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

Pull networking updates from David Miller:
 "Some highlights from this development cycle:

   1) Big refactoring of ipv6 route and neigh handling to support
      nexthop objects configurable as units from userspace. From David
      Ahern.

   2) Convert explored_states in BPF verifier into a hash table,
      significantly decreased state held for programs with bpf2bpf
      calls, from Alexei Starovoitov.

   3) Implement bpf_send_signal() helper, from Yonghong Song.

   4) Various classifier enhancements to mvpp2 driver, from Maxime
      Chevallier.

   5) Add aRFS support to hns3 driver, from Jian Shen.

   6) Fix use after free in inet frags by allocating fqdirs dynamically
      and reworking how rhashtable dismantle occurs, from Eric Dumazet.

   7) Add act_ctinfo packet classifier action, from Kevin
      Darbyshire-Bryant.

   8) Add TFO key backup infrastructure, from Jason Baron.

   9) Remove several old and unused ISDN drivers, from Arnd Bergmann.

  10) Add devlink notifications for flash update status to mlxsw driver,
      from Jiri Pirko.

  11) Lots of kTLS offload infrastructure fixes, from Jakub Kicinski.

  12) Add support for mv88e6250 DSA chips, from Rasmus Villemoes.

  13) Various enhancements to ipv6 flow label handling, from Eric
      Dumazet and Willem de Bruijn.

  14) Support TLS offload in nfp driver, from Jakub Kicinski, Dirk van
      der Merwe, and others.

  15) Various improvements to axienet driver including converting it to
      phylink, from Robert Hancock.

  16) Add PTP support to sja1105 DSA driver, from Vladimir Oltean.

  17) Add mqprio qdisc offload support to dpaa2-eth, from Ioana
      Radulescu.

  18) Add devlink health reporting to mlx5, from Moshe Shemesh.

  19) Convert stmmac over to phylink, from Jose Abreu.

  20) Add PTP PHC (Physical Hardware Clock) support to mlxsw, from
      Shalom Toledo.

  21) Add nftables SYNPROXY support, from Fernando Fernandez Mancera.

  22) Convert tcp_fastopen over to use SipHash, from Ard Biesheuvel.

  23) Track spill/fill of constants in BPF verifier, from Alexei
      Starovoitov.

  24) Support bounded loops in BPF, from Alexei Starovoitov.

  25) Various page_pool API fixes and improvements, from Jesper Dangaard
      Brouer.

  26) Just like ipv4, support ref-countless ipv6 route handling. From
      Wei Wang.

  27) Support VLAN offloading in aquantia driver, from Igor Russkikh.

  28) Add AF_XDP zero-copy support to mlx5, from Maxim Mikityanskiy.

  29) Add flower GRE encap/decap support to nfp driver, from Pieter
      Jansen van Vuuren.

  30) Protect against stack overflow when using act_mirred, from John
      Hurley.

  31) Allow devmap map lookups from eBPF, from Toke Høiland-Jørgensen.

  32) Use page_pool API in netsec driver, Ilias Apalodimas.

  33) Add Google gve network driver, from Catherine Sullivan.

  34) More indirect call avoidance, from Paolo Abeni.

  35) Add kTLS TX HW offload support to mlx5, from Tariq Toukan.

  36) Add XDP_REDIRECT support to bnxt_en, from Andy Gospodarek.

  37) Add MPLS manipulation actions to TC, from John Hurley.

  38) Add sending a packet to connection tracking from TC actions, and
      then allow flower classifier matching on conntrack state. From
      Paul Blakey.

  39) Netfilter hw offload support, from Pablo Neira Ayuso"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (2080 commits)
  net/mlx5e: Return in default case statement in tx_post_resync_params
  mlx5: Return -EINVAL when WARN_ON_ONCE triggers in mlx5e_tls_resync().
  net: dsa: add support for BRIDGE_MROUTER attribute
  pkt_sched: Include const.h
  net: netsec: remove static declaration for netsec_set_tx_de()
  net: netsec: remove superfluous if statement
  netfilter: nf_tables: add hardware offload support
  net: flow_offload: rename tc_cls_flower_offload to flow_cls_offload
  net: flow_offload: add flow_block_cb_is_busy() and use it
  net: sched: remove tcf block API
  drivers: net: use flow block API
  net: sched: use flow block API
  net: flow_offload: add flow_block_cb_{priv, incref, decref}()
  net: flow_offload: add list handling functions
  net: flow_offload: add flow_block_cb_alloc() and flow_block_cb_free()
  net: flow_offload: rename TCF_BLOCK_BINDER_TYPE_* to FLOW_BLOCK_BINDER_TYPE_*
  net: flow_offload: rename TC_BLOCK_{UN}BIND to FLOW_BLOCK_{UN}BIND
  net: flow_offload: add flow_block_cb_setup_simple()
  net: hisilicon: Add an tx_desc to adapt HI13X1_GMAC
  net: hisilicon: Add an rx_desc to adapt HI13X1_GMAC
  ...

1 files changed, 1523 insertions, 332 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 151f7ac1882e..ed07789b3e62 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -32,6 +32,9 @@
 #include <linux/limits.h>
 #include <linux/perf_event.h>
 #include <linux/ring_buffer.h>
+#include <sys/epoll.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/vfs.h>
@@ -188,6 +191,7 @@ struct bpf_program {
 	void *line_info;
 	__u32 line_info_rec_size;
 	__u32 line_info_cnt;
+	__u32 prog_flags;
 };
 
 enum libbpf_map_type {
@@ -206,7 +210,8 @@ static const char * const libbpf_type_to_btf_name[] = {
 struct bpf_map {
 	int fd;
 	char *name;
-	size_t offset;
+	int sec_idx;
+	size_t sec_offset;
 	int map_ifindex;
 	int inner_map_fd;
 	struct bpf_map_def def;
@@ -233,6 +238,7 @@ struct bpf_object {
 	size_t nr_programs;
 	struct bpf_map *maps;
 	size_t nr_maps;
+	size_t maps_cap;
 	struct bpf_secdata sections;
 
 	bool loaded;
@@ -259,6 +265,7 @@ struct bpf_object {
 		} *reloc;
 		int nr_reloc;
 		int maps_shndx;
+		int btf_maps_shndx;
 		int text_shndx;
 		int data_shndx;
 		int rodata_shndx;
@@ -348,8 +355,11 @@ static int
 bpf_program__init(void *data, size_t size, char *section_name, int idx,
 		  struct bpf_program *prog)
 {
-	if (size < sizeof(struct bpf_insn)) {
-		pr_warning("corrupted section '%s'\n", section_name);
+	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);
 		return -EINVAL;
 	}
 
@@ -375,9 +385,8 @@ bpf_program__init(void *data, size_t size, char *section_name, int idx,
 			   section_name);
 		goto errout;
 	}
-	prog->insns_cnt = size / sizeof(struct bpf_insn);
-	memcpy(prog->insns, data,
-	       prog->insns_cnt * sizeof(struct bpf_insn));
+	prog->insns_cnt = size / bpf_insn_sz;
+	memcpy(prog->insns, data, size);
 	prog->idx = idx;
 	prog->instances.fds = NULL;
 	prog->instances.nr = -1;
@@ -494,15 +503,14 @@ static struct bpf_object *bpf_object__new(const char *path,
 
 	strcpy(obj->path, path);
 	/* Using basename() GNU version which doesn't modify arg. */
-	strncpy(obj->name, basename((void *)path),
-		sizeof(obj->name) - 1);
+	strncpy(obj->name, basename((void *)path), sizeof(obj->name) - 1);
 	end = strchr(obj->name, '.');
 	if (end)
 		*end = 0;
 
 	obj->efile.fd = -1;
 	/*
-	 * Caller of this function should also calls
+	 * Caller of this function should also call
 	 * bpf_object__elf_finish() after data collection to return
 	 * obj_buf to user. If not, we should duplicate the buffer to
 	 * avoid user freeing them before elf finish.
@@ -510,6 +518,7 @@ static struct bpf_object *bpf_object__new(const char *path,
 	obj->efile.obj_buf = obj_buf;
 	obj->efile.obj_buf_sz = obj_buf_sz;
 	obj->efile.maps_shndx = -1;
+	obj->efile.btf_maps_shndx = -1;
 	obj->efile.data_shndx = -1;
 	obj->efile.rodata_shndx = -1;
 	obj->efile.bss_shndx = -1;
@@ -562,38 +571,35 @@ static int bpf_object__elf_init(struct bpf_object *obj)
 	} else {
 		obj->efile.fd = open(obj->path, O_RDONLY);
 		if (obj->efile.fd < 0) {
-			char errmsg[STRERR_BUFSIZE];
-			char *cp = libbpf_strerror_r(errno, errmsg,
-						     sizeof(errmsg));
+			char errmsg[STRERR_BUFSIZE], *cp;
 
+			err = -errno;
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
 			pr_warning("failed to open %s: %s\n", obj->path, cp);
-			return -errno;
+			return err;
 		}
 
 		obj->efile.elf = elf_begin(obj->efile.fd,
-				LIBBPF_ELF_C_READ_MMAP,
-				NULL);
+					   LIBBPF_ELF_C_READ_MMAP, NULL);
 	}
 
 	if (!obj->efile.elf) {
-		pr_warning("failed to open %s as ELF file\n",
-				obj->path);
+		pr_warning("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_warning("failed to get EHDR from %s\n", obj->path);
 		err = -LIBBPF_ERRNO__FORMAT;
 		goto errout;
 	}
 	ep = &obj->efile.ehdr;
 
 	/* 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);
+	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);
 		err = -LIBBPF_ERRNO__FORMAT;
 		goto errout;
 	}
@@ -604,47 +610,31 @@ errout:
 	return err;
 }
 
