1 files changed, 305 insertions, 175 deletions

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index d821107f55f9..3d1c25fc97ae 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -8,6 +8,10 @@
 #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>
@@ -17,15 +21,11 @@
 #include "libbpf_internal.h"
 #include "hashmap.h"
 
-#define BTF_MAX_NR_TYPES 0x7fffffff
-#define BTF_MAX_STR_OFFSET 0x7fffffff
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
 
-#define IS_MODIFIER(k) (((k) == BTF_KIND_TYPEDEF) || \
-		((k) == BTF_KIND_VOLATILE) || \
-		((k) == BTF_KIND_CONST) || \
-		((k) == BTF_KIND_RESTRICT))
-
-#define IS_VAR(k) ((k) == BTF_KIND_VAR)
+#define BTF_MAX_NR_TYPES 0x7fffffffU
+#define BTF_MAX_STR_OFFSET 0x7fffffffU
 
 static struct btf_type btf_void;
 
@@ -43,47 +43,6 @@ struct btf {
 	int fd;
 };
 
-struct btf_ext_info {
-	/*
-	 * info points to the individual info section (e.g. func_info and
-	 * line_info) from the .BTF.ext. It does not include the __u32 rec_size.
-	 */
-	void *info;
-	__u32 rec_size;
-	__u32 len;
-};
-
-struct btf_ext {
-	union {
-		struct btf_ext_header *hdr;
-		void *data;
-	};
-	struct btf_ext_info func_info;
-	struct btf_ext_info line_info;
-	__u32 data_size;
-};
-
-struct btf_ext_info_sec {
-	__u32	sec_name_off;
-	__u32	num_info;
-	/* Followed by num_info * record_size number of bytes */
-	__u8	data[0];
-};
-
-/* The minimum bpf_func_info checked by the loader */
-struct bpf_func_info_min {
-	__u32   insn_off;
-	__u32   type_id;
-};
-
-/* The minimum bpf_line_info checked by the loader */
-struct bpf_line_info_min {
-	__u32	insn_off;
-	__u32	file_name_off;
-	__u32	line_off;
-	__u32	line_col;
-};
-
 static inline __u64 ptr_to_u64(const void *ptr)
 {
 	return (__u64) (unsigned long) ptr;
@@ -98,7 +57,7 @@ static int btf_add_type(struct btf *btf, struct btf_type *t)
 		if (btf->types_size == BTF_MAX_NR_TYPES)
 			return -E2BIG;
 
-		expand_by = max(btf->types_size >> 2, 16);
+		expand_by = max(btf->types_size >> 2, 16U);
 		new_size = min(BTF_MAX_NR_TYPES, btf->types_size + expand_by);
 
 		new_types = realloc(btf->types, sizeof(*new_types) * new_size);
@@ -193,9 +152,9 @@ static int btf_parse_str_sec(struct btf *btf)
 static int btf_type_size(struct btf_type *t)
 {
 	int base_size = sizeof(struct btf_type);
-	__u16 vlen = BTF_INFO_VLEN(t->info);
+	__u16 vlen = btf_vlen(t);
 
-	switch (BTF_INFO_KIND(t->info)) {
+	switch (btf_kind(t)) {
 	case BTF_KIND_FWD:
 	case BTF_KIND_CONST:
 	case BTF_KIND_VOLATILE:
@@ -220,7 +179,7 @@ static int btf_type_size(struct btf_type *t)
 	case BTF_KIND_DATASEC:
 		return base_size + vlen * sizeof(struct btf_var_secinfo);
 	default:
-		pr_debug("Unsupported BTF_KIND:%u\n", BTF_INFO_KIND(t->info));
+		pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
 		return -EINVAL;
 	}
 }
@@ -264,7 +223,7 @@ const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
 
 static bool btf_type_is_void(const struct btf_type *t)
 {
-	return t == &btf_void || BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
+	return t == &btf_void || btf_is_fwd(t);
 }
 
 static bool btf_type_is_void_or_null(const struct btf_type *t)
@@ -285,7 +244,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
 	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_INFO_KIND(t->info)) {
+		switch (btf_kind(t)) {
 		case BTF_KIND_INT:
 		case BTF_KIND_STRUCT:
 		case BTF_KIND_UNION:
@@ -304,7 +263,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
 			type_id = t->type;
 			break;
 		case BTF_KIND_ARRAY:
-			array = (const struct btf_array *)(t + 1);
+			array = btf_array(t);
 			if (nelems && array->nelems > UINT32_MAX / nelems)
 				return -E2BIG;
 			nelems *= array->nelems;
@@ -317,16 +276,54 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
 		t = btf__type_by_id(btf, type_id);
 	}
 
