Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Daniel Borkmann says:

====================
pull-request: bpf-next 2019-10-27

The following pull-request contains BPF updates for your *net-next* tree.

We've added 52 non-merge commits during the last 11 day(s) which contain
a total of 65 files changed, 2604 insertions(+), 1100 deletions(-).

The main changes are:

 1) Revolutionize BPF tracing by using in-kernel BTF to type check BPF
    assembly code. The work here teaches BPF verifier to recognize
    kfree_skb()'s first argument as 'struct sk_buff *' in tracepoints
    such that verifier allows direct use of bpf_skb_event_output() helper
    used in tc BPF et al (w/o probing memory access) that dumps skb data
    into perf ring buffer. Also add direct loads to probe memory in order
    to speed up/replace bpf_probe_read() calls, from Alexei Starovoitov.

 2) Big batch of changes to improve libbpf and BPF kselftests. Besides
    others: generalization of libbpf's CO-RE relocation support to now
    also include field existence relocations, revamp the BPF kselftest
    Makefile to add test runner concept allowing to exercise various
    ways to build BPF programs, and teach bpf_object__open() and friends
    to automatically derive BPF program type/expected attach type from
    section names to ease their use, from Andrii Nakryiko.

 3) Fix deadlock in stackmap's build-id lookup on rq_lock(), from Song Liu.

 4) Allow to read BTF as raw data from bpftool. Most notable use case
    is to dump /sys/kernel/btf/vmlinux through this, from Jiri Olsa.

 5) Use bpf_redirect_map() helper in libbpf's AF_XDP helper prog which
    manages to improve "rx_drop" performance by ~4%., from Björn Töpel.

 6) Fix to restore the flow dissector after reattach BPF test and also
    fix error handling in bpf_helper_defs.h generation, from Jakub Sitnicki.

 7) Improve verifier's BTF ctx access for use outside of raw_tp, from
    Martin KaFai Lau.

 8) Improve documentation for AF_XDP with new sections and to reflect
    latest features, from Magnus Karlsson.

 9) Add back 'version' section parsing to libbpf for old kernels, from
    John Fastabend.

10) Fix strncat bounds error in libbpf's libbpf_prog_type_by_name(),
    from KP Singh.

11) Turn on -mattr=+alu32 in LLVM by default for BPF kselftests in order
    to improve insn coverage for built BPF progs, from Yonghong Song.

12) Misc minor cleanups and fixes, from various others.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

11 files changed, 695 insertions, 519 deletions

diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index bfeafb9d2d49..99425d0be6ff 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -300,3 +300,6 @@ tags:
 # Declare the contents of the .PHONY variable as phony.  We keep that
 # information in a variable so we can use it in if_changed and friends.
 .PHONY: $(PHONY)
+
+# Delete partially updated (corrupted) files on error
+.DELETE_ON_ERROR:
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index cbb933532981..79046067720f 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -228,6 +228,9 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
 	memset(&attr, 0, sizeof(attr));
 	attr.prog_type = load_attr->prog_type;
 	attr.expected_attach_type = load_attr->expected_attach_type;
+	if (attr.prog_type == BPF_PROG_TYPE_RAW_TRACEPOINT)
+		/* expected_attach_type is ignored for tracing progs */
+		attr.attach_btf_id = attr.expected_attach_type;
 	attr.insn_cnt = (__u32)load_attr->insns_cnt;
 	attr.insns = ptr_to_u64(load_attr->insns);
 	attr.license = ptr_to_u64(load_attr->license);
diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h
index 4daf04c25493..a273df3784f4 100644
--- a/tools/lib/bpf/bpf_core_read.h
+++ b/tools/lib/bpf/bpf_core_read.h
@@ -3,6 +3,28 @@
 #define __BPF_CORE_READ_H__
 
 /*
+ * enum bpf_field_info_kind is passed as a second argument into
+ * __builtin_preserve_field_info() built-in to get a specific aspect of
+ * a field, captured as a first argument. __builtin_preserve_field_info(field,
+ * info_kind) returns __u32 integer and produces BTF field relocation, which
+ * is understood and processed by libbpf during BPF object loading. See
+ * selftests/bpf for examples.
+ */
+enum bpf_field_info_kind {
+	BPF_FIELD_BYTE_OFFSET = 0,	/* field byte offset */
+	BPF_FIELD_EXISTS = 2,		/* field existence in target kernel */
+};
+
+/*
+ * Convenience macro to check that field actually exists in target kernel's.
+ * Returns:
+ *    1, if matching field is present in target kernel;
+ *    0, if no matching field found.
+ */
+#define bpf_core_field_exists(field)					    \
+	__builtin_preserve_field_info(field, BPF_FIELD_EXISTS)
+
+/*
  * bpf_core_read() abstracts away bpf_probe_read() call and captures offset
  * relocation for source address using __builtin_preserve_access_index()
  * built-in, provided by Clang.
@@ -12,7 +34,7 @@
  * a relocation, which records BTF type ID describing root struct/union and an
  * accessor string which describes exact embedded field that was used to take
  * an address. See detailed description of this relocation format and
- * semantics in comments to struct bpf_offset_reloc in libbpf_internal.h.
+ * semantics in comments to struct bpf_field_reloc in libbpf_internal.h.
  *
  * This relocation allows libbpf to adjust BPF instruction to use correct
  * actual field offset, based on target kernel BTF type that matches original
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 1aa189a9112a..d72e9a79dce1 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -390,14 +390,14 @@ 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);
 	}
 
@@ -405,19 +405,19 @@ 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;
 	}
 
@@ -427,29 +427,29 @@ 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;
@@ -600,9 +600,9 @@ 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;
 	}
 
@@ -707,8 +707,8 @@ 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;
 	}
 
@@ -721,14 +721,14 @@ 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_is_struct(container_type) || btf_vlen(container_type) < 2) {
-		pr_warning("map:%s container_name:%s is an invalid container struct\n",
-			   map_name, container_name);
+		pr_warn("map:%s container_name:%s is an invalid container struct\n",
+			map_name, container_name);
 		return -EINVAL;
 	}
 
@@ -737,25 +737,25 @@ int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
 
 	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;
 	}
 
@@ -888,14 +888,14 @@ 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_offset_reloc(struct btf_ext *btf_ext)
+static int btf_ext_setup_field_reloc(struct btf_ext *btf_ext)
 {
 	struct btf_ext_sec_setup_param param = {
-		.off = btf_ext->hdr->offset_reloc_off,
-		.len = btf_ext->hdr->offset_reloc_len,
-		.min_rec_size = sizeof(struct bpf_offset_reloc),
-		.ext_info = &btf_ext->offset_reloc_info,
-		.desc = "offset_reloc",
+		.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);
@@ -975,9 +975,9 @@ struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
 		goto done;
 
 	if (btf_ext->hdr->hdr_len <
-	    offsetofend(struct btf_ext_header, offset_reloc_len))
+	    offsetofend(struct btf_ext_header, field_reloc_len))
 		goto done;
-	err = btf_ext_setup_offset_reloc(btf_ext);
+	err = btf_ext_setup_field_reloc(btf_ext);
 	if (err)
 		goto done;
 
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 9cb44b4fbf60..b18994116a44 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -60,8 +60,8 @@ struct btf_ext_header {
 	__u32	line_info_len;
 
 	/* optional part of .BTF.ext header */
-	__u32	offset_reloc_off;
-	__u32	offset_reloc_len;
+	__u32	field_reloc_off;
+	__u32	field_reloc_len;
 };
 
 LIBBPF_API void btf__free(struct btf *btf);
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 139812b46c7b..cb126d8fcf75 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -428,7 +428,7 @@ static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
 		/* type loop, but resolvable through fwd declaration */
 		if (btf_is_composite(t) && through_ptr && t->name_off != 0)
 			return 0;
-		pr_warning("unsatisfiable type cycle, id:[%u]\n", id);
+		pr_warn("unsatisfiable type cycle, id:[%u]\n", id);
 		return -ELOOP;
 	}
 
@@ -636,8 +636,8 @@ static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id)
 			if (id == cont_id)
 				return;
 			if (t->name_off == 0) {
-				pr_warning("anonymous struct/union loop, id:[%u]\n",
-					   id);
+				pr_warn("anonymous struct/union loop, id:[%u]\n",
+					id);
 				return;
 			}
 			btf_dump_emit_struct_fwd(d, id, t);
@@ -782,7 +782,7 @@ static int btf_align_of(const struct btf *btf, __u32 id)
 		return align;
 	}
 	default:
-		pr_warning("unsupported BTF_KIND:%u\n", btf_kind(t));
+		pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
 		return 1;
 	}
 }
@@ -1067,7 +1067,7 @@ static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
 			 * chain, restore stack, emit warning, and try to
 			 * proceed nevertheless
 			 */
-			pr_warning("not enough memory for decl stack:%d", err);
+			pr_warn("not enough memory for decl stack:%d", err);
 			d->decl_stack_cnt = stack_start;
 			return;
 		}
@@ -1096,8 +1096,8 @@ static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
 		case BTF_KIND_TYPEDEF:
 			goto done;
 		default:
-			pr_warning("unexpected type in decl chain, kind:%u, id:[%u]\n",
-				   btf_kind(t), id);
+			pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
+				btf_kind(t), id);
 			goto done;
 		}
 	}
@@ -1323,8 +1323,8 @@ static void btf_dump_emit_type_chain(struct btf_dump *d,
 			return;
 		}
 		default:
-			pr_warning("unexpected type in decl chain, kind:%u, id:[%u]\n",
-				   kind, id);
+			pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
+				kind, id);
 			return;
 		}
 
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a02cdedc4e3f..d71631a01926 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -249,6 +249,7 @@ struct bpf_object {
 
 	bool loaded;
 	bool has_pseudo_calls;
+	bool relaxed_core_relocs;
 
 	/*
 	 * Information when doing elf related work. Only valid if fd
@@ -311,8 +312,8 @@ void bpf_program__unload(struct bpf_program *prog)
 		for (i = 0; i < prog->instances.nr; i++)
 			zclose(prog->instances.fds[i]);
 	} else if (prog->instances.nr != -1) {
-		pr_warning("Internal error: instances.nr is %d\n",
-			   prog->instances.nr);
+		pr_warn("Internal error: instances.nr is %d\n",
+			prog->instances.nr);
 	}
 
 	prog->instances.nr = -1;
@@ -363,8 +364,8 @@ bpf_program__init(void *data, size_t size, char *section_name, int idx,
 	const size_t bpf_insn_sz = sizeof(struct bpf_insn);
 
 	if (size == 0 || size % bpf_insn_sz) {
-		pr_warning("corrupted section '%s', size: %zu\n",
-			   section_name, size);
+		pr_warn("corrupted section '%s', size: %zu\n",
+			section_name, size);
 		return -EINVAL;
 	}
 
@@ -372,22 +373,22 @@ bpf_program__init(void *data, size_t size, char *section_name, int idx,
 
 	prog->section_name = strdup(section_name);
 	if (!prog->section_name) {
-		pr_warning("failed to alloc name for prog under section(%d) %s\n",
-			   idx, section_name);
+		pr_warn("failed to alloc name for prog under section(%d) %s\n",
+			idx, section_name);
 		goto errout;
 	}
 
 	prog->pin_name = __bpf_program__pin_name(prog);
 	if (!prog->pin_name) {
-		pr_warning("failed to alloc pin name for prog under section(%d) %s\n",
-			   idx, section_name);
+		pr_warn("failed to alloc pin name for prog under section(%d) %s\n",
+			idx, section_name);
 		goto errout;
 	}
 
 	prog->insns = malloc(size);
 	if (!prog->insns) {
-		pr_warning("failed to alloc insns for prog under section %s\n",
-			   section_name);
+		pr_warn("failed to alloc insns for prog under section %s\n",
+			section_name);
 		goto errout;
 	}
 	prog->insns_cnt = size / bpf_insn_sz;
@@ -425,8 +426,8 @@ bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
 		 * is still valid, so don't need special treat for
 		 * bpf_close_object().
 		 */
-		pr_warning("failed to alloc a new program under section '%s'\n",
-			   section_name);
+		pr_warn("failed to alloc a new program under section '%s'\n",
+			section_name);
 		bpf_program__exit(&prog);
 		return -ENOMEM;
 	}
@@ -466,8 +467,8 @@ bpf_object__init_prog_names(struct bpf_object *obj)
 					  obj->efile.strtabidx,
 					  sym.st_name);
 			if (!name) {
-				pr_warning("failed to get sym name string for prog %s\n",
-					   prog->section_name);
+				pr_warn("failed to get sym name string for prog %s\n",
+					prog->section_name);
 				return -LIBBPF_ERRNO__LIBELF;
 			}
 		}
@@ -476,15 +477,15 @@ bpf_object__init_prog_names(struct bpf_object *obj)
 			name = ".text";
 
 		if (!name) {
-			pr_warning("failed to find sym for prog %s\n",
-				   prog->section_name);
+			pr_warn("failed to find sym for prog %s\n",
+				prog->section_name);
 			return -EINVAL;
 		}
 
 		prog->name = strdup(name);
 		if (!prog->name) {
-			pr_warning("failed to allocate memory for prog sym %s\n",
-				   name);
+			pr_warn("failed to allocate memory for prog sym %s\n",
+				name);
 			return -ENOMEM;
 		}
 	}
@@ -513,7 +514,7 @@ static struct bpf_object *bpf_object__new(const char *path,
 
 	obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
 	if (!obj) {
-		pr_warning("alloc memory failed for %s\n", path);
+		pr_warn("alloc memory failed for %s\n", path);
 		return ERR_PTR(-ENOMEM);
 	}
 
@@ -580,7 +581,7 @@ static int bpf_object__elf_init(struct bpf_object *obj)
 	GElf_Ehdr *ep;
 
 	if (obj_elf_valid(obj)) {
-		pr_warning("elf init: internal error\n");
+		pr_warn("elf init: internal error\n");
 		return -LIBBPF_ERRNO__LIBELF;
 	}
 
@@ -598,7 +599,7 @@ static int bpf_object__elf_init(struct bpf_object *obj)
 
 			err = -errno;
 			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
-			pr_warning("failed to open %s: %s\n", obj->path, cp);
+			pr_warn("failed to open %s: %s\n", obj->path, cp);
 			return err;
 		}
 