-static int
-bpf_object__check_endianness(struct bpf_object *obj)
+static int bpf_object__check_endianness(struct bpf_object *obj)
 {
-	static unsigned int const endian = 1;
-
-	switch (obj->efile.ehdr.e_ident[EI_DATA]) {
-	case ELFDATA2LSB:
-		/* We are big endian, BPF obj is little endian. */
-		if (*(unsigned char const *)&endian != 1)
-			goto mismatch;
-		break;
-
-	case ELFDATA2MSB:
-		/* We are little endian, BPF obj is big endian. */
-		if (*(unsigned char const *)&endian != 0)
-			goto mismatch;
-		break;
-	default:
-		return -LIBBPF_ERRNO__ENDIAN;
-	}
-
-	return 0;
-
-mismatch:
-	pr_warning("Error: endianness mismatch.\n");
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
+		return 0;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+	if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2MSB)
+		return 0;
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+	pr_warning("endianness mismatch.\n");
 	return -LIBBPF_ERRNO__ENDIAN;
 }
 
 static int
-bpf_object__init_license(struct bpf_object *obj,
-			 void *data, size_t size)
+bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
 {
-	memcpy(obj->license, data,
-	       min(size, sizeof(obj->license) - 1));
+	memcpy(obj->license, data, min(size, sizeof(obj->license) - 1));
 	pr_debug("license of %s is %s\n", obj->path, obj->license);
 	return 0;
 }
 
 static int
-bpf_object__init_kversion(struct bpf_object *obj,
-			  void *data, size_t size)
+bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size)
 {
 	__u32 kver;
 
@@ -654,8 +644,7 @@ bpf_object__init_kversion(struct bpf_object *obj,
 	}
 	memcpy(&kver, data, sizeof(kver));
 	obj->kern_version = kver;
-	pr_debug("kernel version of %s is %x\n", obj->path,
-		 obj->kern_version);
+	pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version);
 	return 0;
 }
 
@@ -664,7 +653,9 @@ static int compare_bpf_map(const void *_a, const void *_b)
 	const struct bpf_map *a = _a;
 	const struct bpf_map *b = _b;
 
-	return a->offset - b->offset;
+	if (a->sec_idx != b->sec_idx)
+		return a->sec_idx - b->sec_idx;
+	return a->sec_offset - b->sec_offset;
 }
 
 static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)
@@ -781,24 +772,55 @@ int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
 	return -ENOENT;
 }
 
-static bool bpf_object__has_maps(const struct bpf_object *obj)
+static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
 {
-	return obj->efile.maps_shndx >= 0 ||
-	       obj->efile.data_shndx >= 0 ||
-	       obj->efile.rodata_shndx >= 0 ||
-	       obj->efile.bss_shndx >= 0;
+	struct bpf_map *new_maps;
+	size_t new_cap;
+	int i;
+
+	if (obj->nr_maps < obj->maps_cap)
+		return &obj->maps[obj->nr_maps++];
+
+	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");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	obj->maps_cap = new_cap;
+	obj->maps = new_maps;
+
+	/* zero out new maps */
+	memset(obj->maps + obj->nr_maps, 0,
+	       (obj->maps_cap - obj->nr_maps) * sizeof(*obj->maps));
+	/*
+	 * fill all fd with -1 so won't close incorrect fd (fd=0 is stdin)
+	 * when failure (zclose won't close negative fd)).
+	 */
+	for (i = obj->nr_maps; i < obj->maps_cap; i++) {
+		obj->maps[i].fd = -1;
+		obj->maps[i].inner_map_fd = -1;
+	}
+
+	return &obj->maps[obj->nr_maps++];
 }
 
 static int
-bpf_object__init_internal_map(struct bpf_object *obj, struct bpf_map *map,
-			      enum libbpf_map_type type, Elf_Data *data,
-			      void **data_buff)
+bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
+			      int sec_idx, Elf_Data *data, void **data_buff)
 {
-	struct bpf_map_def *def = &map->def;
 	char map_name[BPF_OBJ_NAME_LEN];
+	struct bpf_map_def *def;
+	struct bpf_map *map;
+
+	map = bpf_object__add_map(obj);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
 
 	map->libbpf_type = type;
-	map->offset = ~(typeof(map->offset))0;
+	map->sec_idx = sec_idx;
+	map->sec_offset = 0;
 	snprintf(map_name, sizeof(map_name), "%.8s%.7s", obj->name,
 		 libbpf_type_to_btf_name[type]);
 	map->name = strdup(map_name);
@@ -806,13 +828,15 @@ bpf_object__init_internal_map(struct bpf_object *obj, struct bpf_map *map,
 		pr_warning("failed to alloc map name\n");
 		return -ENOMEM;
 	}
+	pr_debug("map '%s' (global data): at sec_idx %d, offset %zu.\n",
+		 map_name, map->sec_idx, map->sec_offset);
 
+	def = &map->def;
 	def->type = BPF_MAP_TYPE_ARRAY;
 	def->key_size = sizeof(int);
 	def->value_size = data->d_size;
 	def->max_entries = 1;
-	def->map_flags = type == LIBBPF_MAP_RODATA ?
-			 BPF_F_RDONLY_PROG : 0;
+	def->map_flags = type == LIBBPF_MAP_RODATA ? BPF_F_RDONLY_PROG : 0;
 	if (data_buff) {
 		*data_buff = malloc(data->d_size);
 		if (!*data_buff) {
@@ -827,30 +851,61 @@ bpf_object__init_internal_map(struct bpf_object *obj, struct bpf_map *map,
 	return 0;
 }
 
-static int
-bpf_object__init_maps(struct bpf_object *obj, int flags)
+static int bpf_object__init_global_data_maps(struct bpf_object *obj)
+{
+	int err;
+
+	if (!obj->caps.global_data)
+		return 0;
+	/*
+	 * Populate obj->maps with libbpf internal maps.
+	 */
+	if (obj->efile.data_shndx >= 0) {
+		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
+						    obj->efile.data_shndx,
+						    obj->efile.data,
+						    &obj->sections.data);
+		if (err)
+			return err;
+	}
+	if (obj->efile.rodata_shndx >= 0) {
+		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
+						    obj->efile.rodata_shndx,
+						    obj->efile.rodata,
+						    &obj->sections.rodata);
+		if (err)
+			return err;
+	}
+	if (obj->efile.bss_shndx >= 0) {
+		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
+						    obj->efile.bss_shndx,
+						    obj->efile.bss, NULL);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
 {
-	int i, map_idx, map_def_sz = 0, nr_syms, nr_maps = 0, nr_maps_glob = 0;
-	bool strict = !(flags & MAPS_RELAX_COMPAT);
 	Elf_Data *symbols = obj->efile.symbols;
+	int i, map_def_sz = 0, nr_maps = 0, nr_syms;
 	Elf_Data *data = NULL;
-	int ret = 0;
+	Elf_Scn *scn;
+
+	if (obj->efile.maps_shndx < 0)
+		return 0;
 
 	if (!symbols)
 		return -EINVAL;
-	nr_syms = symbols->d_size / sizeof(GElf_Sym);
 
-	if (obj->efile.maps_shndx >= 0) {
-		Elf_Scn *scn = elf_getscn(obj->efile.elf,
-					  obj->efile.maps_shndx);
-
-		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);
-			return -EINVAL;
-		}
+	scn = elf_getscn(obj->efile.elf, obj->efile.maps_shndx);
+	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);
+		return -EINVAL;
 	}
 
 	/*
@@ -860,16 +915,8 @@ bpf_object__init_maps(struct bpf_object *obj, int flags)
 	 *
 	 * TODO: Detect array of map and report error.
 	 */
-	if (obj->caps.global_data) {
-		if (obj->efile.data_shndx >= 0)
-			nr_maps_glob++;
-		if (obj->efile.rodata_shndx >= 0)
-			nr_maps_glob++;
-		if (obj->efile.bss_shndx >= 0)
-			nr_maps_glob++;
-	}
-
-	for (i = 0; data && i < nr_syms; i++) {
+	nr_syms = symbols->d_size / sizeof(GElf_Sym);
+	for (i = 0; i < nr_syms; i++) {
 		GElf_Sym sym;
 
 		if (!gelf_getsym(symbols, i, &sym))
@@ -878,74 +925,59 @@ bpf_object__init_maps(struct bpf_object *obj, int flags)
 			continue;
 		nr_maps++;
 	}
-
-	if (!nr_maps && !nr_maps_glob)
-		return 0;
-
 	/* Assume equally sized map definitions */
-	if (data) {
-		pr_debug("maps in %s: %d maps in %zd bytes\n", obj->path,
-			 nr_maps, data->d_size);
-
-		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);
-			return -EINVAL;
-		}
-	}
-
-	nr_maps += nr_maps_glob;
-	obj->maps = calloc(nr_maps, sizeof(obj->maps[0]));
-	if (!obj->maps) {
-		pr_warning("alloc maps for object failed\n");
-		return -ENOMEM;
-	}
-	obj->nr_maps = nr_maps;
-
-	for (i = 0; i < nr_maps; i++) {
-		/*
-		 * fill all fd with -1 so won't close incorrect
-		 * fd (fd=0 is stdin) when failure (zclose won't close
-		 * negative fd)).
-		 */
-		obj->maps[i].fd = -1;
-		obj->maps[i].inner_map_fd = -1;
+	pr_debug("maps in %s: %d maps in %zd bytes\n",
+		 obj->path, nr_maps, data->d_size);
+
+	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);
+		return -EINVAL;
 	}
 
-	/*
-	 * Fill obj->maps using data in "maps" section.
-	 */
-	for (i = 0, map_idx = 0; data && i < nr_syms; i++) {
+	/* Fill obj->maps using data in "maps" section.  */
+	for (i = 0; i < nr_syms; i++) {
 		GElf_Sym sym;
 		const char *map_name;
 		struct bpf_map_def *def;
+		struct bpf_map *map;
 
 		if (!gelf_getsym(symbols, i, &sym))
 			continue;
 		if (sym.st_shndx != obj->efile.maps_shndx)
 			continue;
 
-		map_name = elf_strptr(obj->efile.elf,
-				      obj->efile.strtabidx,
+		map = bpf_object__add_map(obj);
+		if (IS_ERR(map))
+			return PTR_ERR(map);
+
+		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);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
 
