /dev/null +++ b/tools/lib/bpf/libbpf_internal.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ + +/* + * Internal libbpf helpers. + * + * Copyright (c) 2019 Facebook + */ + +#ifndef __LIBBPF_LIBBPF_INTERNAL_H +#define __LIBBPF_LIBBPF_INTERNAL_H + +#define BTF_INFO_ENC(kind, kind_flag, vlen) \ + ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN)) +#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type) +#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \ + ((encoding) << 24 | (bits_offset) << 16 | (nr_bits)) +#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \ + BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \ + BTF_INT_ENC(encoding, bits_offset, bits) +#define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset) +#define BTF_PARAM_ENC(name, type) (name), (type) +#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size) + +int libbpf__probe_raw_btf(const char *raw_types, size_t types_len, + const char *str_sec, size_t str_len); + +#endif /* __LIBBPF_LIBBPF_INTERNAL_H */ diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c index a2c64a9ce1a6..5e2aa83f637a 100644 --- a/tools/lib/bpf/libbpf_probes.c +++ b/tools/lib/bpf/libbpf_probes.c @@ -15,6 +15,7 @@ #include "bpf.h" #include "libbpf.h" +#include "libbpf_internal.h" static bool grep(const char *buffer, const char *pattern) { @@ -132,21 +133,43 @@ bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex) return errno != EINVAL && errno != EOPNOTSUPP; } -static int load_btf(void) +int libbpf__probe_raw_btf(const char *raw_types, size_t types_len, + const char *str_sec, size_t str_len) { -#define BTF_INFO_ENC(kind, kind_flag, vlen) \ - ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN)) -#define BTF_TYPE_ENC(name, info, size_or_type) \ - (name), (info), (size_or_type) -#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \ - ((encoding) << 24 | (bits_offset) << 16 | (nr_bits)) -#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \ - BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \ - BTF_INT_ENC(encoding, bits_offset, bits) -#define BTF_MEMBER_ENC(name, type, bits_offset) \ - (name), (type), (bits_offset) + struct btf_header hdr = { + .magic = BTF_MAGIC, + .version = BTF_VERSION, + .hdr_len = sizeof(struct btf_header), + .type_len = types_len, + .str_off = types_len, + .str_len = str_len, + }; + int btf_fd, btf_len; + __u8 *raw_btf; - const char btf_str_sec[] = "\0bpf_spin_lock\0val\0cnt\0l"; + btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len; + raw_btf = malloc(btf_len); + if (!raw_btf) + return -ENOMEM; + + memcpy(raw_btf, &hdr, sizeof(hdr)); + memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len); + memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len); + + btf_fd = bpf_load_btf(raw_btf, btf_len, NULL, 0, false); + if (btf_fd < 0) { + free(raw_btf); + return 0; + } + + close(btf_fd); + free(raw_btf); + return 1; +} + +static int load_sk_storage_btf(void) +{ + const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l"; /* struct bpf_spin_lock { * int val; * }; @@ -155,7 +178,7 @@ static int load_btf(void) * struct bpf_spin_lock l; * }; */ - __u32 btf_raw_types[] = { + __u32 types[] = { /* int */ BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ /* struct bpf_spin_lock */ /* [2] */ @@ -166,23 +189,9 @@ static int load_btf(void) BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */ BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */ }; - struct btf_header btf_hdr = { - .magic = BTF_MAGIC, - .version = BTF_VERSION, - .hdr_len = sizeof(struct btf_header), - .type_len = sizeof(btf_raw_types), - .str_off = sizeof(btf_raw_types), - .str_len = sizeof(btf_str_sec), - }; - __u8 raw_btf[sizeof(struct btf_header) + sizeof(btf_raw_types) + - sizeof(btf_str_sec)]; - memcpy(raw_btf, &btf_hdr, sizeof(btf_hdr)); - memcpy(raw_btf + sizeof(btf_hdr), btf_raw_types, sizeof(btf_raw_types)); - memcpy(raw_btf + sizeof(btf_hdr) + sizeof(btf_raw_types), - btf_str_sec, sizeof(btf_str_sec)); - - return bpf_load_btf(raw_btf, sizeof(raw_btf), 0, 0, 0); + return libbpf__probe_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs)); } bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex) @@ -222,7 +231,7 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex) value_size = 8; max_entries = 0; map_flags = BPF_F_NO_PREALLOC; - btf_fd = load_btf(); + btf_fd = load_sk_storage_btf(); if (btf_fd < 0) return false; break;