@@ -607,13 +608,13 @@ static int bpf_object__elf_init(struct bpf_object *obj)
 	}
 
 	if (!obj->efile.elf) {
-		pr_warning("failed to open %s as ELF file\n", obj->path);
+		pr_warn("failed to open %s as ELF file\n", obj->path);
 		err = -LIBBPF_ERRNO__LIBELF;
 		goto errout;
 	}
 
 	if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) {
-		pr_warning("failed to get EHDR from %s\n", obj->path);
+		pr_warn("failed to get EHDR from %s\n", obj->path);
 		err = -LIBBPF_ERRNO__FORMAT;
 		goto errout;
 	}
@@ -622,7 +623,7 @@ static int bpf_object__elf_init(struct bpf_object *obj)
 	/* Old LLVM set e_machine to EM_NONE */
 	if (ep->e_type != ET_REL ||
 	    (ep->e_machine && ep->e_machine != EM_BPF)) {
-		pr_warning("%s is not an eBPF object file\n", obj->path);
+		pr_warn("%s is not an eBPF object file\n", obj->path);
 		err = -LIBBPF_ERRNO__FORMAT;
 		goto errout;
 	}
@@ -644,7 +645,7 @@ static int bpf_object__check_endianness(struct bpf_object *obj)
 #else
 # error "Unrecognized __BYTE_ORDER__"
 #endif
-	pr_warning("endianness mismatch.\n");
+	pr_warn("endianness mismatch.\n");
 	return -LIBBPF_ERRNO__ENDIAN;
 }
 
@@ -656,6 +657,21 @@ bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
 	return 0;
 }
 
+static int
+bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size)
+{
+	__u32 kver;
+
+	if (size != sizeof(kver)) {
+		pr_warn("invalid kver section in %s\n", obj->path);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	memcpy(&kver, data, sizeof(kver));
+	obj->kern_version = kver;
+	pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version);
+	return 0;
+}
+
 static int compare_bpf_map(const void *_a, const void *_b)
 {
 	const struct bpf_map *a = _a;
@@ -689,15 +705,15 @@ static int bpf_object_search_section_size(const struct bpf_object *obj,
 
 		idx++;
 		if (gelf_getshdr(scn, &sh) != &sh) {
-			pr_warning("failed to get section(%d) header from %s\n",
-				   idx, obj->path);
+			pr_warn("failed to get section(%d) header from %s\n",
+				idx, obj->path);
 			return -EIO;
 		}
 
 		sec_name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
 		if (!sec_name) {
-			pr_warning("failed to get section(%d) name from %s\n",
-				   idx, obj->path);
+			pr_warn("failed to get section(%d) name from %s\n",
+				idx, obj->path);
 			return -EIO;
 		}
 
@@ -706,8 +722,8 @@ static int bpf_object_search_section_size(const struct bpf_object *obj,
 
 		data = elf_getdata(scn, 0);
 		if (!data) {
-			pr_warning("failed to get section(%d) data from %s(%s)\n",
-				   idx, name, obj->path);
+			pr_warn("failed to get section(%d) data from %s(%s)\n",
+				idx, name, obj->path);
 			return -EIO;
 		}
 
@@ -767,8 +783,8 @@ int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
 		sname = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
 				   sym.st_name);
 		if (!sname) {
-			pr_warning("failed to get sym name string for var %s\n",
-				   name);
+			pr_warn("failed to get sym name string for var %s\n",
+				name);
 			return -EIO;
 		}
 		if (strcmp(name, sname) == 0) {
@@ -792,7 +808,7 @@ static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
 	new_cap = max((size_t)4, obj->maps_cap * 3 / 2);
 	new_maps = realloc(obj->maps, new_cap * sizeof(*obj->maps));
 	if (!new_maps) {
-		pr_warning("alloc maps for object failed\n");
+		pr_warn("alloc maps for object failed\n");
 		return ERR_PTR(-ENOMEM);
 	}
 
@@ -833,7 +849,7 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
 		 libbpf_type_to_btf_name[type]);
 	map->name = strdup(map_name);
 	if (!map->name) {
-		pr_warning("failed to alloc map name\n");
+		pr_warn("failed to alloc map name\n");
 		return -ENOMEM;
 	}
 	pr_debug("map '%s' (global data): at sec_idx %d, offset %zu.\n",
@@ -849,7 +865,7 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
 		*data_buff = malloc(data->d_size);
 		if (!*data_buff) {
 			zfree(&map->name);
-			pr_warning("failed to alloc map content buffer\n");
+			pr_warn("failed to alloc map content buffer\n");
 			return -ENOMEM;
 		}
 		memcpy(*data_buff, data->d_buf, data->d_size);
@@ -911,8 +927,8 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
 	if (scn)
 		data = elf_getdata(scn, NULL);
 	if (!scn || !data) {
-		pr_warning("failed to get Elf_Data from map section %d\n",
-			   obj->efile.maps_shndx);
+		pr_warn("failed to get Elf_Data from map section %d\n",
+			obj->efile.maps_shndx);
 		return -EINVAL;
 	}
 
@@ -939,9 +955,9 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
 
 	map_def_sz = data->d_size / nr_maps;
 	if (!data->d_size || (data->d_size % nr_maps) != 0) {
-		pr_warning("unable to determine map definition size "
-			   "section %s, %d maps in %zd bytes\n",
-			   obj->path, nr_maps, data->d_size);
+		pr_warn("unable to determine map definition size "
+			"section %s, %d maps in %zd bytes\n",
+			obj->path, nr_maps, data->d_size);
 		return -EINVAL;
 	}
 
@@ -964,8 +980,8 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
 		map_name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
 				      sym.st_name);
 		if (!map_name) {
-			pr_warning("failed to get map #%d name sym string for obj %s\n",
-				   i, obj->path);
+			pr_warn("failed to get map #%d name sym string for obj %s\n",
+				i, obj->path);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
@@ -975,14 +991,14 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
 		pr_debug("map '%s' (legacy): at sec_idx %d, offset %zu.\n",
 			 map_name, map->sec_idx, map->sec_offset);
 		if (sym.st_value + map_def_sz > data->d_size) {
-			pr_warning("corrupted maps section in %s: last map \"%s\" too small\n",
-				   obj->path, map_name);
+			pr_warn("corrupted maps section in %s: last map \"%s\" too small\n",
+				obj->path, map_name);
 			return -EINVAL;
 		}
 
 		map->name = strdup(map_name);
 		if (!map->name) {
-			pr_warning("failed to alloc map name\n");
+			pr_warn("failed to alloc map name\n");
 			return -ENOMEM;
 		}
 		pr_debug("map %d is \"%s\"\n", i, map->name);
@@ -1006,10 +1022,10 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
 			for (b = ((char *)def) + sizeof(struct bpf_map_def);
 			     b < ((char *)def) + map_def_sz; b++) {
 				if (*b != 0) {
-					pr_warning("maps section in %s: \"%s\" "
-						   "has unrecognized, non-zero "
-						   "options\n",
-						   obj->path, map_name);
+					pr_warn("maps section in %s: \"%s\" "
+						"has unrecognized, non-zero "
+						"options\n",
+						obj->path, map_name);
 					if (strict)
 						return -EINVAL;
 				}
@@ -1053,20 +1069,20 @@ static bool get_map_field_int(const char *map_name, const struct btf *btf,
 	const struct btf_type *arr_t;
 
 	if (!btf_is_ptr(t)) {
-		pr_warning("map '%s': attr '%s': expected PTR, got %u.\n",
-			   map_name, name, btf_kind(t));
+		pr_warn("map '%s': attr '%s': expected PTR, got %u.\n",
+			map_name, name, btf_kind(t));
 		return false;
 	}
 
 	arr_t = btf__type_by_id(btf, t->type);
 	if (!arr_t) {
-		pr_warning("map '%s': attr '%s': type [%u] not found.\n",
-			   map_name, name, t->type);
+		pr_warn("map '%s': attr '%s': type [%u] not found.\n",
+			map_name, name, t->type);
 		return false;
 	}
 	if (!btf_is_array(arr_t)) {
-		pr_warning("map '%s': attr '%s': expected ARRAY, got %u.\n",
-			   map_name, name, btf_kind(arr_t));
+		pr_warn("map '%s': attr '%s': expected ARRAY, got %u.\n",
+			map_name, name, btf_kind(arr_t));
 		return false;
 	}
 	arr_info = btf_array(arr_t);
@@ -1094,33 +1110,33 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 	vlen = btf_vlen(var);
 
 	if (map_name == NULL || map_name[0] == '\0') {
-		pr_warning("map #%d: empty name.\n", var_idx);
+		pr_warn("map #%d: empty name.\n", var_idx);
 		return -EINVAL;
 	}
 	if ((__u64)vi->offset + vi->size > data->d_size) {
-		pr_warning("map '%s' BTF data is corrupted.\n", map_name);
+		pr_warn("map '%s' BTF data is corrupted.\n", map_name);
 		return -EINVAL;
 	}
 	if (!btf_is_var(var)) {
-		pr_warning("map '%s': unexpected var kind %u.\n",
-			   map_name, btf_kind(var));
+		pr_warn("map '%s': unexpected var kind %u.\n",
+			map_name, btf_kind(var));
 		return -EINVAL;
 	}
 	if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED &&
 	    var_extra->linkage != BTF_VAR_STATIC) {
-		pr_warning("map '%s': unsupported var linkage %u.\n",
-			   map_name, var_extra->linkage);
+		pr_warn("map '%s': unsupported var linkage %u.\n",
+			map_name, var_extra->linkage);
 		return -EOPNOTSUPP;
 	}
 
 	def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
 	if (!btf_is_struct(def)) {
-		pr_warning("map '%s': unexpected def kind %u.\n",
-			   map_name, btf_kind(var));
+		pr_warn("map '%s': unexpected def kind %u.\n",
+			map_name, btf_kind(var));
 		return -EINVAL;
 	}
 	if (def->size > vi->size) {
-		pr_warning("map '%s': invalid def size.\n", map_name);
+		pr_warn("map '%s': invalid def size.\n", map_name);
 		return -EINVAL;
 	}
 
@@ -1129,7 +1145,7 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 		return PTR_ERR(map);
 	map->name = strdup(map_name);
 	if (!map->name) {
-		pr_warning("map '%s': failed to alloc map name.\n", map_name);
+		pr_warn("map '%s': failed to alloc map name.\n", map_name);
 		return -ENOMEM;
 	}
 	map->libbpf_type = LIBBPF_MAP_UNSPEC;
@@ -1145,8 +1161,7 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 		const char *name = btf__name_by_offset(obj->btf, m->name_off);
 
 		if (!name) {
-			pr_warning("map '%s': invalid field #%d.\n",
-				   map_name, i);
+			pr_warn("map '%s': invalid field #%d.\n", map_name, i);
 			return -EINVAL;
 		}
 		if (strcmp(name, "type") == 0) {
@@ -1176,8 +1191,8 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 			pr_debug("map '%s': found key_size = %u.\n",
 				 map_name, sz);
 			if (map->def.key_size && map->def.key_size != sz) {
-				pr_warning("map '%s': conflicting key size %u != %u.\n",
-					   map_name, map->def.key_size, sz);
+				pr_warn("map '%s': conflicting key size %u != %u.\n",
+					map_name, map->def.key_size, sz);
 				return -EINVAL;
 			}
 			map->def.key_size = sz;
@@ -1186,26 +1201,26 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 
 			t = btf__type_by_id(obj->btf, m->type);
 			if (!t) {
-				pr_warning("map '%s': key type [%d] not found.\n",
-					   map_name, m->type);
+				pr_warn("map '%s': key type [%d] not found.\n",
+					map_name, m->type);
 				return -EINVAL;
 			}
 			if (!btf_is_ptr(t)) {
-				pr_warning("map '%s': key spec is not PTR: %u.\n",
-					   map_name, btf_kind(t));
+				pr_warn("map '%s': key spec is not PTR: %u.\n",
+					map_name, btf_kind(t));
 				return -EINVAL;
 			}
 			sz = btf__resolve_size(obj->btf, t->type);
 			if (sz < 0) {
-				pr_warning("map '%s': can't determine key size for type [%u]: %lld.\n",
-					   map_name, t->type, sz);
+				pr_warn("map '%s': can't determine key size for type [%u]: %lld.\n",
+					map_name, t->type, sz);
 				return sz;
 			}
 			pr_debug("map '%s': found key [%u], sz = %lld.\n",
 				 map_name, t->type, sz);
 			if (map->def.key_size && map->def.key_size != sz) {
-				pr_warning("map '%s': conflicting key size %u != %lld.\n",
-					   map_name, map->def.key_size, sz);
+				pr_warn("map '%s': conflicting key size %u != %lld.\n",
+					map_name, map->def.key_size, sz);
 				return -EINVAL;
 			}
 			map->def.key_size = sz;
@@ -1219,8 +1234,8 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 			pr_debug("map '%s': found value_size = %u.\n",
 				 map_name, sz);
 			if (map->def.value_size && map->def.value_size != sz) {
-				pr_warning("map '%s': conflicting value size %u != %u.\n",
-					   map_name, map->def.value_size, sz);
+				pr_warn("map '%s': conflicting value size %u != %u.\n",
+					map_name, map->def.value_size, sz);
 				return -EINVAL;
 			}
 			map->def.value_size = sz;
@@ -1229,34 +1244,34 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 
 			t = btf__type_by_id(obj->btf, m->type);
 			if (!t) {
-				pr_warning("map '%s': value type [%d] not found.\n",
-					   map_name, m->type);
+				pr_warn("map '%s': value type [%d] not found.\n",
+					map_name, m->type);
 				return -EINVAL;
 			}
 			if (!btf_is_ptr(t)) {
-				pr_warning("map '%s': value spec is not PTR: %u.\n",
-					   map_name, btf_kind(t));
+				pr_warn("map '%s': value spec is not PTR: %u.\n",
+					map_name, btf_kind(t));
 				return -EINVAL;
 			}
 			sz = btf__resolve_size(obj->btf, t->type);
 			if (sz < 0) {
-				pr_warning("map '%s': can't determine value size for type [%u]: %lld.\n",
-					   map_name, t->type, sz);
+				pr_warn("map '%s': can't determine value size for type [%u]: %lld.\n",
+					map_name, t->type, sz);
 				return sz;
 			}
 			pr_debug("map '%s': found value [%u], sz = %lld.\n",
 				 map_name, t->type, sz);
 			if (map->def.value_size && map->def.value_size != sz) {
-				pr_warning("map '%s': conflicting value size %u != %lld.\n",
-					   map_name, map->def.value_size, sz);
+				pr_warn("map '%s': conflicting value size %u != %lld.\n",
+					map_name, map->def.value_size, sz);
 				return -EINVAL;
 			}
 			map->def.value_size = sz;
 			map->btf_value_type_id = t->type;
 		} else {
 			if (strict) {
-				pr_warning("map '%s': unknown field '%s'.\n",
-					   map_name, name);
+				pr_warn("map '%s': unknown field '%s'.\n",
+					map_name, name);
 				return -ENOTSUP;
 			}
 			pr_debug("map '%s': ignoring unknown field '%s'.\n",
@@ -1265,7 +1280,7 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 	}
 
 	if (map->def.type == BPF_MAP_TYPE_UNSPEC) {
-		pr_warning("map '%s': map type isn't specified.\n", map_name);
+		pr_warn("map '%s': map type isn't specified.\n", map_name);
 		return -EINVAL;
 	}
 
