libbpf_internal.h

  1/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
  2
  3/*
  4 * Internal libbpf helpers.
  5 *
  6 * Copyright (c) 2019 Facebook
  7 */
  8
  9#ifndef __LIBBPF_LIBBPF_INTERNAL_H
 10#define __LIBBPF_LIBBPF_INTERNAL_H
 11
 12#include <stdlib.h>
 13#include <byteswap.h>
 14#include <limits.h>
 15#include <errno.h>
 16#include <linux/err.h>
 17#include <fcntl.h>
 18#include <unistd.h>
 19#include <sys/syscall.h>
 20#include <libelf.h>
 21#include "relo_core.h"
 22
 23/* Android's libc doesn't support AT_EACCESS in faccessat() implementation
 24 * ([0]), and just returns -EINVAL even if file exists and is accessible.
 25 * See [1] for issues caused by this.
 26 *
 27 * So just redefine it to 0 on Android.
 28 *
 29 * [0] https://android.googlesource.com/platform/bionic/+/refs/heads/android13-release/libc/bionic/faccessat.cpp#50
 30 * [1] https://github.com/libbpf/libbpf-bootstrap/issues/250#issuecomment-1911324250
 31 */
 32#ifdef __ANDROID__
 33#undef AT_EACCESS
 34#define AT_EACCESS 0
 35#endif
 36
 37/* make sure libbpf doesn't use kernel-only integer typedefs */
 38#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
 39
 40/* prevent accidental re-addition of reallocarray() */
 41#pragma GCC poison reallocarray
 42
 43#include "libbpf.h"
 44#include "btf.h"
 45
 46#ifndef EM_BPF
 47#define EM_BPF 247
 48#endif
 49
 50#ifndef R_BPF_64_64
 51#define R_BPF_64_64 1
 52#endif
 53#ifndef R_BPF_64_ABS64
 54#define R_BPF_64_ABS64 2
 55#endif
 56#ifndef R_BPF_64_ABS32
 57#define R_BPF_64_ABS32 3
 58#endif
 59#ifndef R_BPF_64_32
 60#define R_BPF_64_32 10
 61#endif
 62
 63#ifndef SHT_LLVM_ADDRSIG
 64#define SHT_LLVM_ADDRSIG 0x6FFF4C03
 65#endif
 66
 67/* if libelf is old and doesn't support mmap(), fall back to read() */
 68#ifndef ELF_C_READ_MMAP
 69#define ELF_C_READ_MMAP ELF_C_READ
 70#endif
 71
 72/* Older libelf all end up in this expression, for both 32 and 64 bit */
 73#ifndef ELF64_ST_VISIBILITY
 74#define ELF64_ST_VISIBILITY(o) ((o) & 0x03)
 75#endif
 76
 77#define JUMPTABLES_SEC ".jumptables"
 78
 79#define BTF_INFO_ENC(kind, kind_flag, vlen) \
 80	((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
 81#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
 82#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
 83	((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
 84#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
 85	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
 86	BTF_INT_ENC(encoding, bits_offset, bits)
 87#define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
 88#define BTF_PARAM_ENC(name, type) (name), (type)
 89#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
 90#define BTF_TYPE_FLOAT_ENC(name, sz) \
 91	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_FLOAT, 0, 0), sz)
 92#define BTF_TYPE_DECL_TAG_ENC(value, type, component_idx) \
 93	BTF_TYPE_ENC(value, BTF_INFO_ENC(BTF_KIND_DECL_TAG, 0, 0), type), (component_idx)
 94#define BTF_TYPE_TYPE_TAG_ENC(value, type) \
 95	BTF_TYPE_ENC(value, BTF_INFO_ENC(BTF_KIND_TYPE_TAG, 0, 0), type)
 96
 97#ifndef likely
 98#define likely(x) __builtin_expect(!!(x), 1)
 99#endif
100#ifndef unlikely
101#define unlikely(x) __builtin_expect(!!(x), 0)
102#endif
103#ifndef min
104# define min(x, y) ((x) < (y) ? (x) : (y))
105#endif
106#ifndef max
107# define max(x, y) ((x) < (y) ? (y) : (x))
108#endif
109#ifndef offsetofend
110# define offsetofend(TYPE, FIELD) \
111	(offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
112#endif
113#ifndef __alias
114#define __alias(symbol) __attribute__((alias(#symbol)))
115#endif
116
117/* Check whether a string `str` has prefix `pfx`, regardless if `pfx` is
118 * a string literal known at compilation time or char * pointer known only at
119 * runtime.
