[PATCH v2 bpf-next] bpf: Charge modmem for struct_ops trampoline

[Song Liu <song@xxxxxxxxxx>]

Current code charges modmem for regular trampoline, but not for struct_ops
trampoline. Add bpf_jit_[charge|uncharge]_modmem() to struct_ops so the
trampoline is charged in both cases.

Signed-off-by: Song Liu <song@xxxxxxxxxx>

---
Changes in v2:
1. Fix error handling path of bpf_struct_ops_map_alloc(). (Martin)
---
 kernel/bpf/bpf_struct_ops.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index fdc3e8705a3c..db6176fb64dc 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -615,7 +615,10 @@ static void __bpf_struct_ops_map_free(struct bpf_map *map)
 	if (st_map->links)
 		bpf_struct_ops_map_put_progs(st_map);
 	bpf_map_area_free(st_map->links);
-	bpf_jit_free_exec(st_map->image);
+	if (st_map->image) {
+		bpf_jit_free_exec(st_map->image);
+		bpf_jit_uncharge_modmem(PAGE_SIZE);
+	}
 	bpf_map_area_free(st_map->uvalue);
 	bpf_map_area_free(st_map);
 }
@@ -657,6 +660,7 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
 	struct bpf_struct_ops_map *st_map;
 	const struct btf_type *t, *vt;
 	struct bpf_map *map;
+	int ret;
 
 	st_ops = bpf_struct_ops_find_value(attr->btf_vmlinux_value_type_id);
 	if (!st_ops)
@@ -681,12 +685,27 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
 	st_map->st_ops = st_ops;
 	map = &st_map->map;
 
+	ret = bpf_jit_charge_modmem(PAGE_SIZE);
+	if (ret) {
+		__bpf_struct_ops_map_free(map);
+		return ERR_PTR(ret);
+	}
+
+	st_map->image = bpf_jit_alloc_exec(PAGE_SIZE);
+	if (!st_map->image) {
+		/* __bpf_struct_ops_map_free() uses st_map->image as flag
+		 * for "charged or not". In this case, we need to unchange
+		 * here.
+		 */
+		bpf_jit_uncharge_modmem(PAGE_SIZE);
+		__bpf_struct_ops_map_free(map);
+		return ERR_PTR(-ENOMEM);
+	}
 	st_map->uvalue = bpf_map_area_alloc(vt->size, NUMA_NO_NODE);
 	st_map->links =
 		bpf_map_area_alloc(btf_type_vlen(t) * sizeof(struct bpf_links *),
 				   NUMA_NO_NODE);
-	st_map->image = bpf_jit_alloc_exec(PAGE_SIZE);
-	if (!st_map->uvalue || !st_map->links || !st_map->image) {
+	if (!st_map->uvalue || !st_map->links) {
 		__bpf_struct_ops_map_free(map);
 		return ERR_PTR(-ENOMEM);
 	}
@@ -907,4 +926,3 @@ int bpf_struct_ops_link_create(union bpf_attr *attr)
 	kfree(link);
 	return err;
 }
-
-- 
2.34.1