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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /tools/lib/bpf/btf.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tools/lib/bpf/btf.c')
-rw-r--r--tools/lib/bpf/btf.c5025
1 files changed, 5025 insertions, 0 deletions
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
new file mode 100644
index 0000000000..8484b563b5
--- /dev/null
+++ b/tools/lib/bpf/btf.c
@@ -0,0 +1,5025 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2018 Facebook */
+
+#include <byteswap.h>
+#include <endian.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/utsname.h>
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/btf.h>
+#include <gelf.h>
+#include "btf.h"
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+#include "hashmap.h"
+#include "strset.h"
+
+#define BTF_MAX_NR_TYPES 0x7fffffffU
+#define BTF_MAX_STR_OFFSET 0x7fffffffU
+
+static struct btf_type btf_void;
+
+struct btf {
+ /* raw BTF data in native endianness */
+ void *raw_data;
+ /* raw BTF data in non-native endianness */
+ void *raw_data_swapped;
+ __u32 raw_size;
+ /* whether target endianness differs from the native one */
+ bool swapped_endian;
+
+ /*
+ * When BTF is loaded from an ELF or raw memory it is stored
+ * in a contiguous memory block. The hdr, type_data, and, strs_data
+ * point inside that memory region to their respective parts of BTF
+ * representation:
+ *
+ * +--------------------------------+
+ * | Header | Types | Strings |
+ * +--------------------------------+
+ * ^ ^ ^
+ * | | |
+ * hdr | |
+ * types_data-+ |
+ * strs_data------------+
+ *
+ * If BTF data is later modified, e.g., due to types added or
+ * removed, BTF deduplication performed, etc, this contiguous
+ * representation is broken up into three independently allocated
+ * memory regions to be able to modify them independently.
+ * raw_data is nulled out at that point, but can be later allocated
+ * and cached again if user calls btf__raw_data(), at which point
+ * raw_data will contain a contiguous copy of header, types, and
+ * strings:
+ *
+ * +----------+ +---------+ +-----------+
+ * | Header | | Types | | Strings |
+ * +----------+ +---------+ +-----------+
+ * ^ ^ ^
+ * | | |
+ * hdr | |
+ * types_data----+ |
+ * strset__data(strs_set)-----+
+ *
+ * +----------+---------+-----------+
+ * | Header | Types | Strings |
+ * raw_data----->+----------+---------+-----------+
+ */
+ struct btf_header *hdr;
+
+ void *types_data;
+ size_t types_data_cap; /* used size stored in hdr->type_len */
+
+ /* type ID to `struct btf_type *` lookup index
+ * type_offs[0] corresponds to the first non-VOID type:
+ * - for base BTF it's type [1];
+ * - for split BTF it's the first non-base BTF type.
+ */
+ __u32 *type_offs;
+ size_t type_offs_cap;
+ /* number of types in this BTF instance:
+ * - doesn't include special [0] void type;
+ * - for split BTF counts number of types added on top of base BTF.
+ */
+ __u32 nr_types;
+ /* if not NULL, points to the base BTF on top of which the current
+ * split BTF is based
+ */
+ struct btf *base_btf;
+ /* BTF type ID of the first type in this BTF instance:
+ * - for base BTF it's equal to 1;
+ * - for split BTF it's equal to biggest type ID of base BTF plus 1.
+ */
+ int start_id;
+ /* logical string offset of this BTF instance:
+ * - for base BTF it's equal to 0;
+ * - for split BTF it's equal to total size of base BTF's string section size.
+ */
+ int start_str_off;
+
+ /* only one of strs_data or strs_set can be non-NULL, depending on
+ * whether BTF is in a modifiable state (strs_set is used) or not
+ * (strs_data points inside raw_data)
+ */
+ void *strs_data;
+ /* a set of unique strings */
+ struct strset *strs_set;
+ /* whether strings are already deduplicated */
+ bool strs_deduped;
+
+ /* BTF object FD, if loaded into kernel */
+ int fd;
+
+ /* Pointer size (in bytes) for a target architecture of this BTF */
+ int ptr_sz;
+};
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+ return (__u64) (unsigned long) ptr;
+}
+
+/* Ensure given dynamically allocated memory region pointed to by *data* with
+ * capacity of *cap_cnt* elements each taking *elem_sz* bytes has enough
+ * memory to accommodate *add_cnt* new elements, assuming *cur_cnt* elements
+ * are already used. At most *max_cnt* elements can be ever allocated.
+ * If necessary, memory is reallocated and all existing data is copied over,
+ * new pointer to the memory region is stored at *data, new memory region
+ * capacity (in number of elements) is stored in *cap.
+ * On success, memory pointer to the beginning of unused memory is returned.
+ * On error, NULL is returned.
+ */
+void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
+ size_t cur_cnt, size_t max_cnt, size_t add_cnt)
+{
+ size_t new_cnt;
+ void *new_data;
+
+ if (cur_cnt + add_cnt <= *cap_cnt)
+ return *data + cur_cnt * elem_sz;
+
+ /* requested more than the set limit */
+ if (cur_cnt + add_cnt > max_cnt)
+ return NULL;
+
+ new_cnt = *cap_cnt;
+ new_cnt += new_cnt / 4; /* expand by 25% */
+ if (new_cnt < 16) /* but at least 16 elements */
+ new_cnt = 16;
+ if (new_cnt > max_cnt) /* but not exceeding a set limit */
+ new_cnt = max_cnt;
+ if (new_cnt < cur_cnt + add_cnt) /* also ensure we have enough memory */
+ new_cnt = cur_cnt + add_cnt;
+
+ new_data = libbpf_reallocarray(*data, new_cnt, elem_sz);
+ if (!new_data)
+ return NULL;
+
+ /* zero out newly allocated portion of memory */
+ memset(new_data + (*cap_cnt) * elem_sz, 0, (new_cnt - *cap_cnt) * elem_sz);
+
+ *data = new_data;
+ *cap_cnt = new_cnt;
+ return new_data + cur_cnt * elem_sz;
+}
+
+/* Ensure given dynamically allocated memory region has enough allocated space
+ * to accommodate *need_cnt* elements of size *elem_sz* bytes each
+ */
+int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt)
+{
+ void *p;
+
+ if (need_cnt <= *cap_cnt)
+ return 0;
+
+ p = libbpf_add_mem(data, cap_cnt, elem_sz, *cap_cnt, SIZE_MAX, need_cnt - *cap_cnt);
+ if (!p)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static void *btf_add_type_offs_mem(struct btf *btf, size_t add_cnt)
+{
+ return libbpf_add_mem((void **)&btf->type_offs, &btf->type_offs_cap, sizeof(__u32),
+ btf->nr_types, BTF_MAX_NR_TYPES, add_cnt);
+}
+
+static int btf_add_type_idx_entry(struct btf *btf, __u32 type_off)
+{
+ __u32 *p;
+
+ p = btf_add_type_offs_mem(btf, 1);
+ if (!p)
+ return -ENOMEM;
+
+ *p = type_off;
+ return 0;
+}
+
+static void btf_bswap_hdr(struct btf_header *h)
+{
+ h->magic = bswap_16(h->magic);
+ h->hdr_len = bswap_32(h->hdr_len);
+ h->type_off = bswap_32(h->type_off);
+ h->type_len = bswap_32(h->type_len);
+ h->str_off = bswap_32(h->str_off);
+ h->str_len = bswap_32(h->str_len);
+}
+
+static int btf_parse_hdr(struct btf *btf)
+{
+ struct btf_header *hdr = btf->hdr;
+ __u32 meta_left;
+
+ if (btf->raw_size < sizeof(struct btf_header)) {
+ pr_debug("BTF header not found\n");
+ return -EINVAL;
+ }
+
+ if (hdr->magic == bswap_16(BTF_MAGIC)) {
+ btf->swapped_endian = true;
+ if (bswap_32(hdr->hdr_len) != sizeof(struct btf_header)) {
+ pr_warn("Can't load BTF with non-native endianness due to unsupported header length %u\n",
+ bswap_32(hdr->hdr_len));
+ return -ENOTSUP;
+ }
+ btf_bswap_hdr(hdr);
+ } else if (hdr->magic != BTF_MAGIC) {
+ pr_debug("Invalid BTF magic: %x\n", hdr->magic);
+ return -EINVAL;
+ }
+
+ if (btf->raw_size < hdr->hdr_len) {
+ pr_debug("BTF header len %u larger than data size %u\n",
+ hdr->hdr_len, btf->raw_size);
+ return -EINVAL;
+ }
+
+ meta_left = btf->raw_size - hdr->hdr_len;
+ if (meta_left < (long long)hdr->str_off + hdr->str_len) {
+ pr_debug("Invalid BTF total size: %u\n", btf->raw_size);
+ return -EINVAL;
+ }
+
+ if ((long long)hdr->type_off + hdr->type_len > hdr->str_off) {
+ pr_debug("Invalid BTF data sections layout: type data at %u + %u, strings data at %u + %u\n",
+ hdr->type_off, hdr->type_len, hdr->str_off, hdr->str_len);
+ return -EINVAL;
+ }
+
+ if (hdr->type_off % 4) {
+ pr_debug("BTF type section is not aligned to 4 bytes\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int btf_parse_str_sec(struct btf *btf)
+{
+ const struct btf_header *hdr = btf->hdr;
+ const char *start = btf->strs_data;
+ const char *end = start + btf->hdr->str_len;
+
+ if (btf->base_btf && hdr->str_len == 0)
+ return 0;
+ if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_STR_OFFSET || end[-1]) {
+ pr_debug("Invalid BTF string section\n");
+ return -EINVAL;
+ }
+ if (!btf->base_btf && start[0]) {
+ pr_debug("Invalid BTF string section\n");
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static int btf_type_size(const struct btf_type *t)
+{
+ const int base_size = sizeof(struct btf_type);
+ __u16 vlen = btf_vlen(t);
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_FWD:
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_FUNC:
+ case BTF_KIND_FLOAT:
+ case BTF_KIND_TYPE_TAG:
+ return base_size;
+ case BTF_KIND_INT:
+ return base_size + sizeof(__u32);
+ case BTF_KIND_ENUM:
+ return base_size + vlen * sizeof(struct btf_enum);
+ case BTF_KIND_ENUM64:
+ return base_size + vlen * sizeof(struct btf_enum64);
+ case BTF_KIND_ARRAY:
+ return base_size + sizeof(struct btf_array);
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION:
+ return base_size + vlen * sizeof(struct btf_member);
+ case BTF_KIND_FUNC_PROTO:
+ return base_size + vlen * sizeof(struct btf_param);
+ case BTF_KIND_VAR:
+ return base_size + sizeof(struct btf_var);
+ case BTF_KIND_DATASEC:
+ return base_size + vlen * sizeof(struct btf_var_secinfo);
+ case BTF_KIND_DECL_TAG:
+ return base_size + sizeof(struct btf_decl_tag);
+ default:
+ pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
+ return -EINVAL;
+ }
+}
+
+static void btf_bswap_type_base(struct btf_type *t)
+{
+ t->name_off = bswap_32(t->name_off);
+ t->info = bswap_32(t->info);
+ t->type = bswap_32(t->type);
+}
+
+static int btf_bswap_type_rest(struct btf_type *t)
+{
+ struct btf_var_secinfo *v;
+ struct btf_enum64 *e64;
+ struct btf_member *m;
+ struct btf_array *a;
+ struct btf_param *p;
+ struct btf_enum *e;
+ __u16 vlen = btf_vlen(t);
+ int i;
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_FWD:
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_FUNC:
+ case BTF_KIND_FLOAT:
+ case BTF_KIND_TYPE_TAG:
+ return 0;
+ case BTF_KIND_INT:
+ *(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
+ return 0;
+ case BTF_KIND_ENUM:
+ for (i = 0, e = btf_enum(t); i < vlen; i++, e++) {
+ e->name_off = bswap_32(e->name_off);
+ e->val = bswap_32(e->val);
+ }
+ return 0;
+ case BTF_KIND_ENUM64:
+ for (i = 0, e64 = btf_enum64(t); i < vlen; i++, e64++) {
+ e64->name_off = bswap_32(e64->name_off);
+ e64->val_lo32 = bswap_32(e64->val_lo32);
+ e64->val_hi32 = bswap_32(e64->val_hi32);
+ }
+ return 0;
+ case BTF_KIND_ARRAY:
+ a = btf_array(t);
+ a->type = bswap_32(a->type);
+ a->index_type = bswap_32(a->index_type);
+ a->nelems = bswap_32(a->nelems);
+ return 0;
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION:
+ for (i = 0, m = btf_members(t); i < vlen; i++, m++) {
+ m->name_off = bswap_32(m->name_off);
+ m->type = bswap_32(m->type);
+ m->offset = bswap_32(m->offset);
+ }
+ return 0;
+ case BTF_KIND_FUNC_PROTO:
+ for (i = 0, p = btf_params(t); i < vlen; i++, p++) {
+ p->name_off = bswap_32(p->name_off);
+ p->type = bswap_32(p->type);
+ }
+ return 0;
+ case BTF_KIND_VAR:
+ btf_var(t)->linkage = bswap_32(btf_var(t)->linkage);
+ return 0;
+ case BTF_KIND_DATASEC:
+ for (i = 0, v = btf_var_secinfos(t); i < vlen; i++, v++) {
+ v->type = bswap_32(v->type);
+ v->offset = bswap_32(v->offset);
+ v->size = bswap_32(v->size);
+ }
+ return 0;
+ case BTF_KIND_DECL_TAG:
+ btf_decl_tag(t)->component_idx = bswap_32(btf_decl_tag(t)->component_idx);
+ return 0;
+ default:
+ pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
+ return -EINVAL;
+ }
+}
+
+static int btf_parse_type_sec(struct btf *btf)
+{
+ struct btf_header *hdr = btf->hdr;
+ void *next_type = btf->types_data;
+ void *end_type = next_type + hdr->type_len;
+ int err, type_size;
+
+ while (next_type + sizeof(struct btf_type) <= end_type) {
+ if (btf->swapped_endian)
+ btf_bswap_type_base(next_type);
+
+ type_size = btf_type_size(next_type);
+ if (type_size < 0)
+ return type_size;
+ if (next_type + type_size > end_type) {
+ pr_warn("BTF type [%d] is malformed\n", btf->start_id + btf->nr_types);
+ return -EINVAL;
+ }
+
+ if (btf->swapped_endian && btf_bswap_type_rest(next_type))
+ return -EINVAL;
+
+ err = btf_add_type_idx_entry(btf, next_type - btf->types_data);
+ if (err)
+ return err;
+
+ next_type += type_size;
+ btf->nr_types++;
+ }
+
+ if (next_type != end_type) {
+ pr_warn("BTF types data is malformed\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+__u32 btf__type_cnt(const struct btf *btf)
+{
+ return btf->start_id + btf->nr_types;
+}
+
+const struct btf *btf__base_btf(const struct btf *btf)
+{
+ return btf->base_btf;
+}
+
+/* internal helper returning non-const pointer to a type */
+struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id)
+{
+ if (type_id == 0)
+ return &btf_void;
+ if (type_id < btf->start_id)
+ return btf_type_by_id(btf->base_btf, type_id);
+ return btf->types_data + btf->type_offs[type_id - btf->start_id];
+}
+
+const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
+{
+ if (type_id >= btf->start_id + btf->nr_types)
+ return errno = EINVAL, NULL;
+ return btf_type_by_id((struct btf *)btf, type_id);
+}
+
+static int determine_ptr_size(const struct btf *btf)
+{
+ static const char * const long_aliases[] = {
+ "long",
+ "long int",
+ "int long",
+ "unsigned long",
+ "long unsigned",
+ "unsigned long int",
+ "unsigned int long",
+ "long unsigned int",
+ "long int unsigned",
+ "int unsigned long",
+ "int long unsigned",
+ };
+ const struct btf_type *t;
+ const char *name;
+ int i, j, n;
+
+ if (btf->base_btf && btf->base_btf->ptr_sz > 0)
+ return btf->base_btf->ptr_sz;
+
+ n = btf__type_cnt(btf);
+ for (i = 1; i < n; i++) {
+ t = btf__type_by_id(btf, i);
+ if (!btf_is_int(t))
+ continue;
+
+ if (t->size != 4 && t->size != 8)
+ continue;
+
+ name = btf__name_by_offset(btf, t->name_off);
+ if (!name)
+ continue;
+
+ for (j = 0; j < ARRAY_SIZE(long_aliases); j++) {
+ if (strcmp(name, long_aliases[j]) == 0)
+ return t->size;
+ }
+ }
+
+ return -1;
+}
+
+static size_t btf_ptr_sz(const struct btf *btf)
+{
+ if (!btf->ptr_sz)
+ ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
+ return btf->ptr_sz < 0 ? sizeof(void *) : btf->ptr_sz;
+}
+
+/* Return pointer size this BTF instance assumes. The size is heuristically
+ * determined by looking for 'long' or 'unsigned long' integer type and
+ * recording its size in bytes. If BTF type information doesn't have any such
+ * type, this function returns 0. In the latter case, native architecture's
+ * pointer size is assumed, so will be either 4 or 8, depending on
+ * architecture that libbpf was compiled for. It's possible to override
+ * guessed value by using btf__set_pointer_size() API.
+ */
+size_t btf__pointer_size(const struct btf *btf)
+{
+ if (!btf->ptr_sz)
+ ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
+
+ if (btf->ptr_sz < 0)
+ /* not enough BTF type info to guess */
+ return 0;
+
+ return btf->ptr_sz;
+}
+
+/* Override or set pointer size in bytes. Only values of 4 and 8 are
+ * supported.
+ */
+int btf__set_pointer_size(struct btf *btf, size_t ptr_sz)
+{
+ if (ptr_sz != 4 && ptr_sz != 8)
+ return libbpf_err(-EINVAL);
+ btf->ptr_sz = ptr_sz;
+ return 0;
+}
+
+static bool is_host_big_endian(void)
+{
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+ return false;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+ return true;
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+}
+
+enum btf_endianness btf__endianness(const struct btf *btf)
+{
+ if (is_host_big_endian())
+ return btf->swapped_endian ? BTF_LITTLE_ENDIAN : BTF_BIG_ENDIAN;
+ else
+ return btf->swapped_endian ? BTF_BIG_ENDIAN : BTF_LITTLE_ENDIAN;
+}
+
+int btf__set_endianness(struct btf *btf, enum btf_endianness endian)
+{
+ if (endian != BTF_LITTLE_ENDIAN && endian != BTF_BIG_ENDIAN)
+ return libbpf_err(-EINVAL);
+
+ btf->swapped_endian = is_host_big_endian() != (endian == BTF_BIG_ENDIAN);
+ if (!btf->swapped_endian) {
+ free(btf->raw_data_swapped);
+ btf->raw_data_swapped = NULL;
+ }
+ return 0;
+}
+
+static bool btf_type_is_void(const struct btf_type *t)
+{
+ return t == &btf_void || btf_is_fwd(t);
+}
+
+static bool btf_type_is_void_or_null(const struct btf_type *t)
+{
+ return !t || btf_type_is_void(t);
+}
+
+#define MAX_RESOLVE_DEPTH 32
+
+__s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
+{
+ const struct btf_array *array;
+ const struct btf_type *t;
+ __u32 nelems = 1;
+ __s64 size = -1;
+ int i;
+
+ t = btf__type_by_id(btf, type_id);
+ for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t); i++) {
+ switch (btf_kind(t)) {
+ case BTF_KIND_INT:
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION:
+ case BTF_KIND_ENUM:
+ case BTF_KIND_ENUM64:
+ case BTF_KIND_DATASEC:
+ case BTF_KIND_FLOAT:
+ size = t->size;
+ goto done;
+ case BTF_KIND_PTR:
+ size = btf_ptr_sz(btf);
+ goto done;
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_CONST:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_VAR:
+ case BTF_KIND_DECL_TAG:
+ case BTF_KIND_TYPE_TAG:
+ type_id = t->type;
+ break;
+ case BTF_KIND_ARRAY:
+ array = btf_array(t);
+ if (nelems && array->nelems > UINT32_MAX / nelems)
+ return libbpf_err(-E2BIG);
+ nelems *= array->nelems;
+ type_id = array->type;
+ break;
+ default:
+ return libbpf_err(-EINVAL);
+ }
+
+ t = btf__type_by_id(btf, type_id);
+ }
+
+done:
+ if (size < 0)
+ return libbpf_err(-EINVAL);
+ if (nelems && size > UINT32_MAX / nelems)
+ return libbpf_err(-E2BIG);
+
+ return nelems * size;
+}
+
+int btf__align_of(const struct btf *btf, __u32 id)
+{
+ const struct btf_type *t = btf__type_by_id(btf, id);
+ __u16 kind = btf_kind(t);
+
+ switch (kind) {
+ case BTF_KIND_INT:
+ case BTF_KIND_ENUM:
+ case BTF_KIND_ENUM64:
+ case BTF_KIND_FLOAT:
+ return min(btf_ptr_sz(btf), (size_t)t->size);
+ case BTF_KIND_PTR:
+ return btf_ptr_sz(btf);
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_CONST:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_TYPE_TAG:
+ return btf__align_of(btf, t->type);
+ case BTF_KIND_ARRAY:
+ return btf__align_of(btf, btf_array(t)->type);
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION: {
+ const struct btf_member *m = btf_members(t);
+ __u16 vlen = btf_vlen(t);
+ int i, max_align = 1, align;
+
+ for (i = 0; i < vlen; i++, m++) {
+ align = btf__align_of(btf, m->type);
+ if (align <= 0)
+ return libbpf_err(align);
+ max_align = max(max_align, align);
+
+ /* if field offset isn't aligned according to field
+ * type's alignment, then struct must be packed
+ */
+ if (btf_member_bitfield_size(t, i) == 0 &&
+ (m->offset % (8 * align)) != 0)
+ return 1;
+ }
+
+ /* if struct/union size isn't a multiple of its alignment,
+ * then struct must be packed
+ */
+ if ((t->size % max_align) != 0)
+ return 1;
+
+ return max_align;
+ }
+ default:
+ pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
+ return errno = EINVAL, 0;
+ }
+}
+
+int btf__resolve_type(const struct btf *btf, __u32 type_id)
+{
+ const struct btf_type *t;
+ int depth = 0;
+
+ t = btf__type_by_id(btf, type_id);
+ while (depth < MAX_RESOLVE_DEPTH &&
+ !btf_type_is_void_or_null(t) &&
+ (btf_is_mod(t) || btf_is_typedef(t) || btf_is_var(t))) {
+ type_id = t->type;
+ t = btf__type_by_id(btf, type_id);
+ depth++;
+ }
+
+ if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
+ return libbpf_err(-EINVAL);
+
+ return type_id;
+}
+
+__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
+{
+ __u32 i, nr_types = btf__type_cnt(btf);
+
+ if (!strcmp(type_name, "void"))
+ return 0;
+
+ for (i = 1; i < nr_types; i++) {
+ const struct btf_type *t = btf__type_by_id(btf, i);
+ const char *name = btf__name_by_offset(btf, t->name_off);
+
+ if (name && !strcmp(type_name, name))
+ return i;
+ }
+
+ return libbpf_err(-ENOENT);
+}
+
+static __s32 btf_find_by_name_kind(const struct btf *btf, int start_id,
+ const char *type_name, __u32 kind)
+{
+ __u32 i, nr_types = btf__type_cnt(btf);
+
+ if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void"))
+ return 0;
+
+ for (i = start_id; i < nr_types; i++) {
+ const struct btf_type *t = btf__type_by_id(btf, i);
+ const char *name;
+
+ if (btf_kind(t) != kind)
+ continue;
+ name = btf__name_by_offset(btf, t->name_off);
+ if (name && !strcmp(type_name, name))
+ return i;
+ }
+
+ return libbpf_err(-ENOENT);
+}
+
+__s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name,
+ __u32 kind)
+{
+ return btf_find_by_name_kind(btf, btf->start_id, type_name, kind);
+}
+
+__s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
+ __u32 kind)
+{
+ return btf_find_by_name_kind(btf, 1, type_name, kind);
+}
+
+static bool btf_is_modifiable(const struct btf *btf)
+{
+ return (void *)btf->hdr != btf->raw_data;
+}
+
+void btf__free(struct btf *btf)
+{
+ if (IS_ERR_OR_NULL(btf))
+ return;
+
+ if (btf->fd >= 0)
+ close(btf->fd);
+
+ if (btf_is_modifiable(btf)) {
+ /* if BTF was modified after loading, it will have a split
+ * in-memory representation for header, types, and strings
+ * sections, so we need to free all of them individually. It
+ * might still have a cached contiguous raw data present,
+ * which will be unconditionally freed below.
+ */
+ free(btf->hdr);
+ free(btf->types_data);
+ strset__free(btf->strs_set);
+ }
+ free(btf->raw_data);
+ free(btf->raw_data_swapped);
+ free(btf->type_offs);
+ free(btf);
+}
+
+static struct btf *btf_new_empty(struct btf *base_btf)
+{
+ struct btf *btf;
+
+ btf = calloc(1, sizeof(*btf));
+ if (!btf)
+ return ERR_PTR(-ENOMEM);
+
+ btf->nr_types = 0;
+ btf->start_id = 1;
+ btf->start_str_off = 0;
+ btf->fd = -1;
+ btf->ptr_sz = sizeof(void *);
+ btf->swapped_endian = false;
+
+ if (base_btf) {
+ btf->base_btf = base_btf;
+ btf->start_id = btf__type_cnt(base_btf);
+ btf->start_str_off = base_btf->hdr->str_len;
+ }
+
+ /* +1 for empty string at offset 0 */
+ btf->raw_size = sizeof(struct btf_header) + (base_btf ? 0 : 1);
+ btf->raw_data = calloc(1, btf->raw_size);
+ if (!btf->raw_data) {
+ free(btf);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ btf->hdr = btf->raw_data;
+ btf->hdr->hdr_len = sizeof(struct btf_header);
+ btf->hdr->magic = BTF_MAGIC;
+ btf->hdr->version = BTF_VERSION;
+
+ btf->types_data = btf->raw_data + btf->hdr->hdr_len;
+ btf->strs_data = btf->raw_data + btf->hdr->hdr_len;
+ btf->hdr->str_len = base_btf ? 0 : 1; /* empty string at offset 0 */
+
+ return btf;
+}
+
+struct btf *btf__new_empty(void)
+{
+ return libbpf_ptr(btf_new_empty(NULL));
+}
+
+struct btf *btf__new_empty_split(struct btf *base_btf)
+{
+ return libbpf_ptr(btf_new_empty(base_btf));
+}
+
+static struct btf *btf_new(const void *data, __u32 size, struct btf *base_btf)
+{
+ struct btf *btf;
+ int err;
+
+ btf = calloc(1, sizeof(struct btf));
+ if (!btf)
+ return ERR_PTR(-ENOMEM);
+
+ btf->nr_types = 0;
+ btf->start_id = 1;
+ btf->start_str_off = 0;
+ btf->fd = -1;
+
+ if (base_btf) {
+ btf->base_btf = base_btf;
+ btf->start_id = btf__type_cnt(base_btf);
+ btf->start_str_off = base_btf->hdr->str_len;
+ }
+
+ btf->raw_data = malloc(size);
+ if (!btf->raw_data) {
+ err = -ENOMEM;
+ goto done;
+ }
+ memcpy(btf->raw_data, data, size);
+ btf->raw_size = size;
+
+ btf->hdr = btf->raw_data;
+ err = btf_parse_hdr(btf);
+ if (err)
+ goto done;
+
+ btf->strs_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->str_off;
+ btf->types_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->type_off;
+
+ err = btf_parse_str_sec(btf);
+ err = err ?: btf_parse_type_sec(btf);
+ if (err)
+ goto done;
+
+done:
+ if (err) {
+ btf__free(btf);
+ return ERR_PTR(err);
+ }
+
+ return btf;
+}
+
+struct btf *btf__new(const void *data, __u32 size)
+{
+ return libbpf_ptr(btf_new(data, size, NULL));
+}
+
+static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
+ struct btf_ext **btf_ext)
+{
+ Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
+ int err = 0, fd = -1, idx = 0;
+ struct btf *btf = NULL;
+ Elf_Scn *scn = NULL;
+ Elf *elf = NULL;
+ GElf_Ehdr ehdr;
+ size_t shstrndx;
+
+ if (elf_version(EV_CURRENT) == EV_NONE) {
+ pr_warn("failed to init libelf for %s\n", path);
+ return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
+ }
+
+ fd = open(path, O_RDONLY | O_CLOEXEC);
+ if (fd < 0) {
+ err = -errno;
+ pr_warn("failed to open %s: %s\n", path, strerror(errno));
+ return ERR_PTR(err);
+ }
+
+ err = -LIBBPF_ERRNO__FORMAT;
+
+ elf = elf_begin(fd, ELF_C_READ, NULL);
+ if (!elf) {
+ pr_warn("failed to open %s as ELF file\n", path);
+ goto done;
+ }
+ if (!gelf_getehdr(elf, &ehdr)) {
+ pr_warn("failed to get EHDR from %s\n", path);
+ goto done;
+ }
+
+ if (elf_getshdrstrndx(elf, &shstrndx)) {
+ pr_warn("failed to get section names section index for %s\n",
+ path);
+ goto done;
+ }
+
+ if (!elf_rawdata(elf_getscn(elf, shstrndx), NULL)) {
+ pr_warn("failed to get e_shstrndx from %s\n", path);
+ goto done;
+ }
+
+ while ((scn = elf_nextscn(elf, scn)) != NULL) {
+ GElf_Shdr sh;
+ char *name;
+
+ idx++;
+ if (gelf_getshdr(scn, &sh) != &sh) {
+ pr_warn("failed to get section(%d) header from %s\n",
+ idx, path);
+ goto done;
+ }
+ name = elf_strptr(elf, shstrndx, sh.sh_name);
+ if (!name) {
+ pr_warn("failed to get section(%d) name from %s\n",
+ idx, path);
+ goto done;
+ }
+ if (strcmp(name, BTF_ELF_SEC) == 0) {
+ btf_data = elf_getdata(scn, 0);
+ if (!btf_data) {
+ pr_warn("failed to get section(%d, %s) data from %s\n",
+ idx, name, path);
+ goto done;
+ }
+ continue;
+ } else if (btf_ext && strcmp(name, BTF_EXT_ELF_SEC) == 0) {
+ btf_ext_data = elf_getdata(scn, 0);
+ if (!btf_ext_data) {
+ pr_warn("failed to get section(%d, %s) data from %s\n",
+ idx, name, path);
+ goto done;
+ }
+ continue;
+ }
+ }
+
+ if (!btf_data) {
+ pr_warn("failed to find '%s' ELF section in %s\n", BTF_ELF_SEC, path);
+ err = -ENODATA;
+ goto done;
+ }
+ btf = btf_new(btf_data->d_buf, btf_data->d_size, base_btf);
+ err = libbpf_get_error(btf);
+ if (err)
+ goto done;
+
+ switch (gelf_getclass(elf)) {
+ case ELFCLASS32:
+ btf__set_pointer_size(btf, 4);
+ break;
+ case ELFCLASS64:
+ btf__set_pointer_size(btf, 8);
+ break;
+ default:
+ pr_warn("failed to get ELF class (bitness) for %s\n", path);
+ break;
+ }
+
+ if (btf_ext && btf_ext_data) {
+ *btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
+ err = libbpf_get_error(*btf_ext);
+ if (err)
+ goto done;
+ } else if (btf_ext) {
+ *btf_ext = NULL;
+ }
+done:
+ if (elf)
+ elf_end(elf);
+ close(fd);
+
+ if (!err)
+ return btf;
+
+ if (btf_ext)
+ btf_ext__free(*btf_ext);
+ btf__free(btf);
+
+ return ERR_PTR(err);
+}
+
+struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
+{
+ return libbpf_ptr(btf_parse_elf(path, NULL, btf_ext));
+}
+
+struct btf *btf__parse_elf_split(const char *path, struct btf *base_btf)
+{
+ return libbpf_ptr(btf_parse_elf(path, base_btf, NULL));
+}
+
+static struct btf *btf_parse_raw(const char *path, struct btf *base_btf)
+{
+ struct btf *btf = NULL;
+ void *data = NULL;
+ FILE *f = NULL;
+ __u16 magic;
+ int err = 0;
+ long sz;
+
+ f = fopen(path, "rbe");
+ if (!f) {
+ err = -errno;
+ goto err_out;
+ }
+
+ /* check BTF magic */
+ if (fread(&magic, 1, sizeof(magic), f) < sizeof(magic)) {
+ err = -EIO;
+ goto err_out;
+ }
+ if (magic != BTF_MAGIC && magic != bswap_16(BTF_MAGIC)) {
+ /* definitely not a raw BTF */
+ err = -EPROTO;
+ goto err_out;
+ }
+
+ /* get file size */
+ if (fseek(f, 0, SEEK_END)) {
+ err = -errno;
+ goto err_out;
+ }
+ sz = ftell(f);
+ if (sz < 0) {
+ err = -errno;
+ goto err_out;
+ }
+ /* rewind to the start */
+ if (fseek(f, 0, SEEK_SET)) {
+ err = -errno;
+ goto err_out;
+ }
+
+ /* pre-alloc memory and read all of BTF data */
+ data = malloc(sz);
+ if (!data) {
+ err = -ENOMEM;
+ goto err_out;
+ }
+ if (fread(data, 1, sz, f) < sz) {
+ err = -EIO;
+ goto err_out;
+ }
+
+ /* finally parse BTF data */
+ btf = btf_new(data, sz, base_btf);
+
+err_out:
+ free(data);
+ if (f)
+ fclose(f);
+ return err ? ERR_PTR(err) : btf;
+}
+
+struct btf *btf__parse_raw(const char *path)
+{
+ return libbpf_ptr(btf_parse_raw(path, NULL));
+}
+
+struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf)
+{
+ return libbpf_ptr(btf_parse_raw(path, base_btf));
+}
+
+static struct btf *btf_parse(const char *path, struct btf *base_btf, struct btf_ext **btf_ext)
+{
+ struct btf *btf;
+ int err;
+
+ if (btf_ext)
+ *btf_ext = NULL;
+
+ btf = btf_parse_raw(path, base_btf);
+ err = libbpf_get_error(btf);
+ if (!err)
+ return btf;
+ if (err != -EPROTO)
+ return ERR_PTR(err);
+ return btf_parse_elf(path, base_btf, btf_ext);
+}
+
+struct btf *btf__parse(const char *path, struct btf_ext **btf_ext)
+{
+ return libbpf_ptr(btf_parse(path, NULL, btf_ext));
+}
+
+struct btf *btf__parse_split(const char *path, struct btf *base_btf)
+{
+ return libbpf_ptr(btf_parse(path, base_btf, NULL));
+}
+
+static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian);
+
+int btf_load_into_kernel(struct btf *btf, char *log_buf, size_t log_sz, __u32 log_level)
+{
+ LIBBPF_OPTS(bpf_btf_load_opts, opts);
+ __u32 buf_sz = 0, raw_size;
+ char *buf = NULL, *tmp;
+ void *raw_data;
+ int err = 0;
+
+ if (btf->fd >= 0)
+ return libbpf_err(-EEXIST);
+ if (log_sz && !log_buf)
+ return libbpf_err(-EINVAL);
+
+ /* cache native raw data representation */
+ raw_data = btf_get_raw_data(btf, &raw_size, false);
+ if (!raw_data) {
+ err = -ENOMEM;
+ goto done;
+ }
+ btf->raw_size = raw_size;
+ btf->raw_data = raw_data;
+
+retry_load:
+ /* if log_level is 0, we won't provide log_buf/log_size to the kernel,
+ * initially. Only if BTF loading fails, we bump log_level to 1 and
+ * retry, using either auto-allocated or custom log_buf. This way
+ * non-NULL custom log_buf provides a buffer just in case, but hopes
+ * for successful load and no need for log_buf.
