Merge branch 'clean-up bpftool from legacy support'

Sahid Orentino Ferdjaoui says:

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

As part of commit 93b8952d ("libbpf: deprecate legacy BPF map
definitions") and commit bd054102 ("libbpf: enforce strict libbpf
1.0 behaviors") The --legacy option is not relevant anymore. #1 is
removing it. #4 is cleaning the code from using libbpf_get_error().

About patches #2 and #3 They are changes discovered while working on
this series (credits to Quentin Monnet). #2 is cleaning-up usage of an
unnecessary PTR_ERR(NULL), finally #3 is fixing an invalid value
passed to strerror().

v1 -> v2:
   - Addressed review comments from Yonghong Song on patch #4
   - Added a patch #5 that removes unwanted function noticed by
     Yonghong Song
v2 -> v3
   - Addressed review comments from Andrii Nakryiko on patch #2, #3, #4
     * clean-up usage of libbpf_get_error() (#2, #3)
     * fix possible return of an uninitialized local variable err
     * fix returned errors using errno
v3 -> v4
   - Addressed review comments from Quentin Monnet
     * fix line moved from patch #2 to patch #3
     * fix missing returned errors using errno
     * fix some returned values to errno instead of -1
====================
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/bpf/bpftool/Documentation/common_options.rst

@@ -23,12 +23,3 @@
 	  Print all logs available, even debug-level information. This includes
 	  logs from libbpf as well as from the verifier, when attempting to
 	  load programs.
-
--l, --legacy
-	  Use legacy libbpf mode which has more relaxed BPF program
-	  requirements. By default, bpftool has more strict requirements
-	  about section names, changes pinning logic and doesn't support
-	  some of the older non-BTF map declarations.
-
-	  See https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0
-	  for details.

tools/bpf/bpftool/Documentation/substitutions.rst

 .. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 
-.. |COMMON_OPTIONS| replace:: { **-j** | **--json** } [{ **-p** | **--pretty** }] | { **-d** | **--debug** } | { **-l** | **--legacy** }
+.. |COMMON_OPTIONS| replace:: { **-j** | **--json** } [{ **-p** | **--pretty** }] | { **-d** | **--debug** }

tools/bpf/bpftool/bash-completion/bpftool

@@ -261,7 +261,7 @@ _bpftool()
     # Deal with options
     if [[ ${words[cword]} == -* ]]; then
         local c='--version --json --pretty --bpffs --mapcompat --debug \
-	       --use-loader --base-btf --legacy'
+	       --use-loader --base-btf'
         COMPREPLY=( $( compgen -W "$c" -- "$cur" ) )
         return 0
     fi

tools/bpf/bpftool/btf.c

@@ -467,9 +467,8 @@ static int dump_btf_c(const struct btf *btf,
 	int err = 0, i;
 
 	d = btf_dump__new(btf, btf_dump_printf, NULL, NULL);
-	err = libbpf_get_error(d);
-	if (err)
-		return err;
+	if (!d)
+		return -errno;
 
 	printf("#ifndef __VMLINUX_H__\n");
 	printf("#define __VMLINUX_H__\n");
@@ -512,11 +511,9 @@ static struct btf *get_vmlinux_btf_from_sysfs(void)
 	struct btf *base;
 
 	base = btf__parse(sysfs_vmlinux, NULL);
-	if (libbpf_get_error(base)) {
-		p_err("failed to parse vmlinux BTF at '%s': %ld\n",
-		      sysfs_vmlinux, libbpf_get_error(base));
-		base = NULL;
-	}
+	if (!base)
+		p_err("failed to parse vmlinux BTF at '%s': %d\n",
+		      sysfs_vmlinux, -errno);
 
 	return base;
 }
@@ -559,7 +556,7 @@ static int do_dump(int argc, char **argv)
 	__u32 btf_id = -1;
 	const char *src;
 	int fd = -1;
-	int err;
+	int err = 0;
 
