[PATCH bpf-next v1 14/14] docs/bpf: Document split arena argument JIT capabilities

Arena kfunc calls and struct_ops callbacks perform opposite conversions
at different JIT boundaries and are now advertised independently.

Document the architectures supporting each capability so users can tell
where arena allocation kfuncs and arena struct_ops arguments can load.

Signed-off-by: Kumar Kartikeya Dwivedi <[email protected]>
---
 Documentation/bpf/kfuncs.rst | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst
index 89dea6b0b024..65e56491cae1 100644
--- a/Documentation/bpf/kfuncs.rst
+++ b/Documentation/bpf/kfuncs.rst
@@ -301,9 +301,10 @@ An example is given below::
         }
 
 Calling such a kfunc requires the program to use an arena map and a JIT with
-arena argument support (currently x86-64 and arm64); verification fails
-otherwise. The program can pass any value without compromising the kernel. A
-value that does not point into the arena is a program bug.
+arena kfunc argument support (currently x86-64, arm64, RISC-V, s390,
+LoongArch, and PowerPC64); verification fails otherwise. The program can pass
+any value without compromising the kernel. A value that does not point into
+the arena is a program bug.
 
 The suffixes have the same meaning on the arguments of struct_ops stub
 functions, with the conversion running in the opposite direction. The
@@ -311,9 +312,11 @@ kernel caller passes the kernel arena address and the trampoline converts
 it while saving the arguments, so the callback receives an arena pointer
 it can dereference directly. With ``__arena`` the kernel caller must not
 pass NULL. With ``__arena__nullable`` a NULL kernel pointer arrives as NULL.
-However, there is no obligation to prove to the verifier that such a pointer is
-non-NULL before use, in-line with existing semantics of arena pointers used in
-a program (or obtained from any other source).
+Struct_ops arena argument conversion is a separate JIT capability, currently
+provided by x86-64, arm64, RISC-V, s390, and LoongArch. However, there is no
+obligation to prove to the verifier that such a pointer is non-NULL before use,
+in-line with existing semantics of arena pointers used in a program (or
+obtained from any other source).
 
 .. _BPF_kfunc_nodef:
 
-- 
2.53.0