+ */
+ if (log_level) {
+ /* if caller didn't provide custom log_buf, we'll keep
+ * allocating our own progressively bigger buffers for BTF
+ * verification log
+ */
+ if (!log_buf) {
+ buf_sz = max((__u32)BPF_LOG_BUF_SIZE, buf_sz * 2);
+ tmp = realloc(buf, buf_sz);
+ if (!tmp) {
+ err = -ENOMEM;
+ goto done;
+ }
+ buf = tmp;
+ buf[0] = '\0';
+ }
+
+ opts.log_buf = log_buf ? log_buf : buf;
+ opts.log_size = log_buf ? log_sz : buf_sz;
+ opts.log_level = log_level;
+ }
+
+ btf->fd = bpf_btf_load(raw_data, raw_size, &opts);
+ if (btf->fd < 0) {
+ /* time to turn on verbose mode and try again */
+ if (log_level == 0) {
+ log_level = 1;
+ goto retry_load;
+ }
+ /* only retry if caller didn't provide custom log_buf, but
+ * make sure we can never overflow buf_sz
+ */
+ if (!log_buf && errno == ENOSPC && buf_sz <= UINT_MAX / 2)
+ goto retry_load;
+
+ err = -errno;
+ pr_warn("BTF loading error: %d\n", err);
+ /* don't print out contents of custom log_buf */
+ if (!log_buf && buf[0])
+ pr_warn("-- BEGIN BTF LOAD LOG ---\n%s\n-- END BTF LOAD LOG --\n", buf);
+ }
+
+done:
+ free(buf);
+ return libbpf_err(err);
+}
+
+int btf__load_into_kernel(struct btf *btf)
+{
+ return btf_load_into_kernel(btf, NULL, 0, 0);
+}
+
+int btf__fd(const struct btf *btf)
+{
+ return btf->fd;
+}
+
+void btf__set_fd(struct btf *btf, int fd)
+{
+ btf->fd = fd;
+}
+
+static const void *btf_strs_data(const struct btf *btf)
+{
+ return btf->strs_data ? btf->strs_data : strset__data(btf->strs_set);
+}
+
+static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian)
+{
+ struct btf_header *hdr = btf->hdr;
+ struct btf_type *t;
+ void *data, *p;
+ __u32 data_sz;
+ int i;
+
+ data = swap_endian ? btf->raw_data_swapped : btf->raw_data;
+ if (data) {
+ *size = btf->raw_size;
+ return data;
+ }
+
+ data_sz = hdr->hdr_len + hdr->type_len + hdr->str_len;
+ data = calloc(1, data_sz);
+ if (!data)
+ return NULL;
+ p = data;
+
+ memcpy(p, hdr, hdr->hdr_len);
+ if (swap_endian)
+ btf_bswap_hdr(p);
+ p += hdr->hdr_len;
+
+ memcpy(p, btf->types_data, hdr->type_len);
+ if (swap_endian) {
+ for (i = 0; i < btf->nr_types; i++) {
+ t = p + btf->type_offs[i];
+ /* btf_bswap_type_rest() relies on native t->info, so
+ * we swap base type info after we swapped all the
+ * additional information
+ */
+ if (btf_bswap_type_rest(t))
+ goto err_out;
+ btf_bswap_type_base(t);
+ }
+ }
+ p += hdr->type_len;
+
+ memcpy(p, btf_strs_data(btf), hdr->str_len);
+ p += hdr->str_len;
+
+ *size = data_sz;
+ return data;
+err_out:
+ free(data);
+ return NULL;
+}
+
+const void *btf__raw_data(const struct btf *btf_ro, __u32 *size)
+{
+ struct btf *btf = (struct btf *)btf_ro;
+ __u32 data_sz;
+ void *data;
+
+ data = btf_get_raw_data(btf, &data_sz, btf->swapped_endian);
+ if (!data)
+ return errno = ENOMEM, NULL;
+
+ btf->raw_size = data_sz;
+ if (btf->swapped_endian)
+ btf->raw_data_swapped = data;
+ else
+ btf->raw_data = data;
+ *size = data_sz;
+ return data;
+}
+
+__attribute__((alias("btf__raw_data")))
+const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
+
+const char *btf__str_by_offset(const struct btf *btf, __u32 offset)
+{
+ if (offset < btf->start_str_off)
+ return btf__str_by_offset(btf->base_btf, offset);
+ else if (offset - btf->start_str_off < btf->hdr->str_len)
+ return btf_strs_data(btf) + (offset - btf->start_str_off);
+ else
+ return errno = EINVAL, NULL;
+}
+
+const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
+{
+ return btf__str_by_offset(btf, offset);
+}
+
+struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf)
+{
+ struct bpf_btf_info btf_info;
+ __u32 len = sizeof(btf_info);
+ __u32 last_size;
+ struct btf *btf;
+ void *ptr;
+ int err;
+
+ /* we won't know btf_size until we call bpf_btf_get_info_by_fd(). so
+ * let's start with a sane default - 4KiB here - and resize it only if
+ * bpf_btf_get_info_by_fd() needs a bigger buffer.
+ */
+ last_size = 4096;
+ ptr = malloc(last_size);
+ if (!ptr)
+ return ERR_PTR(-ENOMEM);
+
+ memset(&btf_info, 0, sizeof(btf_info));
+ btf_info.btf = ptr_to_u64(ptr);
+ btf_info.btf_size = last_size;
+ err = bpf_btf_get_info_by_fd(btf_fd, &btf_info, &len);
+
+ if (!err && btf_info.btf_size > last_size) {
+ void *temp_ptr;
+
+ last_size = btf_info.btf_size;
+ temp_ptr = realloc(ptr, last_size);
+ if (!temp_ptr) {
+ btf = ERR_PTR(-ENOMEM);
+ goto exit_free;
+ }
+ ptr = temp_ptr;
+
+ len = sizeof(btf_info);
+ memset(&btf_info, 0, sizeof(btf_info));
+ btf_info.btf = ptr_to_u64(ptr);
+ btf_info.btf_size = last_size;
+
+ err = bpf_btf_get_info_by_fd(btf_fd, &btf_info, &len);
+ }
+
+ if (err || btf_info.btf_size > last_size) {
+ btf = err ? ERR_PTR(-errno) : ERR_PTR(-E2BIG);
+ goto exit_free;
+ }
+
+ btf = btf_new(ptr, btf_info.btf_size, base_btf);
+
+exit_free:
+ free(ptr);
+ return btf;
+}
+
+struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf)
+{
+ struct btf *btf;
+ int btf_fd;
+
+ btf_fd = bpf_btf_get_fd_by_id(id);
+ if (btf_fd < 0)
+ return libbpf_err_ptr(-errno);
+
+ btf = btf_get_from_fd(btf_fd, base_btf);
+ close(btf_fd);
+
+ return libbpf_ptr(btf);
+}
+
+struct btf *btf__load_from_kernel_by_id(__u32 id)
+{
+ return btf__load_from_kernel_by_id_split(id, NULL);
+}
+
+static void btf_invalidate_raw_data(struct btf *btf)
+{
+ if (btf->raw_data) {
+ free(btf->raw_data);
+ btf->raw_data = NULL;
+ }
+ if (btf->raw_data_swapped) {
+ free(btf->raw_data_swapped);
+ btf->raw_data_swapped = NULL;
+ }
+}
+
+/* Ensure BTF is ready to be modified (by splitting into a three memory
+ * regions for header, types, and strings). Also invalidate cached
+ * raw_data, if any.
+ */
+static int btf_ensure_modifiable(struct btf *btf)
+{
+ void *hdr, *types;
+ struct strset *set = NULL;
+ int err = -ENOMEM;
+
+ if (btf_is_modifiable(btf)) {
+ /* any BTF modification invalidates raw_data */
+ btf_invalidate_raw_data(btf);
+ return 0;
+ }
+
+ /* split raw data into three memory regions */
+ hdr = malloc(btf->hdr->hdr_len);
+ types = malloc(btf->hdr->type_len);
+ if (!hdr || !types)
+ goto err_out;
+
+ memcpy(hdr, btf->hdr, btf->hdr->hdr_len);
+ memcpy(types, btf->types_data, btf->hdr->type_len);
+
+ /* build lookup index for all strings */
+ set = strset__new(BTF_MAX_STR_OFFSET, btf->strs_data, btf->hdr->str_len);
+ if (IS_ERR(set)) {
+ err = PTR_ERR(set);
+ goto err_out;
+ }
+
+ /* only when everything was successful, update internal state */
+ btf->hdr = hdr;
+ btf->types_data = types;
+ btf->types_data_cap = btf->hdr->type_len;
+ btf->strs_data = NULL;
+ btf->strs_set = set;
+ /* if BTF was created from scratch, all strings are guaranteed to be
+ * unique and deduplicated
+ */
+ if (btf->hdr->str_len == 0)
+ btf->strs_deduped = true;
+ if (!btf->base_btf && btf->hdr->str_len == 1)
+ btf->strs_deduped = true;
+
+ /* invalidate raw_data representation */
+ btf_invalidate_raw_data(btf);
+
+ return 0;
+
+err_out:
+ strset__free(set);
+ free(hdr);
+ free(types);
+ return err;
+}
+
+/* Find an offset in BTF string section that corresponds to a given string *s*.
+ * Returns:
+ * - >0 offset into string section, if string is found;
+ * - -ENOENT, if string is not in the string section;
+ * - <0, on any other error.
+ */
+int btf__find_str(struct btf *btf, const char *s)
+{
+ int off;
+
+ if (btf->base_btf) {
+ off = btf__find_str(btf->base_btf, s);
+ if (off != -ENOENT)
+ return off;
+ }
+
+ /* BTF needs to be in a modifiable state to build string lookup index */
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ off = strset__find_str(btf->strs_set, s);
+ if (off < 0)
+ return libbpf_err(off);
+
+ return btf->start_str_off + off;
+}
+
+/* Add a string s to the BTF string section.
+ * Returns:
+ * - > 0 offset into string section, on success;
+ * - < 0, on error.
+ */
+int btf__add_str(struct btf *btf, const char *s)
+{
+ int off;
+
+ if (btf->base_btf) {
+ off = btf__find_str(btf->base_btf, s);
+ if (off != -ENOENT)
+ return off;
+ }
+
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ off = strset__add_str(btf->strs_set, s);
+ if (off < 0)
+ return libbpf_err(off);
+
+ btf->hdr->str_len = strset__data_size(btf->strs_set);
+
+ return btf->start_str_off + off;
+}
+
+static void *btf_add_type_mem(struct btf *btf, size_t add_sz)
+{
+ return libbpf_add_mem(&btf->types_data, &btf->types_data_cap, 1,
+ btf->hdr->type_len, UINT_MAX, add_sz);
+}
+
+static void btf_type_inc_vlen(struct btf_type *t)
+{
+ t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, btf_kflag(t));
+}
+
+static int btf_commit_type(struct btf *btf, int data_sz)
+{
+ int err;
+
+ err = btf_add_type_idx_entry(btf, btf->hdr->type_len);
+ if (err)
+ return libbpf_err(err);
+
+ btf->hdr->type_len += data_sz;
+ btf->hdr->str_off += data_sz;
+ btf->nr_types++;
+ return btf->start_id + btf->nr_types - 1;
+}
+
+struct btf_pipe {
+ const struct btf *src;
+ struct btf *dst;
+ struct hashmap *str_off_map; /* map string offsets from src to dst */
+};
+
+static int btf_rewrite_str(__u32 *str_off, void *ctx)
+{
+ struct btf_pipe *p = ctx;
+ long mapped_off;
+ int off, err;
+
+ if (!*str_off) /* nothing to do for empty strings */
+ return 0;
+
+ if (p->str_off_map &&
+ hashmap__find(p->str_off_map, *str_off, &mapped_off)) {
+ *str_off = mapped_off;
+ return 0;
+ }
+
+ off = btf__add_str(p->dst, btf__str_by_offset(p->src, *str_off));
+ if (off < 0)
+ return off;
+
+ /* Remember string mapping from src to dst. It avoids
+ * performing expensive string comparisons.
+ */
+ if (p->str_off_map) {
+ err = hashmap__append(p->str_off_map, *str_off, off);
+ if (err)
+ return err;
+ }
+
+ *str_off = off;
+ return 0;
+}
+
+int btf__add_type(struct btf *btf, const struct btf *src_btf, const struct btf_type *src_type)
+{
+ struct btf_pipe p = { .src = src_btf, .dst = btf };
+ struct btf_type *t;
+ int sz, err;
+
+ sz = btf_type_size(src_type);
+ if (sz < 0)
+ return libbpf_err(sz);
+
+ /* deconstruct BTF, if necessary, and invalidate raw_data */
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ memcpy(t, src_type, sz);
+
+ err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
+ if (err)
+ return libbpf_err(err);
+
+ return btf_commit_type(btf, sz);
+}
+
+static int btf_rewrite_type_ids(__u32 *type_id, void *ctx)
+{
+ struct btf *btf = ctx;
+
+ if (!*type_id) /* nothing to do for VOID references */
+ return 0;
+
+ /* we haven't updated btf's type count yet, so
+ * btf->start_id + btf->nr_types - 1 is the type ID offset we should
+ * add to all newly added BTF types
+ */
+ *type_id += btf->start_id + btf->nr_types - 1;
+ return 0;
+}
+
+static size_t btf_dedup_identity_hash_fn(long key, void *ctx);
+static bool btf_dedup_equal_fn(long k1, long k2, void *ctx);
+
+int btf__add_btf(struct btf *btf, const struct btf *src_btf)
+{
+ struct btf_pipe p = { .src = src_btf, .dst = btf };
+ int data_sz, sz, cnt, i, err, old_strs_len;
+ __u32 *off;
+ void *t;
+
+ /* appending split BTF isn't supported yet */
+ if (src_btf->base_btf)
+ return libbpf_err(-ENOTSUP);
+
+ /* deconstruct BTF, if necessary, and invalidate raw_data */
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ /* remember original strings section size if we have to roll back
+ * partial strings section changes
+ */
+ old_strs_len = btf->hdr->str_len;
+
+ data_sz = src_btf->hdr->type_len;
+ cnt = btf__type_cnt(src_btf) - 1;
+
+ /* pre-allocate enough memory for new types */
+ t = btf_add_type_mem(btf, data_sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ /* pre-allocate enough memory for type offset index for new types */
+ off = btf_add_type_offs_mem(btf, cnt);
+ if (!off)
+ return libbpf_err(-ENOMEM);
+
+ /* Map the string offsets from src_btf to the offsets from btf to improve performance */
+ p.str_off_map = hashmap__new(btf_dedup_identity_hash_fn, btf_dedup_equal_fn, NULL);
+ if (IS_ERR(p.str_off_map))
+ return libbpf_err(-ENOMEM);
+
+ /* bulk copy types data for all types from src_btf */
+ memcpy(t, src_btf->types_data, data_sz);
+
+ for (i = 0; i < cnt; i++) {
+ sz = btf_type_size(t);
+ if (sz < 0) {
+ /* unlikely, has to be corrupted src_btf */
+ err = sz;
+ goto err_out;
+ }
+
+ /* fill out type ID to type offset mapping for lookups by type ID */
+ *off = t - btf->types_data;
+
+ /* add, dedup, and remap strings referenced by this BTF type */
+ err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
+ if (err)
+ goto err_out;
+
+ /* remap all type IDs referenced from this BTF type */
+ err = btf_type_visit_type_ids(t, btf_rewrite_type_ids, btf);
+ if (err)
+ goto err_out;
+
+ /* go to next type data and type offset index entry */
+ t += sz;
+ off++;
+ }
+
+ /* Up until now any of the copied type data was effectively invisible,
+ * so if we exited early before this point due to error, BTF would be
+ * effectively unmodified. There would be extra internal memory
+ * pre-allocated, but it would not be available for querying. But now
+ * that we've copied and rewritten all the data successfully, we can
+ * update type count and various internal offsets and sizes to
+ * "commit" the changes and made them visible to the outside world.
+ */
+ btf->hdr->type_len += data_sz;
+ btf->hdr->str_off += data_sz;
+ btf->nr_types += cnt;
+
+ hashmap__free(p.str_off_map);
+
+ /* return type ID of the first added BTF type */
+ return btf->start_id + btf->nr_types - cnt;
+err_out:
+ /* zero out preallocated memory as if it was just allocated with
+ * libbpf_add_mem()
+ */
+ memset(btf->types_data + btf->hdr->type_len, 0, data_sz);
+ memset(btf->strs_data + old_strs_len, 0, btf->hdr->str_len - old_strs_len);
+
+ /* and now restore original strings section size; types data size
+ * wasn't modified, so doesn't need restoring, see big comment above
+ */
+ btf->hdr->str_len = old_strs_len;
+
+ hashmap__free(p.str_off_map);
+
+ return libbpf_err(err);
+}
+
+/*
+ * Append new BTF_KIND_INT type with:
+ * - *name* - non-empty, non-NULL type name;
+ * - *sz* - power-of-2 (1, 2, 4, ..) size of the type, in bytes;
+ * - encoding is a combination of BTF_INT_SIGNED, BTF_INT_CHAR, BTF_INT_BOOL.
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding)
+{
+ struct btf_type *t;
+ int sz, name_off;
+
+ /* non-empty name */
+ if (!name || !name[0])
+ return libbpf_err(-EINVAL);
+ /* byte_sz must be power of 2 */
+ if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 16)
+ return libbpf_err(-EINVAL);
+ if (encoding & ~(BTF_INT_SIGNED | BTF_INT_CHAR | BTF_INT_BOOL))
+ return libbpf_err(-EINVAL);
+
+ /* deconstruct BTF, if necessary, and invalidate raw_data */
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_type) + sizeof(int);
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ /* if something goes wrong later, we might end up with an extra string,
+ * but that shouldn't be a problem, because BTF can't be constructed
+ * completely anyway and will most probably be just discarded
+ */
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+
+ t->name_off = name_off;
+ t->info = btf_type_info(BTF_KIND_INT, 0, 0);
+ t->size = byte_sz;
+ /* set INT info, we don't allow setting legacy bit offset/size */
+ *(__u32 *)(t + 1) = (encoding << 24) | (byte_sz * 8);
+
+ return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new BTF_KIND_FLOAT type with:
+ * - *name* - non-empty, non-NULL type name;
+ * - *sz* - size of the type, in bytes;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_float(struct btf *btf, const char *name, size_t byte_sz)
+{
+ struct btf_type *t;
+ int sz, name_off;
+
+ /* non-empty name */
+ if (!name || !name[0])
+ return libbpf_err(-EINVAL);
+
+ /* byte_sz must be one of the explicitly allowed values */
+ if (byte_sz != 2 && byte_sz != 4 && byte_sz != 8 && byte_sz != 12 &&
+ byte_sz != 16)
+ return libbpf_err(-EINVAL);
+
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_type);
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+
+ t->name_off = name_off;
+ t->info = btf_type_info(BTF_KIND_FLOAT, 0, 0);
+ t->size = byte_sz;
+
+ return btf_commit_type(btf, sz);
+}
+
+/* it's completely legal to append BTF types with type IDs pointing forward to
+ * types that haven't been appended yet, so we only make sure that id looks
+ * sane, we can't guarantee that ID will always be valid
+ */
+static int validate_type_id(int id)
+{
+ if (id < 0 || id > BTF_MAX_NR_TYPES)
+ return -EINVAL;
+ return 0;
+}
+
+/* generic append function for PTR, TYPEDEF, CONST/VOLATILE/RESTRICT */
+static int btf_add_ref_kind(struct btf *btf, int kind, const char *name, int ref_type_id)
+{
+ struct btf_type *t;
+ int sz, name_off = 0;
+
+ if (validate_type_id(ref_type_id))
+ return libbpf_err(-EINVAL);
+
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_type);
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ if (name && name[0]) {
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+ }
+
+ t->name_off = name_off;
+ t->info = btf_type_info(kind, 0, 0);
+ t->type = ref_type_id;
+
+ return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new BTF_KIND_PTR type with:
+ * - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_ptr(struct btf *btf, int ref_type_id)
+{
+ return btf_add_ref_kind(btf, BTF_KIND_PTR, NULL, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_ARRAY type with:
+ * - *index_type_id* - type ID of the type describing array index;
+ * - *elem_type_id* - type ID of the type describing array element;
+ * - *nr_elems* - the size of the array;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_array(struct btf *btf, int index_type_id, int elem_type_id, __u32 nr_elems)
+{
+ struct btf_type *t;
+ struct btf_array *a;
+ int sz;
+
+ if (validate_type_id(index_type_id) || validate_type_id(elem_type_id))
+ return libbpf_err(-EINVAL);
+
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_type) + sizeof(struct btf_array);
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ t->name_off = 0;
+ t->info = btf_type_info(BTF_KIND_ARRAY, 0, 0);
+ t->size = 0;
+
+ a = btf_array(t);
+ a->type = elem_type_id;
+ a->index_type = index_type_id;
+ a->nelems = nr_elems;
+
+ return btf_commit_type(btf, sz);
+}
+
+/* generic STRUCT/UNION append function */
+static int btf_add_composite(struct btf *btf, int kind, const char *name, __u32 bytes_sz)
+{
+ struct btf_type *t;
+ int sz, name_off = 0;
+
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_type);
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ if (name && name[0]) {
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+ }
+
+ /* start out with vlen=0 and no kflag; this will be adjusted when
+ * adding each member
+ */
+ t->name_off = name_off;
+ t->info = btf_type_info(kind, 0, 0);
+ t->size = bytes_sz;
+
+ return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new BTF_KIND_STRUCT type with:
+ * - *name* - name of the struct, can be NULL or empty for anonymous structs;
+ * - *byte_sz* - size of the struct, in bytes;
+ *
+ * Struct initially has no fields in it. Fields can be added by
+ * btf__add_field() right after btf__add_struct() succeeds.