+done:
 	if (size < 0)
 		return -EINVAL;
-
-done:
 	if (nelems && size > UINT32_MAX / nelems)
 		return -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:
+		return min(sizeof(void *), (size_t)t->size);
+	case BTF_KIND_PTR:
+		return sizeof(void *);
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_CONST:
+	case BTF_KIND_RESTRICT:
+		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 align;
+			max_align = max(max_align, align);
+		}
+
+		return max_align;
+	}
+	default:
+		pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
+		return 0;
+	}
+}
+
 int btf__resolve_type(const struct btf *btf, __u32 type_id)
 {
 	const struct btf_type *t;
@@ -335,8 +332,7 @@ int btf__resolve_type(const struct btf *btf, __u32 type_id)
 	t = btf__type_by_id(btf, type_id);
 	while (depth < MAX_RESOLVE_DEPTH &&
 	       !btf_type_is_void_or_null(t) &&
-	       (IS_MODIFIER(BTF_INFO_KIND(t->info)) ||
-		IS_VAR(BTF_INFO_KIND(t->info)))) {
+	       (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++;
@@ -366,6 +362,28 @@ __s32 btf__find_by_name(const struct btf *btf, const char *type_name)
 	return -ENOENT;
 }
 
+__s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
+			     __u32 kind)
+{
+	__u32 i;
+
+	if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void"))
+		return 0;
+
+	for (i = 1; i <= btf->nr_types; i++) {
+		const struct btf_type *t = btf->types[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 -ENOENT;
+}
+
 void btf__free(struct btf *btf)
 {
 	if (!btf)
@@ -439,14 +457,14 @@ struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
 	GElf_Ehdr ehdr;
 
 	if (elf_version(EV_CURRENT) == EV_NONE) {
-		pr_warning("failed to init libelf for %s\n", path);
+		pr_warn("failed to init libelf for %s\n", path);
 		return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
 	}
 
 	fd = open(path, O_RDONLY);
 	if (fd < 0) {
 		err = -errno;
-		pr_warning("failed to open %s: %s\n", path, strerror(errno));
+		pr_warn("failed to open %s: %s\n", path, strerror(errno));
 		return ERR_PTR(err);
 	}
 
@@ -454,19 +472,19 @@ struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
 
 	elf = elf_begin(fd, ELF_C_READ, NULL);
 	if (!elf) {
-		pr_warning("failed to open %s as ELF file\n", path);
+		pr_warn("failed to open %s as ELF file\n", path);
 		goto done;
 	}
 	if (!gelf_getehdr(elf, &ehdr)) {
-		pr_warning("failed to get EHDR from %s\n", path);
+		pr_warn("failed to get EHDR from %s\n", path);
 		goto done;
 	}
 	if (!btf_check_endianness(&ehdr)) {
-		pr_warning("non-native ELF endianness is not supported\n");
+		pr_warn("non-native ELF endianness is not supported\n");
 		goto done;
 	}
 	if (!elf_rawdata(elf_getscn(elf, ehdr.e_shstrndx), NULL)) {
-		pr_warning("failed to get e_shstrndx from %s\n", path);
+		pr_warn("failed to get e_shstrndx from %s\n", path);
 		goto done;
 	}
 
