9592eef7 - random: remove CONFIG_ARCH_RANDOM

Tue, 05 Jul 2022 18:48:41 +0000

random: remove CONFIG_ARCH_RANDOMWhen RDRAND was introduced, there was much discussion on whether itshould be trusted and how the kernel should handle that. Initially, twomechanisms cropped up, CONFIG_ARCH_RANDOM, a compile time switch, and"nordrand", a boot-time switch.Later the thinking evolved. With a properly designed RNG, using RDRANDvalues alone won't harm anything, even if the outputs are malicious.Rather, the issue is whether those values are being *trusted* to be goodor not. And so a new set of options were introduced as the realones that people use -- CONFIG_RANDOM_TRUST_CPU and "random.trust_cpu".With these options, RDRAND is used, but it's not always credited. So inthe worst case, it does nothing, and in the best case, maybe it helps.Along the way, CONFIG_ARCH_RANDOM's meaning got sort of pulled into thecenter and became something certain platforms force-select.The old options don't really help with much, and it's a bit odd to havespecial handling for these instructions when the kernel can deal finewith the existence or untrusted existence or broken existence ornon-existence of that CPU capability.Simplify the situation by removing CONFIG_ARCH_RANDOM and using theordinary asm-generic fallback pattern instead, keeping the two optionsthat are actually used. For now it leaves "nordrand" for now, as theremoval of that will take a different route.Acked-by: Michael Ellerman Acked-by: Catalin Marinas Acked-by: Borislav Petkov Acked-by: Heiko Carstens Acked-by: Greg Kroah-Hartman Signed-off-by: Jason A. Donenfeld List of files: /linux-6.15/arch/arm/include/asm/archrandom.h

a37e31fc - firmware: smccc: Introduce SMCCC TRNG framework

Wed, 06 Jan 2021 10:34:50 +0000

firmware: smccc: Introduce SMCCC TRNG frameworkThe ARM DEN0098 document describe an SMCCC based firmware service todeliver hardware generated random numbers. Its existence is advertisedaccording to the SMCCC v1.1 specification.Add a (dummy) call to probe functions implemented in each architecture(ARM and arm64), to determine the existence of this interface.For now this return false, but this will be overwritten by eacharchitecture's support patch.Signed-off-by: Andre Przywara Reviewed-by: Linus Walleij Reviewed-by: Sudeep Holla Signed-off-by: Will Deacon List of files: /linux-6.15/arch/arm/include/asm/archrandom.h

Changes in archrandom.h

9592eef7 - random: remove CONFIG_ARCH_RANDOM

a37e31fc - firmware: smccc: Introduce SMCCC TRNG framework