-		obj->maps[map_idx].libbpf_type = LIBBPF_MAP_UNSPEC;
-		obj->maps[map_idx].offset = sym.st_value;
+		map->libbpf_type = LIBBPF_MAP_UNSPEC;
+		map->sec_idx = sym.st_shndx;
+		map->sec_offset = sym.st_value;
+		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);
 			return -EINVAL;
 		}
 
-		obj->maps[map_idx].name = strdup(map_name);
-		if (!obj->maps[map_idx].name) {
+		map->name = strdup(map_name);
+		if (!map->name) {
 			pr_warning("failed to alloc map name\n");
 			return -ENOMEM;
 		}
-		pr_debug("map %d is \"%s\"\n", map_idx,
-			 obj->maps[map_idx].name);
+		pr_debug("map %d is \"%s\"\n", i, map->name);
 		def = (struct bpf_map_def *)(data->d_buf + sym.st_value);
 		/*
 		 * If the definition of the map in the object file fits in
@@ -954,7 +986,7 @@ bpf_object__init_maps(struct bpf_object *obj, int flags)
 		 * calloc above.
 		 */
 		if (map_def_sz <= sizeof(struct bpf_map_def)) {
-			memcpy(&obj->maps[map_idx].def, def, map_def_sz);
+			memcpy(&map->def, def, map_def_sz);
 		} else {
 			/*
 			 * Here the map structure being read is bigger than what
@@ -974,37 +1006,338 @@ bpf_object__init_maps(struct bpf_object *obj, int flags)
 						return -EINVAL;
 				}
 			}
-			memcpy(&obj->maps[map_idx].def, def,
-			       sizeof(struct bpf_map_def));
+			memcpy(&map->def, def, sizeof(struct bpf_map_def));
 		}
-		map_idx++;
 	}
+	return 0;
+}
 
-	if (!obj->caps.global_data)
-		goto finalize;
+static const struct btf_type *skip_mods_and_typedefs(const struct btf *btf,
+						     __u32 id)
+{
+	const struct btf_type *t = btf__type_by_id(btf, id);
 
-	/*
-	 * Populate rest of obj->maps with libbpf internal maps.
-	 */
-	if (obj->efile.data_shndx >= 0)
-		ret = bpf_object__init_internal_map(obj, &obj->maps[map_idx++],
-						    LIBBPF_MAP_DATA,
-						    obj->efile.data,
-						    &obj->sections.data);
-	if (!ret && obj->efile.rodata_shndx >= 0)
-		ret = bpf_object__init_internal_map(obj, &obj->maps[map_idx++],
-						    LIBBPF_MAP_RODATA,
-						    obj->efile.rodata,
-						    &obj->sections.rodata);
-	if (!ret && obj->efile.bss_shndx >= 0)
-		ret = bpf_object__init_internal_map(obj, &obj->maps[map_idx++],
-						    LIBBPF_MAP_BSS,
-						    obj->efile.bss, NULL);
-finalize:
-	if (!ret)
+	while (true) {
+		switch (BTF_INFO_KIND(t->info)) {
+		case BTF_KIND_VOLATILE:
+		case BTF_KIND_CONST:
+		case BTF_KIND_RESTRICT:
+		case BTF_KIND_TYPEDEF:
+			t = btf__type_by_id(btf, t->type);
+			break;
+		default:
+			return t;
+		}
+	}
+}
+
+/*
+ * Fetch integer attribute of BTF map definition. Such attributes are
+ * represented using a pointer to an array, in which dimensionality of array
+ * encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY];
+ * encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF
+ * type definition, while using only sizeof(void *) space in ELF data section.
+ */
+static bool get_map_field_int(const char *map_name, const struct btf *btf,
+			      const struct btf_type *def,
+			      const struct btf_member *m, __u32 *res) {
+	const struct btf_type *t = skip_mods_and_typedefs(btf, m->type);
+	const char *name = btf__name_by_offset(btf, m->name_off);
+	const struct btf_array *arr_info;
+	const struct btf_type *arr_t;
+
+	if (BTF_INFO_KIND(t->info) != BTF_KIND_PTR) {
+		pr_warning("map '%s': attr '%s': expected PTR, got %u.\n",
+			   map_name, name, BTF_INFO_KIND(t->info));
+		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);
+		return false;
+	}
+	if (BTF_INFO_KIND(arr_t->info) != BTF_KIND_ARRAY) {
+		pr_warning("map '%s': attr '%s': expected ARRAY, got %u.\n",
+			   map_name, name, BTF_INFO_KIND(arr_t->info));
+		return false;
+	}
+	arr_info = (const void *)(arr_t + 1);
+	*res = arr_info->nelems;
+	return true;
+}
+
+static int bpf_object__init_user_btf_map(struct bpf_object *obj,
+					 const struct btf_type *sec,
+					 int var_idx, int sec_idx,
+					 const Elf_Data *data, bool strict)
+{
+	const struct btf_type *var, *def, *t;
+	const struct btf_var_secinfo *vi;
+	const struct btf_var *var_extra;
+	const struct btf_member *m;
+	const char *map_name;
+	struct bpf_map *map;
+	int vlen, i;
+
+	vi = (const struct btf_var_secinfo *)(const void *)(sec + 1) + var_idx;
+	var = btf__type_by_id(obj->btf, vi->type);
+	var_extra = (const void *)(var + 1);
+	map_name = btf__name_by_offset(obj->btf, var->name_off);
+	vlen = BTF_INFO_VLEN(var->info);
+
+	if (map_name == NULL || map_name[0] == '\0') {
+		pr_warning("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);
+		return -EINVAL;
+	}
+	if (BTF_INFO_KIND(var->info) != BTF_KIND_VAR) {
+		pr_warning("map '%s': unexpected var kind %u.\n",
+			   map_name, BTF_INFO_KIND(var->info));
+		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);
+		return -EOPNOTSUPP;
+	}
+
+	def = skip_mods_and_typedefs(obj->btf, var->type);
+	if (BTF_INFO_KIND(def->info) != BTF_KIND_STRUCT) {
+		pr_warning("map '%s': unexpected def kind %u.\n",
+			   map_name, BTF_INFO_KIND(var->info));
+		return -EINVAL;
+	}
+	if (def->size > vi->size) {
+		pr_warning("map '%s': invalid def size.\n", map_name);
+		return -EINVAL;
+	}
+
+	map = bpf_object__add_map(obj);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+	map->name = strdup(map_name);
+	if (!map->name) {
+		pr_warning("map '%s': failed to alloc map name.\n", map_name);
+		return -ENOMEM;
+	}
+	map->libbpf_type = LIBBPF_MAP_UNSPEC;
+	map->def.type = BPF_MAP_TYPE_UNSPEC;
+	map->sec_idx = sec_idx;
+	map->sec_offset = vi->offset;
+	pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
+		 map_name, map->sec_idx, map->sec_offset);
+
+	vlen = BTF_INFO_VLEN(def->info);
+	m = (const void *)(def + 1);
+	for (i = 0; i < vlen; i++, m++) {
+		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);
+			return -EINVAL;
+		}
+		if (strcmp(name, "type") == 0) {
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &map->def.type))
+				return -EINVAL;
+			pr_debug("map '%s': found type = %u.\n",
+				 map_name, map->def.type);
+		} else if (strcmp(name, "max_entries") == 0) {
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &map->def.max_entries))
+				return -EINVAL;
+			pr_debug("map '%s': found max_entries = %u.\n",
+				 map_name, map->def.max_entries);
+		} else if (strcmp(name, "map_flags") == 0) {
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &map->def.map_flags))
+				return -EINVAL;
+			pr_debug("map '%s': found map_flags = %u.\n",
+				 map_name, map->def.map_flags);
+		} else if (strcmp(name, "key_size") == 0) {
+			__u32 sz;
+
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &sz))
+				return -EINVAL;
+			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);
+				return -EINVAL;
+			}
+			map->def.key_size = sz;
+		} else if (strcmp(name, "key") == 0) {
+			__s64 sz;
+
+			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);
+				return -EINVAL;
+			}
+			if (BTF_INFO_KIND(t->info) != BTF_KIND_PTR) {
+				pr_warning("map '%s': key spec is not PTR: %u.\n",
+					   map_name, BTF_INFO_KIND(t->info));
+				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);
+				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);
+				return -EINVAL;
+			}
+			map->def.key_size = sz;
+			map->btf_key_type_id = t->type;
+		} else if (strcmp(name, "value_size") == 0) {
+			__u32 sz;
+
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &sz))
+				return -EINVAL;
+			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);
+				return -EINVAL;
+			}
+			map->def.value_size = sz;
+		} else if (strcmp(name, "value") == 0) {
+			__s64 sz;
+
+			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);
+				return -EINVAL;
+			}
+			if (BTF_INFO_KIND(t->info) != BTF_KIND_PTR) {
+				pr_warning("map '%s': value spec is not PTR: %u.\n",
+					   map_name, BTF_INFO_KIND(t->info));
+				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);
+				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);
+				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);
+				return -ENOTSUP;
+			}
+			pr_debug("map '%s': ignoring unknown field '%s'.\n",
+				 map_name, name);
+		}
+	}
+
+	if (map->def.type == BPF_MAP_TYPE_UNSPEC) {
+		pr_warning("map '%s': map type isn't specified.\n", map_name);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict)
+{
+	const struct btf_type *sec = NULL;
+	int nr_types, i, vlen, err;
+	const struct btf_type *t;
+	const char *name;
+	Elf_Data *data;
+	Elf_Scn *scn;
+
+	if (obj->efile.btf_maps_shndx < 0)
+		return 0;
+
+	scn = elf_getscn(obj->efile.elf, obj->efile.btf_maps_shndx);
+	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);
+		return -EINVAL;
+	}
+
+	nr_types = btf__get_nr_types(obj->btf);
+	for (i = 1; i <= nr_types; i++) {
+		t = btf__type_by_id(obj->btf, i);
+		if (BTF_INFO_KIND(t->info) != BTF_KIND_DATASEC)
+			continue;
+		name = btf__name_by_offset(obj->btf, t->name_off);
+		if (strcmp(name, MAPS_ELF_SEC) == 0) {
+			sec = t;
+			break;
+		}
+	}
+
+	if (!sec) {
+		pr_warning("DATASEC '%s' not found.\n", MAPS_ELF_SEC);
+		return -ENOENT;
+	}
+
+	vlen = BTF_INFO_VLEN(sec->info);
+	for (i = 0; i < vlen; i++) {
+		err = bpf_object__init_user_btf_map(obj, sec, i,
+						    obj->efile.btf_maps_shndx,
+						    data, strict);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int bpf_object__init_maps(struct bpf_object *obj, int flags)
+{
+	bool strict = !(flags & MAPS_RELAX_COMPAT);
+	int err;
+
+	err = bpf_object__init_user_maps(obj, strict);
+	if (err)
+		return err;
+
+	err = bpf_object__init_user_btf_maps(obj, strict);
+	if (err)
+		return err;
+
+	err = bpf_object__init_global_data_maps(obj);
+	if (err)
+		return err;
+
+	if (obj->nr_maps) {
 		qsort(obj->maps, obj->nr_maps, sizeof(obj->maps[0]),
 		      compare_bpf_map);
-	return ret;
+	}
+	return 0;
 }
 
