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 register-backed attributes are root-only read/write files. Reads return the live value from the synchronous target-CPU callback rather than relying on persistent per-attribute sysfs storage. affected_cpus remains world-readable and read-only. Changes since v1: - Remove redundant GPL boilerplate from the new source file while retaining the SPDX identifier and NVIDIA copyright notice. - Address Rob Herring's ABI feedback by adding standard Documentation/ABI/testing/sysfs-devices-system-cpu records and keeping the arm64 guide as a pointer to that ABI, without a second attribute list. - Address Breno Leitao's access/readback feedback by returning live synchronous target-CPU register reads, changing the six register-backed controls to mode 0600, documenting affected_cpus as 0444, and adding deterministic selftest mode checks. Koba Ko (3): arm64: add CPU prefetch and cache modulation sysfs interface Documentation/arch/arm64: document arm_cpumod selftests: arm64: add arm_cpumod kselftest .../ABI/testing/sysfs-devices-system-cpu | 77 +++ Documentation/arch/arm64/arm-cpumod.rst | 66 +++ Documentation/arch/arm64/index.rst | 1 + arch/arm64/Kconfig | 17 + arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/arm_cpumod.c | 458 +++++++++++++++ arch/arm64/kernel/arm_cpumod_internal.h | 93 +++ tools/testing/selftests/arm64/Makefile | 2 +- .../selftests/arm64/arm_cpumod/Makefile | 5 + .../selftests/arm64/arm_cpumod/arm_cpumod.sh | 543 ++++++++++++++++++ 10 files changed, 1262 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
