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libbpf_internal.h
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/* 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 #include <stdlib.h> #include <limits.h> /* make sure libbpf doesn't use kernel-only integer typedefs */ #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64 /* prevent accidental re-addition of reallocarray() */ #pragma GCC poison reallocarray #include "libbpf.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) #ifndef likely #define likely(x) __builtin_expect(!!(x), 1) #endif #ifndef unlikely #define unlikely(x) __builtin_expect(!!(x), 0) #endif #ifndef min # define min(x, y) ((x) < (y) ? (x) : (y)) #endif #ifndef max # define max(x, y) ((x) < (y) ? (y) : (x)) #endif #ifndef offsetofend # define offsetofend(TYPE, FIELD) \ (offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD)) #endif /* Symbol versioning is different between static and shared library. * Properly versioned symbols are needed for shared library, but * only the symbol of the new version is needed for static library. */ #ifdef SHARED # define COMPAT_VERSION(internal_name, api_name, version) \ asm(".symver " #internal_name "," #api_name "@" #version); # define DEFAULT_VERSION(internal_name, api_name, version) \ asm(".symver " #internal_name "," #api_name "@@" #version); #else # define COMPAT_VERSION(internal_name, api_name, version) # define DEFAULT_VERSION(internal_name, api_name, version) \ extern typeof(internal_name) api_name \ __attribute__((alias(#internal_name))); #endif extern void libbpf_print(enum libbpf_print_level level, const char *format, ...) __attribute__((format(printf, 2, 3))); #define __pr(level, fmt, ...) \ do { \ libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \ } while (0) #define pr_warn(fmt, ...) __pr(LIBBPF_WARN, fmt, ##__VA_ARGS__) #define pr_info(fmt, ...) __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__) #define pr_debug(fmt, ...) __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__) #ifndef __has_builtin #define __has_builtin(x) 0 #endif /* * Re-implement glibc's reallocarray() for libbpf internal-only use. * reallocarray(), unfortunately, is not available in all versions of glibc, * so requires extra feature detection and using reallocarray() stub from * <tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates * build of libbpf unnecessarily and is just a maintenance burden. Instead, * it's trivial to implement libbpf-specific internal version and use it * throughout libbpf. */ static inline void *libbpf_reallocarray(void *ptr, size_t nmemb, size_t size) { size_t total; #if __has_builtin(__builtin_mul_overflow) if (unlikely(__builtin_mul_overflow(nmemb, size, &total))) return NULL; #else if (size == 0 || nmemb > ULONG_MAX / size) return NULL; total = nmemb * size; #endif return realloc(ptr, total); } static inline bool libbpf_validate_opts(const char *opts, size_t opts_sz, size_t user_sz, const char *type_name) { if (user_sz < sizeof(size_t)) { pr_warn("%s size (%zu) is too small\n", type_name, user_sz); return false; } if (user_sz > opts_sz) { size_t i; for (i = opts_sz; i < user_sz; i++) { if (opts[i]) { pr_warn("%s has non-zero extra bytes\n", type_name); return false; } } } return true; } #define OPTS_VALID(opts, type) \ (!(opts) || libbpf_validate_opts((const char *)opts, \ offsetofend(struct type, \ type##__last_field), \ (opts)->sz, #type)) #define OPTS_HAS(opts, field) \ ((opts) && opts->sz >= offsetofend(typeof(*(opts)), field)) #define OPTS_GET(opts, field, fallback_value) \ (OPTS_HAS(opts, field) ? (opts)->field : fallback_value) int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz); int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz); int libbpf__load_raw_btf(const char *raw_types, size_t types_len, const char *str_sec, size_t str_len); int bpf_object__section_size(const struct bpf_object *obj, const char *name, __u32 *size); int bpf_object__variable_offset(const struct bpf_object *obj, const char *name, __u32 *off); struct btf_ext_info { /* * info points to the individual info section (e.g. func_info and * line_info) from the .BTF.ext. It does not include the __u32 rec_size. */ void *info; __u32 rec_size; __u32 len; }; #define for_each_btf_ext_sec(seg, sec) \ for (sec = (seg)->info; \ (void *)sec < (seg)->info + (seg)->len; \ sec = (void *)sec + sizeof(struct btf_ext_info_sec) + \ (seg)->rec_size * sec->num_info) #define for_each_btf_ext_rec(seg, sec, i, rec) \ for (i = 0, rec = (void *)&(sec)->data; \ i < (sec)->num_info; \ i++, rec = (void *)rec + (seg)->rec_size) /* * The .BTF.ext ELF section layout defined as * struct btf_ext_header * func_info subsection * * The func_info subsection layout: * record size for struct bpf_func_info in the func_info subsection * struct btf_sec_func_info for section #1 * a list of bpf_func_info records for section #1 * where struct bpf_func_info mimics one in include/uapi/linux/bpf.h * but may not be identical * struct btf_sec_func_info for section #2 * a list of bpf_func_info records for section #2 * ...... * * Note that the bpf_func_info record size in .BTF.ext may not * be the same as the one defined in include/uapi/linux/bpf.h. * The loader should ensure that record_size meets minimum * requirement and pass the record as is to the kernel. The * kernel will handle the func_info properly based on its contents. */ struct btf_ext_header { __u16 magic; __u8 version; __u8 flags; __u32 hdr_len; /* All offsets are in bytes relative to the end of this header */ __u32 func_info_off; __u32 func_info_len; __u32 line_info_off; __u32 line_info_len; /* optional part of .BTF.ext header */ __u32 core_relo_off; __u32 core_relo_len; }; struct btf_ext { union { struct btf_ext_header *hdr; void *data; }; struct btf_ext_info func_info; struct btf_ext_info line_info; struct btf_ext_info core_relo_info; __u32 data_size; }; struct btf_ext_info_sec { __u32 sec_name_off; __u32 num_info; /* Followed by num_info * record_size number of bytes */ __u8 data[]; }; /* The minimum bpf_func_info checked by the loader */ struct bpf_func_info_min { __u32 insn_off; __u32 type_id; }; /* The minimum bpf_line_info checked by the loader */ struct bpf_line_info_min { __u32 insn_off; __u32 file_name_off; __u32 line_off; __u32 line_col; }; /* bpf_core_relo_kind encodes which aspect of captured field/type/enum value * has to be adjusted by relocations. */ enum bpf_core_relo_kind { BPF_FIELD_BYTE_OFFSET = 0, /* field byte offset */ BPF_FIELD_BYTE_SIZE = 1, /* field size in bytes */ BPF_FIELD_EXISTS = 2, /* field existence in target kernel */ BPF_FIELD_SIGNED = 3, /* field signedness (0 - unsigned, 1 - signed) */ BPF_FIELD_LSHIFT_U64 = 4, /* bitfield-specific left bitshift */ BPF_FIELD_RSHIFT_U64 = 5, /* bitfield-specific right bitshift */ BPF_TYPE_ID_LOCAL = 6, /* type ID in local BPF object */ BPF_TYPE_ID_TARGET = 7, /* type ID in target kernel */ BPF_TYPE_EXISTS = 8, /* type existence in target kernel */ BPF_TYPE_SIZE = 9, /* type size in bytes */ BPF_ENUMVAL_EXISTS = 10, /* enum value existence in target kernel */ BPF_ENUMVAL_VALUE = 11, /* enum value integer value */ }; /* The minimum bpf_core_relo checked by the loader * * CO-RE relocation captures the following data: * - insn_off - instruction offset (in bytes) within a BPF program that needs * its insn->imm field to be relocated with actual field info; * - type_id - BTF type ID of the "root" (containing) entity of a relocatable * type or field; * - access_str_off - offset into corresponding .BTF string section. String * interpretation depends on specific relocation kind: * - for field-based relocations, string encodes an accessed field using * a sequence of field and array indices, separated by colon (:). It's * conceptually very close to LLVM's getelementptr ([0]) instruction's * arguments for identifying offset to a field. * - for type-based relocations, strings is expected to be just "0"; * - for enum value-based relocations, string contains an index of enum * value within its enum type; * * Example to provide a better feel. * * struct sample { * int a; * struct { * int b[10]; * }; * }; * * struct sample *s = ...; * int x = &s->a; // encoded as "0:0" (a is field #0) * int y = &s->b[5]; // encoded as "0:1:0:5" (anon struct is field #1, * // b is field #0 inside anon struct, accessing elem #5) * int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array) * * type_id for all relocs in this example will capture BTF type id of * `struct sample`. * * Such relocation is emitted when using __builtin_preserve_access_index() * Clang built-in, passing expression that captures field address, e.g.: * * bpf_probe_read(&dst, sizeof(dst), * __builtin_preserve_access_index(&src->a.b.c)); * * In this case Clang will emit field relocation recording necessary data to * be able to find offset of embedded `a.b.c` field within `src` struct. * * [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction */ struct bpf_core_relo { __u32 insn_off; __u32 type_id; __u32 access_str_off; enum bpf_core_relo_kind kind; }; #endif /* __LIBBPF_LIBBPF_INTERNAL_H */
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