@@ -1288,8 +1303,8 @@ static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict)
 	if (scn)
 		data = elf_getdata(scn, NULL);
 	if (!scn || !data) {
-		pr_warning("failed to get Elf_Data from map section %d (%s)\n",
-			   obj->efile.maps_shndx, MAPS_ELF_SEC);
+		pr_warn("failed to get Elf_Data from map section %d (%s)\n",
+			obj->efile.maps_shndx, MAPS_ELF_SEC);
 		return -EINVAL;
 	}
 
@@ -1306,7 +1321,7 @@ static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict)
 	}
 
 	if (!sec) {
-		pr_warning("DATASEC '%s' not found.\n", MAPS_ELF_SEC);
+		pr_warn("DATASEC '%s' not found.\n", MAPS_ELF_SEC);
 		return -ENOENT;
 	}
 
@@ -1322,9 +1337,9 @@ static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict)
 	return 0;
 }
 
-static int bpf_object__init_maps(struct bpf_object *obj, int flags)
+static int bpf_object__init_maps(struct bpf_object *obj, bool relaxed_maps)
 {
-	bool strict = !(flags & MAPS_RELAX_COMPAT);
+	bool strict = !relaxed_maps;
 	int err;
 
 	err = bpf_object__init_user_maps(obj, strict);
@@ -1450,14 +1465,13 @@ static int bpf_object__init_btf(struct bpf_object *obj,
 	if (btf_data) {
 		obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
 		if (IS_ERR(obj->btf)) {
-			pr_warning("Error loading ELF section %s: %d.\n",
-				   BTF_ELF_SEC, err);
+			pr_warn("Error loading ELF section %s: %d.\n",
+				BTF_ELF_SEC, err);
 			goto out;
 		}
 		err = btf__finalize_data(obj, obj->btf);
 		if (err) {
-			pr_warning("Error finalizing %s: %d.\n",
-				   BTF_ELF_SEC, err);
+			pr_warn("Error finalizing %s: %d.\n", BTF_ELF_SEC, err);
 			goto out;
 		}
 	}
@@ -1470,8 +1484,8 @@ static int bpf_object__init_btf(struct bpf_object *obj,
 		obj->btf_ext = btf_ext__new(btf_ext_data->d_buf,
 					    btf_ext_data->d_size);
 		if (IS_ERR(obj->btf_ext)) {
-			pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
-				   BTF_EXT_ELF_SEC, PTR_ERR(obj->btf_ext));
+			pr_warn("Error loading ELF section %s: %ld. Ignored and continue.\n",
+				BTF_EXT_ELF_SEC, PTR_ERR(obj->btf_ext));
 			obj->btf_ext = NULL;
 			goto out;
 		}
@@ -1487,7 +1501,7 @@ out:
 		obj->btf = NULL;
 	}
 	if (btf_required && !obj->btf) {
-		pr_warning("BTF is required, but is missing or corrupted.\n");
+		pr_warn("BTF is required, but is missing or corrupted.\n");
 		return err == 0 ? -ENOENT : err;
 	}
 	return 0;
@@ -1505,8 +1519,8 @@ static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
 
 	err = btf__load(obj->btf);
 	if (err) {
-		pr_warning("Error loading %s into kernel: %d.\n",
-			   BTF_ELF_SEC, err);
+		pr_warn("Error loading %s into kernel: %d.\n",
+			BTF_ELF_SEC, err);
 		btf__free(obj->btf);
 		obj->btf = NULL;
 		/* btf_ext can't exist without btf, so free it as well */
@@ -1521,7 +1535,7 @@ static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
 	return 0;
 }
 
-static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
+static int bpf_object__elf_collect(struct bpf_object *obj, bool relaxed_maps)
 {
 	Elf *elf = obj->efile.elf;
 	GElf_Ehdr *ep = &obj->efile.ehdr;
@@ -1532,7 +1546,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 
 	/* Elf is corrupted/truncated, avoid calling elf_strptr. */
 	if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) {
-		pr_warning("failed to get e_shstrndx from %s\n", obj->path);
+		pr_warn("failed to get e_shstrndx from %s\n", obj->path);
 		return -LIBBPF_ERRNO__FORMAT;
 	}
 
@@ -1543,22 +1557,22 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 
 		idx++;
 		if (gelf_getshdr(scn, &sh) != &sh) {
-			pr_warning("failed to get section(%d) header from %s\n",
-				   idx, obj->path);
+			pr_warn("failed to get section(%d) header from %s\n",
+				idx, obj->path);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
 		name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
 		if (!name) {
-			pr_warning("failed to get section(%d) name from %s\n",
-				   idx, obj->path);
+			pr_warn("failed to get section(%d) name from %s\n",
+				idx, obj->path);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
 		data = elf_getdata(scn, 0);
 		if (!data) {
-			pr_warning("failed to get section(%d) data from %s(%s)\n",
-				   idx, name, obj->path);
+			pr_warn("failed to get section(%d) data from %s(%s)\n",
+				idx, name, obj->path);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 		pr_debug("section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
@@ -1573,7 +1587,11 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 			if (err)
 				return err;
 		} else if (strcmp(name, "version") == 0) {
-			/* skip, we don't need it anymore */
+			err = bpf_object__init_kversion(obj,
+							data->d_buf,
+							data->d_size);
+			if (err)
+				return err;
 		} else if (strcmp(name, "maps") == 0) {
 			obj->efile.maps_shndx = idx;
 		} else if (strcmp(name, MAPS_ELF_SEC) == 0) {
@@ -1584,8 +1602,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 			btf_ext_data = data;
 		} else if (sh.sh_type == SHT_SYMTAB) {
 			if (obj->efile.symbols) {
-				pr_warning("bpf: multiple SYMTAB in %s\n",
-					   obj->path);
+				pr_warn("bpf: multiple SYMTAB in %s\n",
+					obj->path);
 				return -LIBBPF_ERRNO__FORMAT;
 			}
 			obj->efile.symbols = data;
@@ -1601,8 +1619,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 					char *cp = libbpf_strerror_r(-err, errmsg,
 								     sizeof(errmsg));
 
-					pr_warning("failed to alloc program %s (%s): %s",
-						   name, obj->path, cp);
+					pr_warn("failed to alloc program %s (%s): %s",
+						name, obj->path, cp);
 					return err;
 				}
 			} else if (strcmp(name, ".data") == 0) {
@@ -1629,7 +1647,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 			reloc = reallocarray(reloc, nr_reloc + 1,
 					     sizeof(*obj->efile.reloc));
 			if (!reloc) {
-				pr_warning("realloc failed\n");
+				pr_warn("realloc failed\n");
 				return -ENOMEM;
 			}
 
@@ -1647,12 +1665,12 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 	}
 
 	if (!obj->efile.strtabidx || obj->efile.strtabidx >= idx) {
-		pr_warning("Corrupted ELF file: index of strtab invalid\n");
+		pr_warn("Corrupted ELF file: index of strtab invalid\n");
 		return -LIBBPF_ERRNO__FORMAT;
 	}
 	err = bpf_object__init_btf(obj, btf_data, btf_ext_data);
 	if (!err)
-		err = bpf_object__init_maps(obj, flags);
+		err = bpf_object__init_maps(obj, relaxed_maps);
 	if (!err)
 		err = bpf_object__sanitize_and_load_btf(obj);
 	if (!err)
@@ -1737,7 +1755,7 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 
 	prog->reloc_desc = malloc(sizeof(*prog->reloc_desc) * nrels);
 	if (!prog->reloc_desc) {
-		pr_warning("failed to alloc memory in relocation\n");
+		pr_warn("failed to alloc memory in relocation\n");
 		return -ENOMEM;
 	}
 	prog->nr_reloc = nrels;
@@ -1753,13 +1771,13 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 		GElf_Rel rel;
 
 		if (!gelf_getrel(data, i, &rel)) {
-			pr_warning("relocation: failed to get %d reloc\n", i);
+			pr_warn("relocation: failed to get %d reloc\n", i);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
 		if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) {
-			pr_warning("relocation: symbol %"PRIx64" not found\n",
-				   GELF_R_SYM(rel.r_info));
+			pr_warn("relocation: symbol %"PRIx64" not found\n",
+				GELF_R_SYM(rel.r_info));
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
@@ -1776,20 +1794,20 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 			 insn_idx, shdr_idx);
 
 		if (shdr_idx >= SHN_LORESERVE) {
-			pr_warning("relocation: not yet supported relo for non-static global \'%s\' variable in special section (0x%x) found in insns[%d].code 0x%x\n",
-				   name, shdr_idx, insn_idx,
-				   insns[insn_idx].code);
+			pr_warn("relocation: not yet supported relo for non-static global \'%s\' variable in special section (0x%x) found in insns[%d].code 0x%x\n",
+				name, shdr_idx, insn_idx,
+				insns[insn_idx].code);
 			return -LIBBPF_ERRNO__RELOC;
 		}
 		if (!bpf_object__relo_in_known_section(obj, shdr_idx)) {
-			pr_warning("Program '%s' contains unrecognized relo data pointing to section %u\n",
-				   prog->section_name, shdr_idx);
+			pr_warn("Program '%s' contains unrecognized relo data pointing to section %u\n",
+				prog->section_name, shdr_idx);
 			return -LIBBPF_ERRNO__RELOC;
 		}
 
 		if (insns[insn_idx].code == (BPF_JMP | BPF_CALL)) {
 			if (insns[insn_idx].src_reg != BPF_PSEUDO_CALL) {
-				pr_warning("incorrect bpf_call opcode\n");
+				pr_warn("incorrect bpf_call opcode\n");
 				return -LIBBPF_ERRNO__RELOC;
 			}
 			prog->reloc_desc[i].type = RELO_CALL;
@@ -1800,8 +1818,8 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 		}
 
 		if (insns[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
-			pr_warning("bpf: relocation: invalid relo for insns[%d].code 0x%x\n",
-				   insn_idx, insns[insn_idx].code);
+			pr_warn("bpf: relocation: invalid relo for insns[%d].code 0x%x\n",
+				insn_idx, insns[insn_idx].code);
 			return -LIBBPF_ERRNO__RELOC;
 		}
 
@@ -1810,13 +1828,13 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 			type = bpf_object__section_to_libbpf_map_type(obj, shdr_idx);
 			if (type != LIBBPF_MAP_UNSPEC) {
 				if (GELF_ST_BIND(sym.st_info) == STB_GLOBAL) {
-					pr_warning("bpf: relocation: not yet supported relo for non-static global \'%s\' variable found in insns[%d].code 0x%x\n",
-						   name, insn_idx, insns[insn_idx].code);
+					pr_warn("bpf: relocation: not yet supported relo for non-static global \'%s\' variable found in insns[%d].code 0x%x\n",
+						name, insn_idx, insns[insn_idx].code);
 					return -LIBBPF_ERRNO__RELOC;
 				}
 				if (!obj->caps.global_data) {
-					pr_warning("bpf: relocation: kernel does not support global \'%s\' variable access in insns[%d]\n",
-						   name, insn_idx);
+					pr_warn("bpf: relocation: kernel does not support global \'%s\' variable access in insns[%d]\n",
+						name, insn_idx);
 					return -LIBBPF_ERRNO__RELOC;
 				}
 			}
@@ -1837,8 +1855,8 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 			}
 
 			if (map_idx >= nr_maps) {
-				pr_warning("bpf relocation: map_idx %d larger than %d\n",
-					   (int)map_idx, (int)nr_maps - 1);
+				pr_warn("bpf relocation: map_idx %d larger than %d\n",
+					(int)map_idx, (int)nr_maps - 1);
 				return -LIBBPF_ERRNO__RELOC;
 			}
 
@@ -1965,8 +1983,8 @@ bpf_object__probe_name(struct bpf_object *obj)
 	ret = bpf_load_program_xattr(&attr, NULL, 0);
 	if (ret < 0) {
 		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
-		pr_warning("Error in %s():%s(%d). Couldn't load basic 'r0 = 0' BPF program.\n",
-			   __func__, cp, errno);
+		pr_warn("Error in %s():%s(%d). Couldn't load basic 'r0 = 0' BPF program.\n",
+			__func__, cp, errno);
 		return -errno;
 	}
 	close(ret);
@@ -2006,8 +2024,8 @@ bpf_object__probe_global_data(struct bpf_object *obj)
 	map = bpf_create_map_xattr(&map_attr);
 	if (map < 0) {
 		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
-		pr_warning("Error in %s():%s(%d). Couldn't create simple array map.\n",
-			   __func__, cp, errno);
+		pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
+			__func__, cp, errno);
 		return -errno;
 	}
 
@@ -2122,8 +2140,8 @@ bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
 		err = bpf_map_freeze(map->fd);
 		if (err) {
 			cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
-			pr_warning("Error freezing map(%s) as read-only: %s\n",
-				   map->name, cp);
+			pr_warn("Error freezing map(%s) as read-only: %s\n",
+				map->name, cp);
 			err = 0;
 		}
 	}
@@ -2162,8 +2180,8 @@ bpf_object__create_maps(struct bpf_object *obj)
 			if (!nr_cpus)
 				nr_cpus = libbpf_num_possible_cpus();
 			if (nr_cpus < 0) {
-				pr_warning("failed to determine number of system CPUs: %d\n",
-					   nr_cpus);
+				pr_warn("failed to determine number of system CPUs: %d\n",
+					nr_cpus);
 				err = nr_cpus;
 				goto err_out;
 			}
@@ -2191,8 +2209,8 @@ bpf_object__create_maps(struct bpf_object *obj)
 				 create_attr.btf_value_type_id)) {
 			err = -errno;
 			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
-			pr_warning("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
-				   map->name, cp, err);
+			pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
+				map->name, cp, err);
 			create_attr.btf_fd = 0;
 			create_attr.btf_key_type_id = 0;
 			create_attr.btf_value_type_id = 0;
@@ -2207,8 +2225,8 @@ bpf_object__create_maps(struct bpf_object *obj)
 			err = -errno;
 err_out:
 			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
-			pr_warning("failed to create map (name: '%s'): %s(%d)\n",
-				   map->name, cp, err);
+			pr_warn("failed to create map (name: '%s'): %s(%d)\n",
+				map->name, cp, err);
 			for (j = 0; j < i; j++)
 				zclose(obj->maps[j].fd);
 			return err;
@@ -2233,8 +2251,8 @@ check_btf_ext_reloc_err(struct bpf_program *prog, int err,
 			void *btf_prog_info, const char *info_name)
 {
 	if (err != -ENOENT) {
-		pr_warning("Error in loading %s for sec %s.\n",
-			   info_name, prog->section_name);
+		pr_warn("Error in loading %s for sec %s.\n",
+			info_name, prog->section_name);
 		return err;
 	}
 
