On the kernel side, introduce a new btf_kind_operations. It is
similar to that of BTF_KIND_INT, however, it does not need to
handle encodings and bit offsets. Do not implement printing, since
the kernel does not know how to format floating-point values.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 kernel/bpf/btf.c | 101 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 99 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 756a93f534b6..6f27b7b59d77 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c

@@ -173,8 +173,9 @@
 #define BITS_ROUNDUP_BYTES(bits) \
        (BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))

-#define BTF_INFO_MASK 0x8f00ffff
+#define BTF_INFO_MASK 0x9f00ffff
 #define BTF_INT_MASK 0x0fffffff
+#define BTF_FLOAT_MASK 0x000000ff
 #define BTF_TYPE_ID_VALID(type_id) ((type_id) <= BTF_MAX_TYPE)
 #define BTF_STR_OFFSET_VALID(name_off) ((name_off) <= BTF_MAX_NAME_OFFSET)

@@ -280,6 +281,7 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = {
        [BTF_KIND_FUNC_PROTO]   = "FUNC_PROTO",
        [BTF_KIND_VAR]          = "VAR",
        [BTF_KIND_DATASEC]      = "DATASEC",
+       [BTF_KIND_FLOAT]        = "FLOAT",
 };

 static const char *btf_type_str(const struct btf_type *t)

@@ -574,6 +576,7 @@ static bool btf_type_has_size(const struct btf_type *t)
        case BTF_KIND_UNION:
        case BTF_KIND_ENUM:
        case BTF_KIND_DATASEC:
+       case BTF_KIND_FLOAT:
                return true;
        }

@@ -614,6 +617,11 @@ static const struct btf_var *btf_type_var(const struct btf_type *t)
        return (const struct btf_var *)(t + 1);
 }

+static u32 btf_type_float(const struct btf_type *t)
+{
+       return *(u32 *)(t + 1);
+}
+
 static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
 {
        return kind_ops[BTF_INFO_KIND(t->info)];

@@ -1704,6 +1712,7 @@ __btf_resolve_size(const struct btf *btf, const struct btf_type *type,
                case BTF_KIND_STRUCT:
                case BTF_KIND_UNION:
                case BTF_KIND_ENUM:
+               case BTF_KIND_FLOAT:
                        size = type->size;
                        goto resolved;

@@ -1849,7 +1858,7 @@ static int btf_df_check_kflag_member(struct btf_verifier_env *env,
        return -EINVAL;
 }

-/* Used for ptr, array and struct/union type members.
+/* Used for ptr, array struct/union and float type members.
  * int, enum and modifier types have their specific callback functions.
  */
 static int btf_generic_check_kflag_member(struct btf_verifier_env *env,

@@ -3675,6 +3684,93 @@ static const struct btf_kind_operations datasec_ops = {
        .show                   = btf_datasec_show,
 };

+static s32 btf_float_check_meta(struct btf_verifier_env *env,
+                               const struct btf_type *t,
+                               u32 meta_left)
+{
+       u32 float_data, nr_bits, meta_needed = sizeof(float_data);
+
+       if (meta_left < meta_needed) {
+               btf_verifier_log_basic(env, t,
+                                      "meta_left:%u meta_needed:%u",
+                                      meta_left, meta_needed);
+               return -EINVAL;
+       }
+
+       if (btf_type_vlen(t)) {
+               btf_verifier_log_type(env, t, "vlen != 0");
+               return -EINVAL;
+       }
+
+       if (btf_type_kflag(t)) {
+               btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
+               return -EINVAL;
+       }
+
+       float_data = btf_type_float(t);
+       if (float_data & ~BTF_FLOAT_MASK) {
+               btf_verifier_log_basic(env, t, "Invalid float_data:%x",
+                                      float_data);
+               return -EINVAL;
+       }
+
+       nr_bits = BTF_FLOAT_BITS(float_data);
+
+       if (BITS_ROUNDUP_BYTES(nr_bits) > t->size) {

+               btf_verifier_log_type(env, t, "nr_bits exceeds type_size");
+               return -EINVAL;
+       }
+
+       btf_verifier_log_type(env, t, NULL);
+
+       return meta_needed;
+}
+
+static int btf_float_check_member(struct btf_verifier_env *env,
+                                 const struct btf_type *struct_type,
+                                 const struct btf_member *member,
+                                 const struct btf_type *member_type)
+{
+       u64 end_offset_bytes;
+       u64 end_offset_bits;
+       u64 offset_bits;
+       u32 float_data;
+       u64 size_bits;
+
+       float_data = btf_type_float(member_type);
+       size_bits = BTF_FLOAT_BITS(float_data);
+       offset_bits = member->offset;
+       end_offset_bits = offset_bits + size_bits;
+       end_offset_bytes = BITS_ROUNDUP_BYTES(end_offset_bits);
+
+       if (end_offset_bytes > struct_type->size) {
+               btf_verifier_log_member(env, struct_type, member,
+                                       "Member exceeds struct_size");
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
+static void btf_float_log(struct btf_verifier_env *env,
+                         const struct btf_type *t)
+{
+       int float_data = btf_type_float(t);
+
+       btf_verifier_log(env,
+                        "size=%u nr_bits=%u",
+                        t->size, BTF_FLOAT_BITS(float_data));
+}
+
+static const struct btf_kind_operations float_ops = {
+       .check_meta = btf_float_check_meta,
+       .resolve = btf_df_resolve,
+       .check_member = btf_float_check_member,
+       .check_kflag_member = btf_generic_check_kflag_member,
+       .log_details = btf_float_log,
+       .show = btf_df_show,
+};
+
 static int btf_func_proto_check(struct btf_verifier_env *env,
                                const struct btf_type *t)
 {

@@ -3808,6 +3904,7 @@ static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = {
        [BTF_KIND_FUNC_PROTO] = &func_proto_ops,
        [BTF_KIND_VAR] = &var_ops,
        [BTF_KIND_DATASEC] = &datasec_ops,
+       [BTF_KIND_FLOAT] = &float_ops,
 };

 static s32 btf_check_meta(struct btf_verifier_env *env,
--

2.29.2