120 */
121#define str_has_pfx(str, pfx) \
122	(strncmp(str, pfx, __builtin_constant_p(pfx) ? sizeof(pfx) - 1 : strlen(pfx)) == 0)
123
124/* suffix check */
125static inline bool str_has_sfx(const char *str, const char *sfx)
126{
127	size_t str_len = strlen(str);
128	size_t sfx_len = strlen(sfx);
129
130	if (sfx_len > str_len)
131		return false;
132	return strcmp(str + str_len - sfx_len, sfx) == 0;
133}
134
135/* Symbol versioning is different between static and shared library.
136 * Properly versioned symbols are needed for shared library, but
137 * only the symbol of the new version is needed for static library.
138 * Starting with GNU C 10, use symver attribute instead of .symver assembler
139 * directive, which works better with GCC LTO builds.
140 */
141#if defined(SHARED) && defined(__GNUC__) && __GNUC__ >= 10
142
143#define DEFAULT_VERSION(internal_name, api_name, version) \
144	__attribute__((symver(#api_name "@@" #version)))
145#define COMPAT_VERSION(internal_name, api_name, version) \
146	__attribute__((symver(#api_name "@" #version)))
147
148#elif defined(SHARED)
149
150#define COMPAT_VERSION(internal_name, api_name, version) \
151	asm(".symver " #internal_name "," #api_name "@" #version);
152#define DEFAULT_VERSION(internal_name, api_name, version) \
153	asm(".symver " #internal_name "," #api_name "@@" #version);
154
155#else /* !SHARED */
156
157#define COMPAT_VERSION(internal_name, api_name, version)
158#define DEFAULT_VERSION(internal_name, api_name, version) \
159	extern typeof(internal_name) api_name \
160	__attribute__((alias(#internal_name)));
161
162#endif
163
164extern void libbpf_print(enum libbpf_print_level level,
165			 const char *format, ...)
166	__attribute__((format(printf, 2, 3)));
167
168#define __pr(level, fmt, ...)	\
169do {				\
170	libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__);	\
171} while (0)
172
173#define pr_warn(fmt, ...)	__pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
174#define pr_info(fmt, ...)	__pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
175#define pr_debug(fmt, ...)	__pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
176
177/**
178 * @brief **libbpf_errstr()** returns string corresponding to numeric errno
179 * @param err negative numeric errno
180 * @return pointer to string representation of the errno, that is invalidated
181 * upon the next call.
182 */
183const char *libbpf_errstr(int err);
184
185#define errstr(err) libbpf_errstr(err)
186
187#ifndef __has_builtin
188#define __has_builtin(x) 0
189#endif
190
191struct bpf_link {
192	int (*detach)(struct bpf_link *link);
193	void (*dealloc)(struct bpf_link *link);
194	char *pin_path;		/* NULL, if not pinned */
195	int fd;			/* hook FD, -1 if not applicable */
196	bool disconnected;
197};
198
199/*
200 * Re-implement glibc's reallocarray() for libbpf internal-only use.
201 * reallocarray(), unfortunately, is not available in all versions of glibc,
202 * so requires extra feature detection and using reallocarray() stub from
203 * <tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates
204 * build of libbpf unnecessarily and is just a maintenance burden. Instead,
205 * it's trivial to implement libbpf-specific internal version and use it
206 * throughout libbpf.