+ *
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_struct(struct btf *btf, const char *name, __u32 byte_sz)
+{
+ return btf_add_composite(btf, BTF_KIND_STRUCT, name, byte_sz);
+}
+
+/*
+ * Append new BTF_KIND_UNION type with:
+ * - *name* - name of the union, can be NULL or empty for anonymous union;
+ * - *byte_sz* - size of the union, in bytes;
+ *
+ * Union initially has no fields in it. Fields can be added by
+ * btf__add_field() right after btf__add_union() succeeds. All fields
+ * should have *bit_offset* of 0.
+ *
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_union(struct btf *btf, const char *name, __u32 byte_sz)
+{
+ return btf_add_composite(btf, BTF_KIND_UNION, name, byte_sz);
+}
+
+static struct btf_type *btf_last_type(struct btf *btf)
+{
+ return btf_type_by_id(btf, btf__type_cnt(btf) - 1);
+}
+
+/*
+ * Append new field for the current STRUCT/UNION type with:
+ * - *name* - name of the field, can be NULL or empty for anonymous field;
+ * - *type_id* - type ID for the type describing field type;
+ * - *bit_offset* - bit offset of the start of the field within struct/union;
+ * - *bit_size* - bit size of a bitfield, 0 for non-bitfield fields;
+ * Returns:
+ * - 0, on success;
+ * - <0, on error.
+ */
+int btf__add_field(struct btf *btf, const char *name, int type_id,
+ __u32 bit_offset, __u32 bit_size)
+{
+ struct btf_type *t;
+ struct btf_member *m;
+ bool is_bitfield;
+ int sz, name_off = 0;
+
+ /* last type should be union/struct */
+ if (btf->nr_types == 0)
+ return libbpf_err(-EINVAL);
+ t = btf_last_type(btf);
+ if (!btf_is_composite(t))
+ return libbpf_err(-EINVAL);
+
+ if (validate_type_id(type_id))
+ return libbpf_err(-EINVAL);
+ /* best-effort bit field offset/size enforcement */
+ is_bitfield = bit_size || (bit_offset % 8 != 0);
+ if (is_bitfield && (bit_size == 0 || bit_size > 255 || bit_offset > 0xffffff))
+ return libbpf_err(-EINVAL);
+
+ /* only offset 0 is allowed for unions */
+ if (btf_is_union(t) && bit_offset)
+ return libbpf_err(-EINVAL);
+
+ /* decompose and invalidate raw data */
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_member);
+ m = btf_add_type_mem(btf, sz);
+ if (!m)
+ return libbpf_err(-ENOMEM);
+
+ if (name && name[0]) {
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+ }
+
+ m->name_off = name_off;
+ m->type = type_id;
+ m->offset = bit_offset | (bit_size << 24);
+
+ /* btf_add_type_mem can invalidate t pointer */
+ t = btf_last_type(btf);
+ /* update parent type's vlen and kflag */
+ t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, is_bitfield || btf_kflag(t));
+
+ btf->hdr->type_len += sz;
+ btf->hdr->str_off += sz;
+ return 0;
+}
+
+static int btf_add_enum_common(struct btf *btf, const char *name, __u32 byte_sz,
+ bool is_signed, __u8 kind)
+{
+ struct btf_type *t;
+ int sz, name_off = 0;
+
+ /* byte_sz must be power of 2 */
+ if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 8)
+ return libbpf_err(-EINVAL);
+
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_type);
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ if (name && name[0]) {
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+ }
+
+ /* start out with vlen=0; it will be adjusted when adding enum values */
+ t->name_off = name_off;
+ t->info = btf_type_info(kind, 0, is_signed);
+ t->size = byte_sz;
+
+ return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new BTF_KIND_ENUM type with:
+ * - *name* - name of the enum, can be NULL or empty for anonymous enums;
+ * - *byte_sz* - size of the enum, in bytes.
+ *
+ * Enum initially has no enum values in it (and corresponds to enum forward
+ * declaration). Enumerator values can be added by btf__add_enum_value()
+ * immediately after btf__add_enum() succeeds.
+ *
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_enum(struct btf *btf, const char *name, __u32 byte_sz)
+{
+ /*
+ * set the signedness to be unsigned, it will change to signed
+ * if any later enumerator is negative.
+ */
+ return btf_add_enum_common(btf, name, byte_sz, false, BTF_KIND_ENUM);
+}
+
+/*
+ * Append new enum value for the current ENUM type with:
+ * - *name* - name of the enumerator value, can't be NULL or empty;
+ * - *value* - integer value corresponding to enum value *name*;
+ * Returns:
+ * - 0, on success;
+ * - <0, on error.
+ */
+int btf__add_enum_value(struct btf *btf, const char *name, __s64 value)
+{
+ struct btf_type *t;
+ struct btf_enum *v;
+ int sz, name_off;
+
+ /* last type should be BTF_KIND_ENUM */
+ if (btf->nr_types == 0)
+ return libbpf_err(-EINVAL);
+ t = btf_last_type(btf);
+ if (!btf_is_enum(t))
+ return libbpf_err(-EINVAL);
+
+ /* non-empty name */
+ if (!name || !name[0])
+ return libbpf_err(-EINVAL);
+ if (value < INT_MIN || value > UINT_MAX)
+ return libbpf_err(-E2BIG);
+
+ /* decompose and invalidate raw data */
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_enum);
+ v = btf_add_type_mem(btf, sz);
+ if (!v)
+ return libbpf_err(-ENOMEM);
+
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+
+ v->name_off = name_off;
+ v->val = value;
+
+ /* update parent type's vlen */
+ t = btf_last_type(btf);
+ btf_type_inc_vlen(t);
+
+ /* if negative value, set signedness to signed */
+ if (value < 0)
+ t->info = btf_type_info(btf_kind(t), btf_vlen(t), true);
+
+ btf->hdr->type_len += sz;
+ btf->hdr->str_off += sz;
+ return 0;
+}
+
+/*
+ * Append new BTF_KIND_ENUM64 type with:
+ * - *name* - name of the enum, can be NULL or empty for anonymous enums;
+ * - *byte_sz* - size of the enum, in bytes.
+ * - *is_signed* - whether the enum values are signed or not;
+ *
+ * Enum initially has no enum values in it (and corresponds to enum forward
+ * declaration). Enumerator values can be added by btf__add_enum64_value()
+ * immediately after btf__add_enum64() succeeds.
+ *
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_enum64(struct btf *btf, const char *name, __u32 byte_sz,
+ bool is_signed)
+{
+ return btf_add_enum_common(btf, name, byte_sz, is_signed,
+ BTF_KIND_ENUM64);
+}
+
+/*
+ * Append new enum value for the current ENUM64 type with:
+ * - *name* - name of the enumerator value, can't be NULL or empty;
+ * - *value* - integer value corresponding to enum value *name*;
+ * Returns:
+ * - 0, on success;
+ * - <0, on error.
+ */
+int btf__add_enum64_value(struct btf *btf, const char *name, __u64 value)
+{
+ struct btf_enum64 *v;
+ struct btf_type *t;
+ int sz, name_off;
+
+ /* last type should be BTF_KIND_ENUM64 */
+ if (btf->nr_types == 0)
+ return libbpf_err(-EINVAL);
+ t = btf_last_type(btf);
+ if (!btf_is_enum64(t))
+ return libbpf_err(-EINVAL);
+
+ /* non-empty name */
+ if (!name || !name[0])
+ return libbpf_err(-EINVAL);
+
+ /* decompose and invalidate raw data */
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_enum64);
+ v = btf_add_type_mem(btf, sz);
+ if (!v)
+ return libbpf_err(-ENOMEM);
+
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+
+ v->name_off = name_off;
+ v->val_lo32 = (__u32)value;
+ v->val_hi32 = value >> 32;
+
+ /* update parent type's vlen */
+ t = btf_last_type(btf);
+ btf_type_inc_vlen(t);
+
+ btf->hdr->type_len += sz;
+ btf->hdr->str_off += sz;
+ return 0;
+}
+
+/*
+ * Append new BTF_KIND_FWD type with:
+ * - *name*, non-empty/non-NULL name;
+ * - *fwd_kind*, kind of forward declaration, one of BTF_FWD_STRUCT,
+ * BTF_FWD_UNION, or BTF_FWD_ENUM;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_fwd(struct btf *btf, const char *name, enum btf_fwd_kind fwd_kind)
+{
+ if (!name || !name[0])
+ return libbpf_err(-EINVAL);
+
+ switch (fwd_kind) {
+ case BTF_FWD_STRUCT:
+ case BTF_FWD_UNION: {
+ struct btf_type *t;
+ int id;
+
+ id = btf_add_ref_kind(btf, BTF_KIND_FWD, name, 0);
+ if (id <= 0)
+ return id;
+ t = btf_type_by_id(btf, id);
+ t->info = btf_type_info(BTF_KIND_FWD, 0, fwd_kind == BTF_FWD_UNION);
+ return id;
+ }
+ case BTF_FWD_ENUM:
+ /* enum forward in BTF currently is just an enum with no enum
+ * values; we also assume a standard 4-byte size for it
+ */
+ return btf__add_enum(btf, name, sizeof(int));
+ default:
+ return libbpf_err(-EINVAL);
+ }
+}
+
+/*
+ * Append new BTF_KING_TYPEDEF type with:
+ * - *name*, non-empty/non-NULL name;
+ * - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_typedef(struct btf *btf, const char *name, int ref_type_id)
+{
+ if (!name || !name[0])
+ return libbpf_err(-EINVAL);
+
+ return btf_add_ref_kind(btf, BTF_KIND_TYPEDEF, name, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_VOLATILE type with:
+ * - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_volatile(struct btf *btf, int ref_type_id)
+{
+ return btf_add_ref_kind(btf, BTF_KIND_VOLATILE, NULL, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_CONST type with:
+ * - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_const(struct btf *btf, int ref_type_id)
+{
+ return btf_add_ref_kind(btf, BTF_KIND_CONST, NULL, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_RESTRICT type with:
+ * - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_restrict(struct btf *btf, int ref_type_id)
+{
+ return btf_add_ref_kind(btf, BTF_KIND_RESTRICT, NULL, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_TYPE_TAG type with:
+ * - *value*, non-empty/non-NULL tag value;
+ * - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_type_tag(struct btf *btf, const char *value, int ref_type_id)
+{
+ if (!value || !value[0])
+ return libbpf_err(-EINVAL);
+
+ return btf_add_ref_kind(btf, BTF_KIND_TYPE_TAG, value, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_FUNC type with:
+ * - *name*, non-empty/non-NULL name;
+ * - *proto_type_id* - FUNC_PROTO's type ID, it might not exist yet;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_func(struct btf *btf, const char *name,
+ enum btf_func_linkage linkage, int proto_type_id)
+{
+ int id;
+
+ if (!name || !name[0])
+ return libbpf_err(-EINVAL);
+ if (linkage != BTF_FUNC_STATIC && linkage != BTF_FUNC_GLOBAL &&
+ linkage != BTF_FUNC_EXTERN)
+ return libbpf_err(-EINVAL);
+
+ id = btf_add_ref_kind(btf, BTF_KIND_FUNC, name, proto_type_id);
+ if (id > 0) {
+ struct btf_type *t = btf_type_by_id(btf, id);
+
+ t->info = btf_type_info(BTF_KIND_FUNC, linkage, 0);
+ }
+ return libbpf_err(id);
+}
+
+/*
+ * Append new BTF_KIND_FUNC_PROTO with:
+ * - *ret_type_id* - type ID for return result of a function.
+ *
+ * Function prototype initially has no arguments, but they can be added by
+ * btf__add_func_param() one by one, immediately after
+ * btf__add_func_proto() succeeded.
+ *
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_func_proto(struct btf *btf, int ret_type_id)
+{
+ struct btf_type *t;
+ int sz;
+
+ if (validate_type_id(ret_type_id))
+ return libbpf_err(-EINVAL);
+
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_type);
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ /* start out with vlen=0; this will be adjusted when adding enum
+ * values, if necessary
+ */
+ t->name_off = 0;
+ t->info = btf_type_info(BTF_KIND_FUNC_PROTO, 0, 0);
+ t->type = ret_type_id;
+
+ return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new function parameter for current FUNC_PROTO type with:
+ * - *name* - parameter name, can be NULL or empty;
+ * - *type_id* - type ID describing the type of the parameter.
+ * Returns:
+ * - 0, on success;
+ * - <0, on error.
+ */
+int btf__add_func_param(struct btf *btf, const char *name, int type_id)
+{
+ struct btf_type *t;
+ struct btf_param *p;
+ int sz, name_off = 0;
+
+ if (validate_type_id(type_id))
+ return libbpf_err(-EINVAL);
+
+ /* last type should be BTF_KIND_FUNC_PROTO */
+ if (btf->nr_types == 0)
+ return libbpf_err(-EINVAL);
+ t = btf_last_type(btf);
+ if (!btf_is_func_proto(t))
+ return libbpf_err(-EINVAL);
+
+ /* decompose and invalidate raw data */
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_param);
+ p = btf_add_type_mem(btf, sz);
+ if (!p)
+ return libbpf_err(-ENOMEM);
+
+ if (name && name[0]) {
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+ }
+
+ p->name_off = name_off;
+ p->type = type_id;
+
+ /* update parent type's vlen */
+ t = btf_last_type(btf);
+ btf_type_inc_vlen(t);
+
+ btf->hdr->type_len += sz;
+ btf->hdr->str_off += sz;
+ return 0;
+}
+
+/*
+ * Append new BTF_KIND_VAR type with:
+ * - *name* - non-empty/non-NULL name;
+ * - *linkage* - variable linkage, one of BTF_VAR_STATIC,
+ * BTF_VAR_GLOBAL_ALLOCATED, or BTF_VAR_GLOBAL_EXTERN;
+ * - *type_id* - type ID of the type describing the type of the variable.
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_var(struct btf *btf, const char *name, int linkage, int type_id)
+{
+ struct btf_type *t;
+ struct btf_var *v;
+ int sz, name_off;
+
+ /* non-empty name */
+ if (!name || !name[0])
+ return libbpf_err(-EINVAL);
+ if (linkage != BTF_VAR_STATIC && linkage != BTF_VAR_GLOBAL_ALLOCATED &&
+ linkage != BTF_VAR_GLOBAL_EXTERN)
+ return libbpf_err(-EINVAL);
+ if (validate_type_id(type_id))
+ return libbpf_err(-EINVAL);
+
+ /* deconstruct BTF, if necessary, and invalidate raw_data */
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_type) + sizeof(struct btf_var);
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+
+ t->name_off = name_off;
+ t->info = btf_type_info(BTF_KIND_VAR, 0, 0);
+ t->type = type_id;
+
+ v = btf_var(t);
+ v->linkage = linkage;
+
+ return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new BTF_KIND_DATASEC type with:
+ * - *name* - non-empty/non-NULL name;
+ * - *byte_sz* - data section size, in bytes.
+ *
+ * Data section is initially empty. Variables info can be added with
+ * btf__add_datasec_var_info() calls, after btf__add_datasec() succeeds.
+ *
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz)
+{
+ struct btf_type *t;
+ int sz, name_off;
+
+ /* non-empty name */
+ if (!name || !name[0])
+ return libbpf_err(-EINVAL);
+
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_type);
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ name_off = btf__add_str(btf, name);
+ if (name_off < 0)
+ return name_off;
+
+ /* start with vlen=0, which will be update as var_secinfos are added */
+ t->name_off = name_off;
+ t->info = btf_type_info(BTF_KIND_DATASEC, 0, 0);
+ t->size = byte_sz;
+
+ return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new data section variable information entry for current DATASEC type:
+ * - *var_type_id* - type ID, describing type of the variable;
+ * - *offset* - variable offset within data section, in bytes;
+ * - *byte_sz* - variable size, in bytes.
+ *
+ * Returns:
+ * - 0, on success;
+ * - <0, on error.
