[PATCH bpf-next 0/2] bpftool: Support symbolic map creation flags

[PATCH bpf-next 0/2] bpftool: Support symbolic map creation flags

[Tianyi Chen]

This series adds comma-separated BPF_F_* names to map create flags,
while retaining base-0 numeric input. It also documents the syntax,
completes names within lists, and tests the resulting kernel map flags
and invalid-input diagnostics.

This addresses the map creation part of:
https://github.com/libbpf/bpftool/issues/57

The series is based on bpf-next and is independent of the ring buffer
and batch-dump series sent alongside it.

Validation:
- Full bpftool build and focused BPF selftests build with LLVM 20.
- All 29 bpftool_map_flags subtests passed in an x86-64 KVM guest
  running Linux 7.3.0-rc1, using a bpftool built with only this series.
- Bash syntax and actual completion candidates checked with and without
  comma in COMP_WORDBREAKS; bpftool-map man page generated successfully.

Only focused BPF tests were run; this does not claim a full BPF selftest
suite run. Strict checkpatch has no errors or checks; its new-file
warning is covered by the existing BPF/selftests MAINTAINERS patterns.


Integration check: these three independent series also applied and built
together with my previously posted recursive map-dump v2 series. The
combined 64 subtests passed with no skips or failures in the same guest.

Tianyi Chen (2):
  bpftool: Accept symbolic map creation flags
  selftests/bpf: Cover symbolic bpftool map creation flags

 .../bpf/bpftool/Documentation/bpftool-map.rst | 13 ++-
 tools/bpf/bpftool/bash-completion/bpftool     | 25 ++++-
 tools/bpf/bpftool/map.c                       | 77 ++++++++++++++-
 .../bpf/prog_tests/bpftool_map_flags.c        | 99 +++++++++++++++++++
 4 files changed, 208 insertions(+), 6 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/bpftool_map_flags.c

-- 
2.55.0

[PATCH bpf-next 1/2] bpftool: Accept symbolic map creation flags

[Tianyi Chen]

Accept comma-separated BPF_F_* names for map create flags, so callers
can use the UAPI names without looking up their numeric values. Keep
base-0 numeric input, including bits unknown to this bpftool.

Reject empty names, unknown names, mixed numeric and symbolic lists,
and values outside the unsigned 32-bit range. Limit symbolic names to
map creation flags and let the kernel validate map-specific combinations.
Document the syntax and complete names within comma-separated lists.

Assisted-by: Codex:GPT-6
Signed-off-by: Tianyi Chen <hi@tychen.cc>
---
 .../bpf/bpftool/Documentation/bpftool-map.rst | 13 +++-
 tools/bpf/bpftool/bash-completion/bpftool     | 25 +++++-
 tools/bpf/bpftool/map.c                       | 77 ++++++++++++++++++-
 3 files changed, 109 insertions(+), 6 deletions(-)

diff --git a/tools/bpf/bpftool/Documentation/bpftool-map.rst b/tools/bpf/bpftool/Documentation/bpftool-map.rst
index 5daf3de5c74..375321d5582 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-map.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-map.rst
@@ -76,9 +76,16 @@ bpftool map { show | list }   [*MAP*]
 bpftool map create *FILE* type *TYPE* key *KEY_SIZE* value *VALUE_SIZE*  entries *MAX_ENTRIES* name *NAME* [flags *FLAGS*] [inner_map *MAP*] [offload_dev *NAME*]
     Create a new map with given parameters and pin it to *bpffs* as *FILE*.
 
-    *FLAGS* should be an integer which is the combination of desired flags,
-    e.g. 1024 for **BPF_F_MMAPABLE** (see bpf.h UAPI header for existing
-    flags).
+    *FLAGS* accepts an unsigned 32-bit integer combining the desired flags
+    (decimal, hexadecimal with a **0x** prefix, or octal with a **0** prefix),
+    or a comma-separated list of full, case-sensitive map creation flag names
+    from the bpf.h UAPI header. For example, **1024**, **0x400**, and
+    **BPF_F_MMAPABLE** are equivalent. Multiple names are combined with
+    bitwise OR, for example **BPF_F_NO_PREALLOC,BPF_F_RDONLY_PROG**.
+    Repeated names are allowed. Empty list elements, abbreviated names, and
+    lists mixing numbers with names are not accepted. Use **0** for no flags.
+    Numeric values can include bits unknown to bpftool. The kernel checks
+    whether the flags are valid for the requested map type.
 