207 */
208static inline void *libbpf_reallocarray(void *ptr, size_t nmemb, size_t size)
209{
210	size_t total;
211
212#if __has_builtin(__builtin_mul_overflow)
213	if (unlikely(__builtin_mul_overflow(nmemb, size, &total)))
214		return NULL;
215#else
216	if (size == 0 || nmemb > ULONG_MAX / size)
217		return NULL;
218	total = nmemb * size;
219#endif
220	return realloc(ptr, total);
221}
222
223/* Copy up to sz - 1 bytes from zero-terminated src string and ensure that dst
224 * is zero-terminated string no matter what (unless sz == 0, in which case
225 * it's a no-op). It's conceptually close to FreeBSD's strlcpy(), but differs
226 * in what is returned. Given this is internal helper, it's trivial to extend
227 * this, when necessary. Use this instead of strncpy inside libbpf source code.
228 */
229static inline void libbpf_strlcpy(char *dst, const char *src, size_t sz)
230{
231	size_t i;
232
233	if (sz == 0)
234		return;
235
236	sz--;
237	for (i = 0; i < sz && src[i]; i++)
238		dst[i] = src[i];
239	dst[i] = '\0';
240}
241
242__u32 get_kernel_version(void);
243
244struct btf;
245struct btf_type;
246
247struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id);
248const char *btf_kind_str(const struct btf_type *t);
249const struct btf_type *skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
250const struct btf_header *btf_header(const struct btf *btf);
251void btf_set_base_btf(struct btf *btf, const struct btf *base_btf);
252int btf_relocate(struct btf *btf, const struct btf *base_btf, __u32 **id_map);
253
254static inline enum btf_func_linkage btf_func_linkage(const struct btf_type *t)
255{
256	return (enum btf_func_linkage)(int)btf_vlen(t);
257}
258
259static inline __u32 btf_type_info(int kind, int vlen, int kflag)
260{
261	return (kflag << 31) | (kind << 24) | vlen;
262}
263
264enum map_def_parts {
265	MAP_DEF_MAP_TYPE	= 0x001,
266	MAP_DEF_KEY_TYPE	= 0x002,
267	MAP_DEF_KEY_SIZE	= 0x004,
268	MAP_DEF_VALUE_TYPE	= 0x008,
269	MAP_DEF_VALUE_SIZE	= 0x010,
270	MAP_DEF_MAX_ENTRIES	= 0x020,
271	MAP_DEF_MAP_FLAGS	= 0x040,
272	MAP_DEF_NUMA_NODE	= 0x080,
273	MAP_DEF_PINNING		= 0x100,
274	MAP_DEF_INNER_MAP	= 0x200,
275	MAP_DEF_MAP_EXTRA	= 0x400,
276
277	MAP_DEF_ALL		= 0x7ff, /* combination of all above */
278};
279
280struct btf_map_def {
281	enum map_def_parts parts;
282	__u32 map_type;
283	__u32 key_type_id;
284	__u32 key_size;
285	__u32 value_type_id;
286	__u32 value_size;
287	__u32 max_entries;
288	__u32 map_flags;
289	__u32 numa_node;
290	__u32 pinning;
291	__u64 map_extra;
292};
293
294int parse_btf_map_def(const char *map_name, struct btf *btf,
295		      const struct btf_type *def_t, bool strict,
296		      struct btf_map_def *map_def, struct btf_map_def *inner_def);
297
298void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
299		     size_t cur_cnt, size_t max_cnt, size_t add_cnt);
300int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt);
301
302static inline bool libbpf_is_mem_zeroed(const char *p, ssize_t len)
303{
304	while (len > 0) {
305		if (*p)
306			return false;
307		p++;
308		len--;
309	}
310	return true;
311}
312
313static inline bool libbpf_validate_opts(const char *opts,
314					size_t opts_sz, size_t user_sz,
315					const char *type_name)
316{
317	if (user_sz < sizeof(size_t)) {
318		pr_warn("%s size (%zu) is too small\n", type_name, user_sz);
319		return false;
320	}
321	if (!libbpf_is_mem_zeroed(opts + opts_sz, (ssize_t)user_sz - opts_sz)) {
322		pr_warn("%s has non-zero extra bytes\n", type_name);
323		return false;
324	}
325	return true;
326}
327
328#define OPTS_VALID(opts, type)						      \
329	(!(opts) || libbpf_validate_opts((const char *)opts,		      \
330					 offsetofend(struct type,	      \