 static bool section_have_execinstr(struct bpf_object *obj, int idx)
@@ -1093,6 +1426,86 @@ static void bpf_object__sanitize_btf_ext(struct bpf_object *obj)
 	}
 }
 
+static bool bpf_object__is_btf_mandatory(const struct bpf_object *obj)
+{
+	return obj->efile.btf_maps_shndx >= 0;
+}
+
+static int bpf_object__init_btf(struct bpf_object *obj,
+				Elf_Data *btf_data,
+				Elf_Data *btf_ext_data)
+{
+	bool btf_required = bpf_object__is_btf_mandatory(obj);
+	int err = 0;
+
+	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);
+			goto out;
+		}
+		err = btf__finalize_data(obj, obj->btf);
+		if (err) {
+			pr_warning("Error finalizing %s: %d.\n",
+				   BTF_ELF_SEC, err);
+			goto out;
+		}
+	}
+	if (btf_ext_data) {
+		if (!obj->btf) {
+			pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
+				 BTF_EXT_ELF_SEC, BTF_ELF_SEC);
+			goto out;
+		}
+		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));
+			obj->btf_ext = NULL;
+			goto out;
+		}
+	}
+out:
+	if (err || IS_ERR(obj->btf)) {
+		if (btf_required)
+			err = err ? : PTR_ERR(obj->btf);
+		else
+			err = 0;
+		if (!IS_ERR_OR_NULL(obj->btf))
+			btf__free(obj->btf);
+		obj->btf = NULL;
+	}
+	if (btf_required && !obj->btf) {
+		pr_warning("BTF is required, but is missing or corrupted.\n");
+		return err == 0 ? -ENOENT : err;
+	}
+	return 0;
+}
+
+static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
+{
+	int err = 0;
+
+	if (!obj->btf)
+		return 0;
+
+	bpf_object__sanitize_btf(obj);
+	bpf_object__sanitize_btf_ext(obj);
+
+	err = btf__load(obj->btf);
+	if (err) {
+		pr_warning("Error loading %s into kernel: %d.\n",
+			   BTF_ELF_SEC, err);
+		btf__free(obj->btf);
+		obj->btf = NULL;
+		if (bpf_object__is_btf_mandatory(obj))
+			return err;
+	}
+	return 0;
+}
+
 static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 {
 	Elf *elf = obj->efile.elf;
@@ -1104,8 +1517,7 @@ 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_warning("failed to get e_shstrndx from %s\n", obj->path);
 		return -LIBBPF_ERRNO__FORMAT;
 	}
 
@@ -1118,24 +1530,21 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 		if (gelf_getshdr(scn, &sh) != &sh) {
 			pr_warning("failed to get section(%d) header from %s\n",
 				   idx, obj->path);
-			err = -LIBBPF_ERRNO__FORMAT;
-			goto out;
+			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);
-			err = -LIBBPF_ERRNO__FORMAT;
-			goto out;
+			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);
-			err = -LIBBPF_ERRNO__FORMAT;
-			goto out;
+			return -LIBBPF_ERRNO__FORMAT;
 		}
 		pr_debug("section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
 			 idx, name, (unsigned long)data->d_size,
@@ -1146,12 +1555,18 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 			err = bpf_object__init_license(obj,
 						       data->d_buf,
 						       data->d_size);
+			if (err)
+				return err;
 		} else if (strcmp(name, "version") == 0) {
 			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) {
+			obj->efile.btf_maps_shndx = idx;
 		} else if (strcmp(name, BTF_ELF_SEC) == 0) {
 			btf_data = data;
 		} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
@@ -1160,11 +1575,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 			if (obj->efile.symbols) {
 				pr_warning("bpf: multiple SYMTAB in %s\n",
 					   obj->path);
-				err = -LIBBPF_ERRNO__FORMAT;
-			} else {
-				obj->efile.symbols = data;
-				obj->efile.strtabidx = sh.sh_link;
+				return -LIBBPF_ERRNO__FORMAT;
 			}
+			obj->efile.symbols = data;
+			obj->efile.strtabidx = sh.sh_link;
 		} else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) {
 			if (sh.sh_flags & SHF_EXECINSTR) {
 				if (strcmp(name, ".text") == 0)
@@ -1178,6 +1592,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 
 					pr_warning("failed to alloc program %s (%s): %s",
 						   name, obj->path, cp);
+					return err;
 				}
 			} else if (strcmp(name, ".data") == 0) {
 				obj->efile.data = data;
@@ -1189,8 +1604,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 				pr_debug("skip section(%d) %s\n", idx, name);
 			}
 		} else if (sh.sh_type == SHT_REL) {
+			int nr_reloc = obj->efile.nr_reloc;
 			void *reloc = obj->efile.reloc;
-			int nr_reloc = obj->efile.nr_reloc + 1;
 			int sec = sh.sh_info; /* points to other section */
 
 			/* Only do relo for section with exec instructions */
@@ -1200,79 +1615,37 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 				continue;
 			}
 
-			reloc = reallocarray(reloc, nr_reloc,
+			reloc = reallocarray(reloc, nr_reloc + 1,
 					     sizeof(*obj->efile.reloc));
 			if (!reloc) {
 				pr_warning("realloc failed\n");
-				err = -ENOMEM;
-			} else {
-				int n = nr_reloc - 1;
+				return -ENOMEM;
+			}
 
-				obj->efile.reloc = reloc;
-				obj->efile.nr_reloc = nr_reloc;
+			obj->efile.reloc = reloc;
+			obj->efile.nr_reloc++;
 
-				obj->efile.reloc[n].shdr = sh;
-				obj->efile.reloc[n].data = data;
-			}
+			obj->efile.reloc[nr_reloc].shdr = sh;
+			obj->efile.reloc[nr_reloc].data = data;
 		} else if (sh.sh_type == SHT_NOBITS && strcmp(name, ".bss") == 0) {
 			obj->efile.bss = data;
 			obj->efile.bss_shndx = idx;
 		} else {
 			pr_debug("skip section(%d) %s\n", idx, name);
 		}
-		if (err)
-			goto out;
 	}
 
 	if (!obj->efile.strtabidx || obj->efile.strtabidx >= idx) {
 		pr_warning("Corrupted ELF file: index of strtab invalid\n");
-		return LIBBPF_ERRNO__FORMAT;
-	}
-	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: %ld. Ignored and continue.\n",
-				   BTF_ELF_SEC, PTR_ERR(obj->btf));
-			obj->btf = NULL;
-		} else {
-			err = btf__finalize_data(obj, obj->btf);
-			if (!err) {
-				bpf_object__sanitize_btf(obj);
-				err = btf__load(obj->btf);
-			}
-			if (err) {
-				pr_warning("Error finalizing and loading %s into kernel: %d. Ignored and continue.\n",
-					   BTF_ELF_SEC, err);
-				btf__free(obj->btf);
-				obj->btf = NULL;
-				err = 0;
-			}
-		}
-	}
-	if (btf_ext_data) {
-		if (!obj->btf) {
-			pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
-				 BTF_EXT_ELF_SEC, BTF_ELF_SEC);
-		} else {
-			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));
-				obj->btf_ext = NULL;
-			} else {
-				bpf_object__sanitize_btf_ext(obj);
-			}
-		}
+		return -LIBBPF_ERRNO__FORMAT;
 	}
-	if (bpf_object__has_maps(obj)) {
+	err = bpf_object__init_btf(obj, btf_data, btf_ext_data);
+	if (!err)
 		err = bpf_object__init_maps(obj, flags);
-		if (err)
-			goto out;
-	}
-	err = bpf_object__init_prog_names(obj);
-out:
+	if (!err)
+		err = bpf_object__sanitize_and_load_btf(obj);
+	if (!err)
+		err = bpf_object__init_prog_names(obj);
 	return err;
 }
 
@@ -1291,7 +1664,8 @@ bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
 }
 
 struct bpf_program *
-bpf_object__find_program_by_title(struct bpf_object *obj, const char *title)
+bpf_object__find_program_by_title(const struct bpf_object *obj,
+				  const char *title)
 {
 	struct bpf_program *pos;
 
@@ -1313,7 +1687,8 @@ static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
 static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
 				      int shndx)
 {
-	return shndx == obj->efile.maps_shndx;
+	return shndx == obj->efile.maps_shndx ||
+	       shndx == obj->efile.btf_maps_shndx;
 }
 
 static bool bpf_object__relo_in_known_section(const struct bpf_object *obj,
@@ -1346,8 +1721,7 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 	size_t nr_maps = obj->nr_maps;
 	int i, nrels;
 
