Merge branch 'libbpf: rename btf__get_from_id() and btf__load() APIs, support split BTF'

Quentin Monnet says:

====================

As part of the effort to move towards a v1.0 for libbpf [0], this set
improves some confusing function names related to BTF loading from and to
the kernel:

- btf__load() becomes btf__load_into_kernel().
- btf__get_from_id becomes btf__load_from_kernel_by_id().
- A new version btf__load_from_kernel_by_id_split() extends the former to
  add support for split BTF.

The last patch is a trivial change to bpftool to add support for dumping
split BTF objects by referencing them by their id (and not only by their
BTF path).

[0] https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#btfh-apis

v3:
- Use libbpf_err_ptr() in btf__load_from_kernel_by_id(), ERR_PTR() in
  bpftool's get_map_kv_btf().
- Move the definition of btf__load_from_kernel_by_id() closer to the
  btf__parse() group in btf.h (move the legacy function with it).
- Fix a bug on the return value in libbpf_find_prog_btf_id(), as a new
  patch.
- Move the btf__free() fixes to their own patch.
- Add "Fixes:" tags to relevant patches.

v2:
- Remove deprecation marking of legacy functions (patch 4/6 from v1).
- Make btf__load_from_kernel_by_id{,_split}() return the btf struct, adjust
  surrounding code and call btf__free() when missing.
- Add new functions to v0.5.0 API (and not v0.6.0).
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

1 files changed, 20 insertions, 9 deletions

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index cc48726740ad..b1996b8f1d42 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -249,10 +249,10 @@ static void show_prog_metadata(int fd, __u32 num_maps)
 	struct bpf_map_info map_info;
 	struct btf_var_secinfo *vsi;
 	bool printed_header = false;
-	struct btf *btf = NULL;
 	unsigned int i, vlen;
 	void *value = NULL;
 	const char *name;
+	struct btf *btf;
 	int err;
 
 	if (!num_maps)
@@ -263,8 +263,8 @@ static void show_prog_metadata(int fd, __u32 num_maps)
 	if (!value)
 		return;
 
-	err = btf__get_from_id(map_info.btf_id, &btf);
-	if (err || !btf)
+	btf = btf__load_from_kernel_by_id(map_info.btf_id);
+	if (libbpf_get_error(btf))
 		goto out_free;
 
 	t_datasec = btf__type_by_id(btf, map_info.btf_value_type_id);
@@ -646,9 +646,12 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
 		member_len = info->xlated_prog_len;
 	}
 
-	if (info->btf_id && btf__get_from_id(info->btf_id, &btf)) {
-		p_err("failed to get btf");
-		return -1;
+	if (info->btf_id) {
+		btf = btf__load_from_kernel_by_id(info->btf_id);
+		if (libbpf_get_error(btf)) {
+			p_err("failed to get btf");
+			return -1;
+		}
 	}
 
 	func_info = u64_to_ptr(info->func_info);
@@ -781,6 +784,8 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
 		kernel_syms_destroy(&dd);
 	}
 
+	btf__free(btf);
+
 	return 0;
 }
 
@@ -2002,8 +2007,8 @@ static char *profile_target_name(int tgt_fd)
 	struct bpf_prog_info_linear *info_linear;
 	struct bpf_func_info *func_info;
 	const struct btf_type *t;
+	struct btf *btf = NULL;
 	char *name = NULL;
-	struct btf *btf;
 
 	info_linear = bpf_program__get_prog_info_linear(
 		tgt_fd, 1UL << BPF_PROG_INFO_FUNC_INFO);
@@ -2012,12 +2017,17 @@ static char *profile_target_name(int tgt_fd)
 		return NULL;
 	}
 
-	if (info_linear->info.btf_id == 0 ||
-	    btf__get_from_id(info_linear->info.btf_id, &btf)) {
+	if (info_linear->info.btf_id == 0) {
 		p_err("prog FD %d doesn't have valid btf", tgt_fd);
 		goto out;
 	}
 
+	btf = btf__load_from_kernel_by_id(info_linear->info.btf_id);
+	if (libbpf_get_error(btf)) {
+		p_err("failed to load btf for prog FD %d", tgt_fd);
+		goto out;
+	}
+
 	func_info = u64_to_ptr(info_linear->info.func_info);
 	t = btf__type_by_id(btf, func_info[0].type_id);
 	if (!t) {
@@ -2027,6 +2037,7 @@ static char *profile_target_name(int tgt_fd)
 	}
 	name = strdup(btf__name_by_offset(btf, t->name_off));
 out:
+	btf__free(btf);
 	free(info_linear);
 	return name;
 }