     To create maps of type array-of-maps or hash-of-maps, the **inner_map**
     keyword must be used to pass an inner map. The kernel needs it to collect
diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index 75cbcb512eb..95f16fff876 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -718,6 +718,10 @@ _bpftool()
                     esac
                     ;;
                 create)
+                    # Keep a flags list together if readline splits at commas.
+                    if [[ $COMP_WORDBREAKS == *,* && ( $cur == , || $prev == , ) ]]; then
+                        _get_comp_words_by_ref -n , cur prev
+                    fi
                     case $prev in
                         $command)
                             _filedir
@@ -729,7 +733,26 @@ _bpftool()
                             COMPREPLY=( $( compgen -W "$BPFTOOL_MAP_CREATE_TYPES" -- "$cur" ) )
                             return 0
                             ;;
-                        key|value|flags|entries)
+                        flags)
+                            local flags='BPF_F_NO_PREALLOC BPF_F_NO_COMMON_LRU
+                                BPF_F_NUMA_NODE BPF_F_RDONLY BPF_F_WRONLY
+                                BPF_F_STACK_BUILD_ID BPF_F_ZERO_SEED
+                                BPF_F_RDONLY_PROG BPF_F_WRONLY_PROG BPF_F_CLONE
+                                BPF_F_MMAPABLE BPF_F_PRESERVE_ELEMS BPF_F_INNER_MAP
+                                BPF_F_LINK BPF_F_VTYPE_BTF_OBJ_FD BPF_F_TOKEN_FD
+                                BPF_F_SEGV_ON_FAULT BPF_F_NO_USER_CONV
+                                BPF_F_RB_OVERWRITE'
+                            local prefix= flag
+                            # Readline replaces only the suffix after a word break.
+                            if [[ $cur == *,* && $COMP_WORDBREAKS != *,* ]]; then
+                                prefix="${cur%,*},"
+                            fi
+                            for flag in $(compgen -W "$flags" -- "${cur##*,}"); do
+                                COMPREPLY+=( "${prefix}${flag}" )
+                            done
+                            return 0
+                            ;;
+                        key|value|entries)
                             return 0
                             ;;
                         inner_map)
diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 684a8fb7241..d703af60d0b 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -1250,6 +1250,73 @@ static int do_pin(int argc, char **argv)
 	return err;
 }
 