@@ -476,29 +494,29 @@ struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
 
 		idx++;
 		if (gelf_getshdr(scn, &sh) != &sh) {
-			pr_warning("failed to get section(%d) header from %s\n",
-				   idx, path);
+			pr_warn("failed to get section(%d) header from %s\n",
+				idx, path);
 			goto done;
 		}
 		name = elf_strptr(elf, ehdr.e_shstrndx, sh.sh_name);
 		if (!name) {
-			pr_warning("failed to get section(%d) name from %s\n",
-				   idx, path);
+			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_warning("failed to get section(%d, %s) data from %s\n",
-					   idx, name, path);
+				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_warning("failed to get section(%d, %s) data from %s\n",
-					   idx, name, path);
+				pr_warn("failed to get section(%d, %s) data from %s\n",
+					idx, name, path);
 				goto done;
 			}
 			continue;
@@ -555,11 +573,11 @@ static int compare_vsi_off(const void *_a, const void *_b)
 static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
 			     struct btf_type *t)
 {
-	__u32 size = 0, off = 0, i, vars = BTF_INFO_VLEN(t->info);
+	__u32 size = 0, off = 0, i, vars = btf_vlen(t);
 	const char *name = btf__name_by_offset(btf, t->name_off);
 	const struct btf_type *t_var;
 	struct btf_var_secinfo *vsi;
-	struct btf_var *var;
+	const struct btf_var *var;
 	int ret;
 
 	if (!name) {
@@ -567,6 +585,12 @@ static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
 		return -ENOENT;
 	}
 
+	/* .extern datasec size and var offsets were set correctly during
+	 * extern collection step, so just skip straight to sorting variables
+	 */
+	if (t->size)
+		goto sort_vars;
+
 	ret = bpf_object__section_size(obj, name, &size);
 	if (ret || !size || (t->size && t->size != size)) {
 		pr_debug("Invalid size for section %s: %u bytes\n", name, size);
@@ -575,12 +599,11 @@ static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
 
 	t->size = size;
 
-	for (i = 0, vsi = (struct btf_var_secinfo *)(t + 1);
-	     i < vars; i++, vsi++) {
+	for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
 		t_var = btf__type_by_id(btf, vsi->type);
-		var = (struct btf_var *)(t_var + 1);
+		var = btf_var(t_var);
 
-		if (BTF_INFO_KIND(t_var->info) != BTF_KIND_VAR) {
+		if (!btf_is_var(t_var)) {
 			pr_debug("Non-VAR type seen in section %s\n", name);
 			return -EINVAL;
 		}
@@ -596,14 +619,16 @@ static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
 
 		ret = bpf_object__variable_offset(obj, name, &off);
 		if (ret) {
-			pr_debug("No offset found in symbol table for VAR %s\n", name);
+			pr_debug("No offset found in symbol table for VAR %s\n",
+				 name);
 			return -ENOENT;
 		}
 
 		vsi->offset = off;
 	}
 
-	qsort(t + 1, vars, sizeof(*vsi), compare_vsi_off);
+sort_vars:
+	qsort(btf_var_secinfos(t), vars, sizeof(*vsi), compare_vsi_off);
 	return 0;
 }
 
@@ -620,7 +645,7 @@ int btf__finalize_data(struct bpf_object *obj, struct btf *btf)
 		 * is section size and global variable offset. We use
 		 * the info from the ELF itself for this purpose.
 		 */
-		if (BTF_INFO_KIND(t->info) == BTF_KIND_DATASEC) {
+		if (btf_is_datasec(t)) {
 			err = btf_fixup_datasec(obj, btf, t);
 			if (err)
 				break;
@@ -649,9 +674,9 @@ int btf__load(struct btf *btf)
 			       log_buf, log_buf_size, false);
 	if (btf->fd < 0) {
 		err = -errno;
-		pr_warning("Error loading BTF: %s(%d)\n", strerror(errno), errno);
+		pr_warn("Error loading BTF: %s(%d)\n", strerror(errno), errno);
 		if (*log_buf)
-			pr_warning("%s\n", log_buf);
+			pr_warn("%s\n", log_buf);
 		goto done;
 	}
 
@@ -756,8 +781,8 @@ int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
 
 	if (snprintf(container_name, max_name, "____btf_map_%s", map_name) ==
 	    max_name) {
-		pr_warning("map:%s length of '____btf_map_%s' is too long\n",
-			   map_name, map_name);
+		pr_warn("map:%s length of '____btf_map_%s' is too long\n",
+			map_name, map_name);
 		return -EINVAL;
 	}
 
@@ -770,42 +795,41 @@ int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
 
 	container_type = btf__type_by_id(btf, container_id);
 	if (!container_type) {
-		pr_warning("map:%s cannot find BTF type for container_id:%u\n",
-			   map_name, container_id);
+		pr_warn("map:%s cannot find BTF type for container_id:%u\n",
+			map_name, container_id);
 		return -EINVAL;
 	}
 
