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synced 2024-08-27 11:19:37 +00:00
![Andrii Nakryiko](/assets/img/avatar_default.png)
Instead of using ELF section names as a joining key between .BTF.ext and
corresponding BPF programs, pre-build .BTF.ext section number to ELF
section index mapping during bpf_object__open() and use it later for
matching .BTF.ext information (func/line info or CO-RE relocations) to
their respective BPF programs and subprograms.
This simplifies corresponding joining logic and let's libbpf do
manipulations with BPF program's ELF sections like dropping leading '?'
character for non-autoloaded programs. Original joining logic in
bpf_object__relocate_core() (see relevant comment that's now removed)
was never elegant, so it's a good improvement regardless. But it also
avoids unnecessary internal assumptions about preserving original ELF
section name as BPF program's section name (which was broken when
SEC("?abc") support was added).
Fixes: a3820c4811
("libbpf: Support opting out from autoloading BPF programs declaratively")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220426004511.2691730-5-andrii@kernel.org
583 lines
17 KiB
C
583 lines
17 KiB
C
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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/*
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* Internal libbpf helpers.
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*
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* Copyright (c) 2019 Facebook
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*/
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#ifndef __LIBBPF_LIBBPF_INTERNAL_H
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#define __LIBBPF_LIBBPF_INTERNAL_H
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#include <stdlib.h>
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#include <limits.h>
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#include <errno.h>
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#include <linux/err.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include "libbpf_legacy.h"
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#include "relo_core.h"
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/* make sure libbpf doesn't use kernel-only integer typedefs */
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#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
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/* prevent accidental re-addition of reallocarray() */
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#pragma GCC poison reallocarray
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#include "libbpf.h"
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#include "btf.h"
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#ifndef EM_BPF
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#define EM_BPF 247
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#endif
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#ifndef R_BPF_64_64
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#define R_BPF_64_64 1
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#endif
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#ifndef R_BPF_64_ABS64
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#define R_BPF_64_ABS64 2
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#endif
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#ifndef R_BPF_64_ABS32
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#define R_BPF_64_ABS32 3
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#endif
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#ifndef R_BPF_64_32
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#define R_BPF_64_32 10
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#endif
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#ifndef SHT_LLVM_ADDRSIG
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#define SHT_LLVM_ADDRSIG 0x6FFF4C03
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#endif
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/* if libelf is old and doesn't support mmap(), fall back to read() */
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#ifndef ELF_C_READ_MMAP
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#define ELF_C_READ_MMAP ELF_C_READ
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#endif
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/* Older libelf all end up in this expression, for both 32 and 64 bit */
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#ifndef ELF64_ST_VISIBILITY
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#define ELF64_ST_VISIBILITY(o) ((o) & 0x03)
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#endif
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#define BTF_INFO_ENC(kind, kind_flag, vlen) \
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((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
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#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
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#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
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((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
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#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
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BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
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BTF_INT_ENC(encoding, bits_offset, bits)
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#define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
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#define BTF_PARAM_ENC(name, type) (name), (type)
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#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
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#define BTF_TYPE_FLOAT_ENC(name, sz) \
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BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_FLOAT, 0, 0), sz)
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#define BTF_TYPE_DECL_TAG_ENC(value, type, component_idx) \
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BTF_TYPE_ENC(value, BTF_INFO_ENC(BTF_KIND_DECL_TAG, 0, 0), type), (component_idx)
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#define BTF_TYPE_TYPE_TAG_ENC(value, type) \
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BTF_TYPE_ENC(value, BTF_INFO_ENC(BTF_KIND_TYPE_TAG, 0, 0), type)
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#ifndef likely
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#define likely(x) __builtin_expect(!!(x), 1)
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#endif
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#ifndef unlikely
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#define unlikely(x) __builtin_expect(!!(x), 0)
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#endif
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#ifndef min
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# define min(x, y) ((x) < (y) ? (x) : (y))
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#endif
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#ifndef max
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# define max(x, y) ((x) < (y) ? (y) : (x))
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#endif
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#ifndef offsetofend
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# define offsetofend(TYPE, FIELD) \
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(offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
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#endif
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#ifndef __alias
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#define __alias(symbol) __attribute__((alias(#symbol)))
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#endif
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/* Check whether a string `str` has prefix `pfx`, regardless if `pfx` is
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* a string literal known at compilation time or char * pointer known only at
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* runtime.