 	if (!REQ_ARGS(2)) {
 		usage();
@@ -634,8 +631,8 @@ static int do_dump(int argc, char **argv)
 			base = get_vmlinux_btf_from_sysfs();
 
 		btf = btf__parse_split(*argv, base ?: base_btf);
-		err = libbpf_get_error(btf);
 		if (!btf) {
+			err = -errno;
 			p_err("failed to load BTF from %s: %s",
 			      *argv, strerror(errno));
 			goto done;
@@ -681,8 +678,8 @@ static int do_dump(int argc, char **argv)
 		}
 
 		btf = btf__load_from_kernel_by_id_split(btf_id, base_btf);
-		err = libbpf_get_error(btf);
 		if (!btf) {
+			err = -errno;
 			p_err("get btf by id (%u): %s", btf_id, strerror(errno));
 			goto done;
 		}

tools/bpf/bpftool/btf_dumper.c

@@ -75,7 +75,7 @@ static int dump_prog_id_as_func_ptr(const struct btf_dumper *d,
 		goto print;
 
 	prog_btf = btf__load_from_kernel_by_id(info.btf_id);
-	if (libbpf_get_error(prog_btf))
+	if (!prog_btf)
 		goto print;
 	func_type = btf__type_by_id(prog_btf, finfo.type_id);
 	if (!func_type || !btf_is_func(func_type))

tools/bpf/bpftool/gen.c

@@ -252,9 +252,8 @@ static int codegen_datasecs(struct bpf_object *obj, const char *obj_name)
 	int err = 0;
 
 	d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
-	err = libbpf_get_error(d);
-	if (err)
-		return err;
+	if (!d)
+		return -errno;
 
 	bpf_object__for_each_map(map, obj) {
 		/* only generate definitions for memory-mapped internal maps */
@@ -976,13 +975,12 @@ static int do_skeleton(int argc, char **argv)
 		/* log_level1 + log_level2 + stats, but not stable UAPI */
 		opts.kernel_log_level = 1 + 2 + 4;
 	obj = bpf_object__open_mem(obj_data, file_sz, &opts);
-	err = libbpf_get_error(obj);
-	if (err) {
+	if (!obj) {
 		char err_buf[256];
 
+		err = -errno;
 		libbpf_strerror(err, err_buf, sizeof(err_buf));
 		p_err("failed to open BPF object file: %s", err_buf);
-		obj = NULL;
 		goto out;
 	}
 

tools/bpf/bpftool/iter.c

@@ -4,6 +4,7 @@
 #ifndef _GNU_SOURCE
 #define _GNU_SOURCE
 #endif
+#include <errno.h>
 #include <unistd.h>
 #include <linux/err.h>
 #include <bpf/libbpf.h>
@@ -48,8 +49,8 @@ static int do_pin(int argc, char **argv)
 	}
 
 	obj = bpf_object__open(objfile);
-	err = libbpf_get_error(obj);
-	if (err) {
+	if (!obj) {
+		err = -errno;
 		p_err("can't open objfile %s", objfile);
 		goto close_map_fd;
 	}
@@ -62,13 +63,14 @@ static int do_pin(int argc, char **argv)
 
 	prog = bpf_object__next_program(obj, NULL);
 	if (!prog) {
+		err = -errno;
 		p_err("can't find bpf program in objfile %s", objfile);
 		goto close_obj;
 	}
 
 	link = bpf_program__attach_iter(prog, &iter_opts);
-	err = libbpf_get_error(link);
-	if (err) {
+	if (!link) {
+		err = -errno;
 		p_err("attach_iter failed for program %s",
 		      bpf_program__name(prog));
 		goto close_obj;

tools/bpf/bpftool/main.c

@@ -31,7 +31,6 @@ bool block_mount;
 bool verifier_logs;
 bool relaxed_maps;
 bool use_loader;
-bool legacy_libbpf;
 struct btf *base_btf;
 struct hashmap *refs_table;
 