+ */
+int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __u32 byte_sz)
+{
+ struct btf_type *t;
+ struct btf_var_secinfo *v;
+ int sz;
+
+ /* last type should be BTF_KIND_DATASEC */
+ if (btf->nr_types == 0)
+ return libbpf_err(-EINVAL);
+ t = btf_last_type(btf);
+ if (!btf_is_datasec(t))
+ return libbpf_err(-EINVAL);
+
+ if (validate_type_id(var_type_id))
+ return libbpf_err(-EINVAL);
+
+ /* decompose and invalidate raw data */
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_var_secinfo);
+ v = btf_add_type_mem(btf, sz);
+ if (!v)
+ return libbpf_err(-ENOMEM);
+
+ v->type = var_type_id;
+ v->offset = offset;
+ v->size = byte_sz;
+
+ /* update parent type's vlen */
+ t = btf_last_type(btf);
+ btf_type_inc_vlen(t);
+
+ btf->hdr->type_len += sz;
+ btf->hdr->str_off += sz;
+ return 0;
+}
+
+/*
+ * Append new BTF_KIND_DECL_TAG type with:
+ * - *value* - non-empty/non-NULL string;
+ * - *ref_type_id* - referenced type ID, it might not exist yet;
+ * - *component_idx* - -1 for tagging reference type, otherwise struct/union
+ * member or function argument index;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
+ int component_idx)
+{
+ struct btf_type *t;
+ int sz, value_off;
+
+ if (!value || !value[0] || component_idx < -1)
+ return libbpf_err(-EINVAL);
+
+ if (validate_type_id(ref_type_id))
+ return libbpf_err(-EINVAL);
+
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ sz = sizeof(struct btf_type) + sizeof(struct btf_decl_tag);
+ t = btf_add_type_mem(btf, sz);
+ if (!t)
+ return libbpf_err(-ENOMEM);
+
+ value_off = btf__add_str(btf, value);
+ if (value_off < 0)
+ return value_off;
+
+ t->name_off = value_off;
+ t->info = btf_type_info(BTF_KIND_DECL_TAG, 0, false);
+ t->type = ref_type_id;
+ btf_decl_tag(t)->component_idx = component_idx;
+
+ return btf_commit_type(btf, sz);
+}
+
+struct btf_ext_sec_setup_param {
+ __u32 off;
+ __u32 len;
+ __u32 min_rec_size;
+ struct btf_ext_info *ext_info;
+ const char *desc;
+};
+
+static int btf_ext_setup_info(struct btf_ext *btf_ext,
+ struct btf_ext_sec_setup_param *ext_sec)
+{
+ const struct btf_ext_info_sec *sinfo;
+ struct btf_ext_info *ext_info;
+ __u32 info_left, record_size;
+ size_t sec_cnt = 0;
+ /* The start of the info sec (including the __u32 record_size). */
+ void *info;
+
+ if (ext_sec->len == 0)
+ return 0;
+
+ if (ext_sec->off & 0x03) {
+ pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
+ ext_sec->desc);
+ return -EINVAL;
+ }
+
+ info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;
+ info_left = ext_sec->len;
+
+ if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {
+ pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
+ ext_sec->desc, ext_sec->off, ext_sec->len);
+ return -EINVAL;
+ }
+
+ /* At least a record size */
+ if (info_left < sizeof(__u32)) {
+ pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
+ return -EINVAL;
+ }
+
+ /* The record size needs to meet the minimum standard */
+ record_size = *(__u32 *)info;
+ if (record_size < ext_sec->min_rec_size ||
+ record_size & 0x03) {
+ pr_debug("%s section in .BTF.ext has invalid record size %u\n",
+ ext_sec->desc, record_size);
+ return -EINVAL;
+ }
+
+ sinfo = info + sizeof(__u32);
+ info_left -= sizeof(__u32);
+
+ /* If no records, return failure now so .BTF.ext won't be used. */
+ if (!info_left) {
+ pr_debug("%s section in .BTF.ext has no records", ext_sec->desc);
+ return -EINVAL;
+ }
+
+ while (info_left) {
+ unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
+ __u64 total_record_size;
+ __u32 num_records;
+
+ if (info_left < sec_hdrlen) {
+ pr_debug("%s section header is not found in .BTF.ext\n",
+ ext_sec->desc);
+ return -EINVAL;
+ }
+
+ num_records = sinfo->num_info;
+ if (num_records == 0) {
+ pr_debug("%s section has incorrect num_records in .BTF.ext\n",
+ ext_sec->desc);
+ return -EINVAL;
+ }
+
+ total_record_size = sec_hdrlen + (__u64)num_records * record_size;
+ if (info_left < total_record_size) {
+ pr_debug("%s section has incorrect num_records in .BTF.ext\n",
+ ext_sec->desc);
+ return -EINVAL;
+ }
+
+ info_left -= total_record_size;
+ sinfo = (void *)sinfo + total_record_size;
+ sec_cnt++;
+ }
+
+ ext_info = ext_sec->ext_info;
+ ext_info->len = ext_sec->len - sizeof(__u32);
+ ext_info->rec_size = record_size;
+ ext_info->info = info + sizeof(__u32);
+ ext_info->sec_cnt = sec_cnt;
+
+ return 0;
+}
+
+static int btf_ext_setup_func_info(struct btf_ext *btf_ext)
+{
+ struct btf_ext_sec_setup_param param = {
+ .off = btf_ext->hdr->func_info_off,
+ .len = btf_ext->hdr->func_info_len,
+ .min_rec_size = sizeof(struct bpf_func_info_min),
+ .ext_info = &btf_ext->func_info,
+ .desc = "func_info"
+ };
+
+ return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
+{
+ struct btf_ext_sec_setup_param param = {
+ .off = btf_ext->hdr->line_info_off,
+ .len = btf_ext->hdr->line_info_len,
+ .min_rec_size = sizeof(struct bpf_line_info_min),
+ .ext_info = &btf_ext->line_info,
+ .desc = "line_info",
+ };
+
+ return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_setup_core_relos(struct btf_ext *btf_ext)
+{
+ struct btf_ext_sec_setup_param param = {
+ .off = btf_ext->hdr->core_relo_off,
+ .len = btf_ext->hdr->core_relo_len,
+ .min_rec_size = sizeof(struct bpf_core_relo),
+ .ext_info = &btf_ext->core_relo_info,
+ .desc = "core_relo",
+ };
+
+ return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
+{
+ const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
+
+ if (data_size < offsetofend(struct btf_ext_header, hdr_len) ||
+ data_size < hdr->hdr_len) {
+ pr_debug("BTF.ext header not found");
+ return -EINVAL;
+ }
+
+ if (hdr->magic == bswap_16(BTF_MAGIC)) {
+ pr_warn("BTF.ext in non-native endianness is not supported\n");
+ return -ENOTSUP;
+ } else if (hdr->magic != BTF_MAGIC) {
+ pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic);
+ return -EINVAL;
+ }
+
+ if (hdr->version != BTF_VERSION) {
+ pr_debug("Unsupported BTF.ext version:%u\n", hdr->version);
+ return -ENOTSUP;
+ }
+
+ if (hdr->flags) {
+ pr_debug("Unsupported BTF.ext flags:%x\n", hdr->flags);
+ return -ENOTSUP;
+ }
+
+ if (data_size == hdr->hdr_len) {
+ pr_debug("BTF.ext has no data\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+void btf_ext__free(struct btf_ext *btf_ext)
+{
+ if (IS_ERR_OR_NULL(btf_ext))
+ return;
+ free(btf_ext->func_info.sec_idxs);
+ free(btf_ext->line_info.sec_idxs);
+ free(btf_ext->core_relo_info.sec_idxs);
+ free(btf_ext->data);
+ free(btf_ext);
+}
+
+struct btf_ext *btf_ext__new(const __u8 *data, __u32 size)
+{
+ struct btf_ext *btf_ext;
+ int err;
+
+ btf_ext = calloc(1, sizeof(struct btf_ext));
+ if (!btf_ext)
+ return libbpf_err_ptr(-ENOMEM);
+
+ btf_ext->data_size = size;
+ btf_ext->data = malloc(size);
+ if (!btf_ext->data) {
+ err = -ENOMEM;
+ goto done;
+ }
+ memcpy(btf_ext->data, data, size);
+
+ err = btf_ext_parse_hdr(btf_ext->data, size);
+ if (err)
+ goto done;
+
+ if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, line_info_len)) {
+ err = -EINVAL;
+ goto done;
+ }
+
+ err = btf_ext_setup_func_info(btf_ext);
+ if (err)
+ goto done;
+
+ err = btf_ext_setup_line_info(btf_ext);
+ if (err)
+ goto done;
+
+ if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len))
+ goto done; /* skip core relos parsing */
+
+ err = btf_ext_setup_core_relos(btf_ext);
+ if (err)
+ goto done;
+
+done:
+ if (err) {
+ btf_ext__free(btf_ext);
+ return libbpf_err_ptr(err);
+ }
+
+ return btf_ext;
+}
+
+const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size)
+{
+ *size = btf_ext->data_size;
+ return btf_ext->data;
+}
+
+struct btf_dedup;
+
+static struct btf_dedup *btf_dedup_new(struct btf *btf, const struct btf_dedup_opts *opts);
+static void btf_dedup_free(struct btf_dedup *d);
+static int btf_dedup_prep(struct btf_dedup *d);
+static int btf_dedup_strings(struct btf_dedup *d);
+static int btf_dedup_prim_types(struct btf_dedup *d);
+static int btf_dedup_struct_types(struct btf_dedup *d);
+static int btf_dedup_ref_types(struct btf_dedup *d);
+static int btf_dedup_resolve_fwds(struct btf_dedup *d);
+static int btf_dedup_compact_types(struct btf_dedup *d);
+static int btf_dedup_remap_types(struct btf_dedup *d);
+
+/*
+ * Deduplicate BTF types and strings.
+ *
+ * BTF dedup algorithm takes as an input `struct btf` representing `.BTF` ELF
+ * section with all BTF type descriptors and string data. It overwrites that
+ * memory in-place with deduplicated types and strings without any loss of
+ * information. If optional `struct btf_ext` representing '.BTF.ext' ELF section
+ * is provided, all the strings referenced from .BTF.ext section are honored
+ * and updated to point to the right offsets after deduplication.
+ *
+ * If function returns with error, type/string data might be garbled and should
+ * be discarded.
+ *
+ * More verbose and detailed description of both problem btf_dedup is solving,
+ * as well as solution could be found at:
+ * https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
+ *
+ * Problem description and justification
+ * =====================================
+ *
+ * BTF type information is typically emitted either as a result of conversion
+ * from DWARF to BTF or directly by compiler. In both cases, each compilation
+ * unit contains information about a subset of all the types that are used
+ * in an application. These subsets are frequently overlapping and contain a lot
+ * of duplicated information when later concatenated together into a single
+ * binary. This algorithm ensures that each unique type is represented by single
+ * BTF type descriptor, greatly reducing resulting size of BTF data.
+ *
+ * Compilation unit isolation and subsequent duplication of data is not the only
+ * problem. The same type hierarchy (e.g., struct and all the type that struct
+ * references) in different compilation units can be represented in BTF to
+ * various degrees of completeness (or, rather, incompleteness) due to
+ * struct/union forward declarations.
+ *
+ * Let's take a look at an example, that we'll use to better understand the
+ * problem (and solution). Suppose we have two compilation units, each using
+ * same `struct S`, but each of them having incomplete type information about
+ * struct's fields:
+ *
+ * // CU #1:
+ * struct S;
+ * struct A {
+ * int a;
+ * struct A* self;
+ * struct S* parent;
+ * };
+ * struct B;
+ * struct S {
+ * struct A* a_ptr;
+ * struct B* b_ptr;
+ * };
+ *
+ * // CU #2:
+ * struct S;
+ * struct A;
+ * struct B {
+ * int b;
+ * struct B* self;
+ * struct S* parent;
+ * };
+ * struct S {
+ * struct A* a_ptr;
+ * struct B* b_ptr;
+ * };
+ *
+ * In case of CU #1, BTF data will know only that `struct B` exist (but no
+ * more), but will know the complete type information about `struct A`. While
+ * for CU #2, it will know full type information about `struct B`, but will
+ * only know about forward declaration of `struct A` (in BTF terms, it will
+ * have `BTF_KIND_FWD` type descriptor with name `B`).
+ *
+ * This compilation unit isolation means that it's possible that there is no
+ * single CU with complete type information describing structs `S`, `A`, and
+ * `B`. Also, we might get tons of duplicated and redundant type information.
+ *
+ * Additional complication we need to keep in mind comes from the fact that
+ * types, in general, can form graphs containing cycles, not just DAGs.
+ *
+ * While algorithm does deduplication, it also merges and resolves type
+ * information (unless disabled throught `struct btf_opts`), whenever possible.
+ * E.g., in the example above with two compilation units having partial type
+ * information for structs `A` and `B`, the output of algorithm will emit
+ * a single copy of each BTF type that describes structs `A`, `B`, and `S`
+ * (as well as type information for `int` and pointers), as if they were defined
+ * in a single compilation unit as:
+ *
+ * struct A {
+ * int a;
+ * struct A* self;
+ * struct S* parent;
+ * };
+ * struct B {
+ * int b;
+ * struct B* self;
+ * struct S* parent;
+ * };
+ * struct S {
+ * struct A* a_ptr;
+ * struct B* b_ptr;
+ * };
+ *
+ * Algorithm summary
+ * =================
+ *
+ * Algorithm completes its work in 7 separate passes:
+ *
+ * 1. Strings deduplication.
+ * 2. Primitive types deduplication (int, enum, fwd).
+ * 3. Struct/union types deduplication.
+ * 4. Resolve unambiguous forward declarations.
+ * 5. Reference types deduplication (pointers, typedefs, arrays, funcs, func
+ * protos, and const/volatile/restrict modifiers).
+ * 6. Types compaction.
+ * 7. Types remapping.
+ *
+ * Algorithm determines canonical type descriptor, which is a single
+ * representative type for each truly unique type. This canonical type is the
+ * one that will go into final deduplicated BTF type information. For
+ * struct/unions, it is also the type that algorithm will merge additional type
+ * information into (while resolving FWDs), as it discovers it from data in
+ * other CUs. Each input BTF type eventually gets either mapped to itself, if
+ * that type is canonical, or to some other type, if that type is equivalent
+ * and was chosen as canonical representative. This mapping is stored in
+ * `btf_dedup->map` array. This map is also used to record STRUCT/UNION that
+ * FWD type got resolved to.
+ *
+ * To facilitate fast discovery of canonical types, we also maintain canonical
+ * index (`btf_dedup->dedup_table`), which maps type descriptor's signature hash
+ * (i.e., hashed kind, name, size, fields, etc) into a list of canonical types
+ * that match that signature. With sufficiently good choice of type signature
+ * hashing function, we can limit number of canonical types for each unique type
+ * signature to a very small number, allowing to find canonical type for any
+ * duplicated type very quickly.
+ *
+ * Struct/union deduplication is the most critical part and algorithm for
+ * deduplicating structs/unions is described in greater details in comments for
+ * `btf_dedup_is_equiv` function.
+ */
+int btf__dedup(struct btf *btf, const struct btf_dedup_opts *opts)
+{
+ struct btf_dedup *d;
+ int err;
+
+ if (!OPTS_VALID(opts, btf_dedup_opts))
+ return libbpf_err(-EINVAL);
+
+ d = btf_dedup_new(btf, opts);
+ if (IS_ERR(d)) {
+ pr_debug("btf_dedup_new failed: %ld", PTR_ERR(d));
+ return libbpf_err(-EINVAL);
+ }
+
+ if (btf_ensure_modifiable(btf)) {
+ err = -ENOMEM;
+ goto done;
+ }
+
+ err = btf_dedup_prep(d);
+ if (err) {
+ pr_debug("btf_dedup_prep failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_strings(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_strings failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_prim_types(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_prim_types failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_struct_types(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_struct_types failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_resolve_fwds(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_resolve_fwds failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_ref_types(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_ref_types failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_compact_types(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_compact_types failed:%d\n", err);
+ goto done;
+ }
+ err = btf_dedup_remap_types(d);
+ if (err < 0) {
+ pr_debug("btf_dedup_remap_types failed:%d\n", err);
+ goto done;
+ }
+
+done:
+ btf_dedup_free(d);
+ return libbpf_err(err);
+}
+
+#define BTF_UNPROCESSED_ID ((__u32)-1)
+#define BTF_IN_PROGRESS_ID ((__u32)-2)
+
+struct btf_dedup {
+ /* .BTF section to be deduped in-place */
+ struct btf *btf;
+ /*
+ * Optional .BTF.ext section. When provided, any strings referenced
+ * from it will be taken into account when deduping strings
+ */
+ struct btf_ext *btf_ext;
+ /*
+ * This is a map from any type's signature hash to a list of possible
+ * canonical representative type candidates. Hash collisions are
+ * ignored, so even types of various kinds can share same list of
+ * candidates, which is fine because we rely on subsequent
+ * btf_xxx_equal() checks to authoritatively verify type equality.
+ */
+ struct hashmap *dedup_table;
+ /* Canonical types map */
+ __u32 *map;
+ /* Hypothetical mapping, used during type graph equivalence checks */
+ __u32 *hypot_map;
+ __u32 *hypot_list;
+ size_t hypot_cnt;
+ size_t hypot_cap;
+ /* Whether hypothetical mapping, if successful, would need to adjust
+ * already canonicalized types (due to a new forward declaration to
+ * concrete type resolution). In such case, during split BTF dedup
+ * candidate type would still be considered as different, because base
+ * BTF is considered to be immutable.
+ */
+ bool hypot_adjust_canon;
+ /* Various option modifying behavior of algorithm */
+ struct btf_dedup_opts opts;
+ /* temporary strings deduplication state */
+ struct strset *strs_set;
+};
+
+static long hash_combine(long h, long value)
+{
+ return h * 31 + value;
+}
+
+#define for_each_dedup_cand(d, node, hash) \
+ hashmap__for_each_key_entry(d->dedup_table, node, hash)
+
+static int btf_dedup_table_add(struct btf_dedup *d, long hash, __u32 type_id)
+{
+ return hashmap__append(d->dedup_table, hash, type_id);
+}
+
+static int btf_dedup_hypot_map_add(struct btf_dedup *d,
+ __u32 from_id, __u32 to_id)
+{
+ if (d->hypot_cnt == d->hypot_cap) {
+ __u32 *new_list;
+
+ d->hypot_cap += max((size_t)16, d->hypot_cap / 2);
+ new_list = libbpf_reallocarray(d->hypot_list, d->hypot_cap, sizeof(__u32));
+ if (!new_list)
+ return -ENOMEM;
+ d->hypot_list = new_list;
+ }
+ d->hypot_list[d->hypot_cnt++] = from_id;
+ d->hypot_map[from_id] = to_id;
+ return 0;
+}
+
+static void btf_dedup_clear_hypot_map(struct btf_dedup *d)
+{
+ int i;
+
+ for (i = 0; i < d->hypot_cnt; i++)
+ d->hypot_map[d->hypot_list[i]] = BTF_UNPROCESSED_ID;
+ d->hypot_cnt = 0;
+ d->hypot_adjust_canon = false;
+}
+
+static void btf_dedup_free(struct btf_dedup *d)
+{
+ hashmap__free(d->dedup_table);
+ d->dedup_table = NULL;
+
+ free(d->map);
+ d->map = NULL;
+
+ free(d->hypot_map);
+ d->hypot_map = NULL;
+
+ free(d->hypot_list);
+ d->hypot_list = NULL;
+
+ free(d);
+}
+
+static size_t btf_dedup_identity_hash_fn(long key, void *ctx)
+{
+ return key;
+}
+
+static size_t btf_dedup_collision_hash_fn(long key, void *ctx)
+{
+ return 0;
+}
+
+static bool btf_dedup_equal_fn(long k1, long k2, void *ctx)
+{
+ return k1 == k2;
+}
+
+static struct btf_dedup *btf_dedup_new(struct btf *btf, const struct btf_dedup_opts *opts)
+{
+ struct btf_dedup *d = calloc(1, sizeof(struct btf_dedup));
+ hashmap_hash_fn hash_fn = btf_dedup_identity_hash_fn;
+ int i, err = 0, type_cnt;
+
+ if (!d)
+ return ERR_PTR(-ENOMEM);
+
+ if (OPTS_GET(opts, force_collisions, false))
+ hash_fn = btf_dedup_collision_hash_fn;
+
+ d->btf = btf;
+ d->btf_ext = OPTS_GET(opts, btf_ext, NULL);
+
+ d->dedup_table = hashmap__new(hash_fn, btf_dedup_equal_fn, NULL);
+ if (IS_ERR(d->dedup_table)) {
+ err = PTR_ERR(d->dedup_table);
+ d->dedup_table = NULL;
+ goto done;
+ }
+
+ type_cnt = btf__type_cnt(btf);
+ d->map = malloc(sizeof(__u32) * type_cnt);
+ if (!d->map) {
+ err = -ENOMEM;
+ goto done;
+ }
+ /* special BTF "void" type is made canonical immediately */
+ d->map[0] = 0;
+ for (i = 1; i < type_cnt; i++) {
+ struct btf_type *t = btf_type_by_id(d->btf, i);
+
+ /* VAR and DATASEC are never deduped and are self-canonical */
+ if (btf_is_var(t) || btf_is_datasec(t))
+ d->map[i] = i;
+ else
+ d->map[i] = BTF_UNPROCESSED_ID;
+ }
+
+ d->hypot_map = malloc(sizeof(__u32) * type_cnt);
+ if (!d->hypot_map) {
+ err = -ENOMEM;
+ goto done;
+ }
+ for (i = 0; i < type_cnt; i++)
+ d->hypot_map[i] = BTF_UNPROCESSED_ID;
+
+done:
+ if (err) {
+ btf_dedup_free(d);
+ return ERR_PTR(err);
+ }
+
+ return d;
+}
+
+/*
+ * Iterate over all possible places in .BTF and .BTF.ext that can reference
+ * string and pass pointer to it to a provided callback `fn`.