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*/
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#define str_has_pfx(str, pfx) \
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(strncmp(str, pfx, __builtin_constant_p(pfx) ? sizeof(pfx) - 1 : strlen(pfx)) == 0)
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/* suffix check */
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static inline bool str_has_sfx(const char *str, const char *sfx)
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{
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size_t str_len = strlen(str);
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size_t sfx_len = strlen(sfx);
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if (sfx_len <= str_len)
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return strcmp(str + str_len - sfx_len, sfx);
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return false;
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}
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/* Symbol versioning is different between static and shared library.
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* Properly versioned symbols are needed for shared library, but
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* only the symbol of the new version is needed for static library.
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* Starting with GNU C 10, use symver attribute instead of .symver assembler
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* directive, which works better with GCC LTO builds.
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*/
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#if defined(SHARED) && defined(__GNUC__) && __GNUC__ >= 10
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#define DEFAULT_VERSION(internal_name, api_name, version) \
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__attribute__((symver(#api_name "@@" #version)))
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#define COMPAT_VERSION(internal_name, api_name, version) \
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__attribute__((symver(#api_name "@" #version)))
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#elif defined(SHARED)
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#define COMPAT_VERSION(internal_name, api_name, version) \
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asm(".symver " #internal_name "," #api_name "@" #version);
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#define DEFAULT_VERSION(internal_name, api_name, version) \
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asm(".symver " #internal_name "," #api_name "@@" #version);
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#else /* !SHARED */
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#define COMPAT_VERSION(internal_name, api_name, version)
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#define DEFAULT_VERSION(internal_name, api_name, version) \
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extern typeof(internal_name) api_name \
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__attribute__((alias(#internal_name)));
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#endif
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extern void libbpf_print(enum libbpf_print_level level,
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const char *format, ...)
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__attribute__((format(printf, 2, 3)));
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#define __pr(level, fmt, ...) \
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do { \
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libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \
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} while (0)
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#define pr_warn(fmt, ...) __pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
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#define pr_info(fmt, ...) __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
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#define pr_debug(fmt, ...) __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
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#ifndef __has_builtin
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#define __has_builtin(x) 0
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#endif
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struct bpf_link {
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int (*detach)(struct bpf_link *link);
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void (*dealloc)(struct bpf_link *link);
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char *pin_path; /* NULL, if not pinned */
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int fd; /* hook FD, -1 if not applicable */
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bool disconnected;
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};
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/*
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* Re-implement glibc's reallocarray() for libbpf internal-only use.
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* reallocarray(), unfortunately, is not available in all versions of glibc,
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* so requires extra feature detection and using reallocarray() stub from
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* <tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates
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* build of libbpf unnecessarily and is just a maintenance burden. Instead,
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* it's trivial to implement libbpf-specific internal version and use it
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* throughout libbpf.
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*/
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static inline void *libbpf_reallocarray(void *ptr, size_t nmemb, size_t size)
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{
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size_t total;
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#if __has_builtin(__builtin_mul_overflow)
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if (unlikely(__builtin_mul_overflow(nmemb, size, &total)))
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return NULL;
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#else
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if (size == 0 || nmemb > ULONG_MAX / size)
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return NULL;
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total = nmemb * size;
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#endif
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return realloc(ptr, total);
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}
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/* Copy up to sz - 1 bytes from zero-terminated src string and ensure that dst
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* is zero-terminated string no matter what (unless sz == 0, in which case
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* it's a no-op). It's conceptually close to FreeBSD's strlcpy(), but differs
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* in what is returned. Given this is internal helper, it's trivial to extend
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* this, when necessary. Use this instead of strncpy inside libbpf source code.