+static const struct {
+	const char *name;
+	__u32 value;
+} map_create_flags[] = {
+#define MAP_CREATE_FLAG(flag) { #flag, flag }
+	MAP_CREATE_FLAG(BPF_F_NO_PREALLOC),
+	MAP_CREATE_FLAG(BPF_F_NO_COMMON_LRU),
+	MAP_CREATE_FLAG(BPF_F_NUMA_NODE),
+	MAP_CREATE_FLAG(BPF_F_RDONLY),
+	MAP_CREATE_FLAG(BPF_F_WRONLY),
+	MAP_CREATE_FLAG(BPF_F_STACK_BUILD_ID),
+	MAP_CREATE_FLAG(BPF_F_ZERO_SEED),
+	MAP_CREATE_FLAG(BPF_F_RDONLY_PROG),
+	MAP_CREATE_FLAG(BPF_F_WRONLY_PROG),
+	MAP_CREATE_FLAG(BPF_F_CLONE),
+	MAP_CREATE_FLAG(BPF_F_MMAPABLE),
+	MAP_CREATE_FLAG(BPF_F_PRESERVE_ELEMS),
+	MAP_CREATE_FLAG(BPF_F_INNER_MAP),
+	MAP_CREATE_FLAG(BPF_F_LINK),
+	MAP_CREATE_FLAG(BPF_F_VTYPE_BTF_OBJ_FD),
+	MAP_CREATE_FLAG(BPF_F_TOKEN_FD),
+	MAP_CREATE_FLAG(BPF_F_SEGV_ON_FAULT),
+	MAP_CREATE_FLAG(BPF_F_NO_USER_CONV),
+	MAP_CREATE_FLAG(BPF_F_RB_OVERWRITE),
+#undef MAP_CREATE_FLAG
+};
+
+static int parse_map_create_flags(const char *arg, __u32 *flags)
+{
+	const char *name = arg, *comma;
+	long long value;
+	__u32 parsed = 0;
+	size_t len, i;
+	char *end;
+
+	/* Keep base-0 numeric input, including bits unknown to this bpftool. */
+	if (strncmp(arg, "BPF_F_", 6)) {
+		errno = 0;
+		value = strtoll(arg, &end, 0);
+		if (errno || end == arg || *end || value < 0 || value > UINT32_MAX)
+			goto invalid;
+		*flags = value;
+		return 0;
+	}
+
+	do {
+		comma = strchr(name, ',');
+		len = comma ? (size_t)(comma - name) : strlen(name);
+		for (i = 0; i < ARRAY_SIZE(map_create_flags); i++) {
+			if (strlen(map_create_flags[i].name) == len &&
+			    !strncmp(name, map_create_flags[i].name, len))
+				break;
+		}
+		if (i == ARRAY_SIZE(map_create_flags))
+			goto invalid;
+		parsed |= map_create_flags[i].value;
+		if (comma)
+			name = comma + 1;
+	} while (comma);
+
+	*flags = parsed;
+	return 0;
+invalid:
+	p_err("can't parse %s as map creation flags", arg);
+	return -1;
+}
+
 static int do_create(int argc, char **argv)
 {
 	LIBBPF_OPTS(bpf_map_create_opts, attr);
@@ -1301,9 +1368,14 @@ static int do_create(int argc, char **argv)
 					  "max entries"))
 				goto exit;
 		} else if (is_prefix(*argv, "flags")) {
-			if (parse_u32_arg(&argc, &argv, &attr.map_flags,
-					  "flags"))
+			NEXT_ARG();
+			if (attr.map_flags) {
+				p_err("flags already specified");
+				goto exit;
+			}
+			if (parse_map_create_flags(*argv, &attr.map_flags))
 				goto exit;
+			NEXT_ARG();
 		} else if (is_prefix(*argv, "dev")) {
 			p_info("Warning: 'bpftool map create [...] dev <ifname>' syntax is deprecated.\n"
 			       "Going further, please use 'offload_dev <ifname>' to request hardware offload for the map.");
@@ -1474,6 +1546,7 @@ static int do_help(int argc, char **argv)
 		"       DATA := { [hex] BYTES }\n"
 		"       " HELP_SPEC_PROGRAM "\n"
 		"       VALUE := { DATA | MAP | PROG }\n"
+		"       FLAGS := { integer | BPF_F_NAME[,BPF_F_NAME...] }\n"
 		"       UPDATE_FLAGS := { any | exist | noexist }\n"
 		"       TYPE := { hash | array | prog_array | perf_event_array | percpu_hash |\n"
 		"                 percpu_array | stack_trace | cgroup_array | lru_hash |\n"
-- 
2.55.0

[PATCH bpf-next 2/2] selftests/bpf: Cover symbolic bpftool map creation flags

[Tianyi Chen]

Check numeric and symbolic map creation flags, including combined and
repeated names, against map information read independently with libbpf.
Exercise malformed names and lists, update-only flags, empty input and
numeric range errors. Verify rejected input leaves no pinned map.

Assisted-by: Codex:GPT-6
Signed-off-by: Tianyi Chen <hi@tychen.cc>
---
 .../bpf/prog_tests/bpftool_map_flags.c        | 99 +++++++++++++++++++
 1 file changed, 99 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/bpftool_map_flags.c