@@ -160,7 +159,6 @@ static int do_version(int argc, char **argv)
 		jsonw_start_object(json_wtr);	/* features */
 		jsonw_bool_field(json_wtr, "libbfd", has_libbfd);
 		jsonw_bool_field(json_wtr, "llvm", has_llvm);
-		jsonw_bool_field(json_wtr, "libbpf_strict", !legacy_libbpf);
 		jsonw_bool_field(json_wtr, "skeletons", has_skeletons);
 		jsonw_bool_field(json_wtr, "bootstrap", bootstrap);
 		jsonw_end_object(json_wtr);	/* features */
@@ -179,7 +177,6 @@ static int do_version(int argc, char **argv)
 		printf("features:");
 		print_feature("libbfd", has_libbfd, &nb_features);
 		print_feature("llvm", has_llvm, &nb_features);
-		print_feature("libbpf_strict", !legacy_libbpf, &nb_features);
 		print_feature("skeletons", has_skeletons, &nb_features);
 		print_feature("bootstrap", bootstrap, &nb_features);
 		printf("\n");
@@ -451,7 +448,6 @@ int main(int argc, char **argv)
 		{ "debug",	no_argument,	NULL,	'd' },
 		{ "use-loader",	no_argument,	NULL,	'L' },
 		{ "base-btf",	required_argument, NULL, 'B' },
-		{ "legacy",	no_argument,	NULL,	'l' },
 		{ 0 }
 	};
 	bool version_requested = false;
@@ -514,19 +510,15 @@ int main(int argc, char **argv)
 			break;
 		case 'B':
 			base_btf = btf__parse(optarg, NULL);
-			if (libbpf_get_error(base_btf)) {
-				p_err("failed to parse base BTF at '%s': %ld\n",
-				      optarg, libbpf_get_error(base_btf));
-				base_btf = NULL;
+			if (!base_btf) {
+				p_err("failed to parse base BTF at '%s': %d\n",
+				      optarg, -errno);
 				return -1;
 			}
 			break;
 		case 'L':
 			use_loader = true;
 			break;
-		case 'l':
-			legacy_libbpf = true;
-			break;
 		default:
 			p_err("unrecognized option '%s'", argv[optind - 1]);
 			if (json_output)
@@ -536,14 +528,6 @@ int main(int argc, char **argv)
 		}
 	}
 
-	if (!legacy_libbpf) {
-		/* Allow legacy map definitions for skeleton generation.
-		 * It will still be rejected if users use LIBBPF_STRICT_ALL
-		 * mode for loading generated skeleton.
-		 */
-		libbpf_set_strict_mode(LIBBPF_STRICT_ALL & ~LIBBPF_STRICT_MAP_DEFINITIONS);
-	}
-
 	argc -= optind;
 	argv += optind;
 	if (argc < 0)

tools/bpf/bpftool/main.h

@@ -57,7 +57,7 @@ static inline void *u64_to_ptr(__u64 ptr)
 #define HELP_SPEC_PROGRAM						\
 	"PROG := { id PROG_ID | pinned FILE | tag PROG_TAG | name PROG_NAME }"
 #define HELP_SPEC_OPTIONS						\
-	"OPTIONS := { {-j|--json} [{-p|--pretty}] | {-d|--debug} | {-l|--legacy}"
+	"OPTIONS := { {-j|--json} [{-p|--pretty}] | {-d|--debug}"
 #define HELP_SPEC_MAP							\
 	"MAP := { id MAP_ID | pinned FILE | name MAP_NAME }"
 #define HELP_SPEC_LINK							\
@@ -82,7 +82,6 @@ extern bool block_mount;
 extern bool verifier_logs;
 extern bool relaxed_maps;
 extern bool use_loader;
-extern bool legacy_libbpf;
 extern struct btf *base_btf;
 extern struct hashmap *refs_table;
 

