From: Koba Ko <[email protected]> This series adds CONFIG_ARM64_CPUMOD, a default-off arm64 interface for controlled performance characterization of selected implementation-defined CPU prefetch and cache-management fields. It exposes a small set of named, per-CPU attributes under the path below, with writable control fields range-checked before register state is changed:
/sys/devices/system/cpu/cpuN/cpumod/ The directory is created for online CPUs whose MIDR matches a recognized Grace or Vera profile, with common and profile-specific attributes selected for that CPU. Register accesses execute on the CPU that owns the sysfs instance, and CPU hotplug creates or removes the per-CPU subtree as the CPU transitions online or offline. Unsupported CPU profiles are skipped without blocking module load or CPU hotplug. The implementation keeps each dynamically allocated kobject in a private per-CPU pointer, avoiding use of the CPU device's shared driver-data slot. The documentation defines the ABI, firmware prerequisite, and hotplug lifecycle. The kselftest validates profile-specific layout, unsupported-CPU skipping, decimal affected_cpus reporting, value validation, optional writes, all-online-CPU coverage, and cleanup. The controls require firmware to permit EL1 access to the relevant implementation control registers. This is an RFC interface for controlled evaluation, not a general raw-register or production-default tuning ABI. Compile and static verification passed. DUT runtime validation was not run. Koba Ko (3): arm64: add CPU prefetch and cache modulation sysfs interface Documentation/arch/arm64: document arm_cpumod selftests: arm64: add arm_cpumod kselftest Documentation/arch/arm64/arm-cpumod.rst | 89 +++ Documentation/arch/arm64/index.rst | 1 + arch/arm64/Kconfig | 17 + arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/arm_cpumod.c | 471 ++++++++++++++++ arch/arm64/kernel/arm_cpumod_internal.h | 113 ++++ tools/testing/selftests/arm64/Makefile | 2 +- .../selftests/arm64/arm_cpumod/Makefile | 5 + .../selftests/arm64/arm_cpumod/arm_cpumod.sh | 526 ++++++++++++++++++ 9 files changed, 1224 insertions(+), 1 deletion(-) create mode 100644 Documentation/arch/arm64/arm-cpumod.rst create mode 100644 arch/arm64/kernel/arm_cpumod.c create mode 100644 arch/arm64/kernel/arm_cpumod_internal.h create mode 100644 tools/testing/selftests/arm64/arm_cpumod/Makefile create mode 100755 tools/testing/selftests/arm64/arm_cpumod/arm_cpumod.sh -- 2.43.0
