Merge branch 'bpf_line_info'

Martin Lau says:

====================
This patch series introduces the bpf_line_info.  Please see individual patch
for details.

It will be useful for introspection purpose, like:

[root@arch-fb-vm1 bpf]# ~/devshare/fb-kernel/linux/tools/bpf/bpftool/bpftool prog dump jited pinned /sys/fs/bpf/test_btf_haskv
[...]
int test_long_fname_2(struct dummy_tracepoint_args * arg):
bpf_prog_44a040bf25481309_test_long_fname_2:
; static int test_long_fname_2(struct dummy_tracepoint_args *arg)
   0:   push   %rbp
   1:   mov    %rsp,%rbp
   4:   sub    $0x30,%rsp
   b:   sub    $0x28,%rbp
   f:   mov    %rbx,0x0(%rbp)
  13:   mov    %r13,0x8(%rbp)
  17:   mov    %r14,0x10(%rbp)
  1b:   mov    %r15,0x18(%rbp)
  1f:   xor    %eax,%eax
  21:   mov    %rax,0x20(%rbp)
  25:   xor    %esi,%esi
; int key = 0;
  27:   mov    %esi,-0x4(%rbp)
; if (!arg->sock)
  2a:   mov    0x8(%rdi),%rdi
; if (!arg->sock)
  2e:   cmp    $0x0,%rdi
  32:   je     0x0000000000000070
  34:   mov    %rbp,%rsi
; counts = bpf_map_lookup_elem(&btf_map, &key);
  37:   add    $0xfffffffffffffffc,%rsi
  3b:   movabs $0xffff8881139d7480,%rdi
  45:   add    $0x110,%rdi
  4c:   mov    0x0(%rsi),%eax
  4f:   cmp    $0x4,%rax
  53:   jae    0x000000000000005e
  55:   shl    $0x3,%rax
  59:   add    %rdi,%rax
  5c:   jmp    0x0000000000000060
  5e:   xor    %eax,%eax
; if (!counts)
  60:   cmp    $0x0,%rax
  64:   je     0x0000000000000070
; counts->v6++;
  66:   mov    0x4(%rax),%edi
  69:   add    $0x1,%rdi
  6d:   mov    %edi,0x4(%rax)
  70:   mov    0x0(%rbp),%rbx
  74:   mov    0x8(%rbp),%r13
  78:   mov    0x10(%rbp),%r14
  7c:   mov    0x18(%rbp),%r15
  80:   add    $0x28,%rbp
  84:   leaveq
  85:   retq
[...]
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

arch/x86/net/bpf_jit_comp.c

@@ -1181,6 +1181,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
 	}
 
 	if (!image || !prog->is_func || extra_pass) {
+		if (image)
+			bpf_prog_fill_jited_linfo(prog, addrs);
 out_addrs:
 		kfree(addrs);
 		kfree(jit_data);

include/linux/bpf.h

@@ -319,7 +319,28 @@ struct bpf_prog_aux {
 	struct bpf_prog_offload *offload;
 	struct btf *btf;
 	struct bpf_func_info *func_info;
+	/* bpf_line_info loaded from userspace.  linfo->insn_off
+	 * has the xlated insn offset.
+	 * Both the main and sub prog share the same linfo.
+	 * The subprog can access its first linfo by
+	 * using the linfo_idx.
+	 */
+	struct bpf_line_info *linfo;
+	/* jited_linfo is the jited addr of the linfo.  It has a
+	 * one to one mapping to linfo:
+	 * jited_linfo[i] is the jited addr for the linfo[i]->insn_off.
+	 * Both the main and sub prog share the same jited_linfo.
+	 * The subprog can access its first jited_linfo by
+	 * using the linfo_idx.
+	 */
+	void **jited_linfo;
 	u32 func_info_cnt;
+	u32 nr_linfo;
+	/* subprog can use linfo_idx to access its first linfo and
+	 * jited_linfo.
+	 * main prog always has linfo_idx == 0
+	 */
+	u32 linfo_idx;
 	union {
 		struct work_struct work;
 		struct rcu_head	rcu;

include/linux/bpf_verifier.h

@@ -203,6 +203,7 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
 
 struct bpf_subprog_info {
 	u32 start; /* insn idx of function entry point */
+	u32 linfo_idx; /* The idx to the main_prog->aux->linfo */
 	u16 stack_depth; /* max. stack depth used by this function */
 };
 

include/linux/btf.h

@@ -46,6 +46,7 @@ void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
 		       struct seq_file *m);
 int btf_get_fd_by_id(u32 id);
 u32 btf_id(const struct btf *btf);
+bool btf_name_offset_valid(const struct btf *btf, u32 offset);
 
 #ifdef CONFIG_BPF_SYSCALL
 const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);

include/linux/filter.h

@@ -718,6 +718,13 @@ void bpf_prog_free(struct bpf_prog *fp);
 
 bool bpf_opcode_in_insntable(u8 code);
 
+void bpf_prog_free_linfo(struct bpf_prog *prog);
+void bpf_prog_fill_jited_linfo(struct bpf_prog *prog,
+			       const u32 *insn_to_jit_off);
+int bpf_prog_alloc_jited_linfo(struct bpf_prog *prog);
+void bpf_prog_free_jited_linfo(struct bpf_prog *prog);
+void bpf_prog_free_unused_jited_linfo(struct bpf_prog *prog);
+
 struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags);
 struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
 				  gfp_t gfp_extra_flags);

include/uapi/linux/bpf.h

@@ -356,6 +356,9 @@ union bpf_attr {
 		__u32		func_info_rec_size;	/* userspace bpf_func_info size */
 		__aligned_u64	func_info;	/* func info */
 		__u32		func_info_cnt;	/* number of bpf_func_info records */
+		__u32		line_info_rec_size;	/* userspace bpf_line_info size */
+		__aligned_u64	line_info;	/* line info */
+		__u32		line_info_cnt;	/* number of bpf_line_info records */
 	};
 
 	struct { /* anonymous struct used by BPF_OBJ_* commands */
@@ -2679,6 +2682,12 @@ struct bpf_prog_info {
 	__u32 func_info_rec_size;
 	__aligned_u64 func_info;
 	__u32 func_info_cnt;
+	__u32 line_info_cnt;
+	__aligned_u64 line_info;
+	__aligned_u64 jited_line_info;
+	__u32 jited_line_info_cnt;
+	__u32 line_info_rec_size;
+	__u32 jited_line_info_rec_size;
 } __attribute__((aligned(8)));
 
 struct bpf_map_info {
@@ -2995,4 +3004,14 @@ struct bpf_func_info {
 	__u32	type_id;
 };
 
+#define BPF_LINE_INFO_LINE_NUM(line_col)	((line_col) >> 10)
+#define BPF_LINE_INFO_LINE_COL(line_col)	((line_col) & 0x3ff)
+
+struct bpf_line_info {
+	__u32	insn_off;
+	__u32	file_name_off;
+	__u32	line_off;
+	__u32	line_col;
+};
+
 #endif /* _UAPI__LINUX_BPF_H__ */

kernel/bpf/btf.c

@@ -444,7 +444,7 @@ static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
 	return kind_ops[BTF_INFO_KIND(t->info)];
 }
 
-static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
+bool btf_name_offset_valid(const struct btf *btf, u32 offset)
 {
 	return BTF_STR_OFFSET_VALID(offset) &&
 		offset < btf->hdr.str_len;

kernel/bpf/core.c

@@ -105,6 +105,91 @@ struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags)
 }
 EXPORT_SYMBOL_GPL(bpf_prog_alloc);
 
+int bpf_prog_alloc_jited_linfo(struct bpf_prog *prog)
+{
+	if (!prog->aux->nr_linfo || !prog->jit_requested)
+		return 0;
+
+	prog->aux->jited_linfo = kcalloc(prog->aux->nr_linfo,
+					 sizeof(*prog->aux->jited_linfo),
+					 GFP_KERNEL | __GFP_NOWARN);
+	if (!prog->aux->jited_linfo)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void bpf_prog_free_jited_linfo(struct bpf_prog *prog)
+{
+	kfree(prog->aux->jited_linfo);
+	prog->aux->jited_linfo = NULL;
+}
+
+void bpf_prog_free_unused_jited_linfo(struct bpf_prog *prog)
+{
+	if (prog->aux->jited_linfo && !prog->aux->jited_linfo[0])
+		bpf_prog_free_jited_linfo(prog);
+}
+
+/* The jit engine is responsible to provide an array
+ * for insn_off to the jited_off mapping (insn_to_jit_off).
+ *
+ * The idx to this array is the insn_off.  Hence, the insn_off
+ * here is relative to the prog itself instead of the main prog.
+ * This array has one entry for each xlated bpf insn.
+ *
+ * jited_off is the byte off to the last byte of the jited insn.
+ *
+ * Hence, with
+ * insn_start:
+ *      The first bpf insn off of the prog.  The insn off
+ *      here is relative to the main prog.
+ *      e.g. if prog is a subprog, insn_start > 0
+ * linfo_idx:
+ *      The prog's idx to prog->aux->linfo and jited_linfo
+ *
+ * jited_linfo[linfo_idx] = prog->bpf_func
+ *
+ * For i > linfo_idx,
+ *
+ * jited_linfo[i] = prog->bpf_func +
+ *	insn_to_jit_off[linfo[i].insn_off - insn_start - 1]
+ */
+void bpf_prog_fill_jited_linfo(struct bpf_prog *prog,
+			       const u32 *insn_to_jit_off)
+{
+	u32 linfo_idx, insn_start, insn_end, nr_linfo, i;
+	const struct bpf_line_info *linfo;
+	void **jited_linfo;
+
+	if (!prog->aux->jited_linfo)
+		/* Userspace did not provide linfo */
+		return;
+
+	linfo_idx = prog->aux->linfo_idx;
+	linfo = &prog->aux->linfo[linfo_idx];
+	insn_start = linfo[0].insn_off;
+	insn_end = insn_start + prog->len;
+
+	jited_linfo = &prog->aux->jited_linfo[linfo_idx];
+	jited_linfo[0] = prog->bpf_func;
+
+	nr_linfo = prog->aux->nr_linfo - linfo_idx;
+
+	for (i = 1; i < nr_linfo && linfo[i].insn_off < insn_end; i++)
+		/* The verifier ensures that linfo[i].insn_off is
+		 * strictly increasing
+		 */
+		jited_linfo[i] = prog->bpf_func +
+			insn_to_jit_off[linfo[i].insn_off - insn_start - 1];
+}
+
+void bpf_prog_free_linfo(struct bpf_prog *prog)
+{
+	bpf_prog_free_jited_linfo(prog);
+	kvfree(prog->aux->linfo);
+}
+
 struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
 				  gfp_t gfp_extra_flags)
 {
@@ -294,6 +379,26 @@ static int bpf_adj_branches(struct bpf_prog *prog, u32 pos, u32 delta,
 	return ret;
 }
 