-	pr_debug("collecting relocating info for: '%s'\n",
-		 prog->section_name);
+	pr_debug("collecting relocating info for: '%s'\n", prog->section_name);
 	nrels = shdr->sh_size / shdr->sh_entsize;
 
 	prog->reloc_desc = malloc(sizeof(*prog->reloc_desc) * nrels);
@@ -1358,23 +1732,21 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 	prog->nr_reloc = nrels;
 
 	for (i = 0; i < nrels; i++) {
-		GElf_Sym sym;
-		GElf_Rel rel;
-		unsigned int insn_idx;
-		unsigned int shdr_idx;
 		struct bpf_insn *insns = prog->insns;
 		enum libbpf_map_type type;
+		unsigned int insn_idx;
+		unsigned int shdr_idx;
 		const char *name;
 		size_t map_idx;
+		GElf_Sym sym;
+		GElf_Rel rel;
 
 		if (!gelf_getrel(data, i, &rel)) {
 			pr_warning("relocation: failed to get %d reloc\n", i);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
-		if (!gelf_getsym(symbols,
-				 GELF_R_SYM(rel.r_info),
-				 &sym)) {
+		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));
 			return -LIBBPF_ERRNO__FORMAT;
@@ -1435,16 +1807,19 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 				if (maps[map_idx].libbpf_type != type)
 					continue;
 				if (type != LIBBPF_MAP_UNSPEC ||
-				    (type == LIBBPF_MAP_UNSPEC &&
-				     maps[map_idx].offset == sym.st_value)) {
-					pr_debug("relocation: find map %zd (%s) for insn %u\n",
-						 map_idx, maps[map_idx].name, insn_idx);
+				    (maps[map_idx].sec_idx == sym.st_shndx &&
+				     maps[map_idx].sec_offset == sym.st_value)) {
+					pr_debug("relocation: found map %zd (%s, sec_idx %d, offset %zu) for insn %u\n",
+						 map_idx, maps[map_idx].name,
+						 maps[map_idx].sec_idx,
+						 maps[map_idx].sec_offset,
+						 insn_idx);
 					break;
 				}
 			}
 
 			if (map_idx >= nr_maps) {
-				pr_warning("bpf relocation: map_idx %d large than %d\n",
+				pr_warning("bpf relocation: map_idx %d larger than %d\n",
 					   (int)map_idx, (int)nr_maps - 1);
 				return -LIBBPF_ERRNO__RELOC;
 			}
@@ -1458,14 +1833,18 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 	return 0;
 }
 
-static int bpf_map_find_btf_info(struct bpf_map *map, const struct btf *btf)
+static int bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map)
 {
 	struct bpf_map_def *def = &map->def;
 	__u32 key_type_id = 0, value_type_id = 0;
 	int ret;
 
+	/* if it's BTF-defined map, we don't need to search for type IDs */
+	if (map->sec_idx == obj->efile.btf_maps_shndx)
+		return 0;
+
 	if (!bpf_map__is_internal(map)) {
-		ret = btf__get_map_kv_tids(btf, map->name, def->key_size,
+		ret = btf__get_map_kv_tids(obj->btf, map->name, def->key_size,
 					   def->value_size, &key_type_id,
 					   &value_type_id);
 	} else {
@@ -1473,7 +1852,7 @@ static int bpf_map_find_btf_info(struct bpf_map *map, const struct btf *btf)
 		 * LLVM annotates global data differently in BTF, that is,
 		 * only as '.data', '.bss' or '.rodata'.
 		 */
-		ret = btf__find_by_name(btf,
+		ret = btf__find_by_name(obj->btf,
 				libbpf_type_to_btf_name[map->libbpf_type]);
 	}
 	if (ret < 0)
@@ -1737,6 +2116,7 @@ static int
 bpf_object__create_maps(struct bpf_object *obj)
 {
 	struct bpf_create_map_attr create_attr = {};
+	int nr_cpus = 0;
 	unsigned int i;
 	int err;
 
@@ -1759,7 +2139,22 @@ bpf_object__create_maps(struct bpf_object *obj)
 		create_attr.map_flags = def->map_flags;
 		create_attr.key_size = def->key_size;
 		create_attr.value_size = def->value_size;
-		create_attr.max_entries = def->max_entries;
+		if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY &&
+		    !def->max_entries) {
+			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);
+				err = nr_cpus;
+				goto err_out;
+			}
+			pr_debug("map '%s': setting size to %d\n",
+				 map->name, nr_cpus);
+			create_attr.max_entries = nr_cpus;
+		} else {
+			create_attr.max_entries = def->max_entries;
+		}
 		create_attr.btf_fd = 0;
 		create_attr.btf_key_type_id = 0;
 		create_attr.btf_value_type_id = 0;
@@ -1767,17 +2162,19 @@ bpf_object__create_maps(struct bpf_object *obj)
 		    map->inner_map_fd >= 0)
 			create_attr.inner_map_fd = map->inner_map_fd;
 
-		if (obj->btf && !bpf_map_find_btf_info(map, obj->btf)) {
+		if (obj->btf && !bpf_map_find_btf_info(obj, map)) {
 			create_attr.btf_fd = btf__fd(obj->btf);
 			create_attr.btf_key_type_id = map->btf_key_type_id;
 			create_attr.btf_value_type_id = map->btf_value_type_id;
 		}
 
 		*pfd = bpf_create_map_xattr(&create_attr);
-		if (*pfd < 0 && create_attr.btf_key_type_id) {
-			cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+		if (*pfd < 0 && (create_attr.btf_key_type_id ||
+				 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, errno);
+				   map->name, cp, err);
 			create_attr.btf_fd = 0;
 			create_attr.btf_key_type_id = 0;
 			create_attr.btf_value_type_id = 0;
@@ -1789,11 +2186,11 @@ bpf_object__create_maps(struct bpf_object *obj)
 		if (*pfd < 0) {
 			size_t j;
 
-			err = *pfd;
+			err = -errno;
 err_out:
-			cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
-			pr_warning("failed to create map (name: '%s'): %s\n",
-				   map->name, cp);
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+			pr_warning("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;
@@ -1807,7 +2204,7 @@ err_out:
 			}
 		}
 
-		pr_debug("create map %s: fd=%d\n", map->name, *pfd);
+		pr_debug("created map %s: fd=%d\n", map->name, *pfd);
 	}
 
 	return 0;
@@ -1828,18 +2225,14 @@ check_btf_ext_reloc_err(struct bpf_program *prog, int err,
 	if (btf_prog_info) {
 		/*
 		 * Some info has already been found but has problem
-		 * in the last btf_ext reloc.  Must have to error
-		 * out.
+		 * 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);
 		return err;
 	}
 
-	/*
-	 * Have problem loading the very first info.  Ignore
-	 * the rest.
-	 */
+	/* 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);
 	return 0;
@@ -2043,9 +2436,7 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
 			return -LIBBPF_ERRNO__RELOC;
 		}
 
-		err = bpf_program__collect_reloc(prog,
-						 shdr, data,
-						 obj);
+		err = bpf_program__collect_reloc(prog, shdr, data, obj);
 		if (err)
 			return err;
 	}
@@ -2062,6 +2453,9 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 	char *log_buf;
 	int ret;
 
+	if (!insns || !insns_cnt)
+		return -EINVAL;
+
 	memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));
 	load_attr.prog_type = prog->type;
 	load_attr.expected_attach_type = prog->expected_attach_type;
@@ -2080,8 +2474,7 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 	load_attr.line_info_rec_size = prog->line_info_rec_size;
 	load_attr.line_info_cnt = prog->line_info_cnt;
 	load_attr.log_level = prog->log_level;
-	if (!load_attr.insns || !load_attr.insns_cnt)
-		return -EINVAL;
+	load_attr.prog_flags = prog->prog_flags;
 
 retry_load:
 	log_buf = malloc(log_buf_size);
@@ -2219,14 +2612,14 @@ out:
 	return err;
 }
 
-static bool bpf_program__is_function_storage(struct bpf_program *prog,
-					     struct bpf_object *obj)
+static bool bpf_program__is_function_storage(const struct bpf_program *prog,
+					     const struct bpf_object *obj)
 {
 	return prog->idx == obj->efile.text_shndx && obj->has_pseudo_calls;
 }
 
 static int
-bpf_object__load_progs(struct bpf_object *obj)
+bpf_object__load_progs(struct bpf_object *obj, int log_level)
 {
 	size_t i;
 	int err;
@@ -2234,6 +2627,7 @@ bpf_object__load_progs(struct bpf_object *obj)
 	for (i = 0; i < obj->nr_programs; i++) {
 		if (bpf_program__is_function_storage(&obj->programs[i], obj))
 			continue;
+		obj->programs[i].log_level |= log_level;
 		err = bpf_program__load(&obj->programs[i],
 					obj->license,
 					obj->kern_version);
@@ -2270,6 +2664,7 @@ static bool bpf_prog_type__needs_kver(enum bpf_prog_type type)
 	case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
 	case BPF_PROG_TYPE_PERF_EVENT:
 	case BPF_PROG_TYPE_CGROUP_SYSCTL:
+	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
 		return false;
 	case BPF_PROG_TYPE_KPROBE:
 	default:
@@ -2360,11 +2755,9 @@ struct bpf_object *bpf_object__open_buffer(void *obj_buf,
 		snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
 			 (unsigned long)obj_buf,
 			 (unsigned long)obj_buf_sz);
-		tmp_name[sizeof(tmp_name) - 1] = '\0';
 		name = tmp_name;
 	}
-	pr_debug("loading object '%s' from buffer\n",
-		 name);
+	pr_debug("loading object '%s' from buffer\n", name);
 
 	return __bpf_object__open(name, obj_buf, obj_buf_sz, true, true);
 }
@@ -2385,10 +2778,14 @@ int bpf_object__unload(struct bpf_object *obj)
 	return 0;
 }
 
-int bpf_object__load(struct bpf_object *obj)
+int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
 {
+	struct bpf_object *obj;
 	int err;
 
+	if (!attr)
+		return -EINVAL;
+	obj = attr->obj;
 	if (!obj)
 		return -EINVAL;
 