diff --git a/tools/testing/selftests/bpf/prog_tests/bpftool_map_flags.c b/tools/testing/selftests/bpf/prog_tests/bpftool_map_flags.c
new file mode 100644
index 00000000000..140401dd254
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/bpftool_map_flags.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <errno.h>
+#include <unistd.h>
+#include <bpf/bpf.h>
+#include <bpftool_helpers.h>
+#include <test_progs.h>
+
+static const struct map_flags_test {
+	const char *name;
+	const char *flags;
+	__u32 expected_flags;
+	const char *error;
+} tests[] = {
+	{ "zero", "0", 0 },
+	{ "decimal", "129", BPF_F_NO_PREALLOC | BPF_F_RDONLY_PROG },
+	{ "hexadecimal", "0x81", BPF_F_NO_PREALLOC | BPF_F_RDONLY_PROG },
+	{ "octal", "0201", BPF_F_NO_PREALLOC | BPF_F_RDONLY_PROG },
+	{ "positive_sign", "+1", BPF_F_NO_PREALLOC },
+	{ "single_name", "BPF_F_NO_PREALLOC", BPF_F_NO_PREALLOC },
+	{ "combined_names", "BPF_F_NO_PREALLOC,BPF_F_RDONLY_PROG",
+	  BPF_F_NO_PREALLOC | BPF_F_RDONLY_PROG },
+	{ "repeated_name", "BPF_F_NO_PREALLOC,BPF_F_NO_PREALLOC", BPF_F_NO_PREALLOC },
+	{ "unknown_name", "BPF_F_NOT_A_MAP_FLAG", 0, "can't parse" },
+	{ "other_command_flag", "BPF_F_PATH_FD", 0, "can't parse" },
+	{ "update_flag", "BPF_F_LOCK", 0, "can't parse" },
+	{ "abbreviated_name", "BPF_F_NO_PRE", 0, "can't parse" },
+	{ "lowercase_name", "bpf_f_no_prealloc", 0, "can't parse" },
+	{ "empty", "", 0, "can't parse" },
+	{ "whitespace", " ", 0, "can't parse" },
+	{ "empty_list", ",", 0, "can't parse" },
+	{ "leading_comma", ",BPF_F_NO_PREALLOC", 0, "can't parse" },
+	{ "trailing_comma", "BPF_F_NO_PREALLOC,", 0, "can't parse" },
+	{ "empty_element", "BPF_F_NO_PREALLOC,,BPF_F_RDONLY_PROG", 0, "can't parse" },
+	{ "number_then_name", "1,BPF_F_RDONLY_PROG", 0, "can't parse" },
+	{ "name_then_number", "BPF_F_NO_PREALLOC,128", 0, "can't parse" },
+	{ "numeric_list", "1,128", 0, "can't parse" },
+	{ "whitespace_in_list", "BPF_F_NO_PREALLOC, BPF_F_RDONLY_PROG", 0, "can't parse" },
+	{ "overflow_u32", "4294967296", 0, "can't parse" },
+	{ "overflow_hex", "0x100000000", 0, "can't parse" },
+	{ "overflow_u64", "18446744073709551616", 0, "can't parse" },
+	{ "negative", "-1", 0, "can't parse" },
+	/* Numeric bits unknown to bpftool must still reach the kernel. */
+	{ "all_bits", "0xffffffff", 0, "map create failed" },
+	{ "invalid_combination", "BPF_F_RDONLY,BPF_F_WRONLY", 0, "map create failed" },
+};
+
+static void test_map_flags(const struct map_flags_test *test, const char *path)
+{
+	char cmd[MAX_BPFTOOL_CMD_LEN], output[1024] = {};
+	struct bpf_map_info info = {};
+	__u32 info_len = sizeof(info);
+	int fd, err;
+
+	/* Let the flags parser handle negative numbers instead of getopt(). */
+	err = snprintf(cmd, sizeof(cmd),
+		       "-- map create %s type hash key 4 value 4 entries 1 name flags_test flags '%s' 2>&1",
+		       path, test->flags);
+	if (!ASSERT_GT(err, 0, "format_command") ||
+	    !ASSERT_LT(err, sizeof(cmd), "command_length"))
+		return;
+
+	err = get_bpftool_command_output(cmd, output, sizeof(output));
+	if (test->error) {
+		ASSERT_NEQ(err, 0, "reject_flags");
+		ASSERT_HAS_SUBSTR(output, test->error, "error_message");
+		err = access(path, F_OK);
+		ASSERT_EQ(err, -1, "no_pin");
+		ASSERT_EQ(errno, ENOENT, "pin_absent");
+		goto cleanup;
+	}
+	if (!ASSERT_OK(err, "create_map"))
+		goto cleanup;
+
+	fd = bpf_obj_get(path);
+	if (!ASSERT_OK_FD(fd, "open_map"))
+		goto cleanup;
+	if (ASSERT_OK(bpf_map_get_info_by_fd(fd, &info, &info_len), "map_info"))
+		ASSERT_EQ(info.map_flags, test->expected_flags, "map_flags");
+	close(fd);
+cleanup:
+	unlink(path);
+}
+
+void test_bpftool_map_flags(void)
+{
+	char dir[] = "/sys/fs/bpf/bpftool_flags_XXXXXX";
+	char path[sizeof(dir) + sizeof("/map")];
+	int i;
+
+	if (!ASSERT_OK_PTR(mkdtemp(dir), "create_pin_dir"))
+		return;
+	snprintf(path, sizeof(path), "%s/map", dir);
+	for (i = 0; i < ARRAY_SIZE(tests); i++) {
+		if (test__start_subtest(tests[i].name))
+			test_map_flags(&tests[i], path);
+	}
+	ASSERT_OK(rmdir(dir), "remove_pin_dir");
+}
-- 
2.55.0