+static void bpf_adj_linfo(struct bpf_prog *prog, u32 off, u32 delta)
+{
+	struct bpf_line_info *linfo;
+	u32 i, nr_linfo;
+
+	nr_linfo = prog->aux->nr_linfo;
+	if (!nr_linfo || !delta)
+		return;
+
+	linfo = prog->aux->linfo;
+
+	for (i = 0; i < nr_linfo; i++)
+		if (off < linfo[i].insn_off)
+			break;
+
+	/* Push all off < linfo[i].insn_off by delta */
+	for (; i < nr_linfo; i++)
+		linfo[i].insn_off += delta;
+}
+
 struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
 				       const struct bpf_insn *patch, u32 len)
 {
@@ -349,6 +454,8 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
 	 */
 	BUG_ON(bpf_adj_branches(prog_adj, off, insn_delta, false));
 
+	bpf_adj_linfo(prog_adj, off, insn_delta);
+
 	return prog_adj;
 }
 
@@ -1591,13 +1698,20 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
 	 * be JITed, but falls back to the interpreter.
 	 */
 	if (!bpf_prog_is_dev_bound(fp->aux)) {
+		*err = bpf_prog_alloc_jited_linfo(fp);
+		if (*err)
+			return fp;
+
 		fp = bpf_int_jit_compile(fp);
-#ifdef CONFIG_BPF_JIT_ALWAYS_ON
 		if (!fp->jited) {
+			bpf_prog_free_jited_linfo(fp);
+#ifdef CONFIG_BPF_JIT_ALWAYS_ON
 			*err = -ENOTSUPP;
 			return fp;
-		}
 #endif
+		} else {
+			bpf_prog_free_unused_jited_linfo(fp);
+		}
 	} else {
 		*err = bpf_prog_offload_compile(fp);
 		if (*err)

kernel/bpf/syscall.c

@@ -1215,6 +1215,7 @@ static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)
 		bpf_prog_kallsyms_del_all(prog);
 		btf_put(prog->aux->btf);
 		kvfree(prog->aux->func_info);
+		bpf_prog_free_linfo(prog);
 
 		call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);
 	}
@@ -1439,7 +1440,7 @@ bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type,
 }
 
 /* last field in 'union bpf_attr' used by this command */
-#define	BPF_PROG_LOAD_LAST_FIELD func_info_cnt
+#define	BPF_PROG_LOAD_LAST_FIELD line_info_cnt
 
 static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
 {
@@ -1560,6 +1561,7 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
 	return err;
 
 free_used_maps:
+	bpf_prog_free_linfo(prog);
 	kvfree(prog->aux->func_info);
 	btf_put(prog->aux->btf);
 	bpf_prog_kallsyms_del_subprogs(prog);
@@ -2041,6 +2043,37 @@ static struct bpf_insn *bpf_insn_prepare_dump(const struct bpf_prog *prog)
 	return insns;
 }
 
+static int set_info_rec_size(struct bpf_prog_info *info)
+{
+	/*
+	 * Ensure info.*_rec_size is the same as kernel expected size
+	 *
+	 * or
+	 *
+	 * Only allow zero *_rec_size if both _rec_size and _cnt are
+	 * zero.  In this case, the kernel will set the expected
+	 * _rec_size back to the info.
+	 */
+
+	if ((info->func_info_cnt || info->func_info_rec_size) &&
+	    info->func_info_rec_size != sizeof(struct bpf_func_info))
+		return -EINVAL;
+
+	if ((info->line_info_cnt || info->line_info_rec_size) &&
+	    info->line_info_rec_size != sizeof(struct bpf_line_info))
+		return -EINVAL;
+
+	if ((info->jited_line_info_cnt || info->jited_line_info_rec_size) &&
+	    info->jited_line_info_rec_size != sizeof(__u64))
+		return -EINVAL;
+
+	info->func_info_rec_size = sizeof(struct bpf_func_info);
+	info->line_info_rec_size = sizeof(struct bpf_line_info);
+	info->jited_line_info_rec_size = sizeof(__u64);
+
+	return 0;
+}
+
 static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
 				   const union bpf_attr *attr,
 				   union bpf_attr __user *uattr)
@@ -2083,11 +2116,9 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
 				return -EFAULT;
 	}
 
-	if ((info.func_info_cnt || info.func_info_rec_size) &&
-	    info.func_info_rec_size != sizeof(struct bpf_func_info))
-		return -EINVAL;
-
-	info.func_info_rec_size = sizeof(struct bpf_func_info);
+	err = set_info_rec_size(&info);
+	if (err)
+		return err;
 
 	if (!capable(CAP_SYS_ADMIN)) {
 		info.jited_prog_len = 0;
@@ -2095,6 +2126,8 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
 		info.nr_jited_ksyms = 0;
 		info.nr_jited_func_lens = 0;
 		info.func_info_cnt = 0;
+		info.line_info_cnt = 0;
+		info.jited_line_info_cnt = 0;
 		goto done;
 	}
 
@@ -2251,6 +2284,44 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
 		}
 	}
 
+	ulen = info.line_info_cnt;
+	info.line_info_cnt = prog->aux->nr_linfo;
+	if (info.line_info_cnt && ulen) {
+		if (bpf_dump_raw_ok()) {
+			__u8 __user *user_linfo;
+
+			user_linfo = u64_to_user_ptr(info.line_info);
+			ulen = min_t(u32, info.line_info_cnt, ulen);
+			if (copy_to_user(user_linfo, prog->aux->linfo,
+					 info.line_info_rec_size * ulen))
+				return -EFAULT;
+		} else {
+			info.line_info = 0;
+		}
+	}
+
+	ulen = info.jited_line_info_cnt;
+	if (prog->aux->jited_linfo)
+		info.jited_line_info_cnt = prog->aux->nr_linfo;
+	else
+		info.jited_line_info_cnt = 0;
+	if (info.jited_line_info_cnt && ulen) {
+		if (bpf_dump_raw_ok()) {
+			__u64 __user *user_linfo;
+			u32 i;
+
+			user_linfo = u64_to_user_ptr(info.jited_line_info);
+			ulen = min_t(u32, info.jited_line_info_cnt, ulen);
+			for (i = 0; i < ulen; i++) {
+				if (put_user((__u64)(long)prog->aux->jited_linfo[i],
+					     &user_linfo[i]))
+					return -EFAULT;
+			}
+		} else {
+			info.jited_line_info = 0;
+		}
+	}
+
 done:
 	if (copy_to_user(uinfo, &info, info_len) ||
 	    put_user(info_len, &uattr->info.info_len))

kernel/bpf/verifier.c

@@ -4640,15 +4640,17 @@ static int check_cfg(struct bpf_verifier_env *env)
 #define MIN_BPF_FUNCINFO_SIZE	8
 #define MAX_FUNCINFO_REC_SIZE	252
 
-static int check_btf_func(struct bpf_prog *prog, struct bpf_verifier_env *env,
-			  union bpf_attr *attr, union bpf_attr __user *uattr)
+static int check_btf_func(struct bpf_verifier_env *env,
+			  const union bpf_attr *attr,
+			  union bpf_attr __user *uattr)
 {
 	u32 i, nfuncs, urec_size, min_size, prev_offset;
 	u32 krec_size = sizeof(struct bpf_func_info);
-	struct bpf_func_info *krecord = NULL;
+	struct bpf_func_info *krecord;
 	const struct btf_type *type;
+	struct bpf_prog *prog;
+	const struct btf *btf;
 	void __user *urecord;
-	struct btf *btf;
 	int ret = 0;
 
 	nfuncs = attr->func_info_cnt;
@@ -4668,20 +4670,15 @@ static int check_btf_func(struct bpf_prog *prog, struct bpf_verifier_env *env,
 		return -EINVAL;
 	}
 
-	btf = btf_get_by_fd(attr->prog_btf_fd);
-	if (IS_ERR(btf)) {
-		verbose(env, "unable to get btf from fd\n");
-		return PTR_ERR(btf);
-	}
+	prog = env->prog;
+	btf = prog->aux->btf;
 
 	urecord = u64_to_user_ptr(attr->func_info);
 	min_size = min_t(u32, krec_size, urec_size);
 
 	krecord = kvcalloc(nfuncs, krec_size, GFP_KERNEL | __GFP_NOWARN);
-	if (!krecord) {
-		ret = -ENOMEM;
-		goto free_btf;
-	}
+	if (!krecord)
+		return -ENOMEM;
 
 	for (i = 0; i < nfuncs; i++) {
 		ret = bpf_check_uarg_tail_zero(urecord, krec_size, urec_size);
@@ -4694,12 +4691,12 @@ static int check_btf_func(struct bpf_prog *prog, struct bpf_verifier_env *env,
 				if (put_user(min_size, &uattr->func_info_rec_size))
 					ret = -EFAULT;
 			}
-			goto free_btf;
+			goto err_free;
 		}
 
 		if (copy_from_user(&krecord[i], urecord, min_size)) {
 			ret = -EFAULT;
-			goto free_btf;
+			goto err_free;
 		}
 