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*/
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static inline void libbpf_strlcpy(char *dst, const char *src, size_t sz)
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{
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size_t i;
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if (sz == 0)
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return;
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sz--;
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for (i = 0; i < sz && src[i]; i++)
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dst[i] = src[i];
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dst[i] = '\0';
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}
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__u32 get_kernel_version(void);
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struct btf;
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struct btf_type;
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struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id);
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const char *btf_kind_str(const struct btf_type *t);
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const struct btf_type *skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
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static inline enum btf_func_linkage btf_func_linkage(const struct btf_type *t)
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{
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return (enum btf_func_linkage)(int)btf_vlen(t);
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}
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static inline __u32 btf_type_info(int kind, int vlen, int kflag)
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{
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return (kflag << 31) | (kind << 24) | vlen;
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}
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enum map_def_parts {
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MAP_DEF_MAP_TYPE = 0x001,
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MAP_DEF_KEY_TYPE = 0x002,
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MAP_DEF_KEY_SIZE = 0x004,
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MAP_DEF_VALUE_TYPE = 0x008,
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MAP_DEF_VALUE_SIZE = 0x010,
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MAP_DEF_MAX_ENTRIES = 0x020,
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MAP_DEF_MAP_FLAGS = 0x040,
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MAP_DEF_NUMA_NODE = 0x080,
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MAP_DEF_PINNING = 0x100,
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MAP_DEF_INNER_MAP = 0x200,
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MAP_DEF_MAP_EXTRA = 0x400,
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MAP_DEF_ALL = 0x7ff, /* combination of all above */
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};
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struct btf_map_def {
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enum map_def_parts parts;
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__u32 map_type;
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__u32 key_type_id;
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__u32 key_size;
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__u32 value_type_id;
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__u32 value_size;
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__u32 max_entries;
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__u32 map_flags;
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__u32 numa_node;
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__u32 pinning;
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__u64 map_extra;
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};
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int parse_btf_map_def(const char *map_name, struct btf *btf,
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const struct btf_type *def_t, bool strict,
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struct btf_map_def *map_def, struct btf_map_def *inner_def);
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void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
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size_t cur_cnt, size_t max_cnt, size_t add_cnt);
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int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt);
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static inline bool libbpf_is_mem_zeroed(const char *p, ssize_t len)
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{
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while (len > 0) {
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if (*p)
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return false;
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p++;
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len--;
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}
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return true;
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}
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static inline bool libbpf_validate_opts(const char *opts,
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size_t opts_sz, size_t user_sz,
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const char *type_name)
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{
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if (user_sz < sizeof(size_t)) {
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pr_warn("%s size (%zu) is too small\n", type_name, user_sz);
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return false;
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}
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if (!libbpf_is_mem_zeroed(opts + opts_sz, (ssize_t)user_sz - opts_sz)) {
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pr_warn("%s has non-zero extra bytes\n", type_name);
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return false;
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}
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return true;
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}
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#define OPTS_VALID(opts, type) \
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(!(opts) || libbpf_validate_opts((const char *)opts, \
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offsetofend(struct type, \
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type##__last_field), \
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(opts)->sz, #type))
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#define OPTS_HAS(opts, field) \
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((opts) && opts->sz >= offsetofend(typeof(*(opts)), field))
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#define OPTS_GET(opts, field, fallback_value) \
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(OPTS_HAS(opts, field) ? (opts)->field : fallback_value)
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#define OPTS_SET(opts, field, value) \
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do { \
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if (OPTS_HAS(opts, field)) \
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(opts)->field = value; \
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} while (0)
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#define OPTS_ZEROED(opts, last_nonzero_field) \
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({ \
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ssize_t __off = offsetofend(typeof(*(opts)), last_nonzero_field); \
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!(opts) || libbpf_is_mem_zeroed((const void *)opts + __off, \
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(opts)->sz - __off); \
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})