-	if (BTF_INFO_KIND(container_type->info) != BTF_KIND_STRUCT ||
-	    BTF_INFO_VLEN(container_type->info) < 2) {
-		pr_warning("map:%s container_name:%s is an invalid container struct\n",
-			   map_name, container_name);
+	if (!btf_is_struct(container_type) || btf_vlen(container_type) < 2) {
+		pr_warn("map:%s container_name:%s is an invalid container struct\n",
+			map_name, container_name);
 		return -EINVAL;
 	}
 
-	key = (struct btf_member *)(container_type + 1);
+	key = btf_members(container_type);
 	value = key + 1;
 
 	key_size = btf__resolve_size(btf, key->type);
 	if (key_size < 0) {
-		pr_warning("map:%s invalid BTF key_type_size\n", map_name);
+		pr_warn("map:%s invalid BTF key_type_size\n", map_name);
 		return key_size;
 	}
 
 	if (expected_key_size != key_size) {
-		pr_warning("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
-			   map_name, (__u32)key_size, expected_key_size);
+		pr_warn("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
+			map_name, (__u32)key_size, expected_key_size);
 		return -EINVAL;
 	}
 
 	value_size = btf__resolve_size(btf, value->type);
 	if (value_size < 0) {
-		pr_warning("map:%s invalid BTF value_type_size\n", map_name);
+		pr_warn("map:%s invalid BTF value_type_size\n", map_name);
 		return value_size;
 	}
 
 	if (expected_value_size != value_size) {
-		pr_warning("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
-			   map_name, (__u32)value_size, expected_value_size);
+		pr_warn("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
+			map_name, (__u32)value_size, expected_value_size);
 		return -EINVAL;
 	}
 
@@ -832,6 +856,9 @@ static int btf_ext_setup_info(struct btf_ext *btf_ext,
 	/* 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);
@@ -935,11 +962,24 @@ static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
 	return btf_ext_setup_info(btf_ext, &param);
 }
 
+static int btf_ext_setup_field_reloc(struct btf_ext *btf_ext)
+{
+	struct btf_ext_sec_setup_param param = {
+		.off = btf_ext->hdr->field_reloc_off,
+		.len = btf_ext->hdr->field_reloc_len,
+		.min_rec_size = sizeof(struct bpf_field_reloc),
+		.ext_info = &btf_ext->field_reloc_info,
+		.desc = "field_reloc",
+	};
+
+	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 < offsetof(struct btf_ext_header, func_info_off) ||
+	if (data_size < offsetofend(struct btf_ext_header, hdr_len) ||
 	    data_size < hdr->hdr_len) {
 		pr_debug("BTF.ext header not found");
 		return -EINVAL;
@@ -997,6 +1037,9 @@ struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
 	}
 	memcpy(btf_ext->data, data, size);
 
+	if (btf_ext->hdr->hdr_len <
+	    offsetofend(struct btf_ext_header, line_info_len))
+		goto done;
 	err = btf_ext_setup_func_info(btf_ext);
 	if (err)
 		goto done;
@@ -1005,6 +1048,13 @@ struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
 	if (err)
 		goto done;
 
+	if (btf_ext->hdr->hdr_len <
+	    offsetofend(struct btf_ext_header, field_reloc_len))
+		goto done;
+	err = btf_ext_setup_field_reloc(btf_ext);
+	if (err)
+		goto done;
+
 done:
 	if (err) {
 		btf_ext__free(btf_ext);
@@ -1355,7 +1405,7 @@ static int btf_dedup_hypot_map_add(struct btf_dedup *d,
 	if (d->hypot_cnt == d->hypot_cap) {
 		__u32 *new_list;
 
-		d->hypot_cap += max(16, d->hypot_cap / 2);
+		d->hypot_cap += max((size_t)16, d->hypot_cap / 2);
 		new_list = realloc(d->hypot_list, sizeof(__u32) * d->hypot_cap);
 		if (!new_list)
 			return -ENOMEM;
@@ -1441,10 +1491,9 @@ static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
 	d->map[0] = 0;
 	for (i = 1; i <= btf->nr_types; i++) {
 		struct btf_type *t = d->btf->types[i];
-		__u16 kind = BTF_INFO_KIND(t->info);
 