tools/bpf/bpftool/map.c

@@ -786,18 +786,18 @@ static int get_map_kv_btf(const struct bpf_map_info *info, struct btf **btf)
 	if (info->btf_vmlinux_value_type_id) {
 		if (!btf_vmlinux) {
 			btf_vmlinux = libbpf_find_kernel_btf();
-			err = libbpf_get_error(btf_vmlinux);
-			if (err) {
+			if (!btf_vmlinux) {
 				p_err("failed to get kernel btf");
-				return err;
+				return -errno;
 			}
 		}
 		*btf = btf_vmlinux;
 	} else if (info->btf_value_type_id) {
 		*btf = btf__load_from_kernel_by_id(info->btf_id);
-		err = libbpf_get_error(*btf);
-		if (err)
+		if (!*btf) {
+			err = -errno;
 			p_err("failed to get btf");
+		}
 	} else {
 		*btf = NULL;
 	}
@@ -807,16 +807,10 @@ static int get_map_kv_btf(const struct bpf_map_info *info, struct btf **btf)
 
 static void free_map_kv_btf(struct btf *btf)
 {
-	if (!libbpf_get_error(btf) && btf != btf_vmlinux)
+	if (btf != btf_vmlinux)
 		btf__free(btf);
 }
 
-static void free_btf_vmlinux(void)
-{
-	if (!libbpf_get_error(btf_vmlinux))
-		btf__free(btf_vmlinux);
-}
-
 static int
 map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
 	 bool show_header)
@@ -953,7 +947,7 @@ static int do_dump(int argc, char **argv)
 		close(fds[i]);
 exit_free:
 	free(fds);
-	free_btf_vmlinux();
+	btf__free(btf_vmlinux);
 	return err;
 }
 

tools/bpf/bpftool/prog.c

@@ -322,7 +322,7 @@ static void show_prog_metadata(int fd, __u32 num_maps)
 		return;
 
 	btf = btf__load_from_kernel_by_id(map_info.btf_id);
-	if (libbpf_get_error(btf))
+	if (!btf)
 		goto out_free;
 
 	t_datasec = btf__type_by_id(btf, map_info.btf_value_type_id);
@@ -726,7 +726,7 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
 
 	if (info->btf_id) {
 		btf = btf__load_from_kernel_by_id(info->btf_id);
-		if (libbpf_get_error(btf)) {
+		if (!btf) {
 			p_err("failed to get btf");
 			return -1;
 		}
@@ -1663,7 +1663,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 		open_opts.kernel_log_level = 1 + 2 + 4;
 
 	obj = bpf_object__open_file(file, &open_opts);
-	if (libbpf_get_error(obj)) {
+	if (!obj) {
 		p_err("failed to open object file");
 		goto err_free_reuse_maps;
 	}
@@ -1802,11 +1802,6 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 	else
 		bpf_object__unpin_programs(obj, pinfile);
 err_close_obj:
-	if (!legacy_libbpf) {
-		p_info("Warning: bpftool is now running in libbpf strict mode and has more stringent requirements about BPF programs.\n"
-		       "If it used to work for this object file but now doesn't, see --legacy option for more details.\n");
-	}
-
 	bpf_object__close(obj);
 err_free_reuse_maps:
 	for (i = 0; i < old_map_fds; i++)
@@ -1887,7 +1882,7 @@ static int do_loader(int argc, char **argv)
 		open_opts.kernel_log_level = 1 + 2 + 4;
 
 	obj = bpf_object__open_file(file, &open_opts);
-	if (libbpf_get_error(obj)) {
+	if (!obj) {
 		p_err("failed to open object file");
 		goto err_close_obj;
 	}
@@ -2204,7 +2199,7 @@ static char *profile_target_name(int tgt_fd)
 	}
 
 	btf = btf__load_from_kernel_by_id(info.btf_id);
-	if (libbpf_get_error(btf)) {
+	if (!btf) {
 		p_err("failed to load btf for prog FD %d", tgt_fd);
 		goto out;
 	}

tools/bpf/bpftool/struct_ops.c

@@ -32,7 +32,7 @@ static const struct btf *get_btf_vmlinux(void)
 		return btf_vmlinux;
 