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enum kern_feature_id {
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/* v4.14: kernel support for program & map names. */
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FEAT_PROG_NAME,
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/* v5.2: kernel support for global data sections. */
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FEAT_GLOBAL_DATA,
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/* BTF support */
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FEAT_BTF,
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/* BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO support */
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FEAT_BTF_FUNC,
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/* BTF_KIND_VAR and BTF_KIND_DATASEC support */
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FEAT_BTF_DATASEC,
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/* BTF_FUNC_GLOBAL is supported */
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FEAT_BTF_GLOBAL_FUNC,
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/* BPF_F_MMAPABLE is supported for arrays */
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FEAT_ARRAY_MMAP,
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/* kernel support for expected_attach_type in BPF_PROG_LOAD */
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FEAT_EXP_ATTACH_TYPE,
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/* bpf_probe_read_{kernel,user}[_str] helpers */
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FEAT_PROBE_READ_KERN,
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/* BPF_PROG_BIND_MAP is supported */
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FEAT_PROG_BIND_MAP,
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/* Kernel support for module BTFs */
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FEAT_MODULE_BTF,
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/* BTF_KIND_FLOAT support */
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FEAT_BTF_FLOAT,
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/* BPF perf link support */
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FEAT_PERF_LINK,
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/* BTF_KIND_DECL_TAG support */
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FEAT_BTF_DECL_TAG,
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/* BTF_KIND_TYPE_TAG support */
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FEAT_BTF_TYPE_TAG,
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/* memcg-based accounting for BPF maps and progs */
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FEAT_MEMCG_ACCOUNT,
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/* BPF cookie (bpf_get_attach_cookie() BPF helper) support */
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FEAT_BPF_COOKIE,
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__FEAT_CNT,
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};
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int probe_memcg_account(void);
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bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id);
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int bump_rlimit_memlock(void);
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int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz);
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int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
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int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
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const char *str_sec, size_t str_len);
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int btf_load_into_kernel(struct btf *btf, char *log_buf, size_t log_sz, __u32 log_level);
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struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf);
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void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,
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const char **prefix, int *kind);
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struct btf_ext_info {
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/*
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* info points to the individual info section (e.g. func_info and
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* line_info) from the .BTF.ext. It does not include the __u32 rec_size.
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*/
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void *info;
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__u32 rec_size;
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__u32 len;
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/* optional (maintained internally by libbpf) mapping between .BTF.ext
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* section and corresponding ELF section. This is used to join
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* information like CO-RE relocation records with corresponding BPF
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* programs defined in ELF sections
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*/
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__u32 *sec_idxs;
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int sec_cnt;
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};
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#define for_each_btf_ext_sec(seg, sec) \
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for (sec = (seg)->info; \
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(void *)sec < (seg)->info + (seg)->len; \
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sec = (void *)sec + sizeof(struct btf_ext_info_sec) + \
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(seg)->rec_size * sec->num_info)
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#define for_each_btf_ext_rec(seg, sec, i, rec) \
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for (i = 0, rec = (void *)&(sec)->data; \
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i < (sec)->num_info; \
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i++, rec = (void *)rec + (seg)->rec_size)
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/*
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* The .BTF.ext ELF section layout defined as
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* struct btf_ext_header
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* func_info subsection
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*
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* The func_info subsection layout:
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* record size for struct bpf_func_info in the func_info subsection
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* struct btf_sec_func_info for section #1
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* a list of bpf_func_info records for section #1
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* where struct bpf_func_info mimics one in include/uapi/linux/bpf.h
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* but may not be identical
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* struct btf_sec_func_info for section #2
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* a list of bpf_func_info records for section #2
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* ......
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*
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* Note that the bpf_func_info record size in .BTF.ext may not
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* be the same as the one defined in include/uapi/linux/bpf.h.
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* The loader should ensure that record_size meets minimum
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* requirement and pass the record as is to the kernel. The
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* kernel will handle the func_info properly based on its contents.