 		/* check insn_off */
@@ -4709,20 +4706,20 @@ static int check_btf_func(struct bpf_prog *prog, struct bpf_verifier_env *env,
 					"nonzero insn_off %u for the first func info record",
 					krecord[i].insn_off);
 				ret = -EINVAL;
-				goto free_btf;
+				goto err_free;
 			}
 		} else if (krecord[i].insn_off <= prev_offset) {
 			verbose(env,
 				"same or smaller insn offset (%u) than previous func info record (%u)",
 				krecord[i].insn_off, prev_offset);
 			ret = -EINVAL;
-			goto free_btf;
+			goto err_free;
 		}
 
 		if (env->subprog_info[i].start != krecord[i].insn_off) {
 			verbose(env, "func_info BTF section doesn't match subprog layout in BPF program\n");
 			ret = -EINVAL;
-			goto free_btf;
+			goto err_free;
 		}
 
 		/* check type_id */
@@ -4731,20 +4728,18 @@ static int check_btf_func(struct bpf_prog *prog, struct bpf_verifier_env *env,
 			verbose(env, "invalid type id %d in func info",
 				krecord[i].type_id);
 			ret = -EINVAL;
-			goto free_btf;
+			goto err_free;
 		}
 
 		prev_offset = krecord[i].insn_off;
 		urecord += urec_size;
 	}
 
-	prog->aux->btf = btf;
 	prog->aux->func_info = krecord;
 	prog->aux->func_info_cnt = nfuncs;
 	return 0;
 
-free_btf:
-	btf_put(btf);
+err_free:
 	kvfree(krecord);
 	return ret;
 }
@@ -4760,6 +4755,150 @@ static void adjust_btf_func(struct bpf_verifier_env *env)
 		env->prog->aux->func_info[i].insn_off = env->subprog_info[i].start;
 }
 
+#define MIN_BPF_LINEINFO_SIZE	(offsetof(struct bpf_line_info, line_col) + \
+		sizeof(((struct bpf_line_info *)(0))->line_col))
+#define MAX_LINEINFO_REC_SIZE	MAX_FUNCINFO_REC_SIZE
+
+static int check_btf_line(struct bpf_verifier_env *env,
+			  const union bpf_attr *attr,
+			  union bpf_attr __user *uattr)
+{
+	u32 i, s, nr_linfo, ncopy, expected_size, rec_size, prev_offset = 0;
+	struct bpf_subprog_info *sub;
+	struct bpf_line_info *linfo;
+	struct bpf_prog *prog;
+	const struct btf *btf;
+	void __user *ulinfo;
+	int err;
+
+	nr_linfo = attr->line_info_cnt;
+	if (!nr_linfo)
+		return 0;
+
+	rec_size = attr->line_info_rec_size;
+	if (rec_size < MIN_BPF_LINEINFO_SIZE ||
+	    rec_size > MAX_LINEINFO_REC_SIZE ||
+	    rec_size & (sizeof(u32) - 1))
+		return -EINVAL;
+
+	/* Need to zero it in case the userspace may
+	 * pass in a smaller bpf_line_info object.
+	 */
+	linfo = kvcalloc(nr_linfo, sizeof(struct bpf_line_info),
+			 GFP_KERNEL | __GFP_NOWARN);
+	if (!linfo)
+		return -ENOMEM;
+
+	prog = env->prog;
+	btf = prog->aux->btf;
+
+	s = 0;
+	sub = env->subprog_info;
+	ulinfo = u64_to_user_ptr(attr->line_info);
+	expected_size = sizeof(struct bpf_line_info);
+	ncopy = min_t(u32, expected_size, rec_size);
+	for (i = 0; i < nr_linfo; i++) {
+		err = bpf_check_uarg_tail_zero(ulinfo, expected_size, rec_size);
+		if (err) {
+			if (err == -E2BIG) {
+				verbose(env, "nonzero tailing record in line_info");
+				if (put_user(expected_size,
+					     &uattr->line_info_rec_size))
+					err = -EFAULT;
+			}
+			goto err_free;
+		}
+
+		if (copy_from_user(&linfo[i], ulinfo, ncopy)) {
+			err = -EFAULT;
+			goto err_free;
+		}
+
+		/*
+		 * Check insn_off to ensure
+		 * 1) strictly increasing AND
+		 * 2) bounded by prog->len
+		 *
+		 * The linfo[0].insn_off == 0 check logically falls into
+		 * the later "missing bpf_line_info for func..." case
+		 * because the first linfo[0].insn_off must be the
+		 * first sub also and the first sub must have
+		 * subprog_info[0].start == 0.
+		 */
+		if ((i && linfo[i].insn_off <= prev_offset) ||
+		    linfo[i].insn_off >= prog->len) {
+			verbose(env, "Invalid line_info[%u].insn_off:%u (prev_offset:%u prog->len:%u)\n",
+				i, linfo[i].insn_off, prev_offset,
+				prog->len);
+			err = -EINVAL;
+			goto err_free;
+		}
+
+		if (!btf_name_offset_valid(btf, linfo[i].line_off) ||
+		    !btf_name_offset_valid(btf, linfo[i].file_name_off)) {
+			verbose(env, "Invalid line_info[%u].line_off or .file_name_off\n", i);
+			err = -EINVAL;
+			goto err_free;
+		}
+
+		if (s != env->subprog_cnt) {
+			if (linfo[i].insn_off == sub[s].start) {
+				sub[s].linfo_idx = i;
+				s++;
+			} else if (sub[s].start < linfo[i].insn_off) {
+				verbose(env, "missing bpf_line_info for func#%u\n", s);
+				err = -EINVAL;
+				goto err_free;
+			}
+		}
+
+		prev_offset = linfo[i].insn_off;
+		ulinfo += rec_size;
+	}
+
+	if (s != env->subprog_cnt) {
+		verbose(env, "missing bpf_line_info for %u funcs starting from func#%u\n",
+			env->subprog_cnt - s, s);
+		err = -EINVAL;
+		goto err_free;
+	}
+
+	prog->aux->linfo = linfo;
+	prog->aux->nr_linfo = nr_linfo;
+
+	return 0;
+
+err_free:
+	kvfree(linfo);
+	return err;
+}
+
+static int check_btf_info(struct bpf_verifier_env *env,
+			  const union bpf_attr *attr,
+			  union bpf_attr __user *uattr)
+{
+	struct btf *btf;
+	int err;
+
+	if (!attr->func_info_cnt && !attr->line_info_cnt)
+		return 0;
+
+	btf = btf_get_by_fd(attr->prog_btf_fd);
+	if (IS_ERR(btf))
+		return PTR_ERR(btf);
+	env->prog->aux->btf = btf;
+
+	err = check_btf_func(env, attr, uattr);
+	if (err)
+		return err;
+
+	err = check_btf_line(env, attr, uattr);
+	if (err)
+		return err;
+
+	return 0;
+}
+
 /* check %cur's range satisfies %old's */
 static bool range_within(struct bpf_reg_state *old,
 			 struct bpf_reg_state *cur)
@@ -6004,7 +6143,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
 	int i, j, subprog_start, subprog_end = 0, len, subprog;
 	struct bpf_insn *insn;
 	void *old_bpf_func;
-	int err = -ENOMEM;
+	int err;
 
 	if (env->subprog_cnt <= 1)
 		return 0;
@@ -6035,6 +6174,11 @@ static int jit_subprogs(struct bpf_verifier_env *env)
 		insn->imm = 1;
 	}
 
+	err = bpf_prog_alloc_jited_linfo(prog);
+	if (err)
+		goto out_undo_insn;
+
+	err = -ENOMEM;
 	func = kcalloc(env->subprog_cnt, sizeof(prog), GFP_KERNEL);
 	if (!func)
 		goto out_undo_insn;
@@ -6065,6 +6209,10 @@ static int jit_subprogs(struct bpf_verifier_env *env)
 		func[i]->aux->name[0] = 'F';
 		func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
 		func[i]->jit_requested = 1;
+		func[i]->aux->linfo = prog->aux->linfo;
+		func[i]->aux->nr_linfo = prog->aux->nr_linfo;
+		func[i]->aux->jited_linfo = prog->aux->jited_linfo;
+		func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx;
 		func[i] = bpf_int_jit_compile(func[i]);
 		if (!func[i]->jited) {
 			err = -ENOTSUPP;
@@ -6138,6 +6286,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
 	prog->bpf_func = func[0]->bpf_func;
 	prog->aux->func = func;
 	prog->aux->func_cnt = env->subprog_cnt;
+	bpf_prog_free_unused_jited_linfo(prog);
 	return 0;
 out_free:
 	for (i = 0; i < env->subprog_cnt; i++)
@@ -6154,6 +6303,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
 		insn->off = 0;
 		insn->imm = env->insn_aux_data[i].call_imm;
 	}
+	bpf_prog_free_jited_linfo(prog);
 	return err;
 }
 
@@ -6526,7 +6676,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 	if (ret < 0)
 		goto skip_full_check;
 
-	ret = check_btf_func(env->prog, env, attr, uattr);
+	ret = check_btf_info(env, attr, uattr);
 	if (ret < 0)
 		goto skip_full_check;
 

tools/bpf/bpftool/Documentation/bpftool-prog.rst

@@ -22,8 +22,8 @@ MAP COMMANDS
 =============
 
 |	**bpftool** **prog { show | list }** [*PROG*]
-|	**bpftool** **prog dump xlated** *PROG* [{**file** *FILE* | **opcodes** | **visual**}]
-|	**bpftool** **prog dump jited**  *PROG* [{**file** *FILE* | **opcodes**}]
+|	**bpftool** **prog dump xlated** *PROG* [{**file** *FILE* | **opcodes** | **visual** | **linum**}]
+|	**bpftool** **prog dump jited**  *PROG* [{**file** *FILE* | **opcodes** | **linum**}]
 |	**bpftool** **prog pin** *PROG* *FILE*
 |	**bpftool** **prog { load | loadall }** *OBJ* *PATH* [**type** *TYPE*] [**map** {**idx** *IDX* | **name** *NAME*} *MAP*] [**dev** *NAME*]
 |	**bpftool** **prog attach** *PROG* *ATTACH_TYPE* [*MAP*]
@@ -56,7 +56,7 @@ DESCRIPTION
 		  Output will start with program ID followed by program type and
 		  zero or more named attributes (depending on kernel version).
 