331						     type##__last_field),     \
332					 (opts)->sz, #type))
333#define OPTS_HAS(opts, field) \
334	((opts) && opts->sz >= offsetofend(typeof(*(opts)), field))
335#define OPTS_GET(opts, field, fallback_value) \
336	(OPTS_HAS(opts, field) ? (opts)->field : fallback_value)
337#define OPTS_SET(opts, field, value)		\
338	do {					\
339		if (OPTS_HAS(opts, field))	\
340			(opts)->field = value;	\
341	} while (0)
342
343#define OPTS_ZEROED(opts, last_nonzero_field)				      \
344({									      \
345	ssize_t __off = offsetofend(typeof(*(opts)), last_nonzero_field);     \
346	!(opts) || libbpf_is_mem_zeroed((const void *)opts + __off,	      \
347					(opts)->sz - __off);		      \
348})
349
350enum kern_feature_id {
351	/* v4.14: kernel support for program & map names. */
352	FEAT_PROG_NAME,
353	/* v5.2: kernel support for global data sections. */
354	FEAT_GLOBAL_DATA,
355	/* BTF support */
356	FEAT_BTF,
357	/* BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO support */
358	FEAT_BTF_FUNC,
359	/* BTF_KIND_VAR and BTF_KIND_DATASEC support */
360	FEAT_BTF_DATASEC,
361	/* BTF_FUNC_GLOBAL is supported */
362	FEAT_BTF_GLOBAL_FUNC,
363	/* BPF_F_MMAPABLE is supported for arrays */
364	FEAT_ARRAY_MMAP,
365	/* kernel support for expected_attach_type in BPF_PROG_LOAD */
366	FEAT_EXP_ATTACH_TYPE,
367	/* bpf_probe_read_{kernel,user}[_str] helpers */
368	FEAT_PROBE_READ_KERN,
369	/* BPF_PROG_BIND_MAP is supported */
370	FEAT_PROG_BIND_MAP,
371	/* Kernel support for module BTFs */
372	FEAT_MODULE_BTF,
373	/* BTF_KIND_FLOAT support */
374	FEAT_BTF_FLOAT,
375	/* BPF perf link support */
376	FEAT_PERF_LINK,
377	/* BTF_KIND_DECL_TAG support */
378	FEAT_BTF_DECL_TAG,
379	/* BTF_KIND_TYPE_TAG support */
380	FEAT_BTF_TYPE_TAG,
381	/* memcg-based accounting for BPF maps and progs */
382	FEAT_MEMCG_ACCOUNT,
383	/* BPF cookie (bpf_get_attach_cookie() BPF helper) support */
384	FEAT_BPF_COOKIE,
385	/* BTF_KIND_ENUM64 support and BTF_KIND_ENUM kflag support */
386	FEAT_BTF_ENUM64,
387	/* Kernel uses syscall wrapper (CONFIG_ARCH_HAS_SYSCALL_WRAPPER) */
388	FEAT_SYSCALL_WRAPPER,
389	/* BPF multi-uprobe link support */
390	FEAT_UPROBE_MULTI_LINK,
391	/* Kernel supports arg:ctx tag (__arg_ctx) for global subprogs natively */
392	FEAT_ARG_CTX_TAG,
393	/* Kernel supports '?' at the front of datasec names */
394	FEAT_BTF_QMARK_DATASEC,
395	__FEAT_CNT,
396};
397
398enum kern_feature_result {
399	FEAT_UNKNOWN = 0,
400	FEAT_SUPPORTED = 1,
401	FEAT_MISSING = 2,
402};
403
404struct kern_feature_cache {
405	enum kern_feature_result res[__FEAT_CNT];
406	int token_fd;
407};
408
409bool feat_supported(struct kern_feature_cache *cache, enum kern_feature_id feat_id);
410bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id);
411
412int probe_kern_syscall_wrapper(int token_fd);
413int probe_memcg_account(int token_fd);
414int bump_rlimit_memlock(void);
415
416int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz);
417int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
418int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
419			 const char *str_sec, size_t str_len,
420			 int token_fd);
421int btf_load_into_kernel(struct btf *btf,
422			 char *log_buf, size_t log_sz, __u32 log_level,
423			 int token_fd);
424struct btf *btf_load_from_kernel(__u32 id, struct btf *base_btf, int token_fd);
425
426struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf);
427void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,
428				const char **prefix, int *kind);
429
430struct btf_ext_info {
431	/*
432	 * info points to the individual info section (e.g. func_info and
433	 * line_info) from the .BTF.ext. It does not include the __u32 rec_size.