 		/* VAR and DATASEC are never deduped and are self-canonical */
-		if (kind == BTF_KIND_VAR || kind == BTF_KIND_DATASEC)
+		if (btf_is_var(t) || btf_is_datasec(t))
 			d->map[i] = i;
 		else
 			d->map[i] = BTF_UNPROCESSED_ID;
@@ -1485,11 +1534,11 @@ static int btf_for_each_str_off(struct btf_dedup *d, str_off_fn_t fn, void *ctx)
 		if (r)
 			return r;
 
-		switch (BTF_INFO_KIND(t->info)) {
+		switch (btf_kind(t)) {
 		case BTF_KIND_STRUCT:
 		case BTF_KIND_UNION: {
-			struct btf_member *m = (struct btf_member *)(t + 1);
-			__u16 vlen = BTF_INFO_VLEN(t->info);
+			struct btf_member *m = btf_members(t);
+			__u16 vlen = btf_vlen(t);
 
 			for (j = 0; j < vlen; j++) {
 				r = fn(&m->name_off, ctx);
@@ -1500,8 +1549,8 @@ static int btf_for_each_str_off(struct btf_dedup *d, str_off_fn_t fn, void *ctx)
 			break;
 		}
 		case BTF_KIND_ENUM: {
-			struct btf_enum *m = (struct btf_enum *)(t + 1);
-			__u16 vlen = BTF_INFO_VLEN(t->info);
+			struct btf_enum *m = btf_enum(t);
+			__u16 vlen = btf_vlen(t);
 
 			for (j = 0; j < vlen; j++) {
 				r = fn(&m->name_off, ctx);
@@ -1512,8 +1561,8 @@ static int btf_for_each_str_off(struct btf_dedup *d, str_off_fn_t fn, void *ctx)
 			break;
 		}
 		case BTF_KIND_FUNC_PROTO: {
-			struct btf_param *m = (struct btf_param *)(t + 1);
-			__u16 vlen = BTF_INFO_VLEN(t->info);
+			struct btf_param *m = btf_params(t);
+			__u16 vlen = btf_vlen(t);
 
 			for (j = 0; j < vlen; j++) {
 				r = fn(&m->name_off, ctx);
@@ -1652,7 +1701,7 @@ static int btf_dedup_strings(struct btf_dedup *d)
 		if (strs.cnt + 1 > strs.cap) {
 			struct btf_str_ptr *new_ptrs;
 
-			strs.cap += max(strs.cnt / 2, 16);
+			strs.cap += max(strs.cnt / 2, 16U);
 			new_ptrs = realloc(strs.ptrs,
 					   sizeof(strs.ptrs[0]) * strs.cap);
 			if (!new_ptrs) {
@@ -1802,16 +1851,16 @@ static long btf_hash_enum(struct btf_type *t)
 /* Check structural equality of two ENUMs. */
 static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
 {
-	struct btf_enum *m1, *m2;
+	const struct btf_enum *m1, *m2;
 	__u16 vlen;
 	int i;
 
 	if (!btf_equal_common(t1, t2))
 		return false;
 
-	vlen = BTF_INFO_VLEN(t1->info);
-	m1 = (struct btf_enum *)(t1 + 1);
-	m2 = (struct btf_enum *)(t2 + 1);
+	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;
@@ -1823,8 +1872,7 @@ static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
 
 static inline bool btf_is_enum_fwd(struct btf_type *t)
 {
-	return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM &&
-	       BTF_INFO_VLEN(t->info) == 0;
+	return btf_is_enum(t) && btf_vlen(t) == 0;
 }
 
 static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
@@ -1844,8 +1892,8 @@ static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
  */
 static long btf_hash_struct(struct btf_type *t)
 {
-	struct btf_member *member = (struct btf_member *)(t + 1);
-	__u32 vlen = BTF_INFO_VLEN(t->info);
+	const struct btf_member *member = btf_members(t);
+	__u32 vlen = btf_vlen(t);
 	long h = btf_hash_common(t);
 	int i;
 