-	**bpftool prog dump xlated** *PROG* [{ **file** *FILE* | **opcodes** | **visual** }]
+	**bpftool prog dump xlated** *PROG* [{ **file** *FILE* | **opcodes** | **visual** | **linum** }]
 		  Dump eBPF instructions of the program from the kernel. By
 		  default, eBPF will be disassembled and printed to standard
 		  output in human-readable format. In this case, **opcodes**
@@ -69,13 +69,21 @@ DESCRIPTION
 		  built instead, and eBPF instructions will be presented with
 		  CFG in DOT format, on standard output.
 
-	**bpftool prog dump jited**  *PROG* [{ **file** *FILE* | **opcodes** }]
+		  If the prog has line_info available, the source line will
+		  be displayed by default.  If **linum** is specified,
+		  the filename, line number and line column will also be
+		  displayed on top of the source line.
+	**bpftool prog dump jited**  *PROG* [{ **file** *FILE* | **opcodes** | **linum** }]
 		  Dump jited image (host machine code) of the program.
 		  If *FILE* is specified image will be written to a file,
 		  otherwise it will be disassembled and printed to stdout.
 
 		  **opcodes** controls if raw opcodes will be printed.
 
+		  If the prog has line_info available, the source line will
+		  be displayed by default.  If **linum** is specified,
+		  the filename, line number and line column will also be
+		  displayed on top of the source line.
 	**bpftool prog pin** *PROG* *FILE*
 		  Pin program *PROG* as *FILE*.
 

tools/bpf/bpftool/bash-completion/bpftool

@@ -191,7 +191,7 @@ _bpftool()
 
     # Deal with simplest keywords
     case $prev in
-        help|hex|opcodes|visual)
+        help|hex|opcodes|visual|linum)
             return 0
             ;;
         tag)
@@ -278,10 +278,10 @@ _bpftool()
                     *)
                         _bpftool_once_attr 'file'
                         if _bpftool_search_list 'xlated'; then
-                            COMPREPLY+=( $( compgen -W 'opcodes visual' -- \
+                            COMPREPLY+=( $( compgen -W 'opcodes visual linum' -- \
                                 "$cur" ) )
                         else
-                            COMPREPLY+=( $( compgen -W 'opcodes' -- \
+                            COMPREPLY+=( $( compgen -W 'opcodes linum' -- \
                                 "$cur" ) )
                         fi
                         return 0

tools/bpf/bpftool/btf_dumper.c

@@ -385,3 +385,67 @@ void btf_dumper_type_only(const struct btf *btf, __u32 type_id, char *func_sig,
 	if (err < 0)
 		func_sig[0] = '\0';
 }
+
+static const char *ltrim(const char *s)
+{
+	while (isspace(*s))
+		s++;
+
+	return s;
+}
+
+void btf_dump_linfo_plain(const struct btf *btf,
+			  const struct bpf_line_info *linfo,
+			  const char *prefix, bool linum)
+{
+	const char *line = btf__name_by_offset(btf, linfo->line_off);
+
+	if (!line)
+		return;
+	line = ltrim(line);
+
+	if (!prefix)
+		prefix = "";
+
+	if (linum) {
+		const char *file = btf__name_by_offset(btf, linfo->file_name_off);
+
+		/* More forgiving on file because linum option is
+		 * expected to provide more info than the already
+		 * available src line.
+		 */
+		if (!file)
+			file = "";
+
+		printf("%s%s [file:%s line_num:%u line_col:%u]\n",
+		       prefix, line, file,
+		       BPF_LINE_INFO_LINE_NUM(linfo->line_col),
+		       BPF_LINE_INFO_LINE_COL(linfo->line_col));
+	} else {
+		printf("%s%s\n", prefix, line);
+	}
+}
+
+void btf_dump_linfo_json(const struct btf *btf,
+			 const struct bpf_line_info *linfo, bool linum)
+{
+	const char *line = btf__name_by_offset(btf, linfo->line_off);
+
+	if (line)
+		jsonw_string_field(json_wtr, "src", ltrim(line));
+
+	if (linum) {
+		const char *file = btf__name_by_offset(btf, linfo->file_name_off);
+
+		if (file)
+			jsonw_string_field(json_wtr, "file", file);
+
+		if (BPF_LINE_INFO_LINE_NUM(linfo->line_col))
+			jsonw_int_field(json_wtr, "line_num",
+					BPF_LINE_INFO_LINE_NUM(linfo->line_col));
+
+		if (BPF_LINE_INFO_LINE_COL(linfo->line_col))
+			jsonw_int_field(json_wtr, "line_col",
+					BPF_LINE_INFO_LINE_COL(linfo->line_col));
+	}
+}

tools/bpf/bpftool/jit_disasm.c

@@ -21,6 +21,7 @@
 #include <dis-asm.h>
 #include <sys/stat.h>
 #include <limits.h>
+#include <libbpf.h>
 
 #include "json_writer.h"
 #include "main.h"
@@ -68,10 +69,16 @@ static int fprintf_json(void *out, const char *fmt, ...)
 }
 
 void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
-		       const char *arch, const char *disassembler_options)
+		       const char *arch, const char *disassembler_options,
+		       const struct btf *btf,
+		       const struct bpf_prog_linfo *prog_linfo,
+		       __u64 func_ksym, unsigned int func_idx,
+		       bool linum)
 {
+	const struct bpf_line_info *linfo = NULL;
 	disassembler_ftype disassemble;
 	struct disassemble_info info;
+	unsigned int nr_skip = 0;
 	int count, i, pc = 0;
 	char tpath[PATH_MAX];
 	bfd *bfdf;
@@ -127,12 +134,26 @@ void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
 	if (json_output)
 		jsonw_start_array(json_wtr);
 	do {
+		if (prog_linfo) {
+			linfo = bpf_prog_linfo__lfind_addr_func(prog_linfo,
+								func_ksym + pc,
+								func_idx,
+								nr_skip);
+			if (linfo)
+				nr_skip++;
+		}
+
 		if (json_output) {
 			jsonw_start_object(json_wtr);
 			oper_count = 0;
+			if (linfo)
+				btf_dump_linfo_json(btf, linfo, linum);
 			jsonw_name(json_wtr, "pc");
 			jsonw_printf(json_wtr, "\"0x%x\"", pc);
 		} else {
+			if (linfo)
+				btf_dump_linfo_plain(btf, linfo, "; ",
+						     linum);
 			printf("%4x:\t", pc);
 		}
 

tools/bpf/bpftool/main.h

@@ -138,6 +138,9 @@ struct pinned_obj {
 	struct hlist_node hash;
 };
 
+struct btf;
+struct bpf_line_info;
+
 int build_pinned_obj_table(struct pinned_obj_table *table,
 			   enum bpf_obj_type type);
 void delete_pinned_obj_table(struct pinned_obj_table *tab);
@@ -175,13 +178,23 @@ int map_parse_fd(int *argc, char ***argv);
 int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 *info_len);
 
 #ifdef HAVE_LIBBFD_SUPPORT
+struct bpf_prog_linfo;
 void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
-		       const char *arch, const char *disassembler_options);
+		       const char *arch, const char *disassembler_options,
+		       const struct btf *btf,
+		       const struct bpf_prog_linfo *prog_linfo,
+		       __u64 func_ksym, unsigned int func_idx,
+		       bool linum);
 int disasm_init(void);
 #else
 static inline
 void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
-		       const char *arch, const char *disassembler_options)
+		       const char *arch, const char *disassembler_options,
+		       const struct btf *btf,
+		       const struct bpf_prog_linfo *prog_linfo,
+		       __u64 func_ksym, unsigned int func_idx,
+		       bool linum)
+
 {
 }
 static inline int disasm_init(void)
@@ -217,6 +230,12 @@ int btf_dumper_type(const struct btf_dumper *d, __u32 type_id,
 void btf_dumper_type_only(const struct btf *btf, __u32 func_type_id,
 			  char *func_only, int size);
 