@@ -2401,7 +2798,7 @@ int bpf_object__load(struct bpf_object *obj)
 
 	CHECK_ERR(bpf_object__create_maps(obj), err, out);
 	CHECK_ERR(bpf_object__relocate(obj), err, out);
-	CHECK_ERR(bpf_object__load_progs(obj), err, out);
+	CHECK_ERR(bpf_object__load_progs(obj, attr->log_level), err, out);
 
 	return 0;
 out:
@@ -2410,6 +2807,15 @@ out:
 	return err;
 }
 
+int bpf_object__load(struct bpf_object *obj)
+{
+	struct bpf_object_load_attr attr = {
+		.obj = obj,
+	};
+
+	return bpf_object__load_xattr(&attr);
+}
+
 static int check_path(const char *path)
 {
 	char *cp, errmsg[STRERR_BUFSIZE];
@@ -2914,17 +3320,17 @@ bpf_object__next(struct bpf_object *prev)
 	return next;
 }
 
-const char *bpf_object__name(struct bpf_object *obj)
+const char *bpf_object__name(const struct bpf_object *obj)
 {
 	return obj ? obj->path : ERR_PTR(-EINVAL);
 }
 
-unsigned int bpf_object__kversion(struct bpf_object *obj)
+unsigned int bpf_object__kversion(const struct bpf_object *obj)
 {
 	return obj ? obj->kern_version : 0;
 }
 
-struct btf *bpf_object__btf(struct bpf_object *obj)
+struct btf *bpf_object__btf(const struct bpf_object *obj)
 {
 	return obj ? obj->btf : NULL;
 }
@@ -2945,13 +3351,14 @@ int bpf_object__set_priv(struct bpf_object *obj, void *priv,
 	return 0;
 }
 
-void *bpf_object__priv(struct bpf_object *obj)
+void *bpf_object__priv(const struct bpf_object *obj)
 {
 	return obj ? obj->priv : ERR_PTR(-EINVAL);
 }
 
 static struct bpf_program *
-__bpf_program__iter(struct bpf_program *p, struct bpf_object *obj, bool forward)
+__bpf_program__iter(const struct bpf_program *p, const struct bpf_object *obj,
+		    bool forward)
 {
 	size_t nr_programs = obj->nr_programs;
 	ssize_t idx;
@@ -2976,7 +3383,7 @@ __bpf_program__iter(struct bpf_program *p, struct bpf_object *obj, bool forward)
 }
 
 struct bpf_program *
-bpf_program__next(struct bpf_program *prev, struct bpf_object *obj)
+bpf_program__next(struct bpf_program *prev, const struct bpf_object *obj)
 {
 	struct bpf_program *prog = prev;
 
@@ -2988,7 +3395,7 @@ bpf_program__next(struct bpf_program *prev, struct bpf_object *obj)
 }
 
 struct bpf_program *
-bpf_program__prev(struct bpf_program *next, struct bpf_object *obj)
+bpf_program__prev(struct bpf_program *next, const struct bpf_object *obj)
 {
 	struct bpf_program *prog = next;
 
@@ -3010,7 +3417,7 @@ int bpf_program__set_priv(struct bpf_program *prog, void *priv,
 	return 0;
 }
 
-void *bpf_program__priv(struct bpf_program *prog)
+void *bpf_program__priv(const struct bpf_program *prog)
 {
 	return prog ? prog->priv : ERR_PTR(-EINVAL);
 }
@@ -3020,7 +3427,7 @@ void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
 	prog->prog_ifindex = ifindex;
 }
 
-const char *bpf_program__title(struct bpf_program *prog, bool needs_copy)
+const char *bpf_program__title(const struct bpf_program *prog, bool needs_copy)
 {
 	const char *title;
 
@@ -3036,7 +3443,7 @@ const char *bpf_program__title(struct bpf_program *prog, bool needs_copy)
 	return title;
 }
 
-int bpf_program__fd(struct bpf_program *prog)
+int bpf_program__fd(const struct bpf_program *prog)
 {
 	return bpf_program__nth_fd(prog, 0);
 }
@@ -3069,7 +3476,7 @@ int bpf_program__set_prep(struct bpf_program *prog, int nr_instances,
 	return 0;
 }
 
-int bpf_program__nth_fd(struct bpf_program *prog, int n)
+int bpf_program__nth_fd(const struct bpf_program *prog, int n)
 {
 	int fd;
 
@@ -3097,25 +3504,25 @@ void bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
 	prog->type = type;
 }
 
-static bool bpf_program__is_type(struct bpf_program *prog,
+static bool bpf_program__is_type(const struct bpf_program *prog,
 				 enum bpf_prog_type type)
 {
 	return prog ? (prog->type == type) : false;
 }
 
-#define BPF_PROG_TYPE_FNS(NAME, TYPE)			\
-int bpf_program__set_##NAME(struct bpf_program *prog)	\
-{							\
-	if (!prog)					\
-		return -EINVAL;				\
-	bpf_program__set_type(prog, TYPE);		\
-	return 0;					\
-}							\
-							\
-bool bpf_program__is_##NAME(struct bpf_program *prog)	\
-{							\
-	return bpf_program__is_type(prog, TYPE);	\
-}							\
+#define BPF_PROG_TYPE_FNS(NAME, TYPE)				\
+int bpf_program__set_##NAME(struct bpf_program *prog)		\
+{								\
+	if (!prog)						\
+		return -EINVAL;					\
+	bpf_program__set_type(prog, TYPE);			\
+	return 0;						\
+}								\
+								\
+bool bpf_program__is_##NAME(const struct bpf_program *prog)	\
+{								\
+	return bpf_program__is_type(prog, TYPE);		\
+}								\
 
 BPF_PROG_TYPE_FNS(socket_filter, BPF_PROG_TYPE_SOCKET_FILTER);
 BPF_PROG_TYPE_FNS(kprobe, BPF_PROG_TYPE_KPROBE);
@@ -3216,6 +3623,10 @@ static const struct {
 						BPF_CGROUP_UDP6_RECVMSG),
 	BPF_EAPROG_SEC("cgroup/sysctl",		BPF_PROG_TYPE_CGROUP_SYSCTL,
 						BPF_CGROUP_SYSCTL),
+	BPF_EAPROG_SEC("cgroup/getsockopt",	BPF_PROG_TYPE_CGROUP_SOCKOPT,
+						BPF_CGROUP_GETSOCKOPT),
+	BPF_EAPROG_SEC("cgroup/setsockopt",	BPF_PROG_TYPE_CGROUP_SOCKOPT,
+						BPF_CGROUP_SETSOCKOPT),
 };
 
 #undef BPF_PROG_SEC_IMPL
@@ -3314,17 +3725,17 @@ bpf_program__identify_section(struct bpf_program *prog,
 					expected_attach_type);
 }
 
-int bpf_map__fd(struct bpf_map *map)
+int bpf_map__fd(const struct bpf_map *map)
 {
 	return map ? map->fd : -EINVAL;
 }
 
-const struct bpf_map_def *bpf_map__def(struct bpf_map *map)
+const struct bpf_map_def *bpf_map__def(const struct bpf_map *map)
 {
 	return map ? &map->def : ERR_PTR(-EINVAL);
 }
 
-const char *bpf_map__name(struct bpf_map *map)
+const char *bpf_map__name(const struct bpf_map *map)
 {
 	return map ? map->name : NULL;
 }
@@ -3355,17 +3766,17 @@ int bpf_map__set_priv(struct bpf_map *map, void *priv,
 	return 0;
 }
 
-void *bpf_map__priv(struct bpf_map *map)
+void *bpf_map__priv(const struct bpf_map *map)
 {
 	return map ? map->priv : ERR_PTR(-EINVAL);
 }
 
-bool bpf_map__is_offload_neutral(struct bpf_map *map)
+bool bpf_map__is_offload_neutral(const struct bpf_map *map)
 {
 	return map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY;
 }
 
-bool bpf_map__is_internal(struct bpf_map *map)
+bool bpf_map__is_internal(const struct bpf_map *map)
 {
 	return map->libbpf_type != LIBBPF_MAP_UNSPEC;
 }
@@ -3390,7 +3801,7 @@ int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)
 }
 
 static struct bpf_map *
-__bpf_map__iter(struct bpf_map *m, struct bpf_object *obj, int i)
+__bpf_map__iter(const struct bpf_map *m, const struct bpf_object *obj, int i)
 {
 	ssize_t idx;
 	struct bpf_map *s, *e;
@@ -3414,7 +3825,7 @@ __bpf_map__iter(struct bpf_map *m, struct bpf_object *obj, int i)
 }
 
 struct bpf_map *
-bpf_map__next(struct bpf_map *prev, struct bpf_object *obj)
+bpf_map__next(const struct bpf_map *prev, const struct bpf_object *obj)
 {
 	if (prev == NULL)
 		return obj->maps;
@@ -3423,7 +3834,7 @@ bpf_map__next(struct bpf_map *prev, struct bpf_object *obj)
 }
 
 struct bpf_map *
-bpf_map__prev(struct bpf_map *next, struct bpf_object *obj)
+bpf_map__prev(const struct bpf_map *next, const struct bpf_object *obj)
 {
 	if (next == NULL) {
 		if (!obj->nr_maps)
@@ -3435,7 +3846,7 @@ bpf_map__prev(struct bpf_map *next, struct bpf_object *obj)
 }
 
 struct bpf_map *
-bpf_object__find_map_by_name(struct bpf_object *obj, const char *name)
+bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name)
 {
 	struct bpf_map *pos;
 
