Merge branch 'bpf: arena prerequisites'

Alexei Starovoitov says:

====================
These are bpf_arena prerequisite patches.
Useful on its own.

Alexei Starovoitov (5):
  bpf: Allow kfuncs return 'void *'
  bpf: Recognize '__map' suffix in kfunc arguments
  bpf: Plumb get_unmapped_area() callback into bpf_map_ops
  libbpf: Allow specifying 64-bit integers in map BTF.
  bpf: Tell bpf programs kernel's PAGE_SIZE
====================

Signed-off-by: Martin KaFai Lau <[email protected]>

Author: Martin KaFai Lau

include/linux/bpf.h

@@ -139,6 +139,9 @@ struct bpf_map_ops {
 	int (*map_mmap)(struct bpf_map *map, struct vm_area_struct *vma);
 	__poll_t (*map_poll)(struct bpf_map *map, struct file *filp,
 			     struct poll_table_struct *pts);
+	unsigned long (*map_get_unmapped_area)(struct file *filep, unsigned long addr,
+					       unsigned long len, unsigned long pgoff,
+					       unsigned long flags);
 
 	/* Functions called by bpf_local_storage maps */
 	int (*map_local_storage_charge)(struct bpf_local_storage_map *smap,

kernel/bpf/core.c

@@ -88,13 +88,18 @@ void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, uns
 	return NULL;
 }
 
+/* tell bpf programs that include vmlinux.h kernel's PAGE_SIZE */
+enum page_size_enum {
+	__PAGE_SIZE = PAGE_SIZE
+};
+
 struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flags)
 {
 	gfp_t gfp_flags = bpf_memcg_flags(GFP_KERNEL | __GFP_ZERO | gfp_extra_flags);
 	struct bpf_prog_aux *aux;
 	struct bpf_prog *fp;
 
-	size = round_up(size, PAGE_SIZE);
+	size = round_up(size, __PAGE_SIZE);
 	fp = __vmalloc(size, gfp_flags);
 	if (fp == NULL)
 		return NULL;

kernel/bpf/syscall.c

@@ -937,6 +937,21 @@ static __poll_t bpf_map_poll(struct file *filp, struct poll_table_struct *pts)
 	return EPOLLERR;
 }
 
+static unsigned long bpf_get_unmapped_area(struct file *filp, unsigned long addr,
+					   unsigned long len, unsigned long pgoff,
+					   unsigned long flags)
+{
+	struct bpf_map *map = filp->private_data;
+
+	if (map->ops->map_get_unmapped_area)
+		return map->ops->map_get_unmapped_area(filp, addr, len, pgoff, flags);
+#ifdef CONFIG_MMU
+	return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
+#else
+	return addr;
+#endif
+}
+
 const struct file_operations bpf_map_fops = {
 #ifdef CONFIG_PROC_FS
 	.show_fdinfo	= bpf_map_show_fdinfo,
@@ -946,6 +961,7 @@ const struct file_operations bpf_map_fops = {
 	.write		= bpf_dummy_write,
 	.mmap		= bpf_map_mmap,
 	.poll		= bpf_map_poll,
+	.get_unmapped_area = bpf_get_unmapped_area,
 };
 
 int bpf_map_new_fd(struct bpf_map *map, int flags)

kernel/bpf/verifier.c

@@ -10752,6 +10752,11 @@ static bool is_kfunc_arg_ignore(const struct btf *btf, const struct btf_param *a
 	return btf_param_match_suffix(btf, arg, "__ign");
 }
 
+static bool is_kfunc_arg_map(const struct btf *btf, const struct btf_param *arg)
+{
+	return btf_param_match_suffix(btf, arg, "__map");
+}
+
 static bool is_kfunc_arg_alloc_obj(const struct btf *btf, const struct btf_param *arg)
 {
 	return btf_param_match_suffix(btf, arg, "__alloc");
@@ -10921,6 +10926,7 @@ enum kfunc_ptr_arg_type {
 	KF_ARG_PTR_TO_RB_NODE,
 	KF_ARG_PTR_TO_NULL,
 	KF_ARG_PTR_TO_CONST_STR,
+	KF_ARG_PTR_TO_MAP,
 };
 
 enum special_kfunc_type {
@@ -11074,6 +11080,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
 	if (is_kfunc_arg_const_str(meta->btf, &args[argno]))
 		return KF_ARG_PTR_TO_CONST_STR;
 