@@ -2245,14 +2263,14 @@ check_btf_ext_reloc_err(struct bpf_program *prog, int err,
 		 * Some info has already been found but has problem
 		 * in the last btf_ext reloc. Must have to error out.
 		 */
-		pr_warning("Error in relocating %s for sec %s.\n",
-			   info_name, prog->section_name);
+		pr_warn("Error in relocating %s for sec %s.\n",
+			info_name, prog->section_name);
 		return err;
 	}
 
 	/* Have problem loading the very first info. Ignore the rest. */
-	pr_warning("Cannot find %s for main program sec %s. Ignore all %s.\n",
-		   info_name, prog->section_name, info_name);
+	pr_warn("Cannot find %s for main program sec %s. Ignore all %s.\n",
+		info_name, prog->section_name, info_name);
 	return 0;
 }
 
@@ -2326,7 +2344,7 @@ static bool str_is_empty(const char *s)
 }
 
 /*
- * Turn bpf_offset_reloc into a low- and high-level spec representation,
+ * Turn bpf_field_reloc into a low- and high-level spec representation,
  * validating correctness along the way, as well as calculating resulting
  * field offset (in bytes), specified by accessor string. Low-level spec
  * captures every single level of nestedness, including traversing anonymous
@@ -2453,8 +2471,8 @@ static int bpf_core_spec_parse(const struct btf *btf,
 				return sz;
 			spec->offset += access_idx * sz;
 		} else {
-			pr_warning("relo for [%u] %s (at idx %d) captures type [%d] of unexpected kind %d\n",
-				   type_id, spec_str, i, id, btf_kind(t));
+			pr_warn("relo for [%u] %s (at idx %d) captures type [%d] of unexpected kind %d\n",
+				type_id, spec_str, i, id, btf_kind(t));
 			return -EINVAL;
 		}
 	}
@@ -2598,8 +2616,8 @@ recur:
 		targ_id = btf_array(targ_type)->type;
 		goto recur;
 	default:
-		pr_warning("unexpected kind %d relocated, local [%d], target [%d]\n",
-			   btf_kind(local_type), local_id, targ_id);
+		pr_warn("unexpected kind %d relocated, local [%d], target [%d]\n",
+			btf_kind(local_type), local_id, targ_id);
 		return 0;
 	}
 }
@@ -2771,26 +2789,54 @@ static int bpf_core_spec_match(struct bpf_core_spec *local_spec,
 
 /*
  * Patch relocatable BPF instruction.
- * Expected insn->imm value is provided for validation, as well as the new
- * relocated value.
+ *
+ * Patched value is determined by relocation kind and target specification.
+ * For field existence relocation target spec will be NULL if field is not
+ * found.
+ * Expected insn->imm value is determined using relocation kind and local
+ * spec, and is checked before patching instruction. If actual insn->imm value
+ * is wrong, bail out with error.
  *
  * Currently three kinds of BPF instructions are supported:
  * 1. rX = <imm> (assignment with immediate operand);
  * 2. rX += <imm> (arithmetic operations with immediate operand);
- * 3. *(rX) = <imm> (indirect memory assignment with immediate operand).
- *
- * If actual insn->imm value is wrong, bail out.
  */
-static int bpf_core_reloc_insn(struct bpf_program *prog, int insn_off,
-			       __u32 orig_off, __u32 new_off)
+static int bpf_core_reloc_insn(struct bpf_program *prog,
+			       const struct bpf_field_reloc *relo,
+			       const struct bpf_core_spec *local_spec,
+			       const struct bpf_core_spec *targ_spec)
 {
+	__u32 orig_val, new_val;
 	struct bpf_insn *insn;
 	int insn_idx;
 	__u8 class;
 
-	if (insn_off % sizeof(struct bpf_insn))
+	if (relo->insn_off % sizeof(struct bpf_insn))
+		return -EINVAL;
+	insn_idx = relo->insn_off / sizeof(struct bpf_insn);
+
+	switch (relo->kind) {
+	case BPF_FIELD_BYTE_OFFSET:
+		orig_val = local_spec->offset;
+		if (targ_spec) {
+			new_val = targ_spec->offset;
+		} else {
+			pr_warn("prog '%s': patching insn #%d w/ failed reloc, imm %d -> %d\n",
+				bpf_program__title(prog, false), insn_idx,
+				orig_val, -1);
+			new_val = (__u32)-1;
+		}
+		break;
+	case BPF_FIELD_EXISTS:
+		orig_val = 1; /* can't generate EXISTS relo w/o local field */
+		new_val = targ_spec ? 1 : 0;
+		break;
+	default:
+		pr_warn("prog '%s': unknown relo %d at insn #%d'\n",
+			bpf_program__title(prog, false),
+			relo->kind, insn_idx);
 		return -EINVAL;
-	insn_idx = insn_off / sizeof(struct bpf_insn);
+	}
 
 	insn = &prog->insns[insn_idx];
 	class = BPF_CLASS(insn->code);
@@ -2798,19 +2844,20 @@ static int bpf_core_reloc_insn(struct bpf_program *prog, int insn_off,
 	if (class == BPF_ALU || class == BPF_ALU64) {
 		if (BPF_SRC(insn->code) != BPF_K)
 			return -EINVAL;
-		if (insn->imm != orig_off)
+		if (insn->imm != orig_val)
 			return -EINVAL;
-		insn->imm = new_off;
+		insn->imm = new_val;
 		pr_debug("prog '%s': patched insn #%d (ALU/ALU64) imm %d -> %d\n",
 			 bpf_program__title(prog, false),
-			 insn_idx, orig_off, new_off);
+			 insn_idx, orig_val, new_val);
 	} else {
-		pr_warning("prog '%s': trying to relocate unrecognized insn #%d, code:%x, src:%x, dst:%x, off:%x, imm:%x\n",
-			   bpf_program__title(prog, false),
-			   insn_idx, insn->code, insn->src_reg, insn->dst_reg,
-			   insn->off, insn->imm);
+		pr_warn("prog '%s': trying to relocate unrecognized insn #%d, code:%x, src:%x, dst:%x, off:%x, imm:%x\n",
+			bpf_program__title(prog, false),
+			insn_idx, insn->code, insn->src_reg, insn->dst_reg,
+			insn->off, insn->imm);
 		return -EINVAL;
 	}
+
 	return 0;
 }
 
@@ -2896,7 +2943,7 @@ static struct btf *bpf_core_find_kernel_btf(void)
 		return btf;
 	}
 
-	pr_warning("failed to find valid kernel BTF\n");
+	pr_warn("failed to find valid kernel BTF\n");
 	return ERR_PTR(-ESRCH);
 }
 
@@ -2977,7 +3024,7 @@ static void *u32_as_hash_key(__u32 x)
  *    types should be compatible (see bpf_core_fields_are_compat for details).
  * 3. It is supported and expected that there might be multiple flavors
  *    matching the spec. As long as all the specs resolve to the same set of
- *    offsets across all candidates, there is not error. If there is any
+ *    offsets across all candidates, there is no error. If there is any
  *    ambiguity, CO-RE relocation will fail. This is necessary to accomodate
  *    imprefection of BTF deduplication, which can cause slight duplication of
  *    the same BTF type, if some directly or indirectly referenced (by
@@ -2992,12 +3039,12 @@ static void *u32_as_hash_key(__u32 x)
  *    CPU-wise compared to prebuilding a map from all local type names to
  *    a list of candidate type names. It's also sped up by caching resolved
  *    list of matching candidates per each local "root" type ID, that has at
- *    least one bpf_offset_reloc associated with it. This list is shared
+ *    least one bpf_field_reloc associated with it. This list is shared
  *    between multiple relocations for the same type ID and is updated as some
  *    of the candidates are pruned due to structural incompatibility.
  */
-static int bpf_core_reloc_offset(struct bpf_program *prog,
-				 const struct bpf_offset_reloc *relo,
+static int bpf_core_reloc_field(struct bpf_program *prog,
+				 const struct bpf_field_reloc *relo,
 				 int relo_idx,
 				 const struct btf *local_btf,
 				 const struct btf *targ_btf,
@@ -3028,9 +3075,9 @@ static int bpf_core_reloc_offset(struct bpf_program *prog,
 
 	err = bpf_core_spec_parse(local_btf, local_id, spec_str, &local_spec);
 	if (err) {
-		pr_warning("prog '%s': relo #%d: parsing [%d] %s + %s failed: %d\n",
-			   prog_name, relo_idx, local_id, local_name, spec_str,
-			   err);
+		pr_warn("prog '%s': relo #%d: parsing [%d] %s + %s failed: %d\n",
+			prog_name, relo_idx, local_id, local_name, spec_str,
+			err);
 		return -EINVAL;
 	}
 
@@ -3041,9 +3088,9 @@ static int bpf_core_reloc_offset(struct bpf_program *prog,
 	if (!hashmap__find(cand_cache, type_key, (void **)&cand_ids)) {
 		cand_ids = bpf_core_find_cands(local_btf, local_id, targ_btf);
 		if (IS_ERR(cand_ids)) {
-			pr_warning("prog '%s': relo #%d: target candidate search failed for [%d] %s: %ld",
-				   prog_name, relo_idx, local_id, local_name,
-				   PTR_ERR(cand_ids));
+			pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s: %ld",
+				prog_name, relo_idx, local_id, local_name,
+				PTR_ERR(cand_ids));
 			return PTR_ERR(cand_ids);
 		}
 		err = hashmap__set(cand_cache, type_key, cand_ids, NULL, NULL);
@@ -3065,8 +3112,8 @@ static int bpf_core_reloc_offset(struct bpf_program *prog,
 		bpf_core_dump_spec(LIBBPF_DEBUG, &cand_spec);
 		libbpf_print(LIBBPF_DEBUG, ": %d\n", err);
 		if (err < 0) {
-			pr_warning("prog '%s': relo #%d: matching error: %d\n",
-				   prog_name, relo_idx, err);
+			pr_warn("prog '%s': relo #%d: matching error: %d\n",
+				prog_name, relo_idx, err);
 			return err;
 		}
 		if (err == 0)
@@ -3078,27 +3125,38 @@ static int bpf_core_reloc_offset(struct bpf_program *prog,
 			/* if there are many candidates, they should all
 			 * resolve to the same offset
 			 */
-			pr_warning("prog '%s': relo #%d: offset ambiguity: %u != %u\n",
-				   prog_name, relo_idx, cand_spec.offset,
-				   targ_spec.offset);
+			pr_warn("prog '%s': relo #%d: offset ambiguity: %u != %u\n",
+				prog_name, relo_idx, cand_spec.offset,
+				targ_spec.offset);
 			return -EINVAL;
 		}
 
 		cand_ids->data[j++] = cand_spec.spec[0].type_id;
 	}
 
-	cand_ids->len = j;
-	if (cand_ids->len == 0) {
-		pr_warning("prog '%s': relo #%d: no matching targets found for [%d] %s + %s\n",
-			   prog_name, relo_idx, local_id, local_name, spec_str);
+	/*
+	 * For BPF_FIELD_EXISTS relo or when relaxed CO-RE reloc mode is
+	 * requested, it's expected that we might not find any candidates.
+	 * In this case, if field wasn't found in any candidate, the list of
+	 * candidates shouldn't change at all, we'll just handle relocating
+	 * appropriately, depending on relo's kind.
+	 */
+	if (j > 0)
+		cand_ids->len = j;
+
+	if (j == 0 && !prog->obj->relaxed_core_relocs &&
+	    relo->kind != BPF_FIELD_EXISTS) {
+		pr_warn("prog '%s': relo #%d: no matching targets found for [%d] %s + %s\n",
+			prog_name, relo_idx, local_id, local_name, spec_str);
 		return -ESRCH;
 	}
 
-	err = bpf_core_reloc_insn(prog, relo->insn_off,
-				  local_spec.offset, targ_spec.offset);
+	/* bpf_core_reloc_insn should know how to handle missing targ_spec */
+	err = bpf_core_reloc_insn(prog, relo, &local_spec,
+				  j ? &targ_spec : NULL);
 	if (err) {
-		pr_warning("prog '%s': relo #%d: failed to patch insn at offset %d: %d\n",
-			   prog_name, relo_idx, relo->insn_off, err);
+		pr_warn("prog '%s': relo #%d: failed to patch insn at offset %d: %d\n",
+			prog_name, relo_idx, relo->insn_off, err);
 		return -EINVAL;
 	}
 
@@ -3106,10 +3164,10 @@ static int bpf_core_reloc_offset(struct bpf_program *prog,
 }
 
 static int
-bpf_core_reloc_offsets(struct bpf_object *obj, const char *targ_btf_path)
+bpf_core_reloc_fields(struct bpf_object *obj, const char *targ_btf_path)
 {
 	const struct btf_ext_info_sec *sec;
-	const struct bpf_offset_reloc *rec;
+	const struct bpf_field_reloc *rec;
 	const struct btf_ext_info *seg;
 	struct hashmap_entry *entry;
 	struct hashmap *cand_cache = NULL;
@@ -3123,8 +3181,7 @@ bpf_core_reloc_offsets(struct bpf_object *obj, const char *targ_btf_path)
 	else
 		targ_btf = bpf_core_find_kernel_btf();
 	if (IS_ERR(targ_btf)) {
-		pr_warning("failed to get target BTF: %ld\n",
-			   PTR_ERR(targ_btf));
+		pr_warn("failed to get target BTF: %ld\n", PTR_ERR(targ_btf));
 		return PTR_ERR(targ_btf);
 	}
 
@@ -3134,7 +3191,7 @@ bpf_core_reloc_offsets(struct bpf_object *obj, const char *targ_btf_path)
 		goto out;
 	}
 
