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linux/arch/arm64/include/asm/archrandom.h

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arm64: Implement archrandom.h for ARMv8.5-RNG Expose the ID_AA64ISAR0.RNDR field to userspace, as the RNG system registers are always available at EL0. Implement arch_get_random_seed_long using RNDR. Given that the TRNG is likely to be a shared resource between cores, and VMs, do not explicitly force re-seeding with RNDRRS. In order to avoid code complexity and potential issues with hetrogenous systems only provide values after cpufeature has finalized the system capabilities. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> [Modified to only function after cpufeature has finalized the system capabilities and move all the code into the header -- broonie] Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> [will: Advertise HWCAP via /proc/cpuinfo] Signed-off-by: Will Deacon <will@kernel.org>
2020-01-21 20:58:52 +08:00
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_ARCHRANDOM_H
#define _ASM_ARCHRANDOM_H
#ifdef CONFIG_ARCH_RANDOM
arm64: add credited/trusted RNG support Currently arm64 doesn't initialize the primary CRNG in a (potentially) trusted manner as we only detect the presence of the RNG once secondary CPUs are up. Now that the core RNG code distinguishes the early initialization of the primary CRNG, we can implement arch_get_random_seed_long_early() to support this. This patch does so. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Mark Brown <broonie@kernel.org> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20200210130015.17664-4-mark.rutland@arm.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2020-02-10 21:00:14 +08:00
#include <linux/bug.h>
#include <linux/kernel.h>
arm64: Implement archrandom.h for ARMv8.5-RNG Expose the ID_AA64ISAR0.RNDR field to userspace, as the RNG system registers are always available at EL0. Implement arch_get_random_seed_long using RNDR. Given that the TRNG is likely to be a shared resource between cores, and VMs, do not explicitly force re-seeding with RNDRRS. In order to avoid code complexity and potential issues with hetrogenous systems only provide values after cpufeature has finalized the system capabilities. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> [Modified to only function after cpufeature has finalized the system capabilities and move all the code into the header -- broonie] Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> [will: Advertise HWCAP via /proc/cpuinfo] Signed-off-by: Will Deacon <will@kernel.org>
2020-01-21 20:58:52 +08:00
#include <linux/random.h>
#include <asm/cpufeature.h>
static inline bool __arm64_rndr(unsigned long *v)
{
bool ok;
/*
* Reads of RNDR set PSTATE.NZCV to 0b0000 on success,
* and set PSTATE.NZCV to 0b0100 otherwise.
*/
asm volatile(
__mrs_s("%0", SYS_RNDR_EL0) "\n"
" cset %w1, ne\n"
: "=r" (*v), "=r" (ok)
:
: "cc");
return ok;
}
static inline bool __must_check arch_get_random_long(unsigned long *v)
{
return false;
}
static inline bool __must_check arch_get_random_int(unsigned int *v)
{
return false;
}
static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
{
/*
* Only support the generic interface after we have detected
* the system wide capability, avoiding complexity with the
* cpufeature code and with potential scheduling between CPUs
* with and without the feature.
*/
if (!cpus_have_const_cap(ARM64_HAS_RNG))
return false;
return __arm64_rndr(v);
}
static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
{
unsigned long val;
bool ok = arch_get_random_seed_long(&val);
*v = val;
return ok;
}
arm64: Use v8.5-RNG entropy for KASLR seed When seeding KALSR on a system where we have architecture level random number generation make use of that entropy, mixing it in with the seed passed by the bootloader. Since this is run very early in init before feature detection is complete we open code rather than use archrandom.h. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Will Deacon <will@kernel.org>
2020-01-21 20:58:53 +08:00
static inline bool __init __early_cpu_has_rndr(void)
{
/* Open code as we run prior to the first call to cpufeature. */
unsigned long ftr = read_sysreg_s(SYS_ID_AA64ISAR0_EL1);
return (ftr >> ID_AA64ISAR0_RNDR_SHIFT) & 0xf;
}
arm64: add credited/trusted RNG support Currently arm64 doesn't initialize the primary CRNG in a (potentially) trusted manner as we only detect the presence of the RNG once secondary CPUs are up. Now that the core RNG code distinguishes the early initialization of the primary CRNG, we can implement arch_get_random_seed_long_early() to support this. This patch does so. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Mark Brown <broonie@kernel.org> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20200210130015.17664-4-mark.rutland@arm.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2020-02-10 21:00:14 +08:00
static inline bool __init __must_check
arch_get_random_seed_long_early(unsigned long *v)
{
WARN_ON(system_state != SYSTEM_BOOTING);
if (!__early_cpu_has_rndr())
return false;
return __arm64_rndr(v);
}
#define arch_get_random_seed_long_early arch_get_random_seed_long_early
arm64: Implement archrandom.h for ARMv8.5-RNG Expose the ID_AA64ISAR0.RNDR field to userspace, as the RNG system registers are always available at EL0. Implement arch_get_random_seed_long using RNDR. Given that the TRNG is likely to be a shared resource between cores, and VMs, do not explicitly force re-seeding with RNDRRS. In order to avoid code complexity and potential issues with hetrogenous systems only provide values after cpufeature has finalized the system capabilities. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> [Modified to only function after cpufeature has finalized the system capabilities and move all the code into the header -- broonie] Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> [will: Advertise HWCAP via /proc/cpuinfo] Signed-off-by: Will Deacon <will@kernel.org>
2020-01-21 20:58:52 +08:00
#else
static inline bool __arm64_rndr(unsigned long *v) { return false; }
arm64: Use v8.5-RNG entropy for KASLR seed When seeding KALSR on a system where we have architecture level random number generation make use of that entropy, mixing it in with the seed passed by the bootloader. Since this is run very early in init before feature detection is complete we open code rather than use archrandom.h. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Will Deacon <will@kernel.org>
2020-01-21 20:58:53 +08:00
static inline bool __init __early_cpu_has_rndr(void) { return false; }
arm64: Implement archrandom.h for ARMv8.5-RNG Expose the ID_AA64ISAR0.RNDR field to userspace, as the RNG system registers are always available at EL0. Implement arch_get_random_seed_long using RNDR. Given that the TRNG is likely to be a shared resource between cores, and VMs, do not explicitly force re-seeding with RNDRRS. In order to avoid code complexity and potential issues with hetrogenous systems only provide values after cpufeature has finalized the system capabilities. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> [Modified to only function after cpufeature has finalized the system capabilities and move all the code into the header -- broonie] Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> [will: Advertise HWCAP via /proc/cpuinfo] Signed-off-by: Will Deacon <will@kernel.org>
2020-01-21 20:58:52 +08:00
#endif /* CONFIG_ARCH_RANDOM */
#endif /* _ASM_ARCHRANDOM_H */