diff options
| -rw-r--r-- | arch/arm/include/asm/archrandom.h | 10 | ||||
| -rw-r--r-- | arch/arm64/include/asm/archrandom.h | 82 | ||||
| -rw-r--r-- | drivers/firmware/smccc/smccc.c | 6 | ||||
| -rw-r--r-- | include/linux/arm-smccc.h | 31 |
4 files changed, 119 insertions, 10 deletions
diff --git a/arch/arm/include/asm/archrandom.h b/arch/arm/include/asm/archrandom.h new file mode 100644 index 000000000000..a8e84ca5c2ee --- /dev/null +++ b/arch/arm/include/asm/archrandom.h @@ -0,0 +1,10 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_ARCHRANDOM_H +#define _ASM_ARCHRANDOM_H + +static inline bool __init smccc_probe_trng(void) +{ + return false; +} + +#endif /* _ASM_ARCHRANDOM_H */ diff --git a/arch/arm64/include/asm/archrandom.h b/arch/arm64/include/asm/archrandom.h index ffb1a40d5475..09e43272ccb0 100644 --- a/arch/arm64/include/asm/archrandom.h +++ b/arch/arm64/include/asm/archrandom.h @@ -4,10 +4,26 @@ #ifdef CONFIG_ARCH_RANDOM +#include <linux/arm-smccc.h> #include <linux/bug.h> #include <linux/kernel.h> #include <asm/cpufeature.h> +#define ARM_SMCCC_TRNG_MIN_VERSION 0x10000UL + +extern bool smccc_trng_available; + +static inline bool __init smccc_probe_trng(void) +{ + struct arm_smccc_res res; + + arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_VERSION, &res); + if ((s32)res.a0 < 0) + return false; + + return res.a0 >= ARM_SMCCC_TRNG_MIN_VERSION; +} + static inline bool __arm64_rndr(unsigned long *v) { bool ok; @@ -38,26 +54,55 @@ static inline bool __must_check arch_get_random_int(unsigned int *v) static inline bool __must_check arch_get_random_seed_long(unsigned long *v) { + struct arm_smccc_res res; + + /* + * We prefer the SMCCC call, since its semantics (return actual + * hardware backed entropy) is closer to the idea behind this + * function here than what even the RNDRSS register provides + * (the output of a pseudo RNG freshly seeded by a TRNG). + */ + if (smccc_trng_available) { + arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, 64, &res); + if ((int)res.a0 >= 0) { + *v = res.a3; + return true; + } + } + /* * 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; + if (cpus_have_const_cap(ARM64_HAS_RNG) && __arm64_rndr(v)) + return true; - return __arm64_rndr(v); + return false; } - static inline bool __must_check arch_get_random_seed_int(unsigned int *v) { + struct arm_smccc_res res; unsigned long val; - bool ok = arch_get_random_seed_long(&val); - *v = val; - return ok; + if (smccc_trng_available) { + arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, 32, &res); + if ((int)res.a0 >= 0) { + *v = res.a3 & GENMASK(31, 0); + return true; + } + } + + if (cpus_have_const_cap(ARM64_HAS_RNG)) { + if (__arm64_rndr(&val)) { + *v = val; + return true; + } + } + + return false; } static inline bool __init __early_cpu_has_rndr(void) @@ -72,12 +117,29 @@ arch_get_random_seed_long_early(unsigned long *v) { WARN_ON(system_state != SYSTEM_BOOTING); - if (!__early_cpu_has_rndr()) - return false; + if (smccc_trng_available) { + struct arm_smccc_res res; + + arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, 64, &res); + if ((int)res.a0 >= 0) { + *v = res.a3; + return true; + } + } + + if (__early_cpu_has_rndr() && __arm64_rndr(v)) + return true; - return __arm64_rndr(v); + return false; } #define arch_get_random_seed_long_early arch_get_random_seed_long_early +#else /* !CONFIG_ARCH_RANDOM */ + +static inline bool __init smccc_probe_trng(void) +{ + return false; +} + #endif /* CONFIG_ARCH_RANDOM */ #endif /* _ASM_ARCHRANDOM_H */ diff --git a/drivers/firmware/smccc/smccc.c b/drivers/firmware/smccc/smccc.c index 00c88b809c0c..d52bfc5ed5e4 100644 --- a/drivers/firmware/smccc/smccc.c +++ b/drivers/firmware/smccc/smccc.c @@ -5,16 +5,22 @@ #define pr_fmt(fmt) "smccc: " fmt +#include <linux/cache.h> #include <linux/init.h> #include <linux/arm-smccc.h> +#include <asm/archrandom.h> static u32 smccc_version = ARM_SMCCC_VERSION_1_0; static enum arm_smccc_conduit smccc_conduit = SMCCC_CONDUIT_NONE; +bool __ro_after_init smccc_trng_available = false; + void __init arm_smccc_version_init(u32 version, enum arm_smccc_conduit conduit) { smccc_version = version; smccc_conduit = conduit; + + smccc_trng_available = smccc_probe_trng(); } enum arm_smccc_conduit arm_smccc_1_1_get_conduit(void) diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h index f860645f6512..62c54234576c 100644 --- a/include/linux/arm-smccc.h +++ b/include/linux/arm-smccc.h @@ -102,6 +102,37 @@ ARM_SMCCC_OWNER_STANDARD_HYP, \ 0x21) +/* TRNG entropy source calls (defined by ARM DEN0098) */ +#define ARM_SMCCC_TRNG_VERSION \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ + ARM_SMCCC_SMC_32, \ + ARM_SMCCC_OWNER_STANDARD, \ + 0x50) + +#define ARM_SMCCC_TRNG_FEATURES \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ + ARM_SMCCC_SMC_32, \ + ARM_SMCCC_OWNER_STANDARD, \ + 0x51) + +#define ARM_SMCCC_TRNG_GET_UUID \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ + ARM_SMCCC_SMC_32, \ + ARM_SMCCC_OWNER_STANDARD, \ + 0x52) + +#define ARM_SMCCC_TRNG_RND32 \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ + ARM_SMCCC_SMC_32, \ + ARM_SMCCC_OWNER_STANDARD, \ + 0x53) + +#define ARM_SMCCC_TRNG_RND64 \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ + ARM_SMCCC_SMC_64, \ + ARM_SMCCC_OWNER_STANDARD, \ + 0x53) + /* * Return codes defined in ARM DEN 0070A * ARM DEN 0070A is now merged/consolidated into ARM DEN 0028 C |