+void btf_dump_linfo_plain(const struct btf *btf,
+			  const struct bpf_line_info *linfo,
+			  const char *prefix, bool linum);
+void btf_dump_linfo_json(const struct btf *btf,
+			 const struct bpf_line_info *linfo, bool linum);
+
 struct nlattr;
 struct ifinfomsg;
 struct tcmsg;

tools/bpf/bpftool/prog.c

@@ -423,24 +423,26 @@ static int do_show(int argc, char **argv)
 
 static int do_dump(int argc, char **argv)
 {
+	unsigned int finfo_rec_size, linfo_rec_size, jited_linfo_rec_size;
+	void *func_info = NULL, *linfo = NULL, *jited_linfo = NULL;
+	unsigned int finfo_cnt, linfo_cnt = 0, jited_linfo_cnt = 0;
+	struct bpf_prog_linfo *prog_linfo = NULL;
 	unsigned long *func_ksyms = NULL;
 	struct bpf_prog_info info = {};
 	unsigned int *func_lens = NULL;
 	const char *disasm_opt = NULL;
-	unsigned int finfo_rec_size;
 	unsigned int nr_func_ksyms;
 	unsigned int nr_func_lens;
 	struct dump_data dd = {};
 	__u32 len = sizeof(info);
 	struct btf *btf = NULL;
-	void *func_info = NULL;
-	unsigned int finfo_cnt;
 	unsigned int buf_size;
 	char *filepath = NULL;
 	bool opcodes = false;
 	bool visual = false;
 	char func_sig[1024];
 	unsigned char *buf;
+	bool linum = false;
 	__u32 *member_len;
 	__u64 *member_ptr;
 	ssize_t n;
@@ -484,6 +486,9 @@ static int do_dump(int argc, char **argv)
 	} else if (is_prefix(*argv, "visual")) {
 		visual = true;
 		NEXT_ARG();
+	} else if (is_prefix(*argv, "linum")) {
+		linum = true;
+		NEXT_ARG();
 	}
 
 	if (argc) {
@@ -543,6 +548,32 @@ static int do_dump(int argc, char **argv)
 		}
 	}
 
+	linfo_rec_size = info.line_info_rec_size;
+	if (info.line_info_cnt && linfo_rec_size && info.btf_id) {
+		linfo_cnt = info.line_info_cnt;
+		linfo = malloc(linfo_cnt * linfo_rec_size);
+		if (!linfo) {
+			p_err("mem alloc failed");
+			close(fd);
+			goto err_free;
+		}
+	}
+
+	jited_linfo_rec_size = info.jited_line_info_rec_size;
+	if (info.jited_line_info_cnt &&
+	    jited_linfo_rec_size &&
+	    info.nr_jited_ksyms &&
+	    info.nr_jited_func_lens &&
+	    info.btf_id) {
+		jited_linfo_cnt = info.jited_line_info_cnt;
+		jited_linfo = malloc(jited_linfo_cnt * jited_linfo_rec_size);
+		if (!jited_linfo) {
+			p_err("mem alloc failed");
+			close(fd);
+			goto err_free;
+		}
+	}
+
 	memset(&info, 0, sizeof(info));
 
 	*member_ptr = ptr_to_u64(buf);
@@ -554,6 +585,13 @@ static int do_dump(int argc, char **argv)
 	info.func_info_cnt = finfo_cnt;
 	info.func_info_rec_size = finfo_rec_size;
 	info.func_info = ptr_to_u64(func_info);
+	info.line_info_cnt = linfo_cnt;
+	info.line_info_rec_size = linfo_rec_size;
+	info.line_info = ptr_to_u64(linfo);
+	info.jited_line_info_cnt = jited_linfo_cnt;
+	info.jited_line_info_rec_size = jited_linfo_rec_size;
+	info.jited_line_info = ptr_to_u64(jited_linfo);
+
 
 	err = bpf_obj_get_info_by_fd(fd, &info, &len);
 	close(fd);
@@ -596,6 +634,30 @@ static int do_dump(int argc, char **argv)
 		finfo_cnt = 0;
 	}
 
+	if (linfo && info.line_info_cnt != linfo_cnt) {
+		p_err("incorrect line_info_cnt %u vs. expected %u",
+		      info.line_info_cnt, linfo_cnt);
+		goto err_free;
+	}
+
+	if (info.line_info_rec_size != linfo_rec_size) {
+		p_err("incorrect line_info_rec_size %u vs. expected %u",
+		      info.line_info_rec_size, linfo_rec_size);
+		goto err_free;
+	}
+
+	if (jited_linfo && info.jited_line_info_cnt != jited_linfo_cnt) {
+		p_err("incorrect jited_line_info_cnt %u vs. expected %u",
+		      info.jited_line_info_cnt, jited_linfo_cnt);
+		goto err_free;
+	}
+
+	if (info.jited_line_info_rec_size != jited_linfo_rec_size) {
+		p_err("incorrect jited_line_info_rec_size %u vs. expected %u",
+		      info.jited_line_info_rec_size, jited_linfo_rec_size);
+		goto err_free;
+	}
+
 	if ((member_len == &info.jited_prog_len &&
 	     info.jited_prog_insns == 0) ||
 	    (member_len == &info.xlated_prog_len &&
@@ -609,6 +671,12 @@ static int do_dump(int argc, char **argv)
 		goto err_free;
 	}
 
+	if (linfo_cnt) {
+		prog_linfo = bpf_prog_linfo__new(&info);
+		if (!prog_linfo)
+			p_err("error in processing bpf_line_info.  continue without it.");
+	}
+
 	if (filepath) {
 		fd = open(filepath, O_WRONLY | O_CREAT | O_TRUNC, 0600);
 		if (fd < 0) {
@@ -690,8 +758,11 @@ static int do_dump(int argc, char **argv)
 					printf("%s:\n", sym_name);
 				}
 
-				disasm_print_insn(img, lens[i], opcodes, name,
-						  disasm_opt);
+				disasm_print_insn(img, lens[i], opcodes,
+						  name, disasm_opt, btf,
+						  prog_linfo, ksyms[i], i,
+						  linum);
+
 				img += lens[i];
 
 				if (json_output)
@@ -704,7 +775,7 @@ static int do_dump(int argc, char **argv)
 				jsonw_end_array(json_wtr);
 		} else {
 			disasm_print_insn(buf, *member_len, opcodes, name,
-					  disasm_opt);
+					  disasm_opt, btf, NULL, 0, 0, false);
 		}
 	} else if (visual) {
 		if (json_output)
@@ -718,11 +789,14 @@ static int do_dump(int argc, char **argv)
 		dd.btf = btf;
 		dd.func_info = func_info;
 		dd.finfo_rec_size = finfo_rec_size;
+		dd.prog_linfo = prog_linfo;
 
 		if (json_output)
-			dump_xlated_json(&dd, buf, *member_len, opcodes);
+			dump_xlated_json(&dd, buf, *member_len, opcodes,
+					 linum);
 		else
-			dump_xlated_plain(&dd, buf, *member_len, opcodes);
+			dump_xlated_plain(&dd, buf, *member_len, opcodes,
+					  linum);
 		kernel_syms_destroy(&dd);
 	}
 
@@ -730,6 +804,9 @@ static int do_dump(int argc, char **argv)
 	free(func_ksyms);
 	free(func_lens);
 	free(func_info);
+	free(linfo);
+	free(jited_linfo);
+	bpf_prog_linfo__free(prog_linfo);
 	return 0;
 
 err_free:
@@ -737,6 +814,9 @@ static int do_dump(int argc, char **argv)
 	free(func_ksyms);
 	free(func_lens);
 	free(func_info);
+	free(linfo);
+	free(jited_linfo);
+	bpf_prog_linfo__free(prog_linfo);
 	return -1;
 }
 
@@ -1138,8 +1218,8 @@ static int do_help(int argc, char **argv)
 
 	fprintf(stderr,
 		"Usage: %s %s { show | list } [PROG]\n"
-		"       %s %s dump xlated PROG [{ file FILE | opcodes | visual }]\n"
-		"       %s %s dump jited  PROG [{ file FILE | opcodes }]\n"
+		"       %s %s dump xlated PROG [{ file FILE | opcodes | visual | linum }]\n"
+		"       %s %s dump jited  PROG [{ file FILE | opcodes | linum }]\n"
 		"       %s %s pin   PROG FILE\n"
 		"       %s %s { load | loadall } OBJ  PATH \\\n"
 		"                         [type TYPE] [dev NAME] \\\n"

tools/bpf/bpftool/xlated_dumper.c

@@ -41,6 +41,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
+#include <libbpf.h>
 
 #include "disasm.h"
 #include "json_writer.h"
@@ -234,8 +235,9 @@ static const char *print_imm(void *private_data,
 }
 
 void dump_xlated_json(struct dump_data *dd, void *buf, unsigned int len,
-		      bool opcodes)
+		      bool opcodes, bool linum)
 {
+	const struct bpf_prog_linfo *prog_linfo = dd->prog_linfo;
 	const struct bpf_insn_cbs cbs = {
 		.cb_print	= print_insn_json,
 		.cb_call	= print_call,
@@ -246,6 +248,7 @@ void dump_xlated_json(struct dump_data *dd, void *buf, unsigned int len,
 	struct bpf_insn *insn = buf;
 	struct btf *btf = dd->btf;
 	bool double_insn = false;
+	unsigned int nr_skip = 0;
 	char func_sig[1024];
 	unsigned int i;
 
@@ -273,6 +276,16 @@ void dump_xlated_json(struct dump_data *dd, void *buf, unsigned int len,
 			}
 		}
 
+		if (prog_linfo) {
+			const struct bpf_line_info *linfo;
+
+			linfo = bpf_prog_linfo__lfind(prog_linfo, i, nr_skip);
+			if (linfo) {
+				btf_dump_linfo_json(btf, linfo, linum);
+				nr_skip++;
+			}
+		}
+
 		jsonw_name(json_wtr, "disasm");
 		print_bpf_insn(&cbs, insn + i, true);
 