-	seg = &obj->btf_ext->offset_reloc_info;
+	seg = &obj->btf_ext->field_reloc_info;
 	for_each_btf_ext_sec(seg, sec) {
 		sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
 		if (str_is_empty(sec_name)) {
@@ -3143,8 +3200,8 @@ bpf_core_reloc_offsets(struct bpf_object *obj, const char *targ_btf_path)
 		}
 		prog = bpf_object__find_program_by_title(obj, sec_name);
 		if (!prog) {
-			pr_warning("failed to find program '%s' for CO-RE offset relocation\n",
-				   sec_name);
+			pr_warn("failed to find program '%s' for CO-RE offset relocation\n",
+				sec_name);
 			err = -EINVAL;
 			goto out;
 		}
@@ -3153,11 +3210,11 @@ bpf_core_reloc_offsets(struct bpf_object *obj, const char *targ_btf_path)
 			 sec_name, sec->num_info);
 
 		for_each_btf_ext_rec(seg, sec, i, rec) {
-			err = bpf_core_reloc_offset(prog, rec, i, obj->btf,
-						    targ_btf, cand_cache);
+			err = bpf_core_reloc_field(prog, rec, i, obj->btf,
+						   targ_btf, cand_cache);
 			if (err) {
-				pr_warning("prog '%s': relo #%d: failed to relocate: %d\n",
-					   sec_name, i, err);
+				pr_warn("prog '%s': relo #%d: failed to relocate: %d\n",
+					sec_name, i, err);
 				goto out;
 			}
 		}
@@ -3179,8 +3236,8 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
 {
 	int err = 0;
 
-	if (obj->btf_ext->offset_reloc_info.len)
-		err = bpf_core_reloc_offsets(obj, targ_btf_path);
+	if (obj->btf_ext->field_reloc_info.len)
+		err = bpf_core_reloc_fields(obj, targ_btf_path);
 
 	return err;
 }
@@ -3198,21 +3255,21 @@ bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
 		return -LIBBPF_ERRNO__RELOC;
 
 	if (prog->idx == obj->efile.text_shndx) {
-		pr_warning("relo in .text insn %d into off %d\n",
-			   relo->insn_idx, relo->text_off);
+		pr_warn("relo in .text insn %d into off %d\n",
+			relo->insn_idx, relo->text_off);
 		return -LIBBPF_ERRNO__RELOC;
 	}
 
 	if (prog->main_prog_cnt == 0) {
 		text = bpf_object__find_prog_by_idx(obj, obj->efile.text_shndx);
 		if (!text) {
-			pr_warning("no .text section found yet relo into text exist\n");
+			pr_warn("no .text section found yet relo into text exist\n");
 			return -LIBBPF_ERRNO__RELOC;
 		}
 		new_cnt = prog->insns_cnt + text->insns_cnt;
 		new_insn = reallocarray(prog->insns, new_cnt, sizeof(*insn));
 		if (!new_insn) {
-			pr_warning("oom in prog realloc\n");
+			pr_warn("oom in prog realloc\n");
 			return -ENOMEM;
 		}
 
@@ -3267,8 +3324,8 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
 			map_idx = prog->reloc_desc[i].map_idx;
 
 			if (insn_idx + 1 >= (int)prog->insns_cnt) {
-				pr_warning("relocation out of range: '%s'\n",
-					   prog->section_name);
+				pr_warn("relocation out of range: '%s'\n",
+					prog->section_name);
 				return -LIBBPF_ERRNO__RELOC;
 			}
 
@@ -3302,8 +3359,8 @@ bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
 	if (obj->btf_ext) {
 		err = bpf_object__relocate_core(obj, targ_btf_path);
 		if (err) {
-			pr_warning("failed to perform CO-RE relocations: %d\n",
-				   err);
+			pr_warn("failed to perform CO-RE relocations: %d\n",
+				err);
 			return err;
 		}
 	}
@@ -3312,8 +3369,7 @@ bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
 
 		err = bpf_program__relocate(prog, obj);
 		if (err) {
-			pr_warning("failed to relocate '%s'\n",
-				   prog->section_name);
+			pr_warn("failed to relocate '%s'\n", prog->section_name);
 			return err;
 		}
 	}
@@ -3325,7 +3381,7 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
 	int i, err;
 
 	if (!obj_elf_valid(obj)) {
-		pr_warning("Internal error: elf object is closed\n");
+		pr_warn("Internal error: elf object is closed\n");
 		return -LIBBPF_ERRNO__INTERNAL;
 	}
 
@@ -3336,13 +3392,13 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
 		struct bpf_program *prog;
 
 		if (shdr->sh_type != SHT_REL) {
-			pr_warning("internal error at %d\n", __LINE__);
+			pr_warn("internal error at %d\n", __LINE__);
 			return -LIBBPF_ERRNO__INTERNAL;
 		}
 
 		prog = bpf_object__find_prog_by_idx(obj, idx);
 		if (!prog) {
-			pr_warning("relocation failed: no section(%d)\n", idx);
+			pr_warn("relocation failed: no section(%d)\n", idx);
 			return -LIBBPF_ERRNO__RELOC;
 		}
 
@@ -3394,7 +3450,7 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 retry_load:
 	log_buf = malloc(log_buf_size);
 	if (!log_buf)
-		pr_warning("Alloc log buffer for bpf loader error, continue without log\n");
+		pr_warn("Alloc log buffer for bpf loader error, continue without log\n");
 
 	ret = bpf_load_program_xattr(&load_attr, log_buf, log_buf_size);
 
@@ -3413,16 +3469,16 @@ retry_load:
 	}
 	ret = -LIBBPF_ERRNO__LOAD;
 	cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
-	pr_warning("load bpf program failed: %s\n", cp);
+	pr_warn("load bpf program failed: %s\n", cp);
 
 	if (log_buf && log_buf[0] != '\0') {
 		ret = -LIBBPF_ERRNO__VERIFY;
-		pr_warning("-- BEGIN DUMP LOG ---\n");
-		pr_warning("\n%s\n", log_buf);
-		pr_warning("-- END LOG --\n");
+		pr_warn("-- BEGIN DUMP LOG ---\n");
+		pr_warn("\n%s\n", log_buf);
+		pr_warn("-- END LOG --\n");
 	} else if (load_attr.insns_cnt >= BPF_MAXINSNS) {
-		pr_warning("Program too large (%zu insns), at most %d insns\n",
-			   load_attr.insns_cnt, BPF_MAXINSNS);
+		pr_warn("Program too large (%zu insns), at most %d insns\n",
+			load_attr.insns_cnt, BPF_MAXINSNS);
 		ret = -LIBBPF_ERRNO__PROG2BIG;
 	} else {
 		/* Wrong program type? */
@@ -3456,14 +3512,14 @@ bpf_program__load(struct bpf_program *prog,
 
 	if (prog->instances.nr < 0 || !prog->instances.fds) {
 		if (prog->preprocessor) {
-			pr_warning("Internal error: can't load program '%s'\n",
-				   prog->section_name);
+			pr_warn("Internal error: can't load program '%s'\n",
+				prog->section_name);
 			return -LIBBPF_ERRNO__INTERNAL;
 		}
 
 		prog->instances.fds = malloc(sizeof(int));
 		if (!prog->instances.fds) {
-			pr_warning("Not enough memory for BPF fds\n");
+			pr_warn("Not enough memory for BPF fds\n");
 			return -ENOMEM;
 		}
 		prog->instances.nr = 1;
@@ -3472,8 +3528,8 @@ bpf_program__load(struct bpf_program *prog,
 
 	if (!prog->preprocessor) {
 		if (prog->instances.nr != 1) {
-			pr_warning("Program '%s' is inconsistent: nr(%d) != 1\n",
-				   prog->section_name, prog->instances.nr);
+			pr_warn("Program '%s' is inconsistent: nr(%d) != 1\n",
+				prog->section_name, prog->instances.nr);
 		}
 		err = load_program(prog, prog->insns, prog->insns_cnt,
 				   license, kern_version, &fd);
@@ -3490,8 +3546,8 @@ bpf_program__load(struct bpf_program *prog,
 		err = preprocessor(prog, i, prog->insns,
 				   prog->insns_cnt, &result);
 		if (err) {
-			pr_warning("Preprocessing the %dth instance of program '%s' failed\n",
-				   i, prog->section_name);
+			pr_warn("Preprocessing the %dth instance of program '%s' failed\n",
+				i, prog->section_name);
 			goto out;
 		}
 
@@ -3509,8 +3565,8 @@ bpf_program__load(struct bpf_program *prog,
 				   license, kern_version, &fd);
 
 		if (err) {
-			pr_warning("Loading the %dth instance of program '%s' failed\n",
-					i, prog->section_name);
+			pr_warn("Loading the %dth instance of program '%s' failed\n",
+				i, prog->section_name);
 			goto out;
 		}
 
@@ -3520,8 +3576,7 @@ bpf_program__load(struct bpf_program *prog,
 	}
 out:
 	if (err)
-		pr_warning("failed to load program '%s'\n",
-			   prog->section_name);
+		pr_warn("failed to load program '%s'\n", prog->section_name);
 	zfree(&prog->insns);
 	prog->insns_cnt = 0;
 	return err;
@@ -3554,27 +3609,66 @@ bpf_object__load_progs(struct bpf_object *obj, int log_level)
 
 static struct bpf_object *
 __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
-		   const char *obj_name, int flags)
+		   struct bpf_object_open_opts *opts)
 {
+	struct bpf_program *prog;
 	struct bpf_object *obj;
+	const char *obj_name;
+	char tmp_name[64];
+	bool relaxed_maps;
 	int err;
 
 	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 ? : "(mem buf)");
 		return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
 	}
 
+	if (!OPTS_VALID(opts, bpf_object_open_opts))
+		return ERR_PTR(-EINVAL);
+
+	obj_name = OPTS_GET(opts, object_name, path);
+	if (obj_buf) {
+		if (!obj_name) {
+			snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
+				 (unsigned long)obj_buf,
+				 (unsigned long)obj_buf_sz);
+			obj_name = tmp_name;
+		}
+		path = obj_name;
+		pr_debug("loading object '%s' from buffer\n", obj_name);
+	}
+
 	obj = bpf_object__new(path, obj_buf, obj_buf_sz, obj_name);
 	if (IS_ERR(obj))
 		return obj;
 
+	obj->relaxed_core_relocs = OPTS_GET(opts, relaxed_core_relocs, false);
+	relaxed_maps = OPTS_GET(opts, relaxed_maps, false);
+
 	CHECK_ERR(bpf_object__elf_init(obj), err, out);
 	CHECK_ERR(bpf_object__check_endianness(obj), err, out);
 	CHECK_ERR(bpf_object__probe_caps(obj), err, out);
-	CHECK_ERR(bpf_object__elf_collect(obj, flags), err, out);
+	CHECK_ERR(bpf_object__elf_collect(obj, relaxed_maps), err, out);
 	CHECK_ERR(bpf_object__collect_reloc(obj), err, out);
-
 	bpf_object__elf_finish(obj);
+
+	bpf_object__for_each_program(prog, obj) {
+		enum bpf_prog_type prog_type;
+		enum bpf_attach_type attach_type;
+
+		err = libbpf_prog_type_by_name(prog->section_name, &prog_type,
+					       &attach_type);
+		if (err == -ESRCH)
+			/* couldn't guess, but user might manually specify */
+			continue;
+		if (err)
+			goto out;
+
+		bpf_program__set_type(prog, prog_type);
+		bpf_program__set_expected_attach_type(prog, attach_type);
+	}
+
 	return obj;
 out:
 	bpf_object__close(obj);
@@ -3584,13 +3678,16 @@ out:
 static struct bpf_object *
 __bpf_object__open_xattr(struct bpf_object_open_attr *attr, int flags)
 {
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
+		.relaxed_maps = flags & MAPS_RELAX_COMPAT,
+	);
+
 	/* param validation */
 	if (!attr->file)
 		return NULL;
 
 	pr_debug("loading %s\n", attr->file);
-
-	return __bpf_object__open(attr->file, NULL, 0, NULL, flags);
+	return __bpf_object__open(attr->file, NULL, 0, &opts);
 }
 
 struct bpf_object *bpf_object__open_xattr(struct bpf_object_open_attr *attr)
@@ -3611,54 +3708,29 @@ struct bpf_object *bpf_object__open(const char *path)
 struct bpf_object *
 bpf_object__open_file(const char *path, struct bpf_object_open_opts *opts)
 {
-	const char *obj_name;
-	bool relaxed_maps;
-
-	if (!OPTS_VALID(opts, bpf_object_open_opts))
-		return ERR_PTR(-EINVAL);
 	if (!path)
 		return ERR_PTR(-EINVAL);
 
 	pr_debug("loading %s\n", path);
 
-	obj_name = OPTS_GET(opts, object_name, path);
-	relaxed_maps = OPTS_GET(opts, relaxed_maps, false);
-	return __bpf_object__open(path, NULL, 0, obj_name,
-				  relaxed_maps ? MAPS_RELAX_COMPAT : 0);
+	return __bpf_object__open(path, NULL, 0, opts);
 }
 
 struct bpf_object *
 bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
 		     struct bpf_object_open_opts *opts)
 {
-	char tmp_name[64];
-	const char *obj_name;
-	bool relaxed_maps;
-
-	if (!OPTS_VALID(opts, bpf_object_open_opts))
-		return ERR_PTR(-EINVAL);
 	if (!obj_buf || obj_buf_sz == 0)
 		return ERR_PTR(-EINVAL);
 
-	obj_name = OPTS_GET(opts, object_name, NULL);
-	if (!obj_name) {
-		snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
-			 (unsigned long)obj_buf,
-			 (unsigned long)obj_buf_sz);
-		obj_name = tmp_name;
-	}
-	pr_debug("loading object '%s' from buffer\n", obj_name);
-
-	relaxed_maps = OPTS_GET(opts, relaxed_maps, false);
-	return __bpf_object__open(obj_name, obj_buf, obj_buf_sz, obj_name,
-				  relaxed_maps ? MAPS_RELAX_COMPAT : 0);
+	return __bpf_object__open(NULL, obj_buf, obj_buf_sz, opts);
 }
 
 struct bpf_object *
 bpf_object__open_buffer(const void *obj_buf, size_t obj_buf_sz,
 			const char *name)
 {
-	LIBBPF_OPTS(bpf_object_open_opts, opts,
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
 		.object_name = name,
 		/* wrong default, but backwards-compatible */
 		.relaxed_maps = true,
@@ -3699,7 +3771,7 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
 		return -EINVAL;
 
 	if (obj->loaded) {
-		pr_warning("object should not be loaded twice\n");
+		pr_warn("object should not be loaded twice\n");
 		return -EINVAL;
 	}
 
@@ -3712,7 +3784,7 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
 	return 0;
 out:
 	bpf_object__unload(obj);
-	pr_warning("failed to load object '%s'\n", obj->path);
+	pr_warn("failed to load object '%s'\n", obj->path);
 	return err;
 }
 
