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 <martin.lau@kernel.org>

3 files changed, 41 insertions, 1 deletions

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 9ee4536d0a09..134b7979f537 100644
--- a/kernel/bpf/core.c
+++ b/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;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index b2750b79ac80..f63f4da4db5e 100644
--- a/kernel/bpf/syscall.c
+++ b/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)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index ee86e4d7d5fc..bf084c693507 100644
--- a/kernel/bpf/verifier.c
+++ b/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;