+ */
+static int btf_for_each_str_off(struct btf_dedup *d, str_off_visit_fn fn, void *ctx)
+{
+ int i, r;
+
+ for (i = 0; i < d->btf->nr_types; i++) {
+ struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
+
+ r = btf_type_visit_str_offs(t, fn, ctx);
+ if (r)
+ return r;
+ }
+
+ if (!d->btf_ext)
+ return 0;
+
+ r = btf_ext_visit_str_offs(d->btf_ext, fn, ctx);
+ if (r)
+ return r;
+
+ return 0;
+}
+
+static int strs_dedup_remap_str_off(__u32 *str_off_ptr, void *ctx)
+{
+ struct btf_dedup *d = ctx;
+ __u32 str_off = *str_off_ptr;
+ const char *s;
+ int off, err;
+
+ /* don't touch empty string or string in main BTF */
+ if (str_off == 0 || str_off < d->btf->start_str_off)
+ return 0;
+
+ s = btf__str_by_offset(d->btf, str_off);
+ if (d->btf->base_btf) {
+ err = btf__find_str(d->btf->base_btf, s);
+ if (err >= 0) {
+ *str_off_ptr = err;
+ return 0;
+ }
+ if (err != -ENOENT)
+ return err;
+ }
+
+ off = strset__add_str(d->strs_set, s);
+ if (off < 0)
+ return off;
+
+ *str_off_ptr = d->btf->start_str_off + off;
+ return 0;
+}
+
+/*
+ * Dedup string and filter out those that are not referenced from either .BTF
+ * or .BTF.ext (if provided) sections.
+ *
+ * This is done by building index of all strings in BTF's string section,
+ * then iterating over all entities that can reference strings (e.g., type
+ * names, struct field names, .BTF.ext line info, etc) and marking corresponding
+ * strings as used. After that all used strings are deduped and compacted into
+ * sequential blob of memory and new offsets are calculated. Then all the string
+ * references are iterated again and rewritten using new offsets.
+ */
+static int btf_dedup_strings(struct btf_dedup *d)
+{
+ int err;
+
+ if (d->btf->strs_deduped)
+ return 0;
+
+ d->strs_set = strset__new(BTF_MAX_STR_OFFSET, NULL, 0);
+ if (IS_ERR(d->strs_set)) {
+ err = PTR_ERR(d->strs_set);
+ goto err_out;
+ }
+
+ if (!d->btf->base_btf) {
+ /* insert empty string; we won't be looking it up during strings
+ * dedup, but it's good to have it for generic BTF string lookups
+ */
+ err = strset__add_str(d->strs_set, "");
+ if (err < 0)
+ goto err_out;
+ }
+
+ /* remap string offsets */
+ err = btf_for_each_str_off(d, strs_dedup_remap_str_off, d);
+ if (err)
+ goto err_out;
+
+ /* replace BTF string data and hash with deduped ones */
+ strset__free(d->btf->strs_set);
+ d->btf->hdr->str_len = strset__data_size(d->strs_set);
+ d->btf->strs_set = d->strs_set;
+ d->strs_set = NULL;
+ d->btf->strs_deduped = true;
+ return 0;
+
+err_out:
+ strset__free(d->strs_set);
+ d->strs_set = NULL;
+
+ return err;
+}
+
+static long btf_hash_common(struct btf_type *t)
+{
+ long h;
+
+ h = hash_combine(0, t->name_off);
+ h = hash_combine(h, t->info);
+ h = hash_combine(h, t->size);
+ return h;
+}
+
+static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
+{
+ return t1->name_off == t2->name_off &&
+ t1->info == t2->info &&
+ t1->size == t2->size;
+}
+
+/* Calculate type signature hash of INT or TAG. */
+static long btf_hash_int_decl_tag(struct btf_type *t)
+{
+ __u32 info = *(__u32 *)(t + 1);
+ long h;
+
+ h = btf_hash_common(t);
+ h = hash_combine(h, info);
+ return h;
+}
+
+/* Check structural equality of two INTs or TAGs. */
+static bool btf_equal_int_tag(struct btf_type *t1, struct btf_type *t2)
+{
+ __u32 info1, info2;
+
+ if (!btf_equal_common(t1, t2))
+ return false;
+ info1 = *(__u32 *)(t1 + 1);
+ info2 = *(__u32 *)(t2 + 1);
+ return info1 == info2;
+}
+
+/* Calculate type signature hash of ENUM/ENUM64. */
+static long btf_hash_enum(struct btf_type *t)
+{
+ long h;
+
+ /* don't hash vlen, enum members and size to support enum fwd resolving */
+ h = hash_combine(0, t->name_off);
+ return h;
+}
+
+static bool btf_equal_enum_members(struct btf_type *t1, struct btf_type *t2)
+{
+ const struct btf_enum *m1, *m2;
+ __u16 vlen;
+ int i;
+
+ vlen = btf_vlen(t1);
+ m1 = btf_enum(t1);
+ m2 = btf_enum(t2);
+ for (i = 0; i < vlen; i++) {
+ if (m1->name_off != m2->name_off || m1->val != m2->val)
+ return false;
+ m1++;
+ m2++;
+ }
+ return true;
+}
+
+static bool btf_equal_enum64_members(struct btf_type *t1, struct btf_type *t2)
+{
+ const struct btf_enum64 *m1, *m2;
+ __u16 vlen;
+ int i;
+
+ vlen = btf_vlen(t1);
+ m1 = btf_enum64(t1);
+ m2 = btf_enum64(t2);
+ for (i = 0; i < vlen; i++) {
+ if (m1->name_off != m2->name_off || m1->val_lo32 != m2->val_lo32 ||
+ m1->val_hi32 != m2->val_hi32)
+ return false;
+ m1++;
+ m2++;
+ }
+ return true;
+}
+
+/* Check structural equality of two ENUMs or ENUM64s. */
+static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
+{
+ if (!btf_equal_common(t1, t2))
+ return false;
+
+ /* t1 & t2 kinds are identical because of btf_equal_common */
+ if (btf_kind(t1) == BTF_KIND_ENUM)
+ return btf_equal_enum_members(t1, t2);
+ else
+ return btf_equal_enum64_members(t1, t2);
+}
+
+static inline bool btf_is_enum_fwd(struct btf_type *t)
+{
+ return btf_is_any_enum(t) && btf_vlen(t) == 0;
+}
+
+static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
+{
+ if (!btf_is_enum_fwd(t1) && !btf_is_enum_fwd(t2))
+ return btf_equal_enum(t1, t2);
+ /* At this point either t1 or t2 or both are forward declarations, thus:
+ * - skip comparing vlen because it is zero for forward declarations;
+ * - skip comparing size to allow enum forward declarations
+ * to be compatible with enum64 full declarations;
+ * - skip comparing kind for the same reason.
+ */
+ return t1->name_off == t2->name_off &&
+ btf_is_any_enum(t1) && btf_is_any_enum(t2);
+}
+
+/*
+ * Calculate type signature hash of STRUCT/UNION, ignoring referenced type IDs,
+ * as referenced type IDs equivalence is established separately during type
+ * graph equivalence check algorithm.
+ */
+static long btf_hash_struct(struct btf_type *t)
+{
+ const struct btf_member *member = btf_members(t);
+ __u32 vlen = btf_vlen(t);
+ long h = btf_hash_common(t);
+ int i;
+
+ for (i = 0; i < vlen; i++) {
+ h = hash_combine(h, member->name_off);
+ h = hash_combine(h, member->offset);
+ /* no hashing of referenced type ID, it can be unresolved yet */
+ member++;
+ }
+ return h;
+}
+
+/*
+ * Check structural compatibility of two STRUCTs/UNIONs, ignoring referenced
+ * type IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
+{
+ const struct btf_member *m1, *m2;
+ __u16 vlen;
+ int i;
+
+ if (!btf_equal_common(t1, t2))
+ return false;
+
+ vlen = btf_vlen(t1);
+ m1 = btf_members(t1);
+ m2 = btf_members(t2);
+ for (i = 0; i < vlen; i++) {
+ if (m1->name_off != m2->name_off || m1->offset != m2->offset)
+ return false;
+ m1++;
+ m2++;
+ }
+ return true;
+}
+
+/*
+ * Calculate type signature hash of ARRAY, including referenced type IDs,
+ * under assumption that they were already resolved to canonical type IDs and
+ * are not going to change.
+ */
+static long btf_hash_array(struct btf_type *t)
+{
+ const struct btf_array *info = btf_array(t);
+ long h = btf_hash_common(t);
+
+ h = hash_combine(h, info->type);
+ h = hash_combine(h, info->index_type);
+ h = hash_combine(h, info->nelems);
+ return h;
+}
+
+/*
+ * Check exact equality of two ARRAYs, taking into account referenced
+ * type IDs, under assumption that they were already resolved to canonical
+ * type IDs and are not going to change.
+ * This function is called during reference types deduplication to compare
+ * ARRAY to potential canonical representative.
+ */
+static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
+{
+ const struct btf_array *info1, *info2;
+
+ if (!btf_equal_common(t1, t2))
+ return false;
+
+ info1 = btf_array(t1);
+ info2 = btf_array(t2);
+ return info1->type == info2->type &&
+ info1->index_type == info2->index_type &&
+ info1->nelems == info2->nelems;
+}
+
+/*
+ * Check structural compatibility of two ARRAYs, ignoring referenced type
+ * IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
+{
+ if (!btf_equal_common(t1, t2))
+ return false;
+
+ return btf_array(t1)->nelems == btf_array(t2)->nelems;
+}
+
+/*
+ * Calculate type signature hash of FUNC_PROTO, including referenced type IDs,
+ * under assumption that they were already resolved to canonical type IDs and
+ * are not going to change.
+ */
+static long btf_hash_fnproto(struct btf_type *t)
+{
+ const struct btf_param *member = btf_params(t);
+ __u16 vlen = btf_vlen(t);
+ long h = btf_hash_common(t);
+ int i;
+
+ for (i = 0; i < vlen; i++) {
+ h = hash_combine(h, member->name_off);
+ h = hash_combine(h, member->type);
+ member++;
+ }
+ return h;
+}
+
+/*
+ * Check exact equality of two FUNC_PROTOs, taking into account referenced
+ * type IDs, under assumption that they were already resolved to canonical
+ * type IDs and are not going to change.
+ * This function is called during reference types deduplication to compare
+ * FUNC_PROTO to potential canonical representative.
+ */
+static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
+{
+ const struct btf_param *m1, *m2;
+ __u16 vlen;
+ int i;
+
+ if (!btf_equal_common(t1, t2))
+ return false;
+
+ vlen = btf_vlen(t1);
+ m1 = btf_params(t1);
+ m2 = btf_params(t2);
+ for (i = 0; i < vlen; i++) {
+ if (m1->name_off != m2->name_off || m1->type != m2->type)
+ return false;
+ m1++;
+ m2++;
+ }
+ return true;
+}
+
+/*
+ * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
+ * IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
+{
+ const struct btf_param *m1, *m2;
+ __u16 vlen;
+ int i;
+
+ /* skip return type ID */
+ if (t1->name_off != t2->name_off || t1->info != t2->info)
+ return false;
+
+ vlen = btf_vlen(t1);
+ m1 = btf_params(t1);
+ m2 = btf_params(t2);
+ for (i = 0; i < vlen; i++) {
+ if (m1->name_off != m2->name_off)
+ return false;
+ m1++;
+ m2++;
+ }
+ return true;
+}
+
+/* Prepare split BTF for deduplication by calculating hashes of base BTF's
+ * types and initializing the rest of the state (canonical type mapping) for
+ * the fixed base BTF part.
+ */
+static int btf_dedup_prep(struct btf_dedup *d)
+{
+ struct btf_type *t;
+ int type_id;
+ long h;
+
+ if (!d->btf->base_btf)
+ return 0;
+
+ for (type_id = 1; type_id < d->btf->start_id; type_id++) {
+ t = btf_type_by_id(d->btf, type_id);
+
+ /* all base BTF types are self-canonical by definition */
+ d->map[type_id] = type_id;
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_VAR:
+ case BTF_KIND_DATASEC:
+ /* VAR and DATASEC are never hash/deduplicated */
+ continue;
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_FWD:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_FUNC:
+ case BTF_KIND_FLOAT:
+ case BTF_KIND_TYPE_TAG:
+ h = btf_hash_common(t);
+ break;
+ case BTF_KIND_INT:
+ case BTF_KIND_DECL_TAG:
+ h = btf_hash_int_decl_tag(t);
+ break;
+ case BTF_KIND_ENUM:
+ case BTF_KIND_ENUM64:
+ h = btf_hash_enum(t);
+ break;
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION:
+ h = btf_hash_struct(t);
+ break;
+ case BTF_KIND_ARRAY:
+ h = btf_hash_array(t);
+ break;
+ case BTF_KIND_FUNC_PROTO:
+ h = btf_hash_fnproto(t);
+ break;
+ default:
+ pr_debug("unknown kind %d for type [%d]\n", btf_kind(t), type_id);
+ return -EINVAL;
+ }
+ if (btf_dedup_table_add(d, h, type_id))
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+/*
+ * Deduplicate primitive types, that can't reference other types, by calculating
+ * their type signature hash and comparing them with any possible canonical
+ * candidate. If no canonical candidate matches, type itself is marked as
+ * canonical and is added into `btf_dedup->dedup_table` as another candidate.
+ */
+static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
+{
+ struct btf_type *t = btf_type_by_id(d->btf, type_id);
+ struct hashmap_entry *hash_entry;
+ struct btf_type *cand;
+ /* if we don't find equivalent type, then we are canonical */
+ __u32 new_id = type_id;
+ __u32 cand_id;
+ long h;
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_ARRAY:
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION:
+ case BTF_KIND_FUNC:
+ case BTF_KIND_FUNC_PROTO:
+ case BTF_KIND_VAR:
+ case BTF_KIND_DATASEC:
+ case BTF_KIND_DECL_TAG:
+ case BTF_KIND_TYPE_TAG:
+ return 0;
+
+ case BTF_KIND_INT:
+ h = btf_hash_int_decl_tag(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = hash_entry->value;
+ cand = btf_type_by_id(d->btf, cand_id);
+ if (btf_equal_int_tag(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ }
+ break;
+
+ case BTF_KIND_ENUM:
+ case BTF_KIND_ENUM64:
+ h = btf_hash_enum(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = hash_entry->value;
+ cand = btf_type_by_id(d->btf, cand_id);
+ if (btf_equal_enum(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ if (btf_compat_enum(t, cand)) {
+ if (btf_is_enum_fwd(t)) {
+ /* resolve fwd to full enum */
+ new_id = cand_id;
+ break;
+ }
+ /* resolve canonical enum fwd to full enum */
+ d->map[cand_id] = type_id;
+ }
+ }
+ break;
+
+ case BTF_KIND_FWD:
+ case BTF_KIND_FLOAT:
+ h = btf_hash_common(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = hash_entry->value;
+ cand = btf_type_by_id(d->btf, cand_id);
+ if (btf_equal_common(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ }
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ d->map[type_id] = new_id;
+ if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+ return -ENOMEM;
+
+ return 0;
+}
+
+static int btf_dedup_prim_types(struct btf_dedup *d)
+{
+ int i, err;
+
+ for (i = 0; i < d->btf->nr_types; i++) {
+ err = btf_dedup_prim_type(d, d->btf->start_id + i);
+ if (err)
+ return err;
+ }
+ return 0;
+}
+
+/*
+ * Check whether type is already mapped into canonical one (could be to itself).
+ */
+static inline bool is_type_mapped(struct btf_dedup *d, uint32_t type_id)
+{
+ return d->map[type_id] <= BTF_MAX_NR_TYPES;
+}
+
+/*
+ * Resolve type ID into its canonical type ID, if any; otherwise return original
+ * type ID. If type is FWD and is resolved into STRUCT/UNION already, follow
+ * STRUCT/UNION link and resolve it into canonical type ID as well.
+ */
+static inline __u32 resolve_type_id(struct btf_dedup *d, __u32 type_id)
+{
+ while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
+ type_id = d->map[type_id];
+ return type_id;
+}
+
+/*
+ * Resolve FWD to underlying STRUCT/UNION, if any; otherwise return original
+ * type ID.
+ */
+static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
+{
+ __u32 orig_type_id = type_id;
+
+ if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
+ return type_id;
+
+ while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
+ type_id = d->map[type_id];
+
+ if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
+ return type_id;
+
+ return orig_type_id;
+}
+
+
+static inline __u16 btf_fwd_kind(struct btf_type *t)
+{
+ return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
+}
+
+/* Check if given two types are identical ARRAY definitions */
+static bool btf_dedup_identical_arrays(struct btf_dedup *d, __u32 id1, __u32 id2)
+{
+ struct btf_type *t1, *t2;
+
+ t1 = btf_type_by_id(d->btf, id1);
+ t2 = btf_type_by_id(d->btf, id2);
+ if (!btf_is_array(t1) || !btf_is_array(t2))
+ return false;
+
+ return btf_equal_array(t1, t2);
+}
+
+/* Check if given two types are identical STRUCT/UNION definitions */
+static bool btf_dedup_identical_structs(struct btf_dedup *d, __u32 id1, __u32 id2)
+{
+ const struct btf_member *m1, *m2;
+ struct btf_type *t1, *t2;
+ int n, i;
+
+ t1 = btf_type_by_id(d->btf, id1);
+ t2 = btf_type_by_id(d->btf, id2);
+
+ if (!btf_is_composite(t1) || btf_kind(t1) != btf_kind(t2))
+ return false;
+
+ if (!btf_shallow_equal_struct(t1, t2))
+ return false;
+
+ m1 = btf_members(t1);
+ m2 = btf_members(t2);
+ for (i = 0, n = btf_vlen(t1); i < n; i++, m1++, m2++) {
+ if (m1->type != m2->type &&
+ !btf_dedup_identical_arrays(d, m1->type, m2->type) &&
+ !btf_dedup_identical_structs(d, m1->type, m2->type))
+ return false;
+ }
+ return true;
+}
+
+/*
+ * Check equivalence of BTF type graph formed by candidate struct/union (we'll
+ * call it "candidate graph" in this description for brevity) to a type graph
+ * formed by (potential) canonical struct/union ("canonical graph" for brevity
+ * here, though keep in mind that not all types in canonical graph are
+ * necessarily canonical representatives themselves, some of them might be
+ * duplicates or its uniqueness might not have been established yet).