@@ -307,8 +320,9 @@ void dump_xlated_json(struct dump_data *dd, void *buf, unsigned int len,
 }
 
 void dump_xlated_plain(struct dump_data *dd, void *buf, unsigned int len,
-		       bool opcodes)
+		       bool opcodes, bool linum)
 {
+	const struct bpf_prog_linfo *prog_linfo = dd->prog_linfo;
 	const struct bpf_insn_cbs cbs = {
 		.cb_print	= print_insn,
 		.cb_call	= print_call,
@@ -318,6 +332,7 @@ void dump_xlated_plain(struct dump_data *dd, void *buf, unsigned int len,
 	struct bpf_func_info *record;
 	struct bpf_insn *insn = buf;
 	struct btf *btf = dd->btf;
+	unsigned int nr_skip = 0;
 	bool double_insn = false;
 	char func_sig[1024];
 	unsigned int i;
@@ -340,6 +355,17 @@ void dump_xlated_plain(struct dump_data *dd, void *buf, unsigned int len,
 			}
 		}
 
+		if (prog_linfo) {
+			const struct bpf_line_info *linfo;
+
+			linfo = bpf_prog_linfo__lfind(prog_linfo, i, nr_skip);
+			if (linfo) {
+				btf_dump_linfo_plain(btf, linfo, "; ",
+						     linum);
+				nr_skip++;
+			}
+		}
+
 		double_insn = insn[i].code == (BPF_LD | BPF_IMM | BPF_DW);
 
 		printf("% 4d: ", i);

tools/bpf/bpftool/xlated_dumper.h

@@ -40,6 +40,8 @@
 
 #define SYM_MAX_NAME	256
 
+struct bpf_prog_linfo;
+
 struct kernel_sym {
 	unsigned long address;
 	char name[SYM_MAX_NAME];
@@ -54,6 +56,7 @@ struct dump_data {
 	struct btf *btf;
 	void *func_info;
 	__u32 finfo_rec_size;
+	const struct bpf_prog_linfo *prog_linfo;
 	char scratch_buff[SYM_MAX_NAME + 8];
 };
 
@@ -61,9 +64,9 @@ void kernel_syms_load(struct dump_data *dd);
 void kernel_syms_destroy(struct dump_data *dd);
 struct kernel_sym *kernel_syms_search(struct dump_data *dd, unsigned long key);
 void dump_xlated_json(struct dump_data *dd, void *buf, unsigned int len,
-		      bool opcodes);
+		       bool opcodes, bool linum);
 void dump_xlated_plain(struct dump_data *dd, void *buf, unsigned int len,
-		       bool opcodes);
+		       bool opcodes, bool linum);
 void dump_xlated_for_graph(struct dump_data *dd, void *buf, void *buf_end,
 			   unsigned int start_index);
 

tools/include/uapi/linux/bpf.h

@@ -356,6 +356,9 @@ union bpf_attr {
 		__u32		func_info_rec_size;	/* userspace bpf_func_info size */
 		__aligned_u64	func_info;	/* func info */
 		__u32		func_info_cnt;	/* number of bpf_func_info records */
+		__u32		line_info_rec_size;	/* userspace bpf_line_info size */
+		__aligned_u64	line_info;	/* line info */
+		__u32		line_info_cnt;	/* number of bpf_line_info records */
 	};
 
 	struct { /* anonymous struct used by BPF_OBJ_* commands */
@@ -2679,6 +2682,12 @@ struct bpf_prog_info {
 	__u32 func_info_rec_size;
 	__aligned_u64 func_info;
 	__u32 func_info_cnt;
+	__u32 line_info_cnt;
+	__aligned_u64 line_info;
+	__aligned_u64 jited_line_info;
+	__u32 jited_line_info_cnt;
+	__u32 line_info_rec_size;
+	__u32 jited_line_info_rec_size;
 } __attribute__((aligned(8)));
 
 struct bpf_map_info {
@@ -2995,4 +3004,14 @@ struct bpf_func_info {
 	__u32	type_id;
 };
 
+#define BPF_LINE_INFO_LINE_NUM(line_col)	((line_col) >> 10)
+#define BPF_LINE_INFO_LINE_COL(line_col)	((line_col) & 0x3ff)
+
+struct bpf_line_info {
+	__u32	insn_off;
+	__u32	file_name_off;
+	__u32	line_off;
+	__u32	line_col;
+};
+
 #endif /* _UAPI__LINUX_BPF_H__ */

tools/lib/bpf/Build

-libbpf-y := libbpf.o bpf.o nlattr.o btf.o libbpf_errno.o str_error.o netlink.o
+libbpf-y := libbpf.o bpf.o nlattr.o btf.o libbpf_errno.o str_error.o netlink.o bpf_prog_linfo.o

tools/lib/bpf/bpf.c

@@ -173,11 +173,36 @@ int bpf_create_map_in_map(enum bpf_map_type map_type, const char *name,
 					  -1);
 }
 
+static void *
+alloc_zero_tailing_info(const void *orecord, __u32 cnt,
+			__u32 actual_rec_size, __u32 expected_rec_size)
+{
+	__u64 info_len = actual_rec_size * cnt;
+	void *info, *nrecord;
+	int i;
+
+	info = malloc(info_len);
+	if (!info)
+		return NULL;
+
+	/* zero out bytes kernel does not understand */
+	nrecord = info;
+	for (i = 0; i < cnt; i++) {
+		memcpy(nrecord, orecord, expected_rec_size);
+		memset(nrecord + expected_rec_size, 0,
+		       actual_rec_size - expected_rec_size);
+		orecord += actual_rec_size;
+		nrecord += actual_rec_size;
+	}
+
+	return info;
+}
+
 int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
 			   char *log_buf, size_t log_buf_sz)
 {
+	void *finfo = NULL, *linfo = NULL;
 	union bpf_attr attr;
-	void *finfo = NULL;
 	__u32 name_len;
 	int fd;
 
@@ -201,53 +226,58 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
 	attr.func_info_rec_size = load_attr->func_info_rec_size;
 	attr.func_info_cnt = load_attr->func_info_cnt;
 	attr.func_info = ptr_to_u64(load_attr->func_info);
+	attr.line_info_rec_size = load_attr->line_info_rec_size;
+	attr.line_info_cnt = load_attr->line_info_cnt;
+	attr.line_info = ptr_to_u64(load_attr->line_info);
 	memcpy(attr.prog_name, load_attr->name,
 	       min(name_len, BPF_OBJ_NAME_LEN - 1));
 
 	fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
-	if (fd >= 0 || !log_buf || !log_buf_sz)
+	if (fd >= 0)
 		return fd;
 
 	/* After bpf_prog_load, the kernel may modify certain attributes
 	 * to give user space a hint how to deal with loading failure.
 	 * Check to see whether we can make some changes and load again.
 	 */
-	if (errno == E2BIG && attr.func_info_cnt &&
+	while (errno == E2BIG && (!finfo || !linfo)) {
+		if (!finfo && attr.func_info_cnt &&
 		    attr.func_info_rec_size < load_attr->func_info_rec_size) {
-		__u32 actual_rec_size = load_attr->func_info_rec_size;
-		__u32 expected_rec_size = attr.func_info_rec_size;
-		__u32 finfo_cnt = load_attr->func_info_cnt;
-		__u64 finfo_len = actual_rec_size * finfo_cnt;
-		const void *orecord;
-		void *nrecord;
-		int i;
-
-		finfo = malloc(finfo_len);
+			/* try with corrected func info records */
+			finfo = alloc_zero_tailing_info(load_attr->func_info,
+							load_attr->func_info_cnt,
+							load_attr->func_info_rec_size,
+							attr.func_info_rec_size);
 			if (!finfo)
-			/* further try with log buffer won't help */
-			return fd;
-
-		/* zero out bytes kernel does not understand */
-		orecord = load_attr->func_info;
-		nrecord = finfo;
-		for (i = 0; i < load_attr->func_info_cnt; i++) {
-			memcpy(nrecord, orecord, expected_rec_size);
-			memset(nrecord + expected_rec_size, 0,
-			       actual_rec_size - expected_rec_size);
-			orecord += actual_rec_size;
-			nrecord += actual_rec_size;
-		}
+				goto done;
 
-		/* try with corrected func info records */
 			attr.func_info = ptr_to_u64(finfo);
 			attr.func_info_rec_size = load_attr->func_info_rec_size;
+		} else if (!linfo && attr.line_info_cnt &&
+			   attr.line_info_rec_size <
+			   load_attr->line_info_rec_size) {
+			linfo = alloc_zero_tailing_info(load_attr->line_info,
+							load_attr->line_info_cnt,
+							load_attr->line_info_rec_size,
+							attr.line_info_rec_size);
+			if (!linfo)
+				goto done;
+
+			attr.line_info = ptr_to_u64(linfo);
+			attr.line_info_rec_size = load_attr->line_info_rec_size;
+		} else {
+			break;
+		}
 
 		fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
 
-		if (fd >= 0 || !log_buf || !log_buf_sz)
+		if (fd >= 0)
 			goto done;
 	}
 
+	if (!log_buf || !log_buf_sz)
+		goto done;
+
 	/* Try again with log */
 	attr.log_buf = ptr_to_u64(log_buf);
 	attr.log_size = log_buf_sz;
@@ -256,6 +286,7 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
 	fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
 done:
 	free(finfo);
+	free(linfo);
 	return fd;
 }
 

tools/lib/bpf/bpf.h

@@ -82,6 +82,9 @@ struct bpf_load_program_attr {
 	__u32 func_info_rec_size;
 	const void *func_info;
 	__u32 func_info_cnt;
+	__u32 line_info_rec_size;
+	const void *line_info;
+	__u32 line_info_cnt;
 };
 
