sync with libbpf repo

sync with latest libbpf repo.

Strut definition for btf_ext_header is defined in libbpf/src/btf.h
previously and used by bcc. Now, the struct is moved to
libbpf/src/libbpf_internal.h and not available to bcc.
We do not want to include libbpf/src/libbpf_internal.h as
it is really libbpf internal. Let us define bcc version
of btf_ext_header with struct name bcc_btf_ext_header.
The new name is to avoid conflict when compiling with
old libbpf package.

Signed-off-by: Yonghong Song <yhs@fb.com>

src/cc/bcc_btf.cc

@@ -185,7 +185,7 @@ void BTF::adjust(uint8_t *btf_sec, uintptr_t btf_sec_size,
   }
 
   struct btf_header *hdr = (struct btf_header *)btf_sec;
-  struct btf_ext_header *ehdr = (struct btf_ext_header *)btf_ext_sec;
+  struct bcc_btf_ext_header *ehdr = (struct bcc_btf_ext_header *)btf_ext_sec;
 
   // Fixup btf for old kernels or kernel requirements.
   fixup_btf(btf_sec + hdr->hdr_len + hdr->type_off, hdr->type_len,

src/cc/bcc_btf.h

@@ -45,6 +45,23 @@ class BTFStringTable {
 };
 
 class BTF {
+  struct bcc_btf_ext_header {
+    uint16_t magic;
+    uint8_t version;
+    uint8_t flags;
+    uint32_t hdr_len;
+
+    /* All offsets are in bytes relative to the end of this header */
+    uint32_t func_info_off;
+    uint32_t func_info_len;
+    uint32_t line_info_off;
+    uint32_t line_info_len;
+
+    /* optional part of .BTF.ext header */
+    uint32_t core_relo_off;
+    uint32_t core_relo_len;
+};
+
  public:
   BTF(bool debug, sec_map_def &sections);
   ~BTF();

src/cc/compat/linux/virtual_bpf.h

@@ -768,7 +768,7 @@ union bpf_attr {
  *
  * 		Also, note that **bpf_trace_printk**\ () is slow, and should
  * 		only be used for debugging purposes. For this reason, a notice
- * 		bloc (spanning several lines) is printed to kernel logs and
+ * 		block (spanning several lines) is printed to kernel logs and
  * 		states that the helper should not be used "for production use"
  * 		the first time this helper is used (or more precisely, when
  * 		**trace_printk**\ () buffers are allocated). For passing values
@@ -1034,14 +1034,14 @@ union bpf_attr {
  *
  * 			int ret;
  * 			struct bpf_tunnel_key key = {};
- * 			
+ *
  * 			ret = bpf_skb_get_tunnel_key(skb, &key, sizeof(key), 0);
  * 			if (ret < 0)
  * 				return TC_ACT_SHOT;	// drop packet
- * 			
+ *
  * 			if (key.remote_ipv4 != 0x0a000001)
  * 				return TC_ACT_SHOT;	// drop packet
- * 			
+ *
  * 			return TC_ACT_OK;		// accept packet
  *
  * 		This interface can also be used with all encapsulation devices
@@ -1148,7 +1148,7 @@ union bpf_attr {
  * 	Description
  * 		Retrieve the realm or the route, that is to say the
  * 		**tclassid** field of the destination for the *skb*. The
- * 		indentifier retrieved is a user-provided tag, similar to the
+ * 		identifier retrieved is a user-provided tag, similar to the
  * 		one used with the net_cls cgroup (see description for
  * 		**bpf_get_cgroup_classid**\ () helper), but here this tag is
  * 		held by a route (a destination entry), not by a task.
@@ -4072,6 +4072,13 @@ struct bpf_link_info {
 			__u64 cgroup_id;
 			__u32 attach_type;
 		} cgroup;
+		struct {
+			__aligned_u64 target_name; /* in/out: target_name buffer ptr */
+			__u32 target_name_len;	   /* in/out: target_name buffer len */
+			union {
+				__u32 map_id;
+			} map;
+		} iter;
 		struct  {
 			__u32 netns_ino;
 			__u32 attach_type;