+ * Returns:
+ * - >0, if type graphs are equivalent;
+ * - 0, if not equivalent;
+ * - <0, on error.
+ *
+ * Algorithm performs side-by-side DFS traversal of both type graphs and checks
+ * equivalence of BTF types at each step. If at any point BTF types in candidate
+ * and canonical graphs are not compatible structurally, whole graphs are
+ * incompatible. If types are structurally equivalent (i.e., all information
+ * except referenced type IDs is exactly the same), a mapping from `canon_id` to
+ * a `cand_id` is recored in hypothetical mapping (`btf_dedup->hypot_map`).
+ * If a type references other types, then those referenced types are checked
+ * for equivalence recursively.
+ *
+ * During DFS traversal, if we find that for current `canon_id` type we
+ * already have some mapping in hypothetical map, we check for two possible
+ * situations:
+ * - `canon_id` is mapped to exactly the same type as `cand_id`. This will
+ * happen when type graphs have cycles. In this case we assume those two
+ * types are equivalent.
+ * - `canon_id` is mapped to different type. This is contradiction in our
+ * hypothetical mapping, because same graph in canonical graph corresponds
+ * to two different types in candidate graph, which for equivalent type
+ * graphs shouldn't happen. This condition terminates equivalence check
+ * with negative result.
+ *
+ * If type graphs traversal exhausts types to check and find no contradiction,
+ * then type graphs are equivalent.
+ *
+ * When checking types for equivalence, there is one special case: FWD types.
+ * If FWD type resolution is allowed and one of the types (either from canonical
+ * or candidate graph) is FWD and other is STRUCT/UNION (depending on FWD's kind
+ * flag) and their names match, hypothetical mapping is updated to point from
+ * FWD to STRUCT/UNION. If graphs will be determined as equivalent successfully,
+ * this mapping will be used to record FWD -> STRUCT/UNION mapping permanently.
+ *
+ * Technically, this could lead to incorrect FWD to STRUCT/UNION resolution,
+ * if there are two exactly named (or anonymous) structs/unions that are
+ * compatible structurally, one of which has FWD field, while other is concrete
+ * STRUCT/UNION, but according to C sources they are different structs/unions
+ * that are referencing different types with the same name. This is extremely
+ * unlikely to happen, but btf_dedup API allows to disable FWD resolution if
+ * this logic is causing problems.
+ *
+ * Doing FWD resolution means that both candidate and/or canonical graphs can
+ * consists of portions of the graph that come from multiple compilation units.
+ * This is due to the fact that types within single compilation unit are always
+ * deduplicated and FWDs are already resolved, if referenced struct/union
+ * definiton is available. So, if we had unresolved FWD and found corresponding
+ * STRUCT/UNION, they will be from different compilation units. This
+ * consequently means that when we "link" FWD to corresponding STRUCT/UNION,
+ * type graph will likely have at least two different BTF types that describe
+ * same type (e.g., most probably there will be two different BTF types for the
+ * same 'int' primitive type) and could even have "overlapping" parts of type
+ * graph that describe same subset of types.
+ *
+ * This in turn means that our assumption that each type in canonical graph
+ * must correspond to exactly one type in candidate graph might not hold
+ * anymore and will make it harder to detect contradictions using hypothetical
+ * map. To handle this problem, we allow to follow FWD -> STRUCT/UNION
+ * resolution only in canonical graph. FWDs in candidate graphs are never
+ * resolved. To see why it's OK, let's check all possible situations w.r.t. FWDs
+ * that can occur:
+ * - Both types in canonical and candidate graphs are FWDs. If they are
+ * structurally equivalent, then they can either be both resolved to the
+ * same STRUCT/UNION or not resolved at all. In both cases they are
+ * equivalent and there is no need to resolve FWD on candidate side.
+ * - Both types in canonical and candidate graphs are concrete STRUCT/UNION,
+ * so nothing to resolve as well, algorithm will check equivalence anyway.
+ * - Type in canonical graph is FWD, while type in candidate is concrete
+ * STRUCT/UNION. In this case candidate graph comes from single compilation
+ * unit, so there is exactly one BTF type for each unique C type. After
+ * resolving FWD into STRUCT/UNION, there might be more than one BTF type
+ * in canonical graph mapping to single BTF type in candidate graph, but
+ * because hypothetical mapping maps from canonical to candidate types, it's
+ * alright, and we still maintain the property of having single `canon_id`
+ * mapping to single `cand_id` (there could be two different `canon_id`
+ * mapped to the same `cand_id`, but it's not contradictory).
+ * - Type in canonical graph is concrete STRUCT/UNION, while type in candidate
+ * graph is FWD. In this case we are just going to check compatibility of
+ * STRUCT/UNION and corresponding FWD, and if they are compatible, we'll
+ * assume that whatever STRUCT/UNION FWD resolves to must be equivalent to
+ * a concrete STRUCT/UNION from canonical graph. If the rest of type graphs
+ * turn out equivalent, we'll re-resolve FWD to concrete STRUCT/UNION from
+ * canonical graph.
+ */
+static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
+ __u32 canon_id)
+{
+ struct btf_type *cand_type;
+ struct btf_type *canon_type;
+ __u32 hypot_type_id;
+ __u16 cand_kind;
+ __u16 canon_kind;
+ int i, eq;
+
+ /* if both resolve to the same canonical, they must be equivalent */
+ if (resolve_type_id(d, cand_id) == resolve_type_id(d, canon_id))
+ return 1;
+
+ canon_id = resolve_fwd_id(d, canon_id);
+
+ hypot_type_id = d->hypot_map[canon_id];
+ if (hypot_type_id <= BTF_MAX_NR_TYPES) {
+ if (hypot_type_id == cand_id)
+ return 1;
+ /* In some cases compiler will generate different DWARF types
+ * for *identical* array type definitions and use them for
+ * different fields within the *same* struct. This breaks type
+ * equivalence check, which makes an assumption that candidate
+ * types sub-graph has a consistent and deduped-by-compiler
+ * types within a single CU. So work around that by explicitly
+ * allowing identical array types here.
+ */
+ if (btf_dedup_identical_arrays(d, hypot_type_id, cand_id))
+ return 1;
+ /* It turns out that similar situation can happen with
+ * struct/union sometimes, sigh... Handle the case where
+ * structs/unions are exactly the same, down to the referenced
+ * type IDs. Anything more complicated (e.g., if referenced
+ * types are different, but equivalent) is *way more*
+ * complicated and requires a many-to-many equivalence mapping.
+ */
+ if (btf_dedup_identical_structs(d, hypot_type_id, cand_id))
+ return 1;
+ return 0;
+ }
+
+ if (btf_dedup_hypot_map_add(d, canon_id, cand_id))
+ return -ENOMEM;
+
+ cand_type = btf_type_by_id(d->btf, cand_id);
+ canon_type = btf_type_by_id(d->btf, canon_id);
+ cand_kind = btf_kind(cand_type);
+ canon_kind = btf_kind(canon_type);
+
+ if (cand_type->name_off != canon_type->name_off)
+ return 0;
+
+ /* FWD <--> STRUCT/UNION equivalence check, if enabled */
+ if ((cand_kind == BTF_KIND_FWD || canon_kind == BTF_KIND_FWD)
+ && cand_kind != canon_kind) {
+ __u16 real_kind;
+ __u16 fwd_kind;
+
+ if (cand_kind == BTF_KIND_FWD) {
+ real_kind = canon_kind;
+ fwd_kind = btf_fwd_kind(cand_type);
+ } else {
+ real_kind = cand_kind;
+ fwd_kind = btf_fwd_kind(canon_type);
+ /* we'd need to resolve base FWD to STRUCT/UNION */
+ if (fwd_kind == real_kind && canon_id < d->btf->start_id)
+ d->hypot_adjust_canon = true;
+ }
+ return fwd_kind == real_kind;
+ }
+
+ if (cand_kind != canon_kind)
+ return 0;
+
+ switch (cand_kind) {
+ case BTF_KIND_INT:
+ return btf_equal_int_tag(cand_type, canon_type);
+
+ case BTF_KIND_ENUM:
+ case BTF_KIND_ENUM64:
+ return btf_compat_enum(cand_type, canon_type);
+
+ case BTF_KIND_FWD:
+ case BTF_KIND_FLOAT:
+ return btf_equal_common(cand_type, canon_type);
+
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_FUNC:
+ case BTF_KIND_TYPE_TAG:
+ if (cand_type->info != canon_type->info)
+ return 0;
+ return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
+
+ case BTF_KIND_ARRAY: {
+ const struct btf_array *cand_arr, *canon_arr;
+
+ if (!btf_compat_array(cand_type, canon_type))
+ return 0;
+ cand_arr = btf_array(cand_type);
+ canon_arr = btf_array(canon_type);
+ eq = btf_dedup_is_equiv(d, cand_arr->index_type, canon_arr->index_type);
+ if (eq <= 0)
+ return eq;
+ return btf_dedup_is_equiv(d, cand_arr->type, canon_arr->type);
+ }
+
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION: {
+ const struct btf_member *cand_m, *canon_m;
+ __u16 vlen;
+
+ if (!btf_shallow_equal_struct(cand_type, canon_type))
+ return 0;
+ vlen = btf_vlen(cand_type);
+ cand_m = btf_members(cand_type);
+ canon_m = btf_members(canon_type);
+ for (i = 0; i < vlen; i++) {
+ eq = btf_dedup_is_equiv(d, cand_m->type, canon_m->type);
+ if (eq <= 0)
+ return eq;
+ cand_m++;
+ canon_m++;
+ }
+
+ return 1;
+ }
+
+ case BTF_KIND_FUNC_PROTO: {
+ const struct btf_param *cand_p, *canon_p;
+ __u16 vlen;
+
+ if (!btf_compat_fnproto(cand_type, canon_type))
+ return 0;
+ eq = btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
+ if (eq <= 0)
+ return eq;
+ vlen = btf_vlen(cand_type);
+ cand_p = btf_params(cand_type);
+ canon_p = btf_params(canon_type);
+ for (i = 0; i < vlen; i++) {
+ eq = btf_dedup_is_equiv(d, cand_p->type, canon_p->type);
+ if (eq <= 0)
+ return eq;
+ cand_p++;
+ canon_p++;
+ }
+ return 1;
+ }
+
+ default:
+ return -EINVAL;
+ }
+ return 0;
+}
+
+/*
+ * Use hypothetical mapping, produced by successful type graph equivalence
+ * check, to augment existing struct/union canonical mapping, where possible.
+ *
+ * If BTF_KIND_FWD resolution is allowed, this mapping is also used to record
+ * FWD -> STRUCT/UNION correspondence as well. FWD resolution is bidirectional:
+ * it doesn't matter if FWD type was part of canonical graph or candidate one,
+ * we are recording the mapping anyway. As opposed to carefulness required
+ * for struct/union correspondence mapping (described below), for FWD resolution
+ * it's not important, as by the time that FWD type (reference type) will be
+ * deduplicated all structs/unions will be deduped already anyway.
+ *
+ * Recording STRUCT/UNION mapping is purely a performance optimization and is
+ * not required for correctness. It needs to be done carefully to ensure that
+ * struct/union from candidate's type graph is not mapped into corresponding
+ * struct/union from canonical type graph that itself hasn't been resolved into
+ * canonical representative. The only guarantee we have is that canonical
+ * struct/union was determined as canonical and that won't change. But any
+ * types referenced through that struct/union fields could have been not yet
+ * resolved, so in case like that it's too early to establish any kind of
+ * correspondence between structs/unions.
+ *
+ * No canonical correspondence is derived for primitive types (they are already
+ * deduplicated completely already anyway) or reference types (they rely on
+ * stability of struct/union canonical relationship for equivalence checks).
+ */
+static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
+{
+ __u32 canon_type_id, targ_type_id;
+ __u16 t_kind, c_kind;
+ __u32 t_id, c_id;
+ int i;
+
+ for (i = 0; i < d->hypot_cnt; i++) {
+ canon_type_id = d->hypot_list[i];
+ targ_type_id = d->hypot_map[canon_type_id];
+ t_id = resolve_type_id(d, targ_type_id);
+ c_id = resolve_type_id(d, canon_type_id);
+ t_kind = btf_kind(btf__type_by_id(d->btf, t_id));
+ c_kind = btf_kind(btf__type_by_id(d->btf, c_id));
+ /*
+ * Resolve FWD into STRUCT/UNION.
+ * It's ok to resolve FWD into STRUCT/UNION that's not yet
+ * mapped to canonical representative (as opposed to
+ * STRUCT/UNION <--> STRUCT/UNION mapping logic below), because
+ * eventually that struct is going to be mapped and all resolved
+ * FWDs will automatically resolve to correct canonical
+ * representative. This will happen before ref type deduping,
+ * which critically depends on stability of these mapping. This
+ * stability is not a requirement for STRUCT/UNION equivalence
+ * checks, though.
+ */
+
+ /* if it's the split BTF case, we still need to point base FWD
+ * to STRUCT/UNION in a split BTF, because FWDs from split BTF
+ * will be resolved against base FWD. If we don't point base
+ * canonical FWD to the resolved STRUCT/UNION, then all the
+ * FWDs in split BTF won't be correctly resolved to a proper
+ * STRUCT/UNION.
+ */
+ if (t_kind != BTF_KIND_FWD && c_kind == BTF_KIND_FWD)
+ d->map[c_id] = t_id;
+
+ /* if graph equivalence determined that we'd need to adjust
+ * base canonical types, then we need to only point base FWDs
+ * to STRUCTs/UNIONs and do no more modifications. For all
+ * other purposes the type graphs were not equivalent.
+ */
+ if (d->hypot_adjust_canon)
+ continue;
+
+ if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD)
+ d->map[t_id] = c_id;
+
+ if ((t_kind == BTF_KIND_STRUCT || t_kind == BTF_KIND_UNION) &&
+ c_kind != BTF_KIND_FWD &&
+ is_type_mapped(d, c_id) &&
+ !is_type_mapped(d, t_id)) {
+ /*
+ * as a perf optimization, we can map struct/union
+ * that's part of type graph we just verified for
+ * equivalence. We can do that for struct/union that has
+ * canonical representative only, though.
+ */
+ d->map[t_id] = c_id;
+ }
+ }
+}
+
+/*
+ * Deduplicate struct/union types.
+ *
+ * For each struct/union type its type signature hash is calculated, taking
+ * into account type's name, size, number, order and names of fields, but
+ * ignoring type ID's referenced from fields, because they might not be deduped
+ * completely until after reference types deduplication phase. This type hash
+ * is used to iterate over all potential canonical types, sharing same hash.
+ * For each canonical candidate we check whether type graphs that they form
+ * (through referenced types in fields and so on) are equivalent using algorithm
+ * implemented in `btf_dedup_is_equiv`. If such equivalence is found and
+ * BTF_KIND_FWD resolution is allowed, then hypothetical mapping
+ * (btf_dedup->hypot_map) produced by aforementioned type graph equivalence
+ * algorithm is used to record FWD -> STRUCT/UNION mapping. It's also used to
+ * potentially map other structs/unions to their canonical representatives,
+ * if such relationship hasn't yet been established. This speeds up algorithm
+ * by eliminating some of the duplicate work.
+ *
+ * If no matching canonical representative was found, struct/union is marked
+ * as canonical for itself and is added into btf_dedup->dedup_table hash map
+ * for further look ups.
+ */
+static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
+{
+ struct btf_type *cand_type, *t;
+ struct hashmap_entry *hash_entry;
+ /* if we don't find equivalent type, then we are canonical */
+ __u32 new_id = type_id;
+ __u16 kind;
+ long h;
+
+ /* already deduped or is in process of deduping (loop detected) */
+ if (d->map[type_id] <= BTF_MAX_NR_TYPES)
+ return 0;
+
+ t = btf_type_by_id(d->btf, type_id);
+ kind = btf_kind(t);
+
+ if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
+ return 0;
+
+ h = btf_hash_struct(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ __u32 cand_id = hash_entry->value;
+ int eq;
+
+ /*
+ * Even though btf_dedup_is_equiv() checks for
+ * btf_shallow_equal_struct() internally when checking two
+ * structs (unions) for equivalence, we need to guard here
+ * from picking matching FWD type as a dedup candidate.
+ * This can happen due to hash collision. In such case just
+ * relying on btf_dedup_is_equiv() would lead to potentially
+ * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because
+ * FWD and compatible STRUCT/UNION are considered equivalent.
+ */
+ cand_type = btf_type_by_id(d->btf, cand_id);
+ if (!btf_shallow_equal_struct(t, cand_type))
+ continue;
+
+ btf_dedup_clear_hypot_map(d);
+ eq = btf_dedup_is_equiv(d, type_id, cand_id);
+ if (eq < 0)
+ return eq;
+ if (!eq)
+ continue;
+ btf_dedup_merge_hypot_map(d);
+ if (d->hypot_adjust_canon) /* not really equivalent */
+ continue;
+ new_id = cand_id;
+ break;
+ }
+
+ d->map[type_id] = new_id;
+ if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+ return -ENOMEM;
+
+ return 0;
+}
+
+static int btf_dedup_struct_types(struct btf_dedup *d)
+{
+ int i, err;
+
+ for (i = 0; i < d->btf->nr_types; i++) {
+ err = btf_dedup_struct_type(d, d->btf->start_id + i);
+ if (err)
+ return err;
+ }
+ return 0;
+}
+
+/*
+ * Deduplicate reference type.
+ *
+ * Once all primitive and struct/union types got deduplicated, we can easily
+ * deduplicate all other (reference) BTF types. This is done in two steps:
+ *
+ * 1. Resolve all referenced type IDs into their canonical type IDs. This
+ * resolution can be done either immediately for primitive or struct/union types
+ * (because they were deduped in previous two phases) or recursively for
+ * reference types. Recursion will always terminate at either primitive or
+ * struct/union type, at which point we can "unwind" chain of reference types
+ * one by one. There is no danger of encountering cycles because in C type
+ * system the only way to form type cycle is through struct/union, so any chain
+ * of reference types, even those taking part in a type cycle, will inevitably
+ * reach struct/union at some point.