 /* Flags to direct loading requirements */

tools/lib/bpf/bpf_prog_linfo.c

+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2018 Facebook */
+
+#include <string.h>
+#include <stdlib.h>
+#include <linux/err.h>
+#include <linux/bpf.h>
+#include "libbpf.h"
+
+#ifndef min
+#define min(x, y) ((x) < (y) ? (x) : (y))
+#endif
+
+struct bpf_prog_linfo {
+	void *raw_linfo;
+	void *raw_jited_linfo;
+	__u32 *nr_jited_linfo_per_func;
+	__u32 *jited_linfo_func_idx;
+	__u32 nr_linfo;
+	__u32 nr_jited_func;
+	__u32 rec_size;
+	__u32 jited_rec_size;
+};
+
+static int dissect_jited_func(struct bpf_prog_linfo *prog_linfo,
+			      const __u64 *ksym_func, const __u32 *ksym_len)
+{
+	__u32 nr_jited_func, nr_linfo;
+	const void *raw_jited_linfo;
+	const __u64 *jited_linfo;
+	__u64 last_jited_linfo;
+	/*
+	 * Index to raw_jited_linfo:
+	 *      i: Index for searching the next ksym_func
+	 * prev_i: Index to the last found ksym_func
+	 */
+	__u32 i, prev_i;
+	__u32 f; /* Index to ksym_func */
+
+	raw_jited_linfo = prog_linfo->raw_jited_linfo;
+	jited_linfo = raw_jited_linfo;
+	if (ksym_func[0] != *jited_linfo)
+		goto errout;
+
+	prog_linfo->jited_linfo_func_idx[0] = 0;
+	nr_jited_func = prog_linfo->nr_jited_func;
+	nr_linfo = prog_linfo->nr_linfo;
+
+	for (prev_i = 0, i = 1, f = 1;
+	     i < nr_linfo && f < nr_jited_func;
+	     i++) {
+		raw_jited_linfo += prog_linfo->jited_rec_size;
+		last_jited_linfo = *jited_linfo;
+		jited_linfo = raw_jited_linfo;
+
+		if (ksym_func[f] == *jited_linfo) {
+			prog_linfo->jited_linfo_func_idx[f] = i;
+
+			/* Sanity check */
+			if (last_jited_linfo - ksym_func[f - 1] + 1 >
+			    ksym_len[f - 1])
+				goto errout;
+
+			prog_linfo->nr_jited_linfo_per_func[f - 1] =
+				i - prev_i;
+			prev_i = i;
+
+			/*
+			 * The ksym_func[f] is found in jited_linfo.
+			 * Look for the next one.
+			 */
+			f++;
+		} else if (*jited_linfo <= last_jited_linfo) {
+			/* Ensure the addr is increasing _within_ a func */
+			goto errout;
+		}
+	}
+
+	if (f != nr_jited_func)
+		goto errout;
+
+	prog_linfo->nr_jited_linfo_per_func[nr_jited_func - 1] =
+		nr_linfo - prev_i;
+
+	return 0;
+
+errout:
+	return -EINVAL;
+}
+
+void bpf_prog_linfo__free(struct bpf_prog_linfo *prog_linfo)
+{
+	if (!prog_linfo)
+		return;
+
+	free(prog_linfo->raw_linfo);
+	free(prog_linfo->raw_jited_linfo);
+	free(prog_linfo->nr_jited_linfo_per_func);
+	free(prog_linfo->jited_linfo_func_idx);
+	free(prog_linfo);
+}
+
+struct bpf_prog_linfo *bpf_prog_linfo__new(const struct bpf_prog_info *info)
+{
+	struct bpf_prog_linfo *prog_linfo;
+	__u32 nr_linfo, nr_jited_func;
+
+	nr_linfo = info->line_info_cnt;
+
+	/*
+	 * Test !info->line_info because the kernel may NULL
+	 * the ptr if kernel.kptr_restrict is set.
+	 */
+	if (!nr_linfo || !info->line_info)
+		return NULL;
+
+	/*
+	 * The min size that bpf_prog_linfo has to access for
+	 * searching purpose.
+	 */
+	if (info->line_info_rec_size <
+	    offsetof(struct bpf_line_info, file_name_off))
+		return NULL;
+
+	prog_linfo = calloc(1, sizeof(*prog_linfo));
+	if (!prog_linfo)
+		return NULL;
+
+	/* Copy xlated line_info */
+	prog_linfo->nr_linfo = nr_linfo;
+	prog_linfo->rec_size = info->line_info_rec_size;
+	prog_linfo->raw_linfo = malloc(nr_linfo * prog_linfo->rec_size);
+	if (!prog_linfo->raw_linfo)
+		goto err_free;
+	memcpy(prog_linfo->raw_linfo, (void *)(long)info->line_info,
+	       nr_linfo * prog_linfo->rec_size);
+
+	nr_jited_func = info->nr_jited_ksyms;
+	if (!nr_jited_func ||
+	    !info->jited_line_info ||
+	    info->jited_line_info_cnt != nr_linfo ||
+	    info->jited_line_info_rec_size < sizeof(__u64) ||
+	    info->nr_jited_func_lens != nr_jited_func ||
+	    !info->jited_ksyms ||
+	    !info->jited_func_lens)
+		/* Not enough info to provide jited_line_info */
+		return prog_linfo;
+
+	/* Copy jited_line_info */
+	prog_linfo->nr_jited_func = nr_jited_func;
+	prog_linfo->jited_rec_size = info->jited_line_info_rec_size;
+	prog_linfo->raw_jited_linfo = malloc(nr_linfo *
+					     prog_linfo->jited_rec_size);
+	if (!prog_linfo->raw_jited_linfo)
+		goto err_free;
+	memcpy(prog_linfo->raw_jited_linfo,
+	       (void *)(long)info->jited_line_info,
+	       nr_linfo * prog_linfo->jited_rec_size);
+
+	/* Number of jited_line_info per jited func */
+	prog_linfo->nr_jited_linfo_per_func = malloc(nr_jited_func *
+						     sizeof(__u32));
+	if (!prog_linfo->nr_jited_linfo_per_func)
+		goto err_free;
+
+	/*
+	 * For each jited func,
+	 * the start idx to the "linfo" and "jited_linfo" array,
+	 */
+	prog_linfo->jited_linfo_func_idx = malloc(nr_jited_func *
+						  sizeof(__u32));
+	if (!prog_linfo->jited_linfo_func_idx)
+		goto err_free;
+
+	if (dissect_jited_func(prog_linfo,
+			       (__u64 *)(long)info->jited_ksyms,
+			       (__u32 *)(long)info->jited_func_lens))
+		goto err_free;
+
+	return prog_linfo;
+
+err_free:
+	bpf_prog_linfo__free(prog_linfo);
+	return NULL;
+}
+
+const struct bpf_line_info *
+bpf_prog_linfo__lfind_addr_func(const struct bpf_prog_linfo *prog_linfo,
+				__u64 addr, __u32 func_idx, __u32 nr_skip)
+{
+	__u32 jited_rec_size, rec_size, nr_linfo, start, i;
+	const void *raw_jited_linfo, *raw_linfo;
+	const __u64 *jited_linfo;
+
+	if (func_idx >= prog_linfo->nr_jited_func)
+		return NULL;
+
+	nr_linfo = prog_linfo->nr_jited_linfo_per_func[func_idx];
+	if (nr_skip >= nr_linfo)
+		return NULL;
+
+	start = prog_linfo->jited_linfo_func_idx[func_idx] + nr_skip;
+	jited_rec_size = prog_linfo->jited_rec_size;
+	raw_jited_linfo = prog_linfo->raw_jited_linfo +
+		(start * jited_rec_size);
+	jited_linfo = raw_jited_linfo;
+	if (addr < *jited_linfo)
+		return NULL;
+
+	nr_linfo -= nr_skip;
+	rec_size = prog_linfo->rec_size;
+	raw_linfo = prog_linfo->raw_linfo + (start * rec_size);
+	for (i = 0; i < nr_linfo; i++) {
+		if (addr < *jited_linfo)
+			break;
+
+		raw_linfo += rec_size;
+		raw_jited_linfo += jited_rec_size;
+		jited_linfo = raw_jited_linfo;
+	}
+
+	return raw_linfo - rec_size;
+}
+
+const struct bpf_line_info *
+bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
+		      __u32 insn_off, __u32 nr_skip)
+{
+	const struct bpf_line_info *linfo;
+	__u32 rec_size, nr_linfo, i;
+	const void *raw_linfo;
+
+	nr_linfo = prog_linfo->nr_linfo;
+	if (nr_skip >= nr_linfo)
+		return NULL;
+
+	rec_size = prog_linfo->rec_size;
+	raw_linfo = prog_linfo->raw_linfo + (nr_skip * rec_size);
+	linfo = raw_linfo;
+	if (insn_off < linfo->insn_off)
+		return NULL;
+
+	nr_linfo -= nr_skip;
+	for (i = 0; i < nr_linfo; i++) {
+		if (insn_off < linfo->insn_off)
+			break;
+
+		raw_linfo += rec_size;
+		linfo = raw_linfo;
+	}
+
+	return raw_linfo - rec_size;
+}

tools/lib/bpf/btf.h

@@ -51,13 +51,8 @@ struct btf_ext_header {
 	/* All offsets are in bytes relative to the end of this header */
 	__u32	func_info_off;
 	__u32	func_info_len;
-};
-
-struct btf_sec_func_info {
-	__u32	sec_name_off;
-	__u32	num_func_info;
-	/* Followed by num_func_info number of bpf func_info records */
-	__u8	data[0];
+	__u32	line_info_off;
+	__u32	line_info_len;
 };
 
 typedef int (*btf_print_fn_t)(const char *, ...)
@@ -77,12 +72,16 @@ LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);
 
 struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
 void btf_ext__free(struct btf_ext *btf_ext);
-int btf_ext__reloc_init(struct btf *btf, struct btf_ext *btf_ext,
-			const char *sec_name, void **func_info,
-			__u32 *func_info_rec_size, __u32 *func_info_len);
-int btf_ext__reloc(struct btf *btf, struct btf_ext *btf_ext,
-		   const char *sec_name, __u32 insns_cnt, void **func_info,
-		   __u32 *func_info_len);
+int btf_ext__reloc_func_info(const struct btf *btf,
+			     const struct btf_ext *btf_ext,
+			     const char *sec_name, __u32 insns_cnt,
+			     void **func_info, __u32 *func_info_len);
+int btf_ext__reloc_line_info(const struct btf *btf,
+			     const struct btf_ext *btf_ext,
+			     const char *sec_name, __u32 insns_cnt,
+			     void **line_info, __u32 *cnt);
+__u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
+__u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);
 