@@ -3447,7 +3858,7 @@ bpf_object__find_map_by_name(struct bpf_object *obj, const char *name)
 }
 
 int
-bpf_object__find_map_fd_by_name(struct bpf_object *obj, const char *name)
+bpf_object__find_map_fd_by_name(const struct bpf_object *obj, const char *name)
 {
 	return bpf_map__fd(bpf_object__find_map_by_name(obj, name));
 }
@@ -3455,20 +3866,12 @@ bpf_object__find_map_fd_by_name(struct bpf_object *obj, const char *name)
 struct bpf_map *
 bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset)
 {
-	int i;
-
-	for (i = 0; i < obj->nr_maps; i++) {
-		if (obj->maps[i].offset == offset)
-			return &obj->maps[i];
-	}
-	return ERR_PTR(-ENOENT);
+	return ERR_PTR(-ENOTSUP);
 }
 
 long libbpf_get_error(const void *ptr)
 {
-	if (IS_ERR(ptr))
-		return PTR_ERR(ptr);
-	return 0;
+	return PTR_ERR_OR_ZERO(ptr);
 }
 
 int bpf_prog_load(const char *file, enum bpf_prog_type type,
@@ -3487,10 +3890,7 @@ int bpf_prog_load(const char *file, enum bpf_prog_type type,
 int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 			struct bpf_object **pobj, int *prog_fd)
 {
-	struct bpf_object_open_attr open_attr = {
-		.file		= attr->file,
-		.prog_type	= attr->prog_type,
-	};
+	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;
@@ -3503,6 +3903,9 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 	if (!attr->file)
 		return -EINVAL;
 
+	open_attr.file = attr->file;
+	open_attr.prog_type = attr->prog_type;
+
 	obj = bpf_object__open_xattr(&open_attr);
 	if (IS_ERR_OR_NULL(obj))
 		return -ENOENT;
@@ -3529,6 +3932,7 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 						      expected_attach_type);
 
 		prog->log_level = attr->log_level;
+		prog->prog_flags = attr->prog_flags;
 		if (!first_prog)
 			first_prog = prog;
 	}
@@ -3555,6 +3959,372 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 	return 0;
 }
 
+struct bpf_link {
+	int (*destroy)(struct bpf_link *link);
+};
+
+int bpf_link__destroy(struct bpf_link *link)
+{
+	int err;
+
+	if (!link)
+		return 0;
+
+	err = link->destroy(link);
+	free(link);
+
+	return err;
+}
+
+struct bpf_link_fd {
+	struct bpf_link link; /* has to be at the top of struct */
+	int fd; /* hook FD */
+};
+
+static int bpf_link__destroy_perf_event(struct bpf_link *link)
+{
+	struct bpf_link_fd *l = (void *)link;
+	int err;
+
+	err = ioctl(l->fd, PERF_EVENT_IOC_DISABLE, 0);
+	if (err)
+		err = -errno;
+
+	close(l->fd);
+	return err;
+}
+
+struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
+						int pfd)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link_fd *link;
+	int prog_fd, err;
+
+	if (pfd < 0) {
+		pr_warning("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));
+		return ERR_PTR(-EINVAL);
+	}
+
+	link = malloc(sizeof(*link));
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+	link->link.destroy = &bpf_link__destroy_perf_event;
+	link->fd = pfd;
+
+	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,
+			   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,
+			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return ERR_PTR(err);
+	}
+	return (struct bpf_link *)link;
+}
+
+/*
+ * this function is expected to parse integer in the range of [0, 2^31-1] from
+ * given file using scanf format string fmt. If actual parsed value is
+ * negative, the result might be indistinguishable from error
+ */
+static int parse_uint_from_file(const char *file, const char *fmt)
+{
+	char buf[STRERR_BUFSIZE];
+	int err, ret;
+	FILE *f;
+
+	f = fopen(file, "r");
+	if (!f) {
+		err = -errno;
+		pr_debug("failed to open '%s': %s\n", file,
+			 libbpf_strerror_r(err, buf, sizeof(buf)));
+		return err;
+	}
+	err = fscanf(f, fmt, &ret);
+	if (err != 1) {
+		err = err == EOF ? -EIO : -errno;
+		pr_debug("failed to parse '%s': %s\n", file,
+			libbpf_strerror_r(err, buf, sizeof(buf)));
+		fclose(f);
+		return err;
+	}
+	fclose(f);
+	return ret;
+}
+
+static int determine_kprobe_perf_type(void)
+{
+	const char *file = "/sys/bus/event_source/devices/kprobe/type";
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int determine_uprobe_perf_type(void)
+{
+	const char *file = "/sys/bus/event_source/devices/uprobe/type";
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int determine_kprobe_retprobe_bit(void)
+{
+	const char *file = "/sys/bus/event_source/devices/kprobe/format/retprobe";
+
+	return parse_uint_from_file(file, "config:%d\n");
+}
+
+static int determine_uprobe_retprobe_bit(void)
+{
+	const char *file = "/sys/bus/event_source/devices/uprobe/format/retprobe";
+
+	return parse_uint_from_file(file, "config:%d\n");
+}
+
+static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
+				 uint64_t offset, int pid)
+{
+	struct perf_event_attr attr = {};
+	char errmsg[STRERR_BUFSIZE];
+	int type, pfd, err;
+
+	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)));
+		return type;
+	}
+	if (retprobe) {
+		int bit = uprobe ? determine_uprobe_retprobe_bit()
+				 : 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)));
+			return bit;
+		}
+		attr.config |= 1 << bit;
+	}
+	attr.size = sizeof(attr);
+	attr.type = type;
+	attr.config1 = (uint64_t)(void *)name; /* kprobe_func or uprobe_path */
+	attr.config2 = offset;		       /* kprobe_addr or probe_offset */
+
+	/* pid filter is meaningful only for uprobes */
+	pfd = syscall(__NR_perf_event_open, &attr,
+		      pid < 0 ? -1 : pid /* pid */,
+		      pid == -1 ? 0 : -1 /* cpu */,
+		      -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)));
+		return err;
+	}
+	return pfd;
+}
+
+struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog,
+					    bool retprobe,
+					    const char *func_name)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int pfd, err;
+
+	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)));
+		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)));
+		return link;
+	}
+	return link;
+}
+
+struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
+					    bool retprobe, pid_t pid,
+					    const char *binary_path,
+					    size_t func_offset)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int pfd, err;
+
+	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)));
+		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)));
+		return link;
+	}
+	return link;
+}
+
+static int determine_tracepoint_id(const char *tp_category,
+				   const char *tp_name)
+{
+	char file[PATH_MAX];
+	int ret;
+
+	ret = snprintf(file, sizeof(file),
+		       "/sys/kernel/debug/tracing/events/%s/%s/id",
+		       tp_category, tp_name);
+	if (ret < 0)
+		return -errno;
+	if (ret >= sizeof(file)) {
+		pr_debug("tracepoint %s/%s path is too long\n",
+			 tp_category, tp_name);
+		return -E2BIG;
+	}
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int perf_event_open_tracepoint(const char *tp_category,
+				      const char *tp_name)
+{
+	struct perf_event_attr attr = {};
+	char errmsg[STRERR_BUFSIZE];
+	int tp_id, pfd, err;
+
+	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)));
+		return tp_id;
+	}
+
+	attr.type = PERF_TYPE_TRACEPOINT;
+	attr.size = sizeof(attr);
+	attr.config = tp_id;
+
+	pfd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, 0 /* cpu */,
+		      -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)));
+		return err;
+	}
+	return pfd;
+}
+
+struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
+						const char *tp_category,
+						const char *tp_name)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int pfd, err;
+
+	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)));
+		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)));
+		return link;
+	}
+	return link;
+}
+
+static int bpf_link__destroy_fd(struct bpf_link *link)
+{
+	struct bpf_link_fd *l = (void *)link;
+
+	return close(l->fd);
+}
+
+struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
+						    const char *tp_name)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link_fd *link;
+	int prog_fd, pfd;
+
+	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));
+		return ERR_PTR(-EINVAL);
+	}
+
+	link = malloc(sizeof(*link));
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+	link->link.destroy = &bpf_link__destroy_fd;
+
+	pfd = bpf_raw_tracepoint_open(tp_name, prog_fd);
+	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)));
+		return ERR_PTR(pfd);
+	}
+	link->fd = pfd;
+	return (struct bpf_link *)link;
+}
+
 enum bpf_perf_event_ret
 bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
 			   void **copy_mem, size_t *copy_size,
@@ -3603,6 +4373,370 @@ bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
 	return ret;
 }
 