@@ -3742,13 +3814,13 @@ static int check_path(const char *path)
 	dir = dirname(dname);
 	if (statfs(dir, &st_fs)) {
 		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
-		pr_warning("failed to statfs %s: %s\n", dir, cp);
+		pr_warn("failed to statfs %s: %s\n", dir, cp);
 		err = -errno;
 	}
 	free(dname);
 
 	if (!err && st_fs.f_type != BPF_FS_MAGIC) {
-		pr_warning("specified path %s is not on BPF FS\n", path);
+		pr_warn("specified path %s is not on BPF FS\n", path);
 		err = -EINVAL;
 	}
 
@@ -3766,19 +3838,19 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path,
 		return err;
 
 	if (prog == NULL) {
-		pr_warning("invalid program pointer\n");
+		pr_warn("invalid program pointer\n");
 		return -EINVAL;
 	}
 
 	if (instance < 0 || instance >= prog->instances.nr) {
-		pr_warning("invalid prog instance %d of prog %s (max %d)\n",
-			   instance, prog->section_name, prog->instances.nr);
+		pr_warn("invalid prog instance %d of prog %s (max %d)\n",
+			instance, prog->section_name, prog->instances.nr);
 		return -EINVAL;
 	}
 
 	if (bpf_obj_pin(prog->instances.fds[instance], path)) {
 		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
-		pr_warning("failed to pin program: %s\n", cp);
+		pr_warn("failed to pin program: %s\n", cp);
 		return -errno;
 	}
 	pr_debug("pinned program '%s'\n", path);
@@ -3796,13 +3868,13 @@ int bpf_program__unpin_instance(struct bpf_program *prog, const char *path,
 		return err;
 
 	if (prog == NULL) {
-		pr_warning("invalid program pointer\n");
+		pr_warn("invalid program pointer\n");
 		return -EINVAL;
 	}
 
 	if (instance < 0 || instance >= prog->instances.nr) {
-		pr_warning("invalid prog instance %d of prog %s (max %d)\n",
-			   instance, prog->section_name, prog->instances.nr);
+		pr_warn("invalid prog instance %d of prog %s (max %d)\n",
+			instance, prog->section_name, prog->instances.nr);
 		return -EINVAL;
 	}
 
@@ -3824,7 +3896,7 @@ static int make_dir(const char *path)
 
 	if (err) {
 		cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
-		pr_warning("failed to mkdir %s: %s\n", path, cp);
+		pr_warn("failed to mkdir %s: %s\n", path, cp);
 	}
 	return err;
 }
@@ -3838,12 +3910,12 @@ int bpf_program__pin(struct bpf_program *prog, const char *path)
 		return err;
 
 	if (prog == NULL) {
-		pr_warning("invalid program pointer\n");
+		pr_warn("invalid program pointer\n");
 		return -EINVAL;
 	}
 
 	if (prog->instances.nr <= 0) {
-		pr_warning("no instances of prog %s to pin\n",
+		pr_warn("no instances of prog %s to pin\n",
 			   prog->section_name);
 		return -EINVAL;
 	}
@@ -3905,12 +3977,12 @@ int bpf_program__unpin(struct bpf_program *prog, const char *path)
 		return err;
 
 	if (prog == NULL) {
-		pr_warning("invalid program pointer\n");
+		pr_warn("invalid program pointer\n");
 		return -EINVAL;
 	}
 
 	if (prog->instances.nr <= 0) {
-		pr_warning("no instances of prog %s to pin\n",
+		pr_warn("no instances of prog %s to pin\n",
 			   prog->section_name);
 		return -EINVAL;
 	}
@@ -3952,13 +4024,13 @@ int bpf_map__pin(struct bpf_map *map, const char *path)
 		return err;
 
 	if (map == NULL) {
-		pr_warning("invalid map pointer\n");
+		pr_warn("invalid map pointer\n");
 		return -EINVAL;
 	}
 
 	if (bpf_obj_pin(map->fd, path)) {
 		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
-		pr_warning("failed to pin map: %s\n", cp);
+		pr_warn("failed to pin map: %s\n", cp);
 		return -errno;
 	}
 
@@ -3976,7 +4048,7 @@ int bpf_map__unpin(struct bpf_map *map, const char *path)
 		return err;
 
 	if (map == NULL) {
-		pr_warning("invalid map pointer\n");
+		pr_warn("invalid map pointer\n");
 		return -EINVAL;
 	}
 
@@ -3997,7 +4069,7 @@ int bpf_object__pin_maps(struct bpf_object *obj, const char *path)
 		return -ENOENT;
 
 	if (!obj->loaded) {
-		pr_warning("object not yet loaded; load it first\n");
+		pr_warn("object not yet loaded; load it first\n");
 		return -ENOENT;
 	}
 
@@ -4080,7 +4152,7 @@ int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
 		return -ENOENT;
 
 	if (!obj->loaded) {
-		pr_warning("object not yet loaded; load it first\n");
+		pr_warn("object not yet loaded; load it first\n");
 		return -ENOENT;
 	}
 
@@ -4281,7 +4353,7 @@ __bpf_program__iter(const struct bpf_program *p, const struct bpf_object *obj,
 			&obj->programs[nr_programs - 1];
 
 	if (p->obj != obj) {
-		pr_warning("error: program handler doesn't match object\n");
+		pr_warn("error: program handler doesn't match object\n");
 		return NULL;
 	}
 
@@ -4344,7 +4416,7 @@ const char *bpf_program__title(const struct bpf_program *prog, bool needs_copy)
 	if (needs_copy) {
 		title = strdup(title);
 		if (!title) {
-			pr_warning("failed to strdup program title\n");
+			pr_warn("failed to strdup program title\n");
 			return ERR_PTR(-ENOMEM);
 		}
 	}
@@ -4366,13 +4438,13 @@ int bpf_program__set_prep(struct bpf_program *prog, int nr_instances,
 		return -EINVAL;
 
 	if (prog->instances.nr > 0 || prog->instances.fds) {
-		pr_warning("Can't set pre-processor after loading\n");
+		pr_warn("Can't set pre-processor after loading\n");
 		return -EINVAL;
 	}
 
 	instances_fds = malloc(sizeof(int) * nr_instances);
 	if (!instances_fds) {
-		pr_warning("alloc memory failed for fds\n");
+		pr_warn("alloc memory failed for fds\n");
 		return -ENOMEM;
 	}
 
@@ -4393,21 +4465,26 @@ int bpf_program__nth_fd(const struct bpf_program *prog, int n)
 		return -EINVAL;
 
 	if (n >= prog->instances.nr || n < 0) {
-		pr_warning("Can't get the %dth fd from program %s: only %d instances\n",
-			   n, prog->section_name, prog->instances.nr);
+		pr_warn("Can't get the %dth fd from program %s: only %d instances\n",
+			n, prog->section_name, prog->instances.nr);
 		return -EINVAL;
 	}
 
 	fd = prog->instances.fds[n];
 	if (fd < 0) {
-		pr_warning("%dth instance of program '%s' is invalid\n",
-			   n, prog->section_name);
+		pr_warn("%dth instance of program '%s' is invalid\n",
+			n, prog->section_name);
 		return -ENOENT;
 	}
 
 	return fd;
 }
 
+enum bpf_prog_type bpf_program__get_type(struct bpf_program *prog)
+{
+	return prog->type;
+}
+
 void bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
 {
 	prog->type = type;
@@ -4442,25 +4519,34 @@ BPF_PROG_TYPE_FNS(raw_tracepoint, BPF_PROG_TYPE_RAW_TRACEPOINT);
 BPF_PROG_TYPE_FNS(xdp, BPF_PROG_TYPE_XDP);
 BPF_PROG_TYPE_FNS(perf_event, BPF_PROG_TYPE_PERF_EVENT);
 
+enum bpf_attach_type
+bpf_program__get_expected_attach_type(struct bpf_program *prog)
+{
+	return prog->expected_attach_type;
+}
+
 void bpf_program__set_expected_attach_type(struct bpf_program *prog,
 					   enum bpf_attach_type type)
 {
 	prog->expected_attach_type = type;
 }
 
-#define BPF_PROG_SEC_IMPL(string, ptype, eatype, is_attachable, atype) \
-	{ string, sizeof(string) - 1, ptype, eatype, is_attachable, atype }
+#define BPF_PROG_SEC_IMPL(string, ptype, eatype, is_attachable, btf, atype) \
+	{ string, sizeof(string) - 1, ptype, eatype, is_attachable, btf, atype }
 
 /* Programs that can NOT be attached. */
-#define BPF_PROG_SEC(string, ptype) BPF_PROG_SEC_IMPL(string, ptype, 0, 0, 0)
+#define BPF_PROG_SEC(string, ptype) BPF_PROG_SEC_IMPL(string, ptype, 0, 0, 0, 0)
 
 /* Programs that can be attached. */
 #define BPF_APROG_SEC(string, ptype, atype) \
-	BPF_PROG_SEC_IMPL(string, ptype, 0, 1, atype)
+	BPF_PROG_SEC_IMPL(string, ptype, 0, 1, 0, atype)
 
 /* Programs that must specify expected attach type at load time. */
 #define BPF_EAPROG_SEC(string, ptype, eatype) \
-	BPF_PROG_SEC_IMPL(string, ptype, eatype, 1, eatype)
+	BPF_PROG_SEC_IMPL(string, ptype, eatype, 1, 0, eatype)
+
+/* Programs that use BTF to identify attach point */
+#define BPF_PROG_BTF(string, ptype) BPF_PROG_SEC_IMPL(string, ptype, 0, 0, 1, 0)
 
 /* Programs that can be attached but attach type can't be identified by section
  * name. Kept for backward compatibility.
@@ -4472,16 +4558,22 @@ static const struct {
 	size_t len;
 	enum bpf_prog_type prog_type;
 	enum bpf_attach_type expected_attach_type;
-	int is_attachable;
+	bool is_attachable;
+	bool is_attach_btf;
 	enum bpf_attach_type attach_type;
 } section_names[] = {
 	BPF_PROG_SEC("socket",			BPF_PROG_TYPE_SOCKET_FILTER),
 	BPF_PROG_SEC("kprobe/",			BPF_PROG_TYPE_KPROBE),
+	BPF_PROG_SEC("uprobe/",			BPF_PROG_TYPE_KPROBE),
 	BPF_PROG_SEC("kretprobe/",		BPF_PROG_TYPE_KPROBE),
+	BPF_PROG_SEC("uretprobe/",		BPF_PROG_TYPE_KPROBE),
 	BPF_PROG_SEC("classifier",		BPF_PROG_TYPE_SCHED_CLS),
 	BPF_PROG_SEC("action",			BPF_PROG_TYPE_SCHED_ACT),
 	BPF_PROG_SEC("tracepoint/",		BPF_PROG_TYPE_TRACEPOINT),
+	BPF_PROG_SEC("tp/",			BPF_PROG_TYPE_TRACEPOINT),
 	BPF_PROG_SEC("raw_tracepoint/",		BPF_PROG_TYPE_RAW_TRACEPOINT),
+	BPF_PROG_SEC("raw_tp/",			BPF_PROG_TYPE_RAW_TRACEPOINT),
+	BPF_PROG_BTF("tp_btf/",			BPF_PROG_TYPE_RAW_TRACEPOINT),
 	BPF_PROG_SEC("xdp",			BPF_PROG_TYPE_XDP),
 	BPF_PROG_SEC("perf_event",		BPF_PROG_TYPE_PERF_EVENT),
 	BPF_PROG_SEC("lwt_in",			BPF_PROG_TYPE_LWT_IN),
@@ -4586,16 +4678,37 @@ int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
 			continue;
 		*prog_type = section_names[i].prog_type;
 		*expected_attach_type = section_names[i].expected_attach_type;
+		if (section_names[i].is_attach_btf) {
+			struct btf *btf = bpf_core_find_kernel_btf();
+			char raw_tp_btf_name[128] = "btf_trace_";
+			char *dst = raw_tp_btf_name + sizeof("btf_trace_") - 1;
+			int ret;
+
+			if (IS_ERR(btf)) {
+				pr_warn("vmlinux BTF is not found\n");
+				return -EINVAL;
+			}
+			/* prepend "btf_trace_" prefix per kernel convention */
+			strncat(dst, name + section_names[i].len,
+				sizeof(raw_tp_btf_name) - sizeof("btf_trace_"));
+			ret = btf__find_by_name(btf, raw_tp_btf_name);
+			btf__free(btf);
+			if (ret <= 0) {
+				pr_warn("%s is not found in vmlinux BTF\n", dst);
+				return -EINVAL;
+			}
+			*expected_attach_type = ret;
+		}
 		return 0;
 	}
-	pr_warning("failed to guess program type based on ELF section name '%s'\n", name);
+	pr_warn("failed to guess program type based on ELF section name '%s'\n", name);
 	type_names = libbpf_get_type_names(false);
 	if (type_names != NULL) {
 		pr_info("supported section(type) names are:%s\n", type_names);
 		free(type_names);
 	}
 
-	return -EINVAL;
+	return -ESRCH;
 }
 
 int libbpf_attach_type_by_name(const char *name,
@@ -4615,7 +4728,7 @@ int libbpf_attach_type_by_name(const char *name,
 		*attach_type = section_names[i].attach_type;
 		return 0;
 	}
-	pr_warning("failed to guess attach type based on ELF section name '%s'\n", name);
+	pr_warn("failed to guess attach type based on ELF section name '%s'\n", name);
 	type_names = libbpf_get_type_names(true);
 	if (type_names != NULL) {
 		pr_info("attachable section(type) names are:%s\n", type_names);
@@ -4625,15 +4738,6 @@ int libbpf_attach_type_by_name(const char *name,
 	return -EINVAL;
 }
 
-static int
-bpf_program__identify_section(struct bpf_program *prog,
-			      enum bpf_prog_type *prog_type,
-			      enum bpf_attach_type *expected_attach_type)
-{
-	return libbpf_prog_type_by_name(prog->section_name, prog_type,
-					expected_attach_type);
-}
-
 int bpf_map__fd(const struct bpf_map *map)
 {
 	return map ? map->fd : -EINVAL;
@@ -4698,11 +4802,11 @@ void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
 int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)
 {
 	if (!bpf_map_type__is_map_in_map(map->def.type)) {
-		pr_warning("error: unsupported map type\n");
+		pr_warn("error: unsupported map type\n");
 		return -EINVAL;
 	}
 	if (map->inner_map_fd != -1) {
-		pr_warning("error: inner_map_fd already specified\n");
+		pr_warn("error: inner_map_fd already specified\n");
 		return -EINVAL;
 	}
 	map->inner_map_fd = fd;
@@ -4722,8 +4826,8 @@ __bpf_map__iter(const struct bpf_map *m, const struct bpf_object *obj, int i)
 	e = obj->maps + obj->nr_maps;
 
 	if ((m < s) || (m >= e)) {
-		pr_warning("error in %s: map handler doesn't belong to object\n",
-			   __func__);
+		pr_warn("error in %s: map handler doesn't belong to object\n",
+			 __func__);
 		return NULL;
 	}
 