@@ -1865,16 +1913,16 @@ static long btf_hash_struct(struct btf_type *t)
  */
 static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
 {
-	struct btf_member *m1, *m2;
+	const struct btf_member *m1, *m2;
 	__u16 vlen;
 	int i;
 
 	if (!btf_equal_common(t1, t2))
 		return false;
 
-	vlen = BTF_INFO_VLEN(t1->info);
-	m1 = (struct btf_member *)(t1 + 1);
-	m2 = (struct btf_member *)(t2 + 1);
+	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;
@@ -1891,7 +1939,7 @@ static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
  */
 static long btf_hash_array(struct btf_type *t)
 {
-	struct btf_array *info = (struct btf_array *)(t + 1);
+	const struct btf_array *info = btf_array(t);
 	long h = btf_hash_common(t);
 
 	h = hash_combine(h, info->type);
@@ -1909,13 +1957,13 @@ static long btf_hash_array(struct btf_type *t)
  */
 static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
 {
-	struct btf_array *info1, *info2;
+	const struct btf_array *info1, *info2;
 
 	if (!btf_equal_common(t1, t2))
 		return false;
 
-	info1 = (struct btf_array *)(t1 + 1);
-	info2 = (struct btf_array *)(t2 + 1);
+	info1 = btf_array(t1);
+	info2 = btf_array(t2);
 	return info1->type == info2->type &&
 	       info1->index_type == info2->index_type &&
 	       info1->nelems == info2->nelems;
@@ -1928,14 +1976,10 @@ static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
  */
 static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
 {
-	struct btf_array *info1, *info2;
-
 	if (!btf_equal_common(t1, t2))
 		return false;
 
-	info1 = (struct btf_array *)(t1 + 1);
-	info2 = (struct btf_array *)(t2 + 1);
-	return info1->nelems == info2->nelems;
+	return btf_array(t1)->nelems == btf_array(t2)->nelems;
 }
 
 /*
@@ -1945,8 +1989,8 @@ static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
  */
 static long btf_hash_fnproto(struct btf_type *t)
 {
-	struct btf_param *member = (struct btf_param *)(t + 1);
-	__u16 vlen = BTF_INFO_VLEN(t->info);
+	const struct btf_param *member = btf_params(t);
+	__u16 vlen = btf_vlen(t);
 	long h = btf_hash_common(t);
 	int i;
 
@@ -1967,16 +2011,16 @@ static long btf_hash_fnproto(struct btf_type *t)
  */
 static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
 {
-	struct btf_param *m1, *m2;
+	const struct btf_param *m1, *m2;
 	__u16 vlen;
 	int i;
 
 	if (!btf_equal_common(t1, t2))
 		return false;
 
-	vlen = BTF_INFO_VLEN(t1->info);
-	m1 = (struct btf_param *)(t1 + 1);
-	m2 = (struct btf_param *)(t2 + 1);
+	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;
@@ -1993,7 +2037,7 @@ static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
  */
 static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
 {
-	struct btf_param *m1, *m2;
+	const struct btf_param *m1, *m2;
 	__u16 vlen;
 	int i;
 
@@ -2001,9 +2045,9 @@ static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
 	if (t1->name_off != t2->name_off || t1->info != t2->info)
 		return false;
 
-	vlen = BTF_INFO_VLEN(t1->info);
-	m1 = (struct btf_param *)(t1 + 1);
-	m2 = (struct btf_param *)(t2 + 1);
+	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;
@@ -2029,7 +2073,7 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
 	__u32 cand_id;
 	long h;
 
-	switch (BTF_INFO_KIND(t->info)) {
+	switch (btf_kind(t)) {
 	case BTF_KIND_CONST:
 	case BTF_KIND_VOLATILE:
 	case BTF_KIND_RESTRICT:
@@ -2142,13 +2186,13 @@ static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
 {
 	__u32 orig_type_id = type_id;
 
-	if (BTF_INFO_KIND(d->btf->types[type_id]->info) != BTF_KIND_FWD)
+	if (!btf_is_fwd(d->btf->types[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_INFO_KIND(d->btf->types[type_id]->info) != BTF_KIND_FWD)
+	if (!btf_is_fwd(d->btf->types[type_id]))
 		return type_id;
 
 	return orig_type_id;
@@ -2157,7 +2201,7 @@ static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
 
 static inline __u16 btf_fwd_kind(struct btf_type *t)
 {
-	return BTF_INFO_KFLAG(t->info) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
+	return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
 }
 
