Merge branch 'bpf-bpftool-dbg-output'

Quentin Monnet says:

====================
This series adds an option to bpftool to make it print additional
information via libbpf and the kernel verifier when attempting to load
programs.

A new API function is added to libbpf in order to pass the log_level
from bpftool with the bpf_object__* part of the API.

Options for a finer control over the log levels to use for libbpf and
the verifier could be added in the future, if desired.

v3:
- Fix and clarify commit logs.

v2:
- Do not add distinct options for libbpf and verifier logs, just keep the
  one that sets all log levels to their maximum. Rename the option.
- Do not offer a way to pick desired log levels. The choice is "use the
  option to print all logs" or "stick with the defaults".
- Do not export BPF_LOG_* flags to user header.
- Update all man pages (most bpftool operations use libbpf and may print
  libbpf logs). Verifier logs are only used when attempting to load
  programs for now, so bpftool-prog.rst and bpftool.rst remain the only
  pages updated in that regard.

Previous discussion available at:

https://lore.kernel.org/bpf/20190523105426.3938-1-quentin.monnet@netronome.com/
https://lore.kernel.org/bpf/20190429095227.9745-1-quentin.monnet@netronome.com/
====================

Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

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

@@ -72,6 +72,10 @@ OPTIONS
 	-p, --pretty
 		  Generate human-readable JSON output. Implies **-j**.
 
+	-d, --debug
+		  Print all logs available from libbpf, including debug-level
+		  information.
+
 EXAMPLES
 ========
 **# bpftool btf dump id 1226**

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

@@ -113,6 +113,10 @@ OPTIONS
 	-f, --bpffs
 		  Show file names of pinned programs.
 
+	-d, --debug
+		  Print all logs available from libbpf, including debug-level
+		  information.
+
 EXAMPLES
 ========
 |

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

@@ -73,6 +73,10 @@ OPTIONS
 	-p, --pretty
 		  Generate human-readable JSON output. Implies **-j**.
 
+	-d, --debug
+		  Print all logs available from libbpf, including debug-level
+		  information.
+
 SEE ALSO
 ========
 	**bpf**\ (2),

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

@@ -152,6 +152,10 @@ OPTIONS
 		  Do not automatically attempt to mount any virtual file system
 		  (such as tracefs or BPF virtual file system) when necessary.
 
+	-d, --debug
+		  Print all logs available from libbpf, including debug-level
+		  information.
+
 EXAMPLES
 ========
 **# bpftool map show**

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

@@ -65,6 +65,10 @@ OPTIONS
 	-p, --pretty
 		  Generate human-readable JSON output. Implies **-j**.
 
+	-d, --debug
+		  Print all logs available from libbpf, including debug-level
+		  information.
+
 EXAMPLES
 ========
 

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

@@ -53,6 +53,10 @@ OPTIONS
 	-p, --pretty
 		  Generate human-readable JSON output. Implies **-j**.
 
+	-d, --debug
+		  Print all logs available from libbpf, including debug-level
+		  information.
+
 EXAMPLES
 ========
 

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

@@ -174,6 +174,11 @@ OPTIONS
 		  Do not automatically attempt to mount any virtual file system
 		  (such as tracefs or BPF virtual file system) when necessary.
 
+	-d, --debug
+		  Print all logs available, even debug-level information. This
+		  includes logs from libbpf as well as from the verifier, when
+		  attempting to load programs.
+
 EXAMPLES
 ========
 **# bpftool prog show**

tools/bpf/bpftool/Documentation/bpftool.rst

@@ -66,6 +66,10 @@ OPTIONS
 		  Do not automatically attempt to mount any virtual file system
 		  (such as tracefs or BPF virtual file system) when necessary.
 
+	-d, --debug
+		  Print all logs available, even debug-level information. This
+		  includes logs from libbpf as well as from the verifier, when
+		  attempting to load programs.
 