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*/
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struct btf_ext_header {
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__u16 magic;
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__u8 version;
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__u8 flags;
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__u32 hdr_len;
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/* All offsets are in bytes relative to the end of this header */
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__u32 func_info_off;
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__u32 func_info_len;
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__u32 line_info_off;
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__u32 line_info_len;
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/* optional part of .BTF.ext header */
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|
__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;
|
|
};
|
|
|
|
|
|
typedef int (*type_id_visit_fn)(__u32 *type_id, void *ctx);
|
|
typedef int (*str_off_visit_fn)(__u32 *str_off, void *ctx);
|
|
int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx);
|
|
int btf_type_visit_str_offs(struct btf_type *t, str_off_visit_fn visit, void *ctx);
|
|
int btf_ext_visit_type_ids(struct btf_ext *btf_ext, type_id_visit_fn visit, void *ctx);
|
|
int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void *ctx);
|
|
__s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name,
|
|
__u32 kind);
|
|
|
|
extern enum libbpf_strict_mode libbpf_mode;
|
|
|
|
typedef int (*kallsyms_cb_t)(unsigned long long sym_addr, char sym_type,
|
|
const char *sym_name, void *ctx);
|
|
|
|
int libbpf_kallsyms_parse(kallsyms_cb_t cb, void *arg);
|
|
|
|
/* handle direct returned errors */
|
|
static inline int libbpf_err(int ret)
|
|
{
|
|
if (ret < 0)
|
|
errno = -ret;
|
|
return ret;
|
|
}
|
|
|
|
/* handle errno-based (e.g., syscall or libc) errors according to libbpf's
|
|
* strict mode settings
|
|
*/
|
|
static inline int libbpf_err_errno(int ret)
|
|
{
|
|
if (libbpf_mode & LIBBPF_STRICT_DIRECT_ERRS)
|
|
/* errno is already assumed to be set on error */
|
|
return ret < 0 ? -errno : ret;
|
|
|
|
/* legacy: on error return -1 directly and don't touch errno */
|
|
return ret;
|
|
}
|
|
|
|
/* handle error for pointer-returning APIs, err is assumed to be < 0 always */
|
|
static inline void *libbpf_err_ptr(int err)
|
|
{
|
|
/* set errno on error, this doesn't break anything */
|
|
errno = -err;
|
|
|
|
if (libbpf_mode & LIBBPF_STRICT_CLEAN_PTRS)
|
|
return NULL;
|
|
|
|
/* legacy: encode err as ptr */
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
/* handle pointer-returning APIs' error handling */
|
|
static inline void *libbpf_ptr(void *ret)
|
|
{
|
|
/* set errno on error, this doesn't break anything */
|
|
if (IS_ERR(ret))
|
|
errno = -PTR_ERR(ret);
|
|
|
|
if (libbpf_mode & LIBBPF_STRICT_CLEAN_PTRS)
|
|
return IS_ERR(ret) ? NULL : ret;
|
|
|
|
/* legacy: pass-through original pointer */
|
|
return ret;
|
|
}
|
|
|
|
static inline bool str_is_empty(const char *s)
|
|
{
|
|
return !s || !s[0];
|
|
}
|
|
|
|
static inline bool is_ldimm64_insn(struct bpf_insn *insn)
|
|
{
|
|
return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
|
|
}
|
|
|
|
/* if fd is stdin, stdout, or stderr, dup to a fd greater than 2
|
|
* Takes ownership of the fd passed in, and closes it if calling
|
|
* fcntl(fd, F_DUPFD_CLOEXEC, 3).
|
|
*/
|
|
static inline int ensure_good_fd(int fd)
|
|
{
|
|
int old_fd = fd, saved_errno;
|
|
|
|
if (fd < 0)
|
|
return fd;
|
|
if (fd < 3) {
|
|
fd = fcntl(fd, F_DUPFD_CLOEXEC, 3);
|
|
saved_errno = errno;
|
|
close(old_fd);
|
|
if (fd < 0) {
|
|
pr_warn("failed to dup FD %d to FD > 2: %d\n", old_fd, -saved_errno);
|
|
errno = saved_errno;
|
|
}
|
|
}
|
|
return fd;
|
|
}
|
|
|
|
/* The following two functions are exposed to bpftool */
|
|
int bpf_core_add_cands(struct bpf_core_cand *local_cand,
|
|
size_t local_essent_len,
|
|
const struct btf *targ_btf,
|
|
const char *targ_btf_name,
|
|
int targ_start_id,
|
|
struct bpf_core_cand_list *cands);
|
|
void bpf_core_free_cands(struct bpf_core_cand_list *cands);
|
|
|
|
struct usdt_manager *usdt_manager_new(struct bpf_object *obj);
|
|
void usdt_manager_free(struct usdt_manager *man);
|
|
struct bpf_link * usdt_manager_attach_usdt(struct usdt_manager *man,
|
|
const struct bpf_program *prog,
|
|
pid_t pid, const char *path,
|
|
const char *usdt_provider, const char *usdt_name,
|
|
__u64 usdt_cookie);
|
|
|
|
#endif /* __LIBBPF_LIBBPF_INTERNAL_H */
|