@@ -4801,8 +4905,6 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 {
 	struct bpf_object_open_attr open_attr = {};
 	struct bpf_program *prog, *first_prog = NULL;
-	enum bpf_attach_type expected_attach_type;
-	enum bpf_prog_type prog_type;
 	struct bpf_object *obj;
 	struct bpf_map *map;
 	int err;
@@ -4820,26 +4922,27 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 		return -ENOENT;
 
 	bpf_object__for_each_program(prog, obj) {
+		enum bpf_attach_type attach_type = attr->expected_attach_type;
 		/*
-		 * If type is not specified, try to guess it based on
-		 * section name.
+		 * to preserve backwards compatibility, bpf_prog_load treats
+		 * attr->prog_type, if specified, as an override to whatever
+		 * bpf_object__open guessed
 		 */
-		prog_type = attr->prog_type;
-		prog->prog_ifindex = attr->ifindex;
-		expected_attach_type = attr->expected_attach_type;
-		if (prog_type == BPF_PROG_TYPE_UNSPEC) {
-			err = bpf_program__identify_section(prog, &prog_type,
-							    &expected_attach_type);
-			if (err < 0) {
-				bpf_object__close(obj);
-				return -EINVAL;
-			}
+		if (attr->prog_type != BPF_PROG_TYPE_UNSPEC) {
+			bpf_program__set_type(prog, attr->prog_type);
+			bpf_program__set_expected_attach_type(prog,
+							      attach_type);
+		}
+		if (bpf_program__get_type(prog) == BPF_PROG_TYPE_UNSPEC) {
+			/*
+			 * we haven't guessed from section name and user
+			 * didn't provide a fallback type, too bad...
+			 */
+			bpf_object__close(obj);
+			return -EINVAL;
 		}
 
-		bpf_program__set_type(prog, prog_type);
-		bpf_program__set_expected_attach_type(prog,
-						      expected_attach_type);
-
+		prog->prog_ifindex = attr->ifindex;
 		prog->log_level = attr->log_level;
 		prog->prog_flags = attr->prog_flags;
 		if (!first_prog)
@@ -4852,7 +4955,7 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 	}
 
 	if (!first_prog) {
-		pr_warning("object file doesn't contain bpf program\n");
+		pr_warn("object file doesn't contain bpf program\n");
 		bpf_object__close(obj);
 		return -ENOENT;
 	}
@@ -4911,14 +5014,14 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
 	int prog_fd, err;
 
 	if (pfd < 0) {
-		pr_warning("program '%s': invalid perf event FD %d\n",
-			   bpf_program__title(prog, false), pfd);
+		pr_warn("program '%s': invalid perf event FD %d\n",
+			bpf_program__title(prog, false), pfd);
 		return ERR_PTR(-EINVAL);
 	}
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
-		pr_warning("program '%s': can't attach BPF program w/o FD (did you load it?)\n",
-			   bpf_program__title(prog, false));
+		pr_warn("program '%s': can't attach BPF program w/o FD (did you load it?)\n",
+			bpf_program__title(prog, false));
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -4931,16 +5034,16 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
 	if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
 		err = -errno;
 		free(link);
-		pr_warning("program '%s': failed to attach to pfd %d: %s\n",
-			   bpf_program__title(prog, false), pfd,
+		pr_warn("program '%s': failed to attach to pfd %d: %s\n",
+			bpf_program__title(prog, false), pfd,
 			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return ERR_PTR(err);
 	}
 	if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
 		err = -errno;
 		free(link);
-		pr_warning("program '%s': failed to enable pfd %d: %s\n",
-			   bpf_program__title(prog, false), pfd,
+		pr_warn("program '%s': failed to enable pfd %d: %s\n",
+			bpf_program__title(prog, false), pfd,
 			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return ERR_PTR(err);
 	}
@@ -5015,9 +5118,9 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
 	type = uprobe ? determine_uprobe_perf_type()
 		      : determine_kprobe_perf_type();
 	if (type < 0) {
-		pr_warning("failed to determine %s perf type: %s\n",
-			   uprobe ? "uprobe" : "kprobe",
-			   libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
+		pr_warn("failed to determine %s perf type: %s\n",
+			uprobe ? "uprobe" : "kprobe",
+			libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
 		return type;
 	}
 	if (retprobe) {
@@ -5025,10 +5128,9 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
 				 : determine_kprobe_retprobe_bit();
 
 		if (bit < 0) {
-			pr_warning("failed to determine %s retprobe bit: %s\n",
-				   uprobe ? "uprobe" : "kprobe",
-				   libbpf_strerror_r(bit, errmsg,
-						     sizeof(errmsg)));
+			pr_warn("failed to determine %s retprobe bit: %s\n",
+				uprobe ? "uprobe" : "kprobe",
+				libbpf_strerror_r(bit, errmsg, sizeof(errmsg)));
 			return bit;
 		}
 		attr.config |= 1 << bit;
@@ -5045,9 +5147,9 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
 		      -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
 	if (pfd < 0) {
 		err = -errno;
-		pr_warning("%s perf_event_open() failed: %s\n",
-			   uprobe ? "uprobe" : "kprobe",
-			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		pr_warn("%s perf_event_open() failed: %s\n",
+			uprobe ? "uprobe" : "kprobe",
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return err;
 	}
 	return pfd;
@@ -5064,20 +5166,20 @@ struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog,
 	pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,
 				    0 /* offset */, -1 /* pid */);
 	if (pfd < 0) {
-		pr_warning("program '%s': failed to create %s '%s' perf event: %s\n",
-			   bpf_program__title(prog, false),
-			   retprobe ? "kretprobe" : "kprobe", func_name,
-			   libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		pr_warn("program '%s': failed to create %s '%s' perf event: %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "kretprobe" : "kprobe", func_name,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return ERR_PTR(pfd);
 	}
 	link = bpf_program__attach_perf_event(prog, pfd);
 	if (IS_ERR(link)) {
 		close(pfd);
 		err = PTR_ERR(link);
-		pr_warning("program '%s': failed to attach to %s '%s': %s\n",
-			   bpf_program__title(prog, false),
-			   retprobe ? "kretprobe" : "kprobe", func_name,
-			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		pr_warn("program '%s': failed to attach to %s '%s': %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "kretprobe" : "kprobe", func_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return link;
 	}
 	return link;
@@ -5095,22 +5197,22 @@ struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
 	pfd = perf_event_open_probe(true /* uprobe */, retprobe,
 				    binary_path, func_offset, pid);
 	if (pfd < 0) {
-		pr_warning("program '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
-			   bpf_program__title(prog, false),
-			   retprobe ? "uretprobe" : "uprobe",
-			   binary_path, func_offset,
-			   libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		pr_warn("program '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "uretprobe" : "uprobe",
+			binary_path, func_offset,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return ERR_PTR(pfd);
 	}
 	link = bpf_program__attach_perf_event(prog, pfd);
 	if (IS_ERR(link)) {
 		close(pfd);
 		err = PTR_ERR(link);
-		pr_warning("program '%s': failed to attach to %s '%s:0x%zx': %s\n",
-			   bpf_program__title(prog, false),
-			   retprobe ? "uretprobe" : "uprobe",
-			   binary_path, func_offset,
-			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		pr_warn("program '%s': failed to attach to %s '%s:0x%zx': %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "uretprobe" : "uprobe",
+			binary_path, func_offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return link;
 	}
 	return link;
@@ -5144,9 +5246,9 @@ static int perf_event_open_tracepoint(const char *tp_category,
 
 	tp_id = determine_tracepoint_id(tp_category, tp_name);
 	if (tp_id < 0) {
-		pr_warning("failed to determine tracepoint '%s/%s' perf event ID: %s\n",
-			   tp_category, tp_name,
-			   libbpf_strerror_r(tp_id, errmsg, sizeof(errmsg)));
+		pr_warn("failed to determine tracepoint '%s/%s' perf event ID: %s\n",
+			tp_category, tp_name,
+			libbpf_strerror_r(tp_id, errmsg, sizeof(errmsg)));
 		return tp_id;
 	}
 
@@ -5158,9 +5260,9 @@ static int perf_event_open_tracepoint(const char *tp_category,
 		      -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
 	if (pfd < 0) {
 		err = -errno;
-		pr_warning("tracepoint '%s/%s' perf_event_open() failed: %s\n",
-			   tp_category, tp_name,
-			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		pr_warn("tracepoint '%s/%s' perf_event_open() failed: %s\n",
+			tp_category, tp_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return err;
 	}
 	return pfd;
@@ -5176,20 +5278,20 @@ struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
 
 	pfd = perf_event_open_tracepoint(tp_category, tp_name);
 	if (pfd < 0) {
-		pr_warning("program '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
-			   bpf_program__title(prog, false),
-			   tp_category, tp_name,
-			   libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		pr_warn("program '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
+			bpf_program__title(prog, false),
+			tp_category, tp_name,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return ERR_PTR(pfd);
 	}
 	link = bpf_program__attach_perf_event(prog, pfd);
 	if (IS_ERR(link)) {
 		close(pfd);
 		err = PTR_ERR(link);
-		pr_warning("program '%s': failed to attach to tracepoint '%s/%s': %s\n",
-			   bpf_program__title(prog, false),
-			   tp_category, tp_name,
-			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		pr_warn("program '%s': failed to attach to tracepoint '%s/%s': %s\n",
+			bpf_program__title(prog, false),
+			tp_category, tp_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return link;
 	}
 	return link;
@@ -5211,8 +5313,8 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
 
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
-		pr_warning("program '%s': can't attach before loaded\n",
-			   bpf_program__title(prog, false));
+		pr_warn("program '%s': can't attach before loaded\n",
+			bpf_program__title(prog, false));
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -5225,9 +5327,9 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
 	if (pfd < 0) {
 		pfd = -errno;
 		free(link);
-		pr_warning("program '%s': failed to attach to raw tracepoint '%s': %s\n",
-			   bpf_program__title(prog, false), tp_name,
-			   libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		pr_warn("program '%s': failed to attach to raw tracepoint '%s': %s\n",
+			bpf_program__title(prog, false), tp_name,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return ERR_PTR(pfd);
 	}
 	link->fd = pfd;
@@ -5329,7 +5431,7 @@ static void perf_buffer__free_cpu_buf(struct perf_buffer *pb,
 		return;
 	if (cpu_buf->base &&
 	    munmap(cpu_buf->base, pb->mmap_size + pb->page_size))
-		pr_warning("failed to munmap cpu_buf #%d\n", cpu_buf->cpu);
+		pr_warn("failed to munmap cpu_buf #%d\n", cpu_buf->cpu);
 	if (cpu_buf->fd >= 0) {
 		ioctl(cpu_buf->fd, PERF_EVENT_IOC_DISABLE, 0);
 		close(cpu_buf->fd);
@@ -5379,8 +5481,8 @@ perf_buffer__open_cpu_buf(struct perf_buffer *pb, struct perf_event_attr *attr,
 			      -1, PERF_FLAG_FD_CLOEXEC);
 	if (cpu_buf->fd < 0) {
 		err = -errno;
-		pr_warning("failed to open perf buffer event on cpu #%d: %s\n",
-			   cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		pr_warn("failed to open perf buffer event on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
 		goto error;
 	}
 
@@ -5390,15 +5492,15 @@ perf_buffer__open_cpu_buf(struct perf_buffer *pb, struct perf_event_attr *attr,
 	if (cpu_buf->base == MAP_FAILED) {
 		cpu_buf->base = NULL;
 		err = -errno;
-		pr_warning("failed to mmap perf buffer on cpu #%d: %s\n",
-			   cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		pr_warn("failed to mmap perf buffer on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
 		goto error;
 	}
 
 	if (ioctl(cpu_buf->fd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
 		err = -errno;
-		pr_warning("failed to enable perf buffer event on cpu #%d: %s\n",
-			   cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		pr_warn("failed to enable perf buffer event on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
 		goto error;
 	}
 
@@ -5458,8 +5560,8 @@ static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
 	int err, i;
 
 	if (page_cnt & (page_cnt - 1)) {
-		pr_warning("page count should be power of two, but is %zu\n",
-			   page_cnt);
+		pr_warn("page count should be power of two, but is %zu\n",
+			page_cnt);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -5467,14 +5569,14 @@ static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
 	err = bpf_obj_get_info_by_fd(map_fd, &map, &map_info_len);
 	if (err) {
 		err = -errno;
-		pr_warning("failed to get map info for map FD %d: %s\n",
-			   map_fd, libbpf_strerror_r(err, msg, sizeof(msg)));
+		pr_warn("failed to get map info for map FD %d: %s\n",
+			map_fd, libbpf_strerror_r(err, msg, sizeof(msg)));
 		return ERR_PTR(err);
 	}
 
 	if (map.type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) {
-		pr_warning("map '%s' should be BPF_MAP_TYPE_PERF_EVENT_ARRAY\n",
-			   map.name);
+		pr_warn("map '%s' should be BPF_MAP_TYPE_PERF_EVENT_ARRAY\n",
+			map.name);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -5494,8 +5596,8 @@ static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
 	pb->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
 	if (pb->epoll_fd < 0) {
 		err = -errno;
-		pr_warning("failed to create epoll instance: %s\n",
-			   libbpf_strerror_r(err, msg, sizeof(msg)));
+		pr_warn("failed to create epoll instance: %s\n",
+			libbpf_strerror_r(err, msg, sizeof(msg)));
 		goto error;
 	}
 
@@ -5514,13 +5616,13 @@ static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
 	pb->events = calloc(pb->cpu_cnt, sizeof(*pb->events));
 	if (!pb->events) {
 		err = -ENOMEM;
-		pr_warning("failed to allocate events: out of memory\n");
+		pr_warn("failed to allocate events: out of memory\n");
 		goto error;
 	}
 	pb->cpu_bufs = calloc(pb->cpu_cnt, sizeof(*pb->cpu_bufs));
 	if (!pb->cpu_bufs) {
 		err = -ENOMEM;
-		pr_warning("failed to allocate buffers: out of memory\n");
+		pr_warn("failed to allocate buffers: out of memory\n");
 		goto error;
 	}
 
