bpf: enable cgroup local storage map pretty print with kind_flag

Commit 970289fc0a83 ("bpf: add bpffs pretty print for cgroup
local storage maps") added bpffs pretty print for cgroup
local storage maps. The commit worked for struct without kind_flag
set.

This patch refactored and made pretty print also work
with kind_flag set for the struct.

Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

3 files changed, 36 insertions, 23 deletions

diff --git a/include/linux/btf.h b/include/linux/btf.h
index 58000d7e06e3..12502e25e767 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -7,6 +7,7 @@
 #include <linux/types.h>
 
 struct btf;
+struct btf_member;
 struct btf_type;
 union bpf_attr;
 
@@ -46,7 +47,9 @@ void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
                        struct seq_file *m);
 int btf_get_fd_by_id(u32 id);
 u32 btf_id(const struct btf *btf);
-bool btf_type_is_reg_int(const struct btf_type *t, u32 expected_size);
+bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
+                           const struct btf_member *m,
+                           u32 expected_offset, u32 expected_size);
 
 #ifdef CONFIG_BPF_SYSCALL
 const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 93b6905e3a9b..e804b26a0506 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -546,22 +546,41 @@ static bool btf_type_int_is_regular(const struct btf_type *t)
 }
 
 /*
- * Check that given type is a regular int and has the expected size.
+ * Check that given struct member is a regular int with expected
+ * offset and size.
  */
-bool btf_type_is_reg_int(const struct btf_type *t, u32 expected_size)
+bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
+                           const struct btf_member *m,
+                           u32 expected_offset, u32 expected_size)
 {
-        u8 nr_bits, nr_bytes;
-        u32 int_data;
+        const struct btf_type *t;
+        u32 id, int_data;
+        u8 nr_bits;
 
-        if (!btf_type_is_int(t))
+        id = m->type;
+        t = btf_type_id_size(btf, &id, NULL);
+        if (!t || !btf_type_is_int(t))
                 return false;
 
         int_data = btf_type_int(t);
         nr_bits = BTF_INT_BITS(int_data);
-        nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
-        if (BITS_PER_BYTE_MASKED(nr_bits) ||
-            BTF_INT_OFFSET(int_data) ||
-            nr_bytes != expected_size)
+        if (btf_type_kflag(s)) {
+                u32 bitfield_size = BTF_MEMBER_BITFIELD_SIZE(m->offset);
+                u32 bit_offset = BTF_MEMBER_BIT_OFFSET(m->offset);
+
+                /* if kflag set, int should be a regular int and
+                 * bit offset should be at byte boundary.
+                 */
+                return !bitfield_size &&
+                       BITS_ROUNDUP_BYTES(bit_offset) == expected_offset &&
+                       BITS_ROUNDUP_BYTES(nr_bits) == expected_size;
+        }
+
+        if (BTF_INT_OFFSET(int_data) ||
+            BITS_PER_BYTE_MASKED(m->offset) ||
+            BITS_ROUNDUP_BYTES(m->offset) != expected_offset ||
+            BITS_PER_BYTE_MASKED(nr_bits) ||
+            BITS_ROUNDUP_BYTES(nr_bits) != expected_size)
                 return false;
 
         return true;
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index 5eca03da0989..07a34ef562a0 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -315,9 +315,8 @@ static int cgroup_storage_check_btf(const struct bpf_map *map,
                                     const struct btf_type *key_type,
                                     const struct btf_type *value_type)
 {
-        const struct btf_type *t;
         struct btf_member *m;
-        u32 id, size;
+        u32 offset, size;
 
         /* Key is expected to be of struct bpf_cgroup_storage_key type,
          * which is:
@@ -338,25 +337,17 @@ static int cgroup_storage_check_btf(const struct bpf_map *map,
          * The first field must be a 64 bit integer at 0 offset.
          */
         m = (struct btf_member *)(key_type + 1);
-        if (m->offset)
-                return -EINVAL;
-        id = m->type;
-        t = btf_type_id_size(btf, &id, NULL);
         size = FIELD_SIZEOF(struct bpf_cgroup_storage_key, cgroup_inode_id);
-        if (!t || !btf_type_is_reg_int(t, size))
+        if (!btf_member_is_reg_int(btf, key_type, m, 0, size))
                 return -EINVAL;
 
         /*
          * The second field must be a 32 bit integer at 64 bit offset.
          */
         m++;
-        if (m->offset != offsetof(struct bpf_cgroup_storage_key, attach_type) *
-            BITS_PER_BYTE)
-                return -EINVAL;
-        id = m->type;
-        t = btf_type_id_size(btf, &id, NULL);
+        offset = offsetof(struct bpf_cgroup_storage_key, attach_type);
         size = FIELD_SIZEOF(struct bpf_cgroup_storage_key, attach_type);
-        if (!t || !btf_type_is_reg_int(t, size))
+        if (!btf_member_is_reg_int(btf, key_type, m, offset, size))
                 return -EINVAL;
 
         return 0;