diff mbox series

[RFC,4/6] bpf: Add BTF_KIND_FLOAT support

Message ID 20210210030317.78820-5-iii@linux.ibm.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series Add BTF_KIND_FLOAT support | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Ilya Leoshkevich Feb. 10, 2021, 3:03 a.m. UTC 
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(-)

Comments

Andrii Nakryiko Feb. 11, 2021, 12:20 a.m. UTC | #1 
On Tue, Feb 9, 2021 at 7:04 PM Ilya Leoshkevich <iii@linux.ibm.com> wrote:
>
> 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) {

what's the case where nr_bits != t->size * 8 ? Is that even possible in C?

> +               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
>
diff mbox series

Patch

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,