+ *
+ * 2. Once all referenced type IDs are resolved into canonical ones, BTF type
+ * becomes "stable", in the sense that no further deduplication will cause
+ * any changes to it. With that, it's now possible to calculate type's signature
+ * hash (this time taking into account referenced type IDs) and loop over all
+ * potential canonical representatives. If no match was found, current type
+ * will become canonical representative of itself and will be added into
+ * btf_dedup->dedup_table as another possible canonical representative.
+ */
+static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
+{
+ struct hashmap_entry *hash_entry;
+ __u32 new_id = type_id, cand_id;
+ struct btf_type *t, *cand;
+ /* if we don't find equivalent type, then we are representative type */
+ int ref_type_id;
+ long h;
+
+ if (d->map[type_id] == BTF_IN_PROGRESS_ID)
+ return -ELOOP;
+ if (d->map[type_id] <= BTF_MAX_NR_TYPES)
+ return resolve_type_id(d, type_id);
+
+ t = btf_type_by_id(d->btf, type_id);
+ d->map[type_id] = BTF_IN_PROGRESS_ID;
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_FUNC:
+ case BTF_KIND_TYPE_TAG:
+ ref_type_id = btf_dedup_ref_type(d, t->type);
+ if (ref_type_id < 0)
+ return ref_type_id;
+ t->type = ref_type_id;
+
+ h = btf_hash_common(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = hash_entry->value;
+ cand = btf_type_by_id(d->btf, cand_id);
+ if (btf_equal_common(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ }
+ break;
+
+ case BTF_KIND_DECL_TAG:
+ ref_type_id = btf_dedup_ref_type(d, t->type);
+ if (ref_type_id < 0)
+ return ref_type_id;
+ t->type = ref_type_id;
+
+ h = btf_hash_int_decl_tag(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = hash_entry->value;
+ cand = btf_type_by_id(d->btf, cand_id);
+ if (btf_equal_int_tag(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ }
+ break;
+
+ case BTF_KIND_ARRAY: {
+ struct btf_array *info = btf_array(t);
+
+ ref_type_id = btf_dedup_ref_type(d, info->type);
+ if (ref_type_id < 0)
+ return ref_type_id;
+ info->type = ref_type_id;
+
+ ref_type_id = btf_dedup_ref_type(d, info->index_type);
+ if (ref_type_id < 0)
+ return ref_type_id;
+ info->index_type = ref_type_id;
+
+ h = btf_hash_array(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = hash_entry->value;
+ cand = btf_type_by_id(d->btf, cand_id);
+ if (btf_equal_array(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ }
+ break;
+ }
+
+ case BTF_KIND_FUNC_PROTO: {
+ struct btf_param *param;
+ __u16 vlen;
+ int i;
+
+ ref_type_id = btf_dedup_ref_type(d, t->type);
+ if (ref_type_id < 0)
+ return ref_type_id;
+ t->type = ref_type_id;
+
+ vlen = btf_vlen(t);
+ param = btf_params(t);
+ for (i = 0; i < vlen; i++) {
+ ref_type_id = btf_dedup_ref_type(d, param->type);
+ if (ref_type_id < 0)
+ return ref_type_id;
+ param->type = ref_type_id;
+ param++;
+ }
+
+ h = btf_hash_fnproto(t);
+ for_each_dedup_cand(d, hash_entry, h) {
+ cand_id = hash_entry->value;
+ cand = btf_type_by_id(d->btf, cand_id);
+ if (btf_equal_fnproto(t, cand)) {
+ new_id = cand_id;
+ break;
+ }
+ }
+ break;
+ }
+
+ default:
+ return -EINVAL;
+ }
+
+ d->map[type_id] = new_id;
+ if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+ return -ENOMEM;
+
+ return new_id;
+}
+
+static int btf_dedup_ref_types(struct btf_dedup *d)
+{
+ int i, err;
+
+ for (i = 0; i < d->btf->nr_types; i++) {
+ err = btf_dedup_ref_type(d, d->btf->start_id + i);
+ if (err < 0)
+ return err;
+ }
+ /* we won't need d->dedup_table anymore */
+ hashmap__free(d->dedup_table);
+ d->dedup_table = NULL;
+ return 0;
+}
+
+/*
+ * Collect a map from type names to type ids for all canonical structs
+ * and unions. If the same name is shared by several canonical types
+ * use a special value 0 to indicate this fact.
+ */
+static int btf_dedup_fill_unique_names_map(struct btf_dedup *d, struct hashmap *names_map)
+{
+ __u32 nr_types = btf__type_cnt(d->btf);
+ struct btf_type *t;
+ __u32 type_id;
+ __u16 kind;
+ int err;
+
+ /*
+ * Iterate over base and split module ids in order to get all
+ * available structs in the map.
+ */
+ for (type_id = 1; type_id < nr_types; ++type_id) {
+ t = btf_type_by_id(d->btf, type_id);
+ kind = btf_kind(t);
+
+ if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
+ continue;
+
+ /* Skip non-canonical types */
+ if (type_id != d->map[type_id])
+ continue;
+
+ err = hashmap__add(names_map, t->name_off, type_id);
+ if (err == -EEXIST)
+ err = hashmap__set(names_map, t->name_off, 0, NULL, NULL);
+
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static int btf_dedup_resolve_fwd(struct btf_dedup *d, struct hashmap *names_map, __u32 type_id)
+{
+ struct btf_type *t = btf_type_by_id(d->btf, type_id);
+ enum btf_fwd_kind fwd_kind = btf_kflag(t);
+ __u16 cand_kind, kind = btf_kind(t);
+ struct btf_type *cand_t;
+ uintptr_t cand_id;
+
+ if (kind != BTF_KIND_FWD)
+ return 0;
+
+ /* Skip if this FWD already has a mapping */
+ if (type_id != d->map[type_id])
+ return 0;
+
+ if (!hashmap__find(names_map, t->name_off, &cand_id))
+ return 0;
+
+ /* Zero is a special value indicating that name is not unique */
+ if (!cand_id)
+ return 0;
+
+ cand_t = btf_type_by_id(d->btf, cand_id);
+ cand_kind = btf_kind(cand_t);
+ if ((cand_kind == BTF_KIND_STRUCT && fwd_kind != BTF_FWD_STRUCT) ||
+ (cand_kind == BTF_KIND_UNION && fwd_kind != BTF_FWD_UNION))
+ return 0;
+
+ d->map[type_id] = cand_id;
+
+ return 0;
+}
+
+/*
+ * Resolve unambiguous forward declarations.
+ *
+ * The lion's share of all FWD declarations is resolved during
+ * `btf_dedup_struct_types` phase when different type graphs are
+ * compared against each other. However, if in some compilation unit a
+ * FWD declaration is not a part of a type graph compared against
+ * another type graph that declaration's canonical type would not be
+ * changed. Example:
+ *
+ * CU #1:
+ *
+ * struct foo;
+ * struct foo *some_global;
+ *
+ * CU #2:
+ *
+ * struct foo { int u; };
+ * struct foo *another_global;
+ *
+ * After `btf_dedup_struct_types` the BTF looks as follows:
+ *
+ * [1] STRUCT 'foo' size=4 vlen=1 ...
+ * [2] INT 'int' size=4 ...
+ * [3] PTR '(anon)' type_id=1
+ * [4] FWD 'foo' fwd_kind=struct
+ * [5] PTR '(anon)' type_id=4
+ *
+ * This pass assumes that such FWD declarations should be mapped to
+ * structs or unions with identical name in case if the name is not
+ * ambiguous.
+ */
+static int btf_dedup_resolve_fwds(struct btf_dedup *d)
+{
+ int i, err;
+ struct hashmap *names_map;
+
+ names_map = hashmap__new(btf_dedup_identity_hash_fn, btf_dedup_equal_fn, NULL);
+ if (IS_ERR(names_map))
+ return PTR_ERR(names_map);
+
+ err = btf_dedup_fill_unique_names_map(d, names_map);
+ if (err < 0)
+ goto exit;
+
+ for (i = 0; i < d->btf->nr_types; i++) {
+ err = btf_dedup_resolve_fwd(d, names_map, d->btf->start_id + i);
+ if (err < 0)
+ break;
+ }
+
+exit:
+ hashmap__free(names_map);
+ return err;
+}
+
+/*
+ * Compact types.
+ *
+ * After we established for each type its corresponding canonical representative
+ * type, we now can eliminate types that are not canonical and leave only
+ * canonical ones layed out sequentially in memory by copying them over
+ * duplicates. During compaction btf_dedup->hypot_map array is reused to store
+ * a map from original type ID to a new compacted type ID, which will be used
+ * during next phase to "fix up" type IDs, referenced from struct/union and
+ * reference types.
+ */
+static int btf_dedup_compact_types(struct btf_dedup *d)
+{
+ __u32 *new_offs;
+ __u32 next_type_id = d->btf->start_id;
+ const struct btf_type *t;
+ void *p;
+ int i, id, len;
+
+ /* we are going to reuse hypot_map to store compaction remapping */
+ d->hypot_map[0] = 0;
+ /* base BTF types are not renumbered */
+ for (id = 1; id < d->btf->start_id; id++)
+ d->hypot_map[id] = id;
+ for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++)
+ d->hypot_map[id] = BTF_UNPROCESSED_ID;
+
+ p = d->btf->types_data;
+
+ for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++) {
+ if (d->map[id] != id)
+ continue;
+
+ t = btf__type_by_id(d->btf, id);
+ len = btf_type_size(t);
+ if (len < 0)
+ return len;
+
+ memmove(p, t, len);
+ d->hypot_map[id] = next_type_id;
+ d->btf->type_offs[next_type_id - d->btf->start_id] = p - d->btf->types_data;
+ p += len;
+ next_type_id++;
+ }
+
+ /* shrink struct btf's internal types index and update btf_header */
+ d->btf->nr_types = next_type_id - d->btf->start_id;
+ d->btf->type_offs_cap = d->btf->nr_types;
+ d->btf->hdr->type_len = p - d->btf->types_data;
+ new_offs = libbpf_reallocarray(d->btf->type_offs, d->btf->type_offs_cap,
+ sizeof(*new_offs));
+ if (d->btf->type_offs_cap && !new_offs)
+ return -ENOMEM;
+ d->btf->type_offs = new_offs;
+ d->btf->hdr->str_off = d->btf->hdr->type_len;
+ d->btf->raw_size = d->btf->hdr->hdr_len + d->btf->hdr->type_len + d->btf->hdr->str_len;
+ return 0;
+}
+
+/*
+ * Figure out final (deduplicated and compacted) type ID for provided original
+ * `type_id` by first resolving it into corresponding canonical type ID and
+ * then mapping it to a deduplicated type ID, stored in btf_dedup->hypot_map,
+ * which is populated during compaction phase.
+ */
+static int btf_dedup_remap_type_id(__u32 *type_id, void *ctx)
+{
+ struct btf_dedup *d = ctx;
+ __u32 resolved_type_id, new_type_id;
+
+ resolved_type_id = resolve_type_id(d, *type_id);
+ new_type_id = d->hypot_map[resolved_type_id];
+ if (new_type_id > BTF_MAX_NR_TYPES)
+ return -EINVAL;
+
+ *type_id = new_type_id;
+ return 0;
+}
+
+/*
+ * Remap referenced type IDs into deduped type IDs.
+ *
+ * After BTF types are deduplicated and compacted, their final type IDs may
+ * differ from original ones. The map from original to a corresponding
+ * deduped type ID is stored in btf_dedup->hypot_map and is populated during
+ * compaction phase. During remapping phase we are rewriting all type IDs
+ * referenced from any BTF type (e.g., struct fields, func proto args, etc) to
+ * their final deduped type IDs.
+ */
+static int btf_dedup_remap_types(struct btf_dedup *d)
+{
+ int i, r;
+
+ for (i = 0; i < d->btf->nr_types; i++) {
+ struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
+
+ r = btf_type_visit_type_ids(t, btf_dedup_remap_type_id, d);
+ if (r)
+ return r;
+ }
+
+ if (!d->btf_ext)
+ return 0;
+
+ r = btf_ext_visit_type_ids(d->btf_ext, btf_dedup_remap_type_id, d);
+ if (r)
+ return r;
+
+ return 0;
+}
+
+/*
+ * Probe few well-known locations for vmlinux kernel image and try to load BTF
+ * data out of it to use for target BTF.
+ */
+struct btf *btf__load_vmlinux_btf(void)
+{
+ const char *locations[] = {
+ /* try canonical vmlinux BTF through sysfs first */
+ "/sys/kernel/btf/vmlinux",
+ /* fall back to trying to find vmlinux on disk otherwise */
+ "/boot/vmlinux-%1$s",
+ "/lib/modules/%1$s/vmlinux-%1$s",
+ "/lib/modules/%1$s/build/vmlinux",
+ "/usr/lib/modules/%1$s/kernel/vmlinux",
+ "/usr/lib/debug/boot/vmlinux-%1$s",
+ "/usr/lib/debug/boot/vmlinux-%1$s.debug",
+ "/usr/lib/debug/lib/modules/%1$s/vmlinux",
+ };
+ char path[PATH_MAX + 1];
+ struct utsname buf;
+ struct btf *btf;
+ int i, err;
+
+ uname(&buf);
+
+ for (i = 0; i < ARRAY_SIZE(locations); i++) {
+ snprintf(path, PATH_MAX, locations[i], buf.release);
+
+ if (faccessat(AT_FDCWD, path, R_OK, AT_EACCESS))
+ continue;
+
+ btf = btf__parse(path, NULL);
+ err = libbpf_get_error(btf);
+ pr_debug("loading kernel BTF '%s': %d\n", path, err);
+ if (err)
+ continue;
+
+ return btf;
+ }
+
+ pr_warn("failed to find valid kernel BTF\n");
+ return libbpf_err_ptr(-ESRCH);
+}
+
+struct btf *libbpf_find_kernel_btf(void) __attribute__((alias("btf__load_vmlinux_btf")));
+
+struct btf *btf__load_module_btf(const char *module_name, struct btf *vmlinux_btf)
+{
+ char path[80];
+
+ snprintf(path, sizeof(path), "/sys/kernel/btf/%s", module_name);
+ return btf__parse_split(path, vmlinux_btf);
+}
+
+int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx)
+{
+ int i, n, err;
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_INT:
+ case BTF_KIND_FLOAT:
+ case BTF_KIND_ENUM:
+ case BTF_KIND_ENUM64:
+ return 0;
+
+ case BTF_KIND_FWD:
+ case BTF_KIND_CONST:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_RESTRICT:
+ case BTF_KIND_PTR:
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_FUNC:
+ case BTF_KIND_VAR:
+ case BTF_KIND_DECL_TAG:
+ case BTF_KIND_TYPE_TAG:
+ return visit(&t->type, ctx);
+
+ case BTF_KIND_ARRAY: {
+ struct btf_array *a = btf_array(t);
+
+ err = visit(&a->type, ctx);
+ err = err ?: visit(&a->index_type, ctx);
+ return err;
+ }
+
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION: {
+ struct btf_member *m = btf_members(t);
+
+ for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+ err = visit(&m->type, ctx);
+ if (err)
+ return err;
+ }
+ return 0;
+ }
+
+ case BTF_KIND_FUNC_PROTO: {
+ struct btf_param *m = btf_params(t);
+
+ err = visit(&t->type, ctx);
+ if (err)
+ return err;
+ for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+ err = visit(&m->type, ctx);
+ if (err)
+ return err;
+ }
+ return 0;
+ }
+
+ case BTF_KIND_DATASEC: {
+ struct btf_var_secinfo *m = btf_var_secinfos(t);
+
+ for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+ err = visit(&m->type, ctx);
+ if (err)
+ return err;
+ }
+ return 0;
+ }
+
+ default:
+ return -EINVAL;
+ }
+}
+
+int btf_type_visit_str_offs(struct btf_type *t, str_off_visit_fn visit, void *ctx)
+{
+ int i, n, err;
+
+ err = visit(&t->name_off, ctx);
+ if (err)
+ return err;
+
+ switch (btf_kind(t)) {
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION: {
+ struct btf_member *m = btf_members(t);
+
+ for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+ err = visit(&m->name_off, ctx);
+ if (err)
+ return err;
+ }
+ break;
+ }
+ case BTF_KIND_ENUM: {
+ struct btf_enum *m = btf_enum(t);
+
+ for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+ err = visit(&m->name_off, ctx);
+ if (err)
+ return err;
+ }
+ break;
+ }
+ case BTF_KIND_ENUM64: {
+ struct btf_enum64 *m = btf_enum64(t);
+
+ for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+ err = visit(&m->name_off, ctx);
+ if (err)
+ return err;
+ }
+ break;
+ }
+ case BTF_KIND_FUNC_PROTO: {
+ struct btf_param *m = btf_params(t);
+
+ for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+ err = visit(&m->name_off, ctx);
+ if (err)
+ return err;
+ }
+ break;
+ }
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+int btf_ext_visit_type_ids(struct btf_ext *btf_ext, type_id_visit_fn visit, void *ctx)
+{
+ const struct btf_ext_info *seg;
+ struct btf_ext_info_sec *sec;
+ int i, err;
+
+ seg = &btf_ext->func_info;
+ for_each_btf_ext_sec(seg, sec) {
+ struct bpf_func_info_min *rec;
+
+ for_each_btf_ext_rec(seg, sec, i, rec) {
+ err = visit(&rec->type_id, ctx);
+ if (err < 0)
+ return err;
+ }
+ }
+
+ seg = &btf_ext->core_relo_info;
+ for_each_btf_ext_sec(seg, sec) {
+ struct bpf_core_relo *rec;
+
+ for_each_btf_ext_rec(seg, sec, i, rec) {
+ err = visit(&rec->type_id, ctx);
+ if (err < 0)
+ return err;
+ }
+ }
+
+ return 0;
+}
+
+int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void *ctx)
+{
+ const struct btf_ext_info *seg;
+ struct btf_ext_info_sec *sec;
+ int i, err;
+
+ seg = &btf_ext->func_info;
+ for_each_btf_ext_sec(seg, sec) {
+ err = visit(&sec->sec_name_off, ctx);
+ if (err)
+ return err;
+ }
+
+ seg = &btf_ext->line_info;
+ for_each_btf_ext_sec(seg, sec) {
+ struct bpf_line_info_min *rec;
+
+ err = visit(&sec->sec_name_off, ctx);
+ if (err)
+ return err;
+
+ for_each_btf_ext_rec(seg, sec, i, rec) {
+ err = visit(&rec->file_name_off, ctx);
+ if (err)
+ return err;
+ err = visit(&rec->line_off, ctx);
+ if (err)
+ return err;
+ }
+ }
+
+ seg = &btf_ext->core_relo_info;
+ for_each_btf_ext_sec(seg, sec) {
+ struct bpf_core_relo *rec;
+
+ err = visit(&sec->sec_name_off, ctx);
+ if (err)
+ return err;
+
+ for_each_btf_ext_rec(seg, sec, i, rec) {
+ err = visit(&rec->access_str_off, ctx);
+ if (err)
+ return err;
+ }
+ }
+
+ return 0;
+}