On Wed, 20 Aug 2025 19:29:02 +0100, Mark Brown wrote:

Currently it is not possible to disable streaming mode via ptrace on SME
only systems, the interface for doing this is to write via NT_ARM_SVE but
such writes will be rejected on a system without SVE support. Enable this
functionality by allowing userspace to write SVE_PT_REGS_FPSIMD format data
via NT_ARM_SVE with the vector length set to 0 on SME only systems. Such
writes currently error since we require that a vector length is specified
which should minimise the risk that existing software is relying on current
behaviour.

[...]

Applied first two selftests to arm64 (for-next/selftests), thanks!

[1/5] kselftest/arm64: Verify that we reject out of bounds VLs in sve-ptrace
      https://git.kernel.org/arm64/c/dd68f51febbd
[2/5] kselftest/arm64: Check that unsupported regsets fail in sve-ptrace
      https://git.kernel.org/arm64/c/09b5febf8426

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev