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[bpf-next,4/6] bpf: Add BTF_KIND_FLOAT support

Message ID 20210216011216.3168-5-iii@linux.ibm.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series Add BTF_KIND_FLOAT support | expand

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Commit Message

Ilya Leoshkevich Feb. 16, 2021, 1:12 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 | 66 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 64 insertions(+), 2 deletions(-)

Comments

Yonghong Song Feb. 18, 2021, 7:13 a.m. UTC | #1 
On 2/15/21 5:12 PM, Ilya Leoshkevich 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 | 66 ++++++++++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 64 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index 2efeb5f4b343..6c73e5484409 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -173,7 +173,7 @@
>   #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_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 +280,7 @@ 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 +575,7 @@ 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;
>   	}
>   
> @@ -1704,6 +1706,7 @@ __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 +1852,7 @@ 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 +3678,64 @@ 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)
> +{
> +	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;
> +	}

I think we should enforce proper float size as well (2/4/8/16).

> +
> +	btf_verifier_log_type(env, t, NULL);
> +
> +	return 0;
> +}
> +
> +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;
> +	u64 size_bits;
> +
> +	size_bits = member_type->size * BITS_PER_BYTE;
> +	offset_bits = member->offset;

float type cannot be used for bitfield, so offset here must of
a multiple of allowed alignment, i.e., min(ptr_size, member_type->size).
We should enforce here.

> +	end_offset_bits = offset_bits + size_bits;
> +	end_offset_bytes = BITS_ROUNDUP_BYTES(end_offset_bits);

There is no need to do BITS_ROUNDUP_BYTES if we enforce member->offset
as in the above.

> +
> +	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)
> +{
> +	btf_verifier_log(env, "size=%u", t->size);
> +}
> +
> +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 +3869,7 @@ 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,
>
diff mbox series

Patch

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 2efeb5f4b343..6c73e5484409 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -173,7 +173,7 @@ 
 #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_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 +280,7 @@  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 +575,7 @@  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;
 	}
 
@@ -1704,6 +1706,7 @@  __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 +1852,7 @@  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 +3678,64 @@  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)
+{
+	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;
+	}
+
+	btf_verifier_log_type(env, t, NULL);
+
+	return 0;
+}
+
+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;
+	u64 size_bits;
+
+	size_bits = member_type->size * BITS_PER_BYTE;
+	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)
+{
+	btf_verifier_log(env, "size=%u", t->size);
+}
+
+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 +3869,7 @@  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,