 /*
@@ -2278,8 +2322,8 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
 
 	cand_type = d->btf->types[cand_id];
 	canon_type = d->btf->types[canon_id];
-	cand_kind = BTF_INFO_KIND(cand_type->info);
-	canon_kind = BTF_INFO_KIND(canon_type->info);
+	cand_kind = btf_kind(cand_type);
+	canon_kind = btf_kind(canon_type);
 
 	if (cand_type->name_off != canon_type->name_off)
 		return 0;
@@ -2328,12 +2372,12 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
 		return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
 
 	case BTF_KIND_ARRAY: {
-		struct btf_array *cand_arr, *canon_arr;
+		const struct btf_array *cand_arr, *canon_arr;
 
 		if (!btf_compat_array(cand_type, canon_type))
 			return 0;
-		cand_arr = (struct btf_array *)(cand_type + 1);
-		canon_arr = (struct btf_array *)(canon_type + 1);
+		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)
@@ -2343,14 +2387,14 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
 
 	case BTF_KIND_STRUCT:
 	case BTF_KIND_UNION: {
-		struct btf_member *cand_m, *canon_m;
+		const struct btf_member *cand_m, *canon_m;
 		__u16 vlen;
 
 		if (!btf_shallow_equal_struct(cand_type, canon_type))
 			return 0;
-		vlen = BTF_INFO_VLEN(cand_type->info);
-		cand_m = (struct btf_member *)(cand_type + 1);
-		canon_m = (struct btf_member *)(canon_type + 1);
+		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)
@@ -2363,7 +2407,7 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
 	}
 
 	case BTF_KIND_FUNC_PROTO: {
-		struct btf_param *cand_p, *canon_p;
+		const struct btf_param *cand_p, *canon_p;
 		__u16 vlen;
 
 		if (!btf_compat_fnproto(cand_type, canon_type))
@@ -2371,9 +2415,9 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
 		eq = btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
 		if (eq <= 0)
 			return eq;
-		vlen = BTF_INFO_VLEN(cand_type->info);
-		cand_p = (struct btf_param *)(cand_type + 1);
-		canon_p = (struct btf_param *)(canon_type + 1);
+		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)
@@ -2428,8 +2472,8 @@ static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
 		targ_type_id = d->hypot_map[cand_type_id];
 		t_id = resolve_type_id(d, targ_type_id);
 		c_id = resolve_type_id(d, cand_type_id);
-		t_kind = BTF_INFO_KIND(d->btf->types[t_id]->info);
-		c_kind = BTF_INFO_KIND(d->btf->types[c_id]->info);
+		t_kind = btf_kind(d->btf->types[t_id]);
+		c_kind = btf_kind(d->btf->types[c_id]);
 		/*
 		 * Resolve FWD into STRUCT/UNION.
 		 * It's ok to resolve FWD into STRUCT/UNION that's not yet
@@ -2498,7 +2542,7 @@ static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
 		return 0;
 
 	t = d->btf->types[type_id];
-	kind = BTF_INFO_KIND(t->info);
+	kind = btf_kind(t);
 
 	if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
 		return 0;
@@ -2593,7 +2637,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
 	t = d->btf->types[type_id];
 	d->map[type_id] = BTF_IN_PROGRESS_ID;
 
-	switch (BTF_INFO_KIND(t->info)) {
+	switch (btf_kind(t)) {
 	case BTF_KIND_CONST:
 	case BTF_KIND_VOLATILE:
 	case BTF_KIND_RESTRICT:
@@ -2617,7 +2661,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
 		break;
 
 	case BTF_KIND_ARRAY: {
-		struct btf_array *info = (struct btf_array *)(t + 1);
+		struct btf_array *info = btf_array(t);
 
 		ref_type_id = btf_dedup_ref_type(d, info->type);
 		if (ref_type_id < 0)
@@ -2651,8 +2695,8 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
 			return ref_type_id;
 		t->type = ref_type_id;
 
-		vlen = BTF_INFO_VLEN(t->info);
-		param = (struct btf_param *)(t + 1);
+		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)
@@ -2792,7 +2836,7 @@ static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
 	struct btf_type *t = d->btf->types[type_id];
 	int i, r;
 
