[PATCH v2 0/1] arm64: Implement archrandom.h for ARMv8.5-RNG

[richard.henderson@linaro.org]

From: Richard Henderson <richard.henderson@linaro.org>

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 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.

I have a separate patch set to add __must_check to the other
architectures.  But it doesn't affect this.

Tested with QEMU.


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           | 32 +++++++
 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                    | 95 +++++++++++++++++++
 arch/arm64/Kconfig                            | 12 +++
 arch/arm64/kernel/Makefile                    |  1 +
 drivers/char/Kconfig                          |  4 +-
 9 files changed, 163 insertions(+), 3 deletions(-)
 create mode 100644 arch/arm64/include/asm/archrandom.h
 create mode 100644 arch/arm64/kernel/random.c

-- 
2.17.1