+struct perf_buffer;
+
+struct perf_buffer_params {
+	struct perf_event_attr *attr;
+	/* if event_cb is specified, it takes precendence */
+	perf_buffer_event_fn event_cb;
+	/* sample_cb and lost_cb are higher-level common-case callbacks */
+	perf_buffer_sample_fn sample_cb;
+	perf_buffer_lost_fn lost_cb;
+	void *ctx;
+	int cpu_cnt;
+	int *cpus;
+	int *map_keys;
+};
+
+struct perf_cpu_buf {
+	struct perf_buffer *pb;
+	void *base; /* mmap()'ed memory */
+	void *buf; /* for reconstructing segmented data */
+	size_t buf_size;
+	int fd;
+	int cpu;
+	int map_key;
+};
+
+struct perf_buffer {
+	perf_buffer_event_fn event_cb;
+	perf_buffer_sample_fn sample_cb;
+	perf_buffer_lost_fn lost_cb;
+	void *ctx; /* passed into callbacks */
+
+	size_t page_size;
+	size_t mmap_size;
+	struct perf_cpu_buf **cpu_bufs;
+	struct epoll_event *events;
+	int cpu_cnt;
+	int epoll_fd; /* perf event FD */
+	int map_fd; /* BPF_MAP_TYPE_PERF_EVENT_ARRAY BPF map FD */
+};
+
+static void perf_buffer__free_cpu_buf(struct perf_buffer *pb,
+				      struct perf_cpu_buf *cpu_buf)
+{
+	if (!cpu_buf)
+		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);
+	if (cpu_buf->fd >= 0) {
+		ioctl(cpu_buf->fd, PERF_EVENT_IOC_DISABLE, 0);
+		close(cpu_buf->fd);
+	}
+	free(cpu_buf->buf);
+	free(cpu_buf);
+}
+
+void perf_buffer__free(struct perf_buffer *pb)
+{
+	int i;
+
+	if (!pb)
+		return;
+	if (pb->cpu_bufs) {
+		for (i = 0; i < pb->cpu_cnt && pb->cpu_bufs[i]; i++) {
+			struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
+
+			bpf_map_delete_elem(pb->map_fd, &cpu_buf->map_key);
+			perf_buffer__free_cpu_buf(pb, cpu_buf);
+		}
+		free(pb->cpu_bufs);
+	}
+	if (pb->epoll_fd >= 0)
+		close(pb->epoll_fd);
+	free(pb->events);
+	free(pb);
+}
+
+static struct perf_cpu_buf *
+perf_buffer__open_cpu_buf(struct perf_buffer *pb, struct perf_event_attr *attr,
+			  int cpu, int map_key)
+{
+	struct perf_cpu_buf *cpu_buf;
+	char msg[STRERR_BUFSIZE];
+	int err;
+
+	cpu_buf = calloc(1, sizeof(*cpu_buf));
+	if (!cpu_buf)
+		return ERR_PTR(-ENOMEM);
+
+	cpu_buf->pb = pb;
+	cpu_buf->cpu = cpu;
+	cpu_buf->map_key = map_key;
+
+	cpu_buf->fd = syscall(__NR_perf_event_open, attr, -1 /* pid */, cpu,
+			      -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)));
+		goto error;
+	}
+
+	cpu_buf->base = mmap(NULL, pb->mmap_size + pb->page_size,
+			     PROT_READ | PROT_WRITE, MAP_SHARED,
+			     cpu_buf->fd, 0);
+	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)));
+		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)));
+		goto error;
+	}
+
+	return cpu_buf;
+
+error:
+	perf_buffer__free_cpu_buf(pb, cpu_buf);
+	return (struct perf_cpu_buf *)ERR_PTR(err);
+}
+
+static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
+					      struct perf_buffer_params *p);
+
+struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
+				     const struct perf_buffer_opts *opts)
+{
+	struct perf_buffer_params p = {};
+	struct perf_event_attr attr = {
+		.config = PERF_COUNT_SW_BPF_OUTPUT,
+		.type = PERF_TYPE_SOFTWARE,
+		.sample_type = PERF_SAMPLE_RAW,
+		.sample_period = 1,
+		.wakeup_events = 1,
+	};
+
+	p.attr = &attr;
+	p.sample_cb = opts ? opts->sample_cb : NULL;
+	p.lost_cb = opts ? opts->lost_cb : NULL;
+	p.ctx = opts ? opts->ctx : NULL;
+
+	return __perf_buffer__new(map_fd, page_cnt, &p);
+}
+
+struct perf_buffer *
+perf_buffer__new_raw(int map_fd, size_t page_cnt,
+		     const struct perf_buffer_raw_opts *opts)
+{
+	struct perf_buffer_params p = {};
+
+	p.attr = opts->attr;
+	p.event_cb = opts->event_cb;
+	p.ctx = opts->ctx;
+	p.cpu_cnt = opts->cpu_cnt;
+	p.cpus = opts->cpus;
+	p.map_keys = opts->map_keys;
+
+	return __perf_buffer__new(map_fd, page_cnt, &p);
+}
+
+static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
+					      struct perf_buffer_params *p)
+{
+	struct bpf_map_info map = {};
+	char msg[STRERR_BUFSIZE];
+	struct perf_buffer *pb;
+	__u32 map_info_len;
+	int err, i;
+
+	if (page_cnt & (page_cnt - 1)) {
+		pr_warning("page count should be power of two, but is %zu\n",
+			   page_cnt);
+		return ERR_PTR(-EINVAL);
+	}
+
+	map_info_len = sizeof(map);
+	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)));
+		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);
+		return ERR_PTR(-EINVAL);
+	}
+
+	pb = calloc(1, sizeof(*pb));
+	if (!pb)
+		return ERR_PTR(-ENOMEM);
+
+	pb->event_cb = p->event_cb;
+	pb->sample_cb = p->sample_cb;
+	pb->lost_cb = p->lost_cb;
+	pb->ctx = p->ctx;
+
+	pb->page_size = getpagesize();
+	pb->mmap_size = pb->page_size * page_cnt;
+	pb->map_fd = map_fd;
+
+	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)));
+		goto error;
+	}
+
+	if (p->cpu_cnt > 0) {
+		pb->cpu_cnt = p->cpu_cnt;
+	} else {
+		pb->cpu_cnt = libbpf_num_possible_cpus();
+		if (pb->cpu_cnt < 0) {
+			err = pb->cpu_cnt;
+			goto error;
+		}
+		if (map.max_entries < pb->cpu_cnt)
+			pb->cpu_cnt = map.max_entries;
+	}
+
+	pb->events = calloc(pb->cpu_cnt, sizeof(*pb->events));
+	if (!pb->events) {
+		err = -ENOMEM;
+		pr_warning("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");
+		goto error;
+	}
+
+	for (i = 0; i < pb->cpu_cnt; i++) {
+		struct perf_cpu_buf *cpu_buf;
+		int cpu, map_key;
+
+		cpu = p->cpu_cnt > 0 ? p->cpus[i] : i;
+		map_key = p->cpu_cnt > 0 ? p->map_keys[i] : i;
+
+		cpu_buf = perf_buffer__open_cpu_buf(pb, p->attr, cpu, map_key);
+		if (IS_ERR(cpu_buf)) {
+			err = PTR_ERR(cpu_buf);
+			goto error;
+		}
+
+		pb->cpu_bufs[i] = cpu_buf;
+
+		err = bpf_map_update_elem(pb->map_fd, &map_key,
+					  &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)));
+			goto error;
+		}
+
+		pb->events[i].events = EPOLLIN;
+		pb->events[i].data.ptr = cpu_buf;
+		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)));
+			goto error;
+		}
+	}
+
+	return pb;
+
+error:
+	if (pb)
+		perf_buffer__free(pb);
+	return ERR_PTR(err);
+}
+
+struct perf_sample_raw {
+	struct perf_event_header header;
+	uint32_t size;
+	char data[0];
+};
+
+struct perf_sample_lost {
+	struct perf_event_header header;
+	uint64_t id;
+	uint64_t lost;
+	uint64_t sample_id;
+};
+
+static enum bpf_perf_event_ret
+perf_buffer__process_record(struct perf_event_header *e, void *ctx)
+{
+	struct perf_cpu_buf *cpu_buf = ctx;
+	struct perf_buffer *pb = cpu_buf->pb;
+	void *data = e;
+
+	/* user wants full control over parsing perf event */
+	if (pb->event_cb)
+		return pb->event_cb(pb->ctx, cpu_buf->cpu, e);
+
+	switch (e->type) {
+	case PERF_RECORD_SAMPLE: {
+		struct perf_sample_raw *s = data;
+
+		if (pb->sample_cb)
+			pb->sample_cb(pb->ctx, cpu_buf->cpu, s->data, s->size);
+		break;
+	}
+	case PERF_RECORD_LOST: {
+		struct perf_sample_lost *s = data;
+
+		if (pb->lost_cb)
+			pb->lost_cb(pb->ctx, cpu_buf->cpu, s->lost);
+		break;
+	}
+	default:
+		pr_warning("unknown perf sample type %d\n", e->type);
+		return LIBBPF_PERF_EVENT_ERROR;
+	}
+	return LIBBPF_PERF_EVENT_CONT;
+}
+
+static int perf_buffer__process_records(struct perf_buffer *pb,
+					struct perf_cpu_buf *cpu_buf)
+{
+	enum bpf_perf_event_ret ret;
+
+	ret = bpf_perf_event_read_simple(cpu_buf->base, pb->mmap_size,
+					 pb->page_size, &cpu_buf->buf,
+					 &cpu_buf->buf_size,
+					 perf_buffer__process_record, cpu_buf);
+	if (ret != LIBBPF_PERF_EVENT_CONT)
+		return ret;
+	return 0;
+}
+
+int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms)
+{
+	int i, cnt, err;
+
+	cnt = epoll_wait(pb->epoll_fd, pb->events, pb->cpu_cnt, timeout_ms);
+	for (i = 0; i < cnt; i++) {
+		struct perf_cpu_buf *cpu_buf = pb->events[i].data.ptr;
+
+		err = perf_buffer__process_records(pb, cpu_buf);
+		if (err) {
+			pr_warning("error while processing records: %d\n", err);
+			return err;
+		}
+	}
+	return cnt < 0 ? -errno : cnt;
+}
+
 struct bpf_prog_info_array_desc {
 	int	array_offset;	/* e.g. offset of jited_prog_insns */
 	int	count_offset;	/* e.g. offset of jited_prog_len */
@@ -3848,3 +4982,60 @@ void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear)
 					     desc->array_offset, addr);
 	}
 }
+
+int libbpf_num_possible_cpus(void)
+{
+	static const char *fcpu = "/sys/devices/system/cpu/possible";
+	int len = 0, n = 0, il = 0, ir = 0;
+	unsigned int start = 0, end = 0;
+	static int cpus;
+	char buf[128];
+	int error = 0;
+	int fd = -1;
+
+	if (cpus > 0)
+		return cpus;
+
+	fd = open(fcpu, O_RDONLY);
+	if (fd < 0) {
+		error = errno;
+		pr_warning("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));
+		return -error;
+	}
+	if (len == sizeof(buf)) {
+		pr_warning("File %s size overflow\n", fcpu);
+		return -EOVERFLOW;
+	}
+	buf[len] = '\0';
+
+	for (ir = 0, cpus = 0; ir <= len; ir++) {
+		/* Each sub string separated by ',' has format \d+-\d+ or \d+ */
+		if (buf[ir] == ',' || buf[ir] == '\0') {
+			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]);
+				return -EINVAL;
+			} else if (n == 1) {
+				end = start;
+			}
+			cpus += end - start + 1;
+			il = ir + 1;
+		}
+	}
+	if (cpus <= 0) {
+		pr_warning("Invalid #CPUs %d from %s\n", cpus, fcpu);
+		return -EINVAL;
+	}
+	return cpus;
+}