434	 */
435	void *info;
436	__u32 rec_size;
437	__u32 len;
438	/* optional (maintained internally by libbpf) mapping between .BTF.ext
439	 * section and corresponding ELF section. This is used to join
440	 * information like CO-RE relocation records with corresponding BPF
441	 * programs defined in ELF sections
442	 */
443	__u32 *sec_idxs;
444	int sec_cnt;
445};
446
447#define for_each_btf_ext_sec(seg, sec)					\
448	for (sec = (seg)->info;						\
449	     (void *)sec < (seg)->info + (seg)->len;			\
450	     sec = (void *)sec + sizeof(struct btf_ext_info_sec) +	\
451		   (seg)->rec_size * sec->num_info)
452
453#define for_each_btf_ext_rec(seg, sec, i, rec)				\
454	for (i = 0, rec = (void *)&(sec)->data;				\
455	     i < (sec)->num_info;					\
456	     i++, rec = (void *)rec + (seg)->rec_size)
457
458/*
459 * The .BTF.ext ELF section layout defined as
460 *   struct btf_ext_header
461 *   func_info subsection
462 *
463 * The func_info subsection layout:
464 *   record size for struct bpf_func_info in the func_info subsection
465 *   struct btf_ext_info_sec for section #1
466 *   a list of bpf_func_info records for section #1
467 *     where struct bpf_func_info mimics one in include/uapi/linux/bpf.h
468 *     but may not be identical
469 *   struct btf_ext_info_sec for section #2
470 *   a list of bpf_func_info records for section #2
471 *   ......
472 *
473 * Note that the bpf_func_info record size in .BTF.ext may not
474 * be the same as the one defined in include/uapi/linux/bpf.h.
475 * The loader should ensure that record_size meets minimum
476 * requirement and pass the record as is to the kernel. The
477 * kernel will handle the func_info properly based on its contents.
478 */
479struct btf_ext_header {
480	__u16	magic;
481	__u8	version;
482	__u8	flags;
483	__u32	hdr_len;
484
485	/* All offsets are in bytes relative to the end of this header */
486	__u32	func_info_off;
487	__u32	func_info_len;
488	__u32	line_info_off;
489	__u32	line_info_len;
490
491	/* optional part of .BTF.ext header */
492	__u32	core_relo_off;
493	__u32	core_relo_len;
494};
495
496struct btf_ext {
497	union {
498		struct btf_ext_header *hdr;
499		void *data;
500	};
501	void *data_swapped;
502	bool swapped_endian;
503	struct btf_ext_info func_info;
504	struct btf_ext_info line_info;
505	struct btf_ext_info core_relo_info;
506	__u32 data_size;
507};
508
509struct btf_ext_info_sec {
510	__u32	sec_name_off;
511	__u32	num_info;
512	/* Followed by num_info * record_size number of bytes */
513	__u8	data[];
514};
515
516/* The minimum bpf_func_info checked by the loader */
517struct bpf_func_info_min {
518	__u32   insn_off;
519	__u32   type_id;
520};
521
522/* The minimum bpf_line_info checked by the loader */
523struct bpf_line_info_min {
524	__u32	insn_off;
525	__u32	file_name_off;
526	__u32	line_off;
527	__u32	line_col;
528};
529
530/* Functions to byte-swap info records */
531
532typedef void (*info_rec_bswap_fn)(void *);
533
534static inline void bpf_func_info_bswap(struct bpf_func_info *i)
535{
536	i->insn_off = bswap_32(i->insn_off);
537	i->type_id = bswap_32(i->type_id);