 SEE ALSO
 ========

tools/bpf/bpftool/bash-completion/bpftool

@@ -187,7 +187,7 @@ _bpftool()
 
     # Deal with options
     if [[ ${words[cword]} == -* ]]; then
-        local c='--version --json --pretty --bpffs --mapcompat'
+        local c='--version --json --pretty --bpffs --mapcompat --debug'
         COMPREPLY=( $( compgen -W "$c" -- "$cur" ) )
         return 0
     fi

tools/bpf/bpftool/main.c

@@ -10,6 +10,7 @@
 #include <string.h>
 
 #include <bpf.h>
+#include <libbpf.h>
 
 #include "main.h"
 
@@ -25,6 +26,7 @@ bool pretty_output;
 bool json_output;
 bool show_pinned;
 bool block_mount;
+bool verifier_logs;
 int bpf_flags;
 struct pinned_obj_table prog_table;
 struct pinned_obj_table map_table;
@@ -77,6 +79,13 @@ static int do_version(int argc, char **argv)
 	return 0;
 }
 
+static int __printf(2, 0)
+print_all_levels(__maybe_unused enum libbpf_print_level level,
+		 const char *format, va_list args)
+{
+	return vfprintf(stderr, format, args);
+}
+
 int cmd_select(const struct cmd *cmds, int argc, char **argv,
 	       int (*help)(int argc, char **argv))
 {
@@ -317,6 +326,7 @@ int main(int argc, char **argv)
 		{ "bpffs",	no_argument,	NULL,	'f' },
 		{ "mapcompat",	no_argument,	NULL,	'm' },
 		{ "nomount",	no_argument,	NULL,	'n' },
+		{ "debug",	no_argument,	NULL,	'd' },
 		{ 0 }
 	};
 	int opt, ret;
@@ -332,7 +342,7 @@ int main(int argc, char **argv)
 	hash_init(map_table.table);
 
 	opterr = 0;
-	while ((opt = getopt_long(argc, argv, "Vhpjfmn",
+	while ((opt = getopt_long(argc, argv, "Vhpjfmnd",
 				  options, NULL)) >= 0) {
 		switch (opt) {
 		case 'V':
@@ -362,6 +372,10 @@ int main(int argc, char **argv)
 		case 'n':
 			block_mount = true;
 			break;
+		case 'd':
+			libbpf_set_print(print_all_levels);
+			verifier_logs = true;
+			break;
 		default:
 			p_err("unrecognized option '%s'", argv[optind - 1]);
 			if (json_output)

tools/bpf/bpftool/main.h

@@ -91,6 +91,7 @@ extern json_writer_t *json_wtr;
 extern bool json_output;
 extern bool show_pinned;
 extern bool block_mount;
+extern bool verifier_logs;
 extern int bpf_flags;
 extern struct pinned_obj_table prog_table;
 extern struct pinned_obj_table map_table;

tools/bpf/bpftool/prog.c

@@ -750,10 +750,11 @@ static int do_detach(int argc, char **argv)
 
 static int load_with_options(int argc, char **argv, bool first_prog_only)
 {
-	enum bpf_attach_type expected_attach_type;
-	struct bpf_object_open_attr attr = {
-		.prog_type	= BPF_PROG_TYPE_UNSPEC,
+	struct bpf_object_load_attr load_attr = { 0 };
+	struct bpf_object_open_attr open_attr = {
+		.prog_type = BPF_PROG_TYPE_UNSPEC,
 	};
+	enum bpf_attach_type expected_attach_type;
 	struct map_replace *map_replace = NULL;
 	struct bpf_program *prog = NULL, *pos;
 	unsigned int old_map_fds = 0;
@@ -767,7 +768,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 
 	if (!REQ_ARGS(2))
 		return -1;
-	attr.file = GET_ARG();
+	open_attr.file = GET_ARG();
 	pinfile = GET_ARG();
 
 	while (argc) {
@@ -776,7 +777,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 
 			NEXT_ARG();
 
