The ARMv8.5-RNG extension adds a hardware random number generator.
The plumbing for this is already present in the kernel; we just
have to take advantage of that.
Changes since v2:
* Keep arch_get_random{,_seed}_long in sync.
* Use __cpus_have_const_cap before falling back to this_cpu_has_cap.
Changes since v1:
* Use __mrs_s and fix missing cc clobber (Mark),
* Log rng failures with pr_warn (Mark),
* Use __must_check; put RNDR in arch_get_random_long and RNDRRS
in arch_get_random_seed_long (Ard),
* Use ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE, and check this_cpu_has_cap
when reading random data.
* Move everything out of line, now that there are 5 other function
calls involved, and to unify the rate limiting on the pr_warn.
Tested with QEMU. What's not tested is hot plugging cpus with differing
capabilities; QEMU would need some extension to allow that sort of thing.
r~
Richard Henderson (1):
arm64: Implement archrandom.h for ARMv8.5-RNG
Documentation/arm64/cpu-feature-registers.rst | 2 +
arch/arm64/include/asm/archrandom.h | 35 ++++++++
arch/arm64/include/asm/cpucaps.h | 3 +-
arch/arm64/include/asm/sysreg.h | 4 +
arch/arm64/kernel/cpufeature.c | 13 +++
arch/arm64/kernel/random.c | 79 +++++++++++++++++++
arch/arm64/Kconfig | 12 +++
arch/arm64/kernel/Makefile | 1 +
drivers/char/Kconfig | 4 +-
9 files changed, 150 insertions(+), 3 deletions(-)
create mode 100644 arch/arm64/include/asm/archrandom.h
create mode 100644 arch/arm64/kernel/random.c
--
2.17.1