538}
539
540static inline void bpf_line_info_bswap(struct bpf_line_info *i)
541{
542	i->insn_off = bswap_32(i->insn_off);
543	i->file_name_off = bswap_32(i->file_name_off);
544	i->line_off = bswap_32(i->line_off);
545	i->line_col = bswap_32(i->line_col);
546}
547
548static inline void bpf_core_relo_bswap(struct bpf_core_relo *i)
549{
550	i->insn_off = bswap_32(i->insn_off);
551	i->type_id = bswap_32(i->type_id);
552	i->access_str_off = bswap_32(i->access_str_off);
553	i->kind = bswap_32(i->kind);
554}
555
556enum btf_field_iter_kind {
557	BTF_FIELD_ITER_IDS,
558	BTF_FIELD_ITER_STRS,
559};
560
561struct btf_field_desc {
562	/* once-per-type offsets */
563	int t_off_cnt, t_offs[2];
564	/* member struct size, or zero, if no members */
565	int m_sz;
566	/* repeated per-member offsets */
567	int m_off_cnt, m_offs[1];
568};
569
570struct btf_field_iter {
571	struct btf_field_desc desc;
572	void *p;
573	int m_idx;
574	int off_idx;
575	int vlen;
576};
577
578int btf_field_iter_init(struct btf_field_iter *it, struct btf_type *t, enum btf_field_iter_kind iter_kind);
579__u32 *btf_field_iter_next(struct btf_field_iter *it);
580
581typedef int (*type_id_visit_fn)(__u32 *type_id, void *ctx);
582typedef int (*str_off_visit_fn)(__u32 *str_off, void *ctx);
583int btf_ext_visit_type_ids(struct btf_ext *btf_ext, type_id_visit_fn visit, void *ctx);
584int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void *ctx);
585__s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name,
586				 __u32 kind);
587
588/* handle direct returned errors */
589static inline int libbpf_err(int ret)
590{
591	if (ret < 0)
592		errno = -ret;
593	return ret;
594}
595
596/* handle errno-based (e.g., syscall or libc) errors according to libbpf's
597 * strict mode settings
598 */
599static inline int libbpf_err_errno(int ret)
600{
601	/* errno is already assumed to be set on error */
602	return ret < 0 ? -errno : ret;
603}
604
605/* handle error for pointer-returning APIs, err is assumed to be < 0 always */
606static inline void *libbpf_err_ptr(int err)
607{
608	/* set errno on error, this doesn't break anything */
609	errno = -err;
610	return NULL;
611}
612
613/* handle pointer-returning APIs' error handling */
614static inline void *libbpf_ptr(void *ret)
615{
616	/* set errno on error, this doesn't break anything */
617	if (IS_ERR(ret))
618		errno = -PTR_ERR(ret);
619
620	return IS_ERR(ret) ? NULL : ret;
621}
622
623static inline bool str_is_empty(const char *s)
624{
625	return !s || !s[0];
626}
627
628static inline bool is_ldimm64_insn(struct bpf_insn *insn)
629{
630	return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
631}
632
633static inline void bpf_insn_bswap(struct bpf_insn *insn)
634{
635	__u8 tmp_reg = insn->dst_reg;
636
637	insn->dst_reg = insn->src_reg;
638	insn->src_reg = tmp_reg;
639	insn->off = bswap_16(insn->off);
640	insn->imm = bswap_32(insn->imm);
641}
642
643/* Unconditionally dup FD, ensuring it doesn't use [0, 2] range.
644 * Original FD is not closed or altered in any other way.
645 * Preserves original FD value, if it's invalid (negative).