 #ifdef __cplusplus
 } /* extern "C" */

tools/lib/bpf/libbpf.c

@@ -167,9 +167,13 @@ struct bpf_program {
 	int btf_fd;
 	void *func_info;
 	__u32 func_info_rec_size;
-	__u32 func_info_len;
+	__u32 func_info_cnt;
 
 	struct bpf_capabilities *caps;
+
+	void *line_info;
+	__u32 line_info_rec_size;
+	__u32 line_info_cnt;
 };
 
 struct bpf_map {
@@ -779,6 +783,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 {
 	Elf *elf = obj->efile.elf;
 	GElf_Ehdr *ep = &obj->efile.ehdr;
+	Elf_Data *btf_ext_data = NULL;
 	Elf_Scn *scn = NULL;
 	int idx = 0, err = 0;
 
@@ -841,14 +846,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 				obj->btf = NULL;
 			}
 		} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
-			obj->btf_ext = btf_ext__new(data->d_buf, data->d_size,
-						    __pr_debug);
-			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;
-			}
+			btf_ext_data = data;
 		} else if (sh.sh_type == SHT_SYMTAB) {
 			if (obj->efile.symbols) {
 				pr_warning("bpf: multiple SYMTAB in %s\n",
@@ -910,6 +908,22 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 		pr_warning("Corrupted ELF file: index of strtab invalid\n");
 		return LIBBPF_ERRNO__FORMAT;
 	}
+	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,
+						    __pr_debug);
+			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;
+			}
+		}
+	}
 	if (obj->efile.maps_shndx >= 0) {
 		err = bpf_object__init_maps(obj, flags);
 		if (err)
@@ -1275,6 +1289,82 @@ bpf_object__create_maps(struct bpf_object *obj)
 	return 0;
 }
 
+static int
+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);
+		return err;
+	}
+
+	/* err == -ENOENT (i.e. prog->section_name not found in btf_ext) */
+
+	if (btf_prog_info) {
+		/*
+		 * 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);
+		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);
+	return 0;
+}
+
+static int
+bpf_program_reloc_btf_ext(struct bpf_program *prog, struct bpf_object *obj,
+			  const char *section_name,  __u32 insn_offset)
+{
+	int err;
+
+	if (!insn_offset || prog->func_info) {
+		/*
+		 * !insn_offset => main program
+		 *
+		 * For sub prog, the main program's func_info has to
+		 * be loaded first (i.e. prog->func_info != NULL)
+		 */
+		err = btf_ext__reloc_func_info(obj->btf, obj->btf_ext,
+					       section_name, insn_offset,
+					       &prog->func_info,
+					       &prog->func_info_cnt);
+		if (err)
+			return check_btf_ext_reloc_err(prog, err,
+						       prog->func_info,
+						       "bpf_func_info");
+
+		prog->func_info_rec_size = btf_ext__func_info_rec_size(obj->btf_ext);
+	}
+
+	if (!insn_offset || prog->line_info) {
+		err = btf_ext__reloc_line_info(obj->btf, obj->btf_ext,
+					       section_name, insn_offset,
+					       &prog->line_info,
+					       &prog->line_info_cnt);
+		if (err)
+			return check_btf_ext_reloc_err(prog, err,
+						       prog->line_info,
+						       "bpf_line_info");
+
+		prog->line_info_rec_size = btf_ext__line_info_rec_size(obj->btf_ext);
+	}
+
+	if (!insn_offset)
+		prog->btf_fd = btf__fd(obj->btf);
+
+	return 0;
+}
+
 static int
 bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
 			struct reloc_desc *relo)
@@ -1306,18 +1396,13 @@ bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
 			return -ENOMEM;
 		}
 
-		if (obj->btf && obj->btf_ext) {
-			err = btf_ext__reloc(obj->btf, obj->btf_ext,
+		if (obj->btf_ext) {
+			err = bpf_program_reloc_btf_ext(prog, obj,
 							text->section_name,
-					     prog->insns_cnt,
-					     &prog->func_info,
-					     &prog->func_info_len);
-			if (err) {
-				pr_warning("error in btf_ext__reloc for sec %s\n",
-					   text->section_name);
+							prog->insns_cnt);
+			if (err)
 				return err;
 		}
-		}
 
 		memcpy(new_insn + prog->insns_cnt, text->insns,
 		       text->insns_cnt * sizeof(*insn));
@@ -1341,19 +1426,12 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
 	if (!prog)
 		return 0;
 
-	if (obj->btf && obj->btf_ext) {
-		err = btf_ext__reloc_init(obj->btf, obj->btf_ext,
-					  prog->section_name,
-					  &prog->func_info,
-					  &prog->func_info_rec_size,
-					  &prog->func_info_len);
-		if (err) {
-			pr_warning("err in btf_ext__reloc_init for sec %s\n",
-				   prog->section_name);
+	if (obj->btf_ext) {
+		err = bpf_program_reloc_btf_ext(prog, obj,
+						prog->section_name, 0);
+		if (err)
 			return err;
 	}
-		prog->btf_fd = btf__fd(obj->btf);
-	}
 
 	if (!prog->reloc_desc)
 		return 0;
@@ -1444,8 +1522,7 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
 
 static int
 load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
-	     char *license, __u32 kern_version, int *pfd,
-	     __u32 func_info_cnt)
+	     char *license, __u32 kern_version, int *pfd)
 {
 	struct bpf_load_program_attr load_attr;
 	char *cp, errmsg[STRERR_BUFSIZE];
@@ -1465,8 +1542,10 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 	load_attr.prog_btf_fd = prog->btf_fd >= 0 ? prog->btf_fd : 0;
 	load_attr.func_info = prog->func_info;
 	load_attr.func_info_rec_size = prog->func_info_rec_size;
-	load_attr.func_info_cnt = func_info_cnt;
-
+	load_attr.func_info_cnt = prog->func_info_cnt;
+	load_attr.line_info = prog->line_info;
+	load_attr.line_info_rec_size = prog->line_info_rec_size;
+	load_attr.line_info_cnt = prog->line_info_cnt;
 	if (!load_attr.insns || !load_attr.insns_cnt)
 		return -EINVAL;
 
@@ -1523,14 +1602,8 @@ int
 bpf_program__load(struct bpf_program *prog,
 		  char *license, __u32 kern_version)
 {
-	__u32 func_info_cnt;
 	int err = 0, fd, i;
 
-	if (prog->func_info_len == 0)
-		func_info_cnt = 0;
-	else
-		func_info_cnt = prog->func_info_len / prog->func_info_rec_size;
-
 	if (prog->instances.nr < 0 || !prog->instances.fds) {
 		if (prog->preprocessor) {
 			pr_warning("Internal error: can't load program '%s'\n",
@@ -1553,8 +1626,7 @@ bpf_program__load(struct bpf_program *prog,
 				   prog->section_name, prog->instances.nr);
 		}
 		err = load_program(prog, prog->insns, prog->insns_cnt,
-				   license, kern_version, &fd,
-				   func_info_cnt);
+				   license, kern_version, &fd);
 		if (!err)
 			prog->instances.fds[0] = fd;
 		goto out;
@@ -1584,8 +1656,7 @@ bpf_program__load(struct bpf_program *prog,
 
 		err = load_program(prog, result.new_insn_ptr,
 				   result.new_insn_cnt,
-				   license, kern_version, &fd,
-				   func_info_cnt);
+				   license, kern_version, &fd);
 
 		if (err) {
 			pr_warning("Loading the %dth instance of program '%s' failed\n",

tools/lib/bpf/libbpf.h

@@ -342,6 +342,19 @@ int libbpf_nl_get_qdisc(int sock, unsigned int nl_pid, int ifindex,
 int libbpf_nl_get_filter(int sock, unsigned int nl_pid, int ifindex, int handle,
 			 libbpf_dump_nlmsg_t dump_filter_nlmsg, void *cookie);
 
+struct bpf_prog_linfo;
+struct bpf_prog_info;
+
+LIBBPF_API void bpf_prog_linfo__free(struct bpf_prog_linfo *prog_linfo);
+LIBBPF_API struct bpf_prog_linfo *
+bpf_prog_linfo__new(const struct bpf_prog_info *info);
+LIBBPF_API const struct bpf_line_info *
+bpf_prog_linfo__lfind_addr_func(const struct bpf_prog_linfo *prog_linfo,
+				__u64 addr, __u32 func_idx, __u32 nr_skip);
+LIBBPF_API const struct bpf_line_info *
+bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
+		      __u32 insn_off, __u32 nr_skip);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif

tools/lib/bpf/libbpf.map

@@ -99,6 +99,10 @@ LIBBPF_0.0.1 {
 		bpf_program__unload;
 		bpf_program__unpin;
 		bpf_program__unpin_instance;
+		bpf_prog_linfo__free;
+		bpf_prog_linfo__new;
+		bpf_prog_linfo__lfind_addr_func;
+		bpf_prog_linfo__lfind;
 		bpf_raw_tracepoint_open;
 		bpf_set_link_xdp_fd;
 		bpf_task_fd_query;