Re: [PATCH bpf-next 1/2] bpftool: Accept symbolic map creation flags

[bot+bpf-ci]

[-- Attachment #1: Type: text/plain, Size: 3502 bytes --]

> diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
> index 75cbcb512eba..95f16fff876e 100644
> --- a/tools/bpf/bpftool/bash-completion/bpftool
> +++ b/tools/bpf/bpftool/bash-completion/bpftool
> @@ -718,6 +718,10 @@ _bpftool()
>                      esac
>                      ;;
>                  create)
> +                    # Keep a flags list together if readline splits at commas.
> +                    if [[ $COMP_WORDBREAKS == *,* && ( $cur == , || $prev == , ) ]]; then
> +                        _get_comp_words_by_ref -n , cur prev
> +                    fi
>                      case $prev in
>                          $command)
>                              _filedir
> @@ -729,7 +733,26 @@ _bpftool()
>                              COMPREPLY=( $( compgen -W "$BPFTOOL_MAP_CREATE_TYPES" -- "$cur" ) )
>                              return 0
>                              ;;
> -                        key|value|flags|entries)
> +                        flags)
> +                            local flags='BPF_F_NO_PREALLOC BPF_F_NO_COMMON_LRU
> +                                BPF_F_NUMA_NODE BPF_F_RDONLY BPF_F_WRONLY
> +                                BPF_F_STACK_BUILD_ID BPF_F_ZERO_SEED
> +                                BPF_F_RDONLY_PROG BPF_F_WRONLY_PROG BPF_F_CLONE
> +                                BPF_F_MMAPABLE BPF_F_PRESERVE_ELEMS BPF_F_INNER_MAP
> +                                BPF_F_LINK BPF_F_VTYPE_BTF_OBJ_FD BPF_F_TOKEN_FD
> +                                BPF_F_SEGV_ON_FAULT BPF_F_NO_USER_CONV
> +                                BPF_F_RB_OVERWRITE'
> +                            local prefix= flag
> +                            # Readline replaces only the suffix after a word break.
> +                            if [[ $cur == *,* && $COMP_WORDBREAKS != *,* ]]; then
> +                                prefix="${cur%,*},"
> +                            fi
> +                            for flag in $(compgen -W "$flags" -- "${cur##*,}"); do
> +                                COMPREPLY+=( "${prefix}${flag}" )
> +                            done
> +                            return 0
> +                            ;;
> +                        key|value|entries)
>                              return 0
>                              ;;

Can the comma-separated completion work as written? When bash completes a
single match, it appends a trailing space, which splits the argument into
two words. Example:

  $ bpftool map create /sys/fs/bpf/m type hash key 4 value 4 \
    entries 1 name m flags BPF_F_MM<TAB>

completes to:

  ... flags BPF_F_MMAPABLE ,BPF_F_RDONLY

That becomes two argv words (the space before the comma). do_create() in
map.c consumes "flags BPF_F_MMAPABLE" and re-enters its loop with only
",BPF_F_RDONLY" left, so REQ_ARGS(2) fails with the message "'
BPF_F_MMAPABLE' needs at least 2 arguments, 1 found". To build a multi-
flag list the user has to delete the inserted space by hand, which defeats
the prefix-preservation logic at lines 745-749.

The usual fix is `compopt -o nospace` when emitting list elements (guarded
for shells without compopt), or suppressing the space only when more than
one flag remains plausible.

[ ... ]


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/34048916873