646 */
647static inline int dup_good_fd(int fd)
648{
649	if (fd < 0)
650		return fd;
651	return fcntl(fd, F_DUPFD_CLOEXEC, 3);
652}
653
654/* if fd is stdin, stdout, or stderr, dup to a fd greater than 2
655 * Takes ownership of the fd passed in, and closes it if calling
656 * fcntl(fd, F_DUPFD_CLOEXEC, 3).
657 */
658static inline int ensure_good_fd(int fd)
659{
660	int old_fd = fd, saved_errno;
661
662	if (fd < 0)
663		return fd;
664	if (fd < 3) {
665		fd = dup_good_fd(fd);
666		saved_errno = errno;
667		close(old_fd);
668		errno = saved_errno;
669		if (fd < 0) {
670			pr_warn("failed to dup FD %d to FD > 2: %d\n", old_fd, -saved_errno);
671			errno = saved_errno;
672		}
673	}
674	return fd;
675}
676
677static inline int sys_dup3(int oldfd, int newfd, int flags)
678{
679	return syscall(__NR_dup3, oldfd, newfd, flags);
680}
681
682/* Some versions of Android don't provide memfd_create() in their libc
683 * implementation, so avoid complications and just go straight to Linux
684 * syscall.
685 */
686static inline int sys_memfd_create(const char *name, unsigned flags)
687{
688	return syscall(__NR_memfd_create, name, flags);
689}
690
691/* Point *fixed_fd* to the same file that *tmp_fd* points to.
692 * Regardless of success, *tmp_fd* is closed.
693 * Whatever *fixed_fd* pointed to is closed silently.
694 */
695static inline int reuse_fd(int fixed_fd, int tmp_fd)
696{
697	int err;
698
699	err = sys_dup3(tmp_fd, fixed_fd, O_CLOEXEC);
700	err = err < 0 ? -errno : 0;
701	close(tmp_fd); /* clean up temporary FD */
702	return err;
703}
704
705/* The following two functions are exposed to bpftool */
706int bpf_core_add_cands(struct bpf_core_cand *local_cand,
707		       size_t local_essent_len,
708		       const struct btf *targ_btf,
709		       const char *targ_btf_name,
710		       int targ_start_id,
711		       struct bpf_core_cand_list *cands);
712void bpf_core_free_cands(struct bpf_core_cand_list *cands);
713
714struct usdt_manager *usdt_manager_new(struct bpf_object *obj);
715void usdt_manager_free(struct usdt_manager *man);
716struct bpf_link * usdt_manager_attach_usdt(struct usdt_manager *man,
717					   const struct bpf_program *prog,
718					   pid_t pid, const char *path,
719					   const char *usdt_provider, const char *usdt_name,
720					   __u64 usdt_cookie);
721
722static inline bool is_pow_of_2(size_t x)
723{
724	return x && (x & (x - 1)) == 0;
725}
726
727static inline __u32 ror32(__u32 v, int bits)
728{
729	return (v >> bits) | (v << (32 - bits));
730}
731
732#define PROG_LOAD_ATTEMPTS 5
733int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts);
734
735bool glob_match(const char *str, const char *pat);
736
737long elf_find_func_offset(Elf *elf, const char *binary_path, const char *name);
738long elf_find_func_offset_from_file(const char *binary_path, const char *name);
739
740struct elf_fd {
741	Elf *elf;
742	int fd;
743};
744
745int elf_open(const char *binary_path, struct elf_fd *elf_fd);
746void elf_close(struct elf_fd *elf_fd);
747
748int elf_resolve_syms_offsets(const char *binary_path, int cnt,
749			     const char **syms, unsigned long **poffsets,
750			     int st_type);
751int elf_resolve_pattern_offsets(const char *binary_path, const char *pattern,
752				 unsigned long **poffsets, size_t *pcnt);
753
754int probe_fd(int fd);
755
756#define SHA256_DIGEST_LENGTH 32
757#define SHA256_DWORD_SIZE SHA256_DIGEST_LENGTH / sizeof(__u64)
758
759void libbpf_sha256(const void *data, size_t len, __u8 out[SHA256_DIGEST_LENGTH]);
760#endif /* __LIBBPF_LIBBPF_INTERNAL_H */