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authorIlya Leoshkevich <iii@linux.ibm.com>2021-02-26 21:22:56 +0100
committerAlexei Starovoitov <ast@kernel.org>2021-03-04 18:31:53 -0800
commit6be6a0baffc1357b6d2023155753f111624c4fec (patch)
tree206f7fc16a8f368467e3a2e7c5ac716494ace314
parent7999cf7df899caf244236dcc11cce844347dab4a (diff)
bpf: Document BTF_KIND_FLOAT in btf.rst
Also document the expansion of the kind bitfield. Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210226202256.116518-11-iii@linux.ibm.com
-rw-r--r--Documentation/bpf/btf.rst17
1 files changed, 15 insertions, 2 deletions
diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
index 44dc789de2b4..846354cd2d69 100644
--- a/Documentation/bpf/btf.rst
+++ b/Documentation/bpf/btf.rst
@@ -84,6 +84,7 @@ sequentially and type id is assigned to each recognized type starting from id
#define BTF_KIND_FUNC_PROTO 13 /* Function Proto */
#define BTF_KIND_VAR 14 /* Variable */
#define BTF_KIND_DATASEC 15 /* Section */
+ #define BTF_KIND_FLOAT 16 /* Floating point */
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.
@@ -95,8 +96,8 @@ Each type contains the following common data::
/* "info" bits arrangement
* bits 0-15: vlen (e.g. # of struct's members)
* bits 16-23: unused
- * bits 24-27: kind (e.g. int, ptr, array...etc)
- * bits 28-30: unused
+ * 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
*/
@@ -452,6 +453,18 @@ map definition.
* ``offset``: the in-section offset of the variable
* ``size``: the size of the variable in bytes
+2.2.16 BTF_KIND_FLOAT
+~~~~~~~~~~~~~~~~~~~~~
+
+``struct btf_type`` encoding requirement:
+ * ``name_off``: any valid offset
+ * ``info.kind_flag``: 0
+ * ``info.kind``: BTF_KIND_FLOAT
+ * ``info.vlen``: 0
+ * ``size``: the size of the float type in bytes: 2, 4, 8, 12 or 16.
+
+No additional type data follow ``btf_type``.
+
3. BTF Kernel API
*****************