Add BTF_KIND_ENUM64 documentation in btf.rst.
Also fixed a typo for section number for BTF_KIND_TYPE_TAG
from 2.2.17 to 2.2.18, and fixed a type size issue for
BTF_KIND_ENUM.
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
Documentation/bpf/btf.rst | 43 +++++++++++++++++++++++++++++++++------
1 file changed, 37 insertions(+), 6 deletions(-)
diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
index 7940da9bc6c1..f49aeef62d0c 100644
--- a/Documentation/bpf/btf.rst
+++ b/Documentation/bpf/btf.rst
@@ -74,7 +74,7 @@ sequentially and type id is assigned to each recognized type starting from id
#define BTF_KIND_ARRAY 3 /* Array */
#define BTF_KIND_STRUCT 4 /* Struct */
#define BTF_KIND_UNION 5 /* Union */
- #define BTF_KIND_ENUM 6 /* Enumeration */
+ #define BTF_KIND_ENUM 6 /* Enumeration up to 32-bit values */
#define BTF_KIND_FWD 7 /* Forward */
#define BTF_KIND_TYPEDEF 8 /* Typedef */
#define BTF_KIND_VOLATILE 9 /* Volatile */
@@ -87,6 +87,7 @@ sequentially and type id is assigned to each recognized type starting from id
#define BTF_KIND_FLOAT 16 /* Floating point */
#define BTF_KIND_DECL_TAG 17 /* Decl Tag */
#define BTF_KIND_TYPE_TAG 18 /* Type Tag */
+ #define BTF_KIND_ENUM64 19 /* Enumeration up to 64-bit values */
Note that the type section encodes debug info, not just pure types.
``BTF_KIND_FUNC`` is not a type, and it represents a defined subprogram.
@@ -101,10 +102,10 @@ Each type contains the following common data::
* bits 24-28: kind (e.g. int, ptr, array...etc)
* bits 29-30: unused
* bit 31: kind_flag, currently used by
- * struct, union and fwd
+ * struct, union, fwd, enum and enum64.
*/
__u32 info;
- /* "size" is used by INT, ENUM, STRUCT and UNION.
+ /* "size" is used by INT, ENUM, STRUCT, UNION and ENUM64.
* "size" tells the size of the type it is describing.
*
* "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
@@ -281,10 +282,10 @@ modes exist:
``struct btf_type`` encoding requirement:
* ``name_off``: 0 or offset to a valid C identifier
- * ``info.kind_flag``: 0
+ * ``info.kind_flag``: 0 for unsigned, 1 for signed
* ``info.kind``: BTF_KIND_ENUM
* ``info.vlen``: number of enum values
- * ``size``: 4
+ * ``size``: 1/2/4/8
``btf_type`` is followed by ``info.vlen`` number of ``struct btf_enum``.::
@@ -297,6 +298,10 @@ The ``btf_enum`` encoding:
* ``name_off``: offset to a valid C identifier
* ``val``: any value
+If the original enum value is signed and the size is less than 4,
+that value will be sign extended into 4 bytes. If the size is 8,
+the value will be truncated into 4 bytes.
+
2.2.7 BTF_KIND_FWD
~~~~~~~~~~~~~~~~~~
@@ -493,7 +498,7 @@ the attribute is applied to a ``struct``/``union`` member or
a ``func`` argument, and ``btf_decl_tag.component_idx`` should be a
valid index (starting from 0) pointing to a member or an argument.
-2.2.17 BTF_KIND_TYPE_TAG
+2.2.18 BTF_KIND_TYPE_TAG
~~~~~~~~~~~~~~~~~~~~~~~~
``struct btf_type`` encoding requirement:
@@ -516,6 +521,32 @@ type_tag, then zero or more const/volatile/restrict/typedef
and finally the base type. The base type is one of
int, ptr, array, struct, union, enum, func_proto and float types.
+2.2.19 BTF_KIND_ENUM64
+~~~~~~~~~~~~~~~~~~~~~~
+
+``struct btf_type`` encoding requirement:
+ * ``name_off``: 0 or offset to a valid C identifier
+ * ``info.kind_flag``: 0 for unsigned, 1 for signed
+ * ``info.kind``: BTF_KIND_ENUM64
+ * ``info.vlen``: number of enum values
+ * ``size``: 1/2/4/8
+
+``btf_type`` is followed by ``info.vlen`` number of ``struct btf_enum64``.::
+
+ struct btf_enum64 {
+ __u32 name_off;
+ __u32 val_lo32;
+ __u32 val_hi32;
+ };
+
+The ``btf_enum64`` encoding:
+ * ``name_off``: offset to a valid C identifier
+ * ``val_lo32``: lower 32-bit value for a 64-bit value
+ * ``val_hi32``: high 32-bit value for a 64-bit value
+
+If the original enum value is signed and the size is less than 8,
+that value will be sign extended into 8 bytes.
+
3. BTF Kernel API
=================
--
2.30.2