 	btf_vmlinux = libbpf_find_kernel_btf();
-	if (libbpf_get_error(btf_vmlinux))
+	if (!btf_vmlinux)
 		p_err("struct_ops requires kernel CONFIG_DEBUG_INFO_BTF=y");
 
 	return btf_vmlinux;
@@ -45,7 +45,7 @@ static const char *get_kern_struct_ops_name(const struct bpf_map_info *info)
 	const char *st_ops_name;
 
 	kern_btf = get_btf_vmlinux();
-	if (libbpf_get_error(kern_btf))
+	if (!kern_btf)
 		return "<btf_vmlinux_not_found>";
 
 	t = btf__type_by_id(kern_btf, info->btf_vmlinux_value_type_id);
@@ -63,10 +63,8 @@ static __s32 get_map_info_type_id(void)
 		return map_info_type_id;
 
 	kern_btf = get_btf_vmlinux();
-	if (libbpf_get_error(kern_btf)) {
-		map_info_type_id = PTR_ERR(kern_btf);
-		return map_info_type_id;
-	}
+	if (!kern_btf)
+		return 0;
 
 	map_info_type_id = btf__find_by_name_kind(kern_btf, "bpf_map_info",
 						  BTF_KIND_STRUCT);
@@ -415,7 +413,7 @@ static int do_dump(int argc, char **argv)
 	}
 
 	kern_btf = get_btf_vmlinux();
-	if (libbpf_get_error(kern_btf))
+	if (!kern_btf)
 		return -1;
 
 	if (!json_output) {
@@ -498,7 +496,7 @@ static int do_register(int argc, char **argv)
 		open_opts.kernel_log_level = 1 + 2 + 4;
 
 	obj = bpf_object__open_file(file, &open_opts);
-	if (libbpf_get_error(obj))
+	if (!obj)
 		return -1;
 
 	set_max_rlimit();
@@ -513,10 +511,9 @@ static int do_register(int argc, char **argv)
 			continue;
 
 		link = bpf_map__attach_struct_ops(map);
-		if (libbpf_get_error(link)) {
+		if (!link) {
 			p_err("can't register struct_ops %s: %s",
-			      bpf_map__name(map),
-			      strerror(-PTR_ERR(link)));
+			      bpf_map__name(map), strerror(errno));
 			nr_errs++;
 			continue;
 		}
@@ -593,8 +590,7 @@ int do_struct_ops(int argc, char **argv)
 
 	err = cmd_select(cmds, argc, argv, do_help);
 
-	if (!libbpf_get_error(btf_vmlinux))
-		btf__free(btf_vmlinux);
+	btf__free(btf_vmlinux);
 
 	return err;
 }

tools/testing/selftests/bpf/test_bpftool_synctypes.py

@@ -309,11 +309,11 @@ class MainHeaderFileExtractor(SourceFileExtractor):
         commands), which looks to the lists of options in other source files
         but has different start and end markers:
 
-            "OPTIONS := { {-j|--json} [{-p|--pretty}] | {-d|--debug} | {-l|--legacy}"
+            "OPTIONS := { {-j|--json} [{-p|--pretty}] | {-d|--debug}"
 
         Return a set containing all options, such as:
 
-            {'-p', '-d', '--legacy', '--pretty', '--debug', '--json', '-l', '-j'}
+            {'-p', '-d', '--pretty', '--debug', '--json', '-j'}
         """
         start_marker = re.compile(f'"OPTIONS :=')
         pattern = re.compile('([\w-]+) ?(?:\||}[ }\]"])')
@@ -336,7 +336,7 @@ class ManSubstitutionsExtractor(SourceFileExtractor):
 
         Return a set containing all options, such as:
 
-            {'-p', '-d', '--legacy', '--pretty', '--debug', '--json', '-l', '-j'}
+            {'-p', '-d', '--pretty', '--debug', '--json', '-j'}
         """
         start_marker = re.compile('\|COMMON_OPTIONS\| replace:: {')
         pattern = re.compile('\*\*([\w/-]+)\*\*')