-			if (attr.prog_type != BPF_PROG_TYPE_UNSPEC) {
+			if (open_attr.prog_type != BPF_PROG_TYPE_UNSPEC) {
 				p_err("program type already specified");
 				goto err_free_reuse_maps;
 			}
@@ -793,7 +794,8 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 			strcat(type, *argv);
 			strcat(type, "/");
 
-			err = libbpf_prog_type_by_name(type, &attr.prog_type,
+			err = libbpf_prog_type_by_name(type,
+						       &open_attr.prog_type,
 						       &expected_attach_type);
 			free(type);
 			if (err < 0)
@@ -881,16 +883,16 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 
 	set_max_rlimit();
 
-	obj = __bpf_object__open_xattr(&attr, bpf_flags);
+	obj = __bpf_object__open_xattr(&open_attr, bpf_flags);
 	if (IS_ERR_OR_NULL(obj)) {
 		p_err("failed to open object file");
 		goto err_free_reuse_maps;
 	}
 
 	bpf_object__for_each_program(pos, obj) {
-		enum bpf_prog_type prog_type = attr.prog_type;
+		enum bpf_prog_type prog_type = open_attr.prog_type;
 
-		if (attr.prog_type == BPF_PROG_TYPE_UNSPEC) {
+		if (open_attr.prog_type == BPF_PROG_TYPE_UNSPEC) {
 			const char *sec_name = bpf_program__title(pos, false);
 
 			err = libbpf_prog_type_by_name(sec_name, &prog_type,
@@ -960,7 +962,12 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 		goto err_close_obj;
 	}
 
-	err = bpf_object__load(obj);
+	load_attr.obj = obj;
+	if (verifier_logs)
+		/* log_level1 + log_level2 + stats, but not stable UAPI */
+		load_attr.log_level = 1 + 2 + 4;
+
+	err = bpf_object__load_xattr(&load_attr);
 	if (err) {
 		p_err("failed to load object file");
 		goto err_close_obj;

tools/lib/bpf/Makefile

@@ -3,7 +3,7 @@
 
 BPF_VERSION = 0
 BPF_PATCHLEVEL = 0
-BPF_EXTRAVERSION = 3
+BPF_EXTRAVERSION = 4
 
 MAKEFLAGS += --no-print-directory
 

tools/lib/bpf/libbpf.c

@@ -2224,7 +2224,7 @@ static bool bpf_program__is_function_storage(struct bpf_program *prog,
 }
 
 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;
@@ -2232,6 +2232,7 @@ 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);
@@ -2383,10 +2384,14 @@ 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;
 
@@ -2399,7 +2404,7 @@ 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:
@@ -2408,6 +2413,15 @@ 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];

tools/lib/bpf/libbpf.h

@@ -89,8 +89,14 @@ LIBBPF_API int bpf_object__unpin_programs(struct bpf_object *obj,
 LIBBPF_API int bpf_object__pin(struct bpf_object *object, const char *path);
 LIBBPF_API void bpf_object__close(struct bpf_object *object);
 
+struct bpf_object_load_attr {
+	struct bpf_object *obj;
+	int log_level;
+};
+
 /* Load/unload object into/from kernel */
 LIBBPF_API int bpf_object__load(struct bpf_object *obj);
+LIBBPF_API int bpf_object__load_xattr(struct bpf_object_load_attr *attr);
 LIBBPF_API int bpf_object__unload(struct bpf_object *obj);
 LIBBPF_API const char *bpf_object__name(struct bpf_object *obj);
 LIBBPF_API unsigned int bpf_object__kversion(struct bpf_object *obj);

tools/lib/bpf/libbpf.map

@@ -171,4 +171,5 @@ LIBBPF_0.0.4 {
 		btf_dump__free;
 		btf_dump__new;
 		btf__parse_elf;
+		bpf_object__load_xattr;
 } LIBBPF_0.0.3;