+	if (is_kfunc_arg_map(meta->btf, &args[argno]))
+		return KF_ARG_PTR_TO_MAP;
+
 	if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) {
 		if (!btf_type_is_struct(ref_t)) {
 			verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n",
@@ -11674,6 +11683,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
 		switch (kf_arg_type) {
 		case KF_ARG_PTR_TO_NULL:
 			continue;
+		case KF_ARG_PTR_TO_MAP:
 		case KF_ARG_PTR_TO_ALLOC_BTF_ID:
 		case KF_ARG_PTR_TO_BTF_ID:
 			if (!is_kfunc_trusted_args(meta) && !is_kfunc_rcu(meta))
@@ -11890,6 +11900,12 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
 			if (ret < 0)
 				return ret;
 			break;
+		case KF_ARG_PTR_TO_MAP:
+			/* If argument has '__map' suffix expect 'struct bpf_map *' */
+			ref_id = *reg2btf_ids[CONST_PTR_TO_MAP];
+			ref_t = btf_type_by_id(btf_vmlinux, ref_id);
+			ref_tname = btf_name_by_offset(btf, ref_t->name_off);
+			fallthrough;
 		case KF_ARG_PTR_TO_BTF_ID:
 			/* Only base_type is checked, further checks are done here */
 			if ((base_type(reg->type) != PTR_TO_BTF_ID ||
@@ -12364,6 +12380,9 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 					meta.func_name);
 				return -EFAULT;
 			}
+		} else if (btf_type_is_void(ptr_type)) {
+			/* kfunc returning 'void *' is equivalent to returning scalar */
+			mark_reg_unknown(env, regs, BPF_REG_0);
 		} else if (!__btf_type_is_struct(ptr_type)) {
 			if (!meta.r0_size) {
 				__u32 sz;

tools/bpf/bpftool/gen.c

@@ -248,7 +248,7 @@ static const struct btf_type *find_type_for_map(struct btf *btf, const char *map
 	return NULL;
 }
 
-static bool is_internal_mmapable_map(const struct bpf_map *map, char *buf, size_t sz)
+static bool is_mmapable_map(const struct bpf_map *map, char *buf, size_t sz)
 {
 	if (!bpf_map__is_internal(map) || !(bpf_map__map_flags(map) & BPF_F_MMAPABLE))
 		return false;
@@ -274,7 +274,7 @@ static int codegen_datasecs(struct bpf_object *obj, const char *obj_name)
 
 	bpf_object__for_each_map(map, obj) {
 		/* only generate definitions for memory-mapped internal maps */
-		if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
+		if (!is_mmapable_map(map, map_ident, sizeof(map_ident)))
 			continue;
 
 		sec = find_type_for_map(btf, map_ident);
@@ -327,7 +327,7 @@ static int codegen_subskel_datasecs(struct bpf_object *obj, const char *obj_name
 
 	bpf_object__for_each_map(map, obj) {
 		/* only generate definitions for memory-mapped internal maps */
-		if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
+		if (!is_mmapable_map(map, map_ident, sizeof(map_ident)))
 			continue;
 
 		sec = find_type_for_map(btf, map_ident);
@@ -504,7 +504,7 @@ static void codegen_asserts(struct bpf_object *obj, const char *obj_name)
 		", obj_name);
 
 	bpf_object__for_each_map(map, obj) {
-		if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
+		if (!is_mmapable_map(map, map_ident, sizeof(map_ident)))
 			continue;
 
 		sec = find_type_for_map(btf, map_ident);
@@ -720,7 +720,7 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
 		const void *mmap_data = NULL;
 		size_t mmap_size = 0;
 
-		if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
+		if (!is_mmapable_map(map, ident, sizeof(ident)))
 			continue;
 
 		codegen("\
@@ -782,7 +782,7 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
 	bpf_object__for_each_map(map, obj) {
 		const char *mmap_flags;
 
-		if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
+		if (!is_mmapable_map(map, ident, sizeof(ident)))
 			continue;
 
 		if (bpf_map__map_flags(map) & BPF_F_RDONLY_PROG)
@@ -871,7 +871,7 @@ codegen_maps_skeleton(struct bpf_object *obj, size_t map_cnt, bool mmaped)
 			",
 			i, bpf_map__name(map), i, ident);
 		/* memory-mapped internal maps */
-		if (mmaped && is_internal_mmapable_map(map, ident, sizeof(ident))) {
+		if (mmaped && is_mmapable_map(map, ident, sizeof(ident))) {
 			printf("\ts->maps[%zu].mmaped = (void **)&obj->%s;\n",
 				i, ident);
 		}
@@ -1617,7 +1617,7 @@ static int do_subskeleton(int argc, char **argv)
 		/* Also count all maps that have a name */
 		map_cnt++;
 
-		if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
+		if (!is_mmapable_map(map, ident, sizeof(ident)))
 			continue;
 
 		map_type_id = bpf_map__btf_value_type_id(map);
@@ -1739,7 +1739,7 @@ static int do_subskeleton(int argc, char **argv)
 
 	/* walk through each symbol and emit the runtime representation */
 	bpf_object__for_each_map(map, obj) {
-		if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
+		if (!is_mmapable_map(map, ident, sizeof(ident)))
 			continue;
 
 		map_type_id = bpf_map__btf_value_type_id(map);

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

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;