@@ -5543,9 +5645,9 @@ static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
 					  &cpu_buf->fd, 0);
 		if (err) {
 			err = -errno;
-			pr_warning("failed to set cpu #%d, key %d -> perf FD %d: %s\n",
-				   cpu, map_key, cpu_buf->fd,
-				   libbpf_strerror_r(err, msg, sizeof(msg)));
+			pr_warn("failed to set cpu #%d, key %d -> perf FD %d: %s\n",
+				cpu, map_key, cpu_buf->fd,
+				libbpf_strerror_r(err, msg, sizeof(msg)));
 			goto error;
 		}
 
@@ -5554,9 +5656,9 @@ static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
 		if (epoll_ctl(pb->epoll_fd, EPOLL_CTL_ADD, cpu_buf->fd,
 			      &pb->events[i]) < 0) {
 			err = -errno;
-			pr_warning("failed to epoll_ctl cpu #%d perf FD %d: %s\n",
-				   cpu, cpu_buf->fd,
-				   libbpf_strerror_r(err, msg, sizeof(msg)));
+			pr_warn("failed to epoll_ctl cpu #%d perf FD %d: %s\n",
+				cpu, cpu_buf->fd,
+				libbpf_strerror_r(err, msg, sizeof(msg)));
 			goto error;
 		}
 	}
@@ -5609,7 +5711,7 @@ perf_buffer__process_record(struct perf_event_header *e, void *ctx)
 		break;
 	}
 	default:
-		pr_warning("unknown perf sample type %d\n", e->type);
+		pr_warn("unknown perf sample type %d\n", e->type);
 		return LIBBPF_PERF_EVENT_ERROR;
 	}
 	return LIBBPF_PERF_EVENT_CONT;
@@ -5639,7 +5741,7 @@ int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms)
 
 		err = perf_buffer__process_records(pb, cpu_buf);
 		if (err) {
-			pr_warning("error while processing records: %d\n", err);
+			pr_warn("error while processing records: %d\n", err);
 			return err;
 		}
 	}
@@ -5836,13 +5938,13 @@ bpf_program__get_prog_info_linear(int fd, __u64 arrays)
 		v2 = bpf_prog_info_read_offset_u32(&info_linear->info,
 						   desc->count_offset);
 		if (v1 != v2)
-			pr_warning("%s: mismatch in element count\n", __func__);
+			pr_warn("%s: mismatch in element count\n", __func__);
 
 		v1 = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
 		v2 = bpf_prog_info_read_offset_u32(&info_linear->info,
 						   desc->size_offset);
 		if (v1 != v2)
-			pr_warning("%s: mismatch in rec size\n", __func__);
+			pr_warn("%s: mismatch in rec size\n", __func__);
 	}
 
 	/* step 7: update info_len and data_len */
@@ -5910,20 +6012,19 @@ int libbpf_num_possible_cpus(void)
 	fd = open(fcpu, O_RDONLY);
 	if (fd < 0) {
 		error = errno;
-		pr_warning("Failed to open file %s: %s\n",
-			   fcpu, strerror(error));
+		pr_warn("Failed to open file %s: %s\n", fcpu, strerror(error));
 		return -error;
 	}
 	len = read(fd, buf, sizeof(buf));
 	close(fd);
 	if (len <= 0) {
 		error = len ? errno : EINVAL;
-		pr_warning("Failed to read # of possible cpus from %s: %s\n",
-			   fcpu, strerror(error));
+		pr_warn("Failed to read # of possible cpus from %s: %s\n",
+			fcpu, strerror(error));
 		return -error;
 	}
 	if (len == sizeof(buf)) {
-		pr_warning("File %s size overflow\n", fcpu);
+		pr_warn("File %s size overflow\n", fcpu);
 		return -EOVERFLOW;
 	}
 	buf[len] = '\0';
@@ -5934,8 +6035,8 @@ int libbpf_num_possible_cpus(void)
 			buf[ir] = '\0';
 			n = sscanf(&buf[il], "%u-%u", &start, &end);
 			if (n <= 0) {
-				pr_warning("Failed to get # CPUs from %s\n",
-					   &buf[il]);
+				pr_warn("Failed to get # CPUs from %s\n",
+					&buf[il]);
 				return -EINVAL;
 			} else if (n == 1) {
 				end = start;
@@ -5945,7 +6046,7 @@ int libbpf_num_possible_cpus(void)
 		}
 	}
 	if (tmp_cpus <= 0) {
-		pr_warning("Invalid #CPUs %d from %s\n", tmp_cpus, fcpu);
+		pr_warn("Invalid #CPUs %d from %s\n", tmp_cpus, fcpu);
 		return -EINVAL;
 	}
 
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 667e6853e51f..c63e2ff84abc 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -75,14 +75,19 @@ struct bpf_object_open_attr {
  * have all the padding bytes initialized to zero. It's not guaranteed though,
  * when copying literal, that compiler won't copy garbage in literal's padding
  * bytes, but that's the best way I've found and it seems to work in practice.
+ *
+ * Macro declares opts struct of given type and name, zero-initializes,
+ * including any extra padding, it with memset() and then assigns initial
+ * values provided by users in struct initializer-syntax as varargs.
  */
-#define LIBBPF_OPTS(TYPE, NAME, ...)					    \
-	struct TYPE NAME;						    \
-	memset(&NAME, 0, sizeof(struct TYPE));				    \
-	NAME = (struct TYPE) {						    \
-		.sz = sizeof(struct TYPE),				    \
-		__VA_ARGS__						    \
-	}
+#define DECLARE_LIBBPF_OPTS(TYPE, NAME, ...)				    \
+	struct TYPE NAME = ({ 						    \
+		memset(&NAME, 0, sizeof(struct TYPE));			    \
+		(struct TYPE) {						    \
+			.sz = sizeof(struct TYPE),			    \
+			__VA_ARGS__					    \
+		};							    \
+	})
 
 struct bpf_object_open_opts {
 	/* size of this struct, for forward/backward compatiblity */
@@ -96,8 +101,10 @@ struct bpf_object_open_opts {
 	const char *object_name;
 	/* parse map definitions non-strictly, allowing extra attributes/data */
 	bool relaxed_maps;
+	/* process CO-RE relocations non-strictly, allowing them to fail */
+	bool relaxed_core_relocs;
 };
-#define bpf_object_open_opts__last_field relaxed_maps
+#define bpf_object_open_opts__last_field relaxed_core_relocs
 
 LIBBPF_API struct bpf_object *bpf_object__open(const char *path);
 LIBBPF_API struct bpf_object *
@@ -300,8 +307,13 @@ LIBBPF_API int bpf_program__set_sched_cls(struct bpf_program *prog);
 LIBBPF_API int bpf_program__set_sched_act(struct bpf_program *prog);
 LIBBPF_API int bpf_program__set_xdp(struct bpf_program *prog);
 LIBBPF_API int bpf_program__set_perf_event(struct bpf_program *prog);
+
+LIBBPF_API enum bpf_prog_type bpf_program__get_type(struct bpf_program *prog);
 LIBBPF_API void bpf_program__set_type(struct bpf_program *prog,
 				      enum bpf_prog_type type);
+
+LIBBPF_API enum bpf_attach_type
+bpf_program__get_expected_attach_type(struct bpf_program *prog);
 LIBBPF_API void
 bpf_program__set_expected_attach_type(struct bpf_program *prog,
 				      enum bpf_attach_type type);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 4d241fd92dd4..d1473ea4d7a5 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -195,4 +195,6 @@ LIBBPF_0.0.6 {
 	global:
 		bpf_object__open_file;
 		bpf_object__open_mem;
+		bpf_program__get_expected_attach_type;
+		bpf_program__get_type;
 } LIBBPF_0.0.5;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index f4ff8c3dae72..bd6f48ea407b 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -59,7 +59,7 @@ do {				\
 	libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__);	\
 } while (0)
 
-#define pr_warning(fmt, ...)	__pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
+#define pr_warn(fmt, ...)	__pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
 #define pr_info(fmt, ...)	__pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
 #define pr_debug(fmt, ...)	__pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
 
@@ -68,7 +68,7 @@ static inline bool libbpf_validate_opts(const char *opts,
 					const char *type_name)
 {
 	if (user_sz < sizeof(size_t)) {
-		pr_warning("%s size (%zu) is too small\n", type_name, user_sz);
+		pr_warn("%s size (%zu) is too small\n", type_name, user_sz);
 		return false;
 	}
 	if (user_sz > opts_sz) {
@@ -76,8 +76,8 @@ static inline bool libbpf_validate_opts(const char *opts,
 
 		for (i = opts_sz; i < user_sz; i++) {
 			if (opts[i]) {
-				pr_warning("%s has non-zero extra bytes",
-					   type_name);
+				pr_warn("%s has non-zero extra bytes",
+					type_name);
 				return false;
 			}
 		}
@@ -126,7 +126,7 @@ struct btf_ext {
 	};
 	struct btf_ext_info func_info;
 	struct btf_ext_info line_info;
-	struct btf_ext_info offset_reloc_info;
+	struct btf_ext_info field_reloc_info;
 	__u32 data_size;
 };
 
@@ -151,13 +151,23 @@ struct bpf_line_info_min {
 	__u32	line_col;
 };
 
-/* The minimum bpf_offset_reloc checked by the loader
+/* bpf_field_info_kind encodes which aspect of captured field has to be
+ * adjusted by relocations. Currently supported values are:
+ *   - BPF_FIELD_BYTE_OFFSET: field offset (in bytes);
+ *   - BPF_FIELD_EXISTS: field existence (1, if field exists; 0, otherwise);
+ */
+enum bpf_field_info_kind {
+	BPF_FIELD_BYTE_OFFSET = 0,	/* field byte offset */
+	BPF_FIELD_EXISTS = 2,		/* field existence in target kernel */
+};
+
+/* The minimum bpf_field_reloc checked by the loader
  *
- * Offset relocation captures the following data:
+ * Field relocation captures the following data:
  * - insn_off - instruction offset (in bytes) within a BPF program that needs
- *   its insn->imm field to be relocated with actual offset;
+ *   its insn->imm field to be relocated with actual field info;
  * - type_id - BTF type ID of the "root" (containing) entity of a relocatable
- *   offset;
+ *   field;
  * - access_str_off - offset into corresponding .BTF string section. String
  *   itself encodes an accessed field using a sequence of field and array
  *   indicies, separated by colon (:). It's conceptually very close to LLVM's
@@ -188,15 +198,16 @@ struct bpf_line_info_min {
  * bpf_probe_read(&dst, sizeof(dst),
  *		  __builtin_preserve_access_index(&src->a.b.c));
  *
- * In this case Clang will emit offset relocation recording necessary data to
+ * In this case Clang will emit field relocation recording necessary data to
  * be able to find offset of embedded `a.b.c` field within `src` struct.
  *
  *   [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction
  */
-struct bpf_offset_reloc {
+struct bpf_field_reloc {
 	__u32   insn_off;
 	__u32   type_id;
 	__u32   access_str_off;
+	enum bpf_field_info_kind kind;
 };
 
 #endif /* __LIBBPF_LIBBPF_INTERNAL_H */
diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index 9d5348086203..0b6287d1b15e 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -274,33 +274,55 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
 	/* This is the C-program:
 	 * SEC("xdp_sock") int xdp_sock_prog(struct xdp_md *ctx)
 	 * {
-	 *     int index = ctx->rx_queue_index;
+	 *     int ret, index = ctx->rx_queue_index;
 	 *
 	 *     // A set entry here means that the correspnding queue_id
 	 *     // has an active AF_XDP socket bound to it.
+	 *     ret = bpf_redirect_map(&xsks_map, index, XDP_PASS);
+	 *     if (ret > 0)
+	 *         return ret;
+	 *
+	 *     // Fallback for pre-5.3 kernels, not supporting default
+	 *     // action in the flags parameter.
 	 *     if (bpf_map_lookup_elem(&xsks_map, &index))
 	 *         return bpf_redirect_map(&xsks_map, index, 0);
-	 *
 	 *     return XDP_PASS;
 	 * }
 	 */
 	struct bpf_insn prog[] = {
-		/* r1 = *(u32 *)(r1 + 16) */
-		BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, 16),
-		/* *(u32 *)(r10 - 4) = r1 */
-		BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_1, -4),
+		/* r2 = *(u32 *)(r1 + 16) */
+		BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 16),
+		/* *(u32 *)(r10 - 4) = r2 */
+		BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_2, -4),
+		/* r1 = xskmap[] */
+		BPF_LD_MAP_FD(BPF_REG_1, xsk->xsks_map_fd),
+		/* r3 = XDP_PASS */
+		BPF_MOV64_IMM(BPF_REG_3, 2),
+		/* call bpf_redirect_map */
+		BPF_EMIT_CALL(BPF_FUNC_redirect_map),
+		/* if w0 != 0 goto pc+13 */
+		BPF_JMP32_IMM(BPF_JSGT, BPF_REG_0, 0, 13),
+		/* r2 = r10 */
 		BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+		/* r2 += -4 */
 		BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),
+		/* r1 = xskmap[] */
 		BPF_LD_MAP_FD(BPF_REG_1, xsk->xsks_map_fd),
+		/* call bpf_map_lookup_elem */
 		BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+		/* r1 = r0 */
 		BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
-		BPF_MOV32_IMM(BPF_REG_0, 2),
-		/* if r1 == 0 goto +5 */
+		/* r0 = XDP_PASS */
+		BPF_MOV64_IMM(BPF_REG_0, 2),
+		/* if r1 == 0 goto pc+5 */
 		BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 5),
 		/* r2 = *(u32 *)(r10 - 4) */
-		BPF_LD_MAP_FD(BPF_REG_1, xsk->xsks_map_fd),
 		BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_10, -4),
-		BPF_MOV32_IMM(BPF_REG_3, 0),
+		/* r1 = xskmap[] */
+		BPF_LD_MAP_FD(BPF_REG_1, xsk->xsks_map_fd),
+		/* r3 = 0 */
+		BPF_MOV64_IMM(BPF_REG_3, 0),
+		/* call bpf_redirect_map */
 		BPF_EMIT_CALL(BPF_FUNC_redirect_map),
 		/* The jumps are to this instruction */
 		BPF_EXIT_INSN(),
@@ -311,7 +333,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
 				   "LGPL-2.1 or BSD-2-Clause", 0, log_buf,
 				   log_buf_size);
 	if (prog_fd < 0) {
-		pr_warning("BPF log buffer:\n%s", log_buf);
+		pr_warn("BPF log buffer:\n%s", log_buf);
 		return prog_fd;
 	}
 
@@ -499,7 +521,7 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
 		return -EFAULT;
 
 	if (umem->refcount) {
-		pr_warning("Error: shared umems not supported by libbpf.\n");
+		pr_warn("Error: shared umems not supported by libbpf.\n");
 		return -EBUSY;
 	}