-	switch (BTF_INFO_KIND(t->info)) {
+	switch (btf_kind(t)) {
 	case BTF_KIND_INT:
 	case BTF_KIND_ENUM:
 		break;
@@ -2812,7 +2856,7 @@ static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
 		break;
 
 	case BTF_KIND_ARRAY: {
-		struct btf_array *arr_info = (struct btf_array *)(t + 1);
+		struct btf_array *arr_info = btf_array(t);
 
 		r = btf_dedup_remap_type_id(d, arr_info->type);
 		if (r < 0)
@@ -2827,8 +2871,8 @@ static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
 
 	case BTF_KIND_STRUCT:
 	case BTF_KIND_UNION: {
-		struct btf_member *member = (struct btf_member *)(t + 1);
-		__u16 vlen = BTF_INFO_VLEN(t->info);
+		struct btf_member *member = btf_members(t);
+		__u16 vlen = btf_vlen(t);
 
 		for (i = 0; i < vlen; i++) {
 			r = btf_dedup_remap_type_id(d, member->type);
@@ -2841,8 +2885,8 @@ static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
 	}
 
 	case BTF_KIND_FUNC_PROTO: {
-		struct btf_param *param = (struct btf_param *)(t + 1);
-		__u16 vlen = BTF_INFO_VLEN(t->info);
+		struct btf_param *param = btf_params(t);
+		__u16 vlen = btf_vlen(t);
 
 		r = btf_dedup_remap_type_id(d, t->type);
 		if (r < 0)
@@ -2860,8 +2904,8 @@ static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
 	}
 
 	case BTF_KIND_DATASEC: {
-		struct btf_var_secinfo *var = (struct btf_var_secinfo *)(t + 1);
-		__u16 vlen = BTF_INFO_VLEN(t->info);
+		struct btf_var_secinfo *var = btf_var_secinfos(t);
+		__u16 vlen = btf_vlen(t);
 
 		for (i = 0; i < vlen; i++) {
 			r = btf_dedup_remap_type_id(d, var->type);
@@ -2891,3 +2935,89 @@ static int btf_dedup_remap_types(struct btf_dedup *d)
 	}
 	return 0;
 }
+
+static struct btf *btf_load_raw(const char *path)
+{
+	struct btf *btf;
+	size_t read_cnt;
+	struct stat st;
+	void *data;
+	FILE *f;
+
+	if (stat(path, &st))
+		return ERR_PTR(-errno);
+
+	data = malloc(st.st_size);
+	if (!data)
+		return ERR_PTR(-ENOMEM);
+
+	f = fopen(path, "rb");
+	if (!f) {
+		btf = ERR_PTR(-errno);
+		goto cleanup;
+	}
+
+	read_cnt = fread(data, 1, st.st_size, f);
+	fclose(f);
+	if (read_cnt < st.st_size) {
+		btf = ERR_PTR(-EBADF);
+		goto cleanup;
+	}
+
+	btf = btf__new(data, read_cnt);
+
+cleanup:
+	free(data);
+	return btf;
+}
+
+/*
+ * 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 *libbpf_find_kernel_btf(void)
+{
+	struct {
+		const char *path_fmt;
+		bool raw_btf;
+	} locations[] = {
+		/* try canonical vmlinux BTF through sysfs first */
+		{ "/sys/kernel/btf/vmlinux", true /* raw BTF */ },
+		/* fall back to trying to find vmlinux ELF 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;
+
+	uname(&buf);
+
+	for (i = 0; i < ARRAY_SIZE(locations); i++) {
+		snprintf(path, PATH_MAX, locations[i].path_fmt, buf.release);
+
+		if (access(path, R_OK))
+			continue;
+
+		if (locations[i].raw_btf)
+			btf = btf_load_raw(path);
+		else
+			btf = btf__parse_elf(path, NULL);
+
+		pr_debug("loading kernel BTF '%s': %ld\n",
+			 path, IS_ERR(btf) ? PTR_ERR(btf) : 0);
+		if (IS_ERR(btf))
+			continue;
+
+		return btf;
+	}
+
+	pr_warn("failed to find valid kernel BTF\n");
+	return ERR_PTR(-ESRCH);
+}