[v4,bpf-next,4/6] libbpf: Allow specifying 64-bit integers in map BTF.

Commit Message

Alexei Starovoitov March 7, 2024, 3:12 a.m. UTC

From: Alexei Starovoitov <[e-mail]>

__uint() macro that is used to specify map attributes like:
  __uint(type, BPF_MAP_TYPE_ARRAY);
  __uint(map_flags, BPF_F_MMAPABLE);
It is limited to 32-bit, since BTF_KIND_ARRAY has u32 "number of elements"
field in "struct btf_array".

Introduce __ulong() macro that allows specifying values bigger than 32-bit.
In map definition "map_extra" is the only u64 field, so far.

Signed-off-by: Alexei Starovoitov <[e-mail]>
---
 tools/lib/bpf/bpf_helpers.h |  1 +
 tools/lib/bpf/libbpf.c      | 44 +++++++++++++++++++++++++++++++++++--
 2 files changed, 43 insertions(+), 2 deletions(-)

Patch

diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index 79eaa581be98..112b1504e072 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -13,6 +13,7 @@ 
 #define __uint(name, val) int (*name)[val]
 #define __type(name, val) typeof(val) *name
 #define __array(name, val) typeof(val) *name[]
+#define __ulong(name, val) enum { ___bpf_concat(__unique_value, __COUNTER__) = val } name
 
 /*
  * Helper macro to place programs, maps, license in
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 672fca94ff53..567ad367e7aa 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2335,6 +2335,46 @@  static bool get_map_field_int(const char *map_name, const struct btf *btf,
 	return true;
 }
 
+static bool get_map_field_long(const char *map_name, const struct btf *btf,
+			       const struct btf_member *m, __u64 *res)
+{
+	const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL);
+	const char *name = btf__name_by_offset(btf, m->name_off);
+
+	if (btf_is_ptr(t)) {
+		__u32 res32;
+		bool ret;
+
+		ret = get_map_field_int(map_name, btf, m, &res32);
+		if (ret)
+			*res = (__u64)res32;
+		return ret;
+	}
+
+	if (!btf_is_enum(t) && !btf_is_enum64(t)) {
+		pr_warn("map '%s': attr '%s': expected ENUM or ENUM64, got %s.\n",
+			map_name, name, btf_kind_str(t));
+		return false;
+	}
+
+	if (btf_vlen(t) != 1) {
+		pr_warn("map '%s': attr '%s': invalid __ulong\n",
+			map_name, name);
+		return false;
+	}
+
+	if (btf_is_enum(t)) {
+		const struct btf_enum *e = btf_enum(t);
+
+		*res = e->val;
+	} else {
+		const struct btf_enum64 *e = btf_enum64(t);
+
+		*res = btf_enum64_value(e);
+	}
+	return true;
+}
+
 static int pathname_concat(char *buf, size_t buf_sz, const char *path, const char *name)
 {
 	int len;
@@ -2568,9 +2608,9 @@  int parse_btf_map_def(const char *map_name, struct btf *btf,
 			map_def->pinning = val;
 			map_def->parts |= MAP_DEF_PINNING;
 		} else if (strcmp(name, "map_extra") == 0) {
-			__u32 map_extra;
+			__u64 map_extra;
 
-			if (!get_map_field_int(map_name, btf, m, &map_extra))
+			if (!get_map_field_long(map_name, btf, m, &map_extra))
 				return -EINVAL;
 			map_def->map_extra = map_extra;
 			map_def->parts |= MAP_DEF_MAP_EXTRA;