diff options
Diffstat (limited to 'arch/arm64/include/asm/archrandom.h')
| -rw-r--r-- | arch/arm64/include/asm/archrandom.h | 131 |
1 files changed, 73 insertions, 58 deletions
diff --git a/arch/arm64/include/asm/archrandom.h b/arch/arm64/include/asm/archrandom.h index 09e43272ccb0..109e2a4454be 100644 --- a/arch/arm64/include/asm/archrandom.h +++ b/arch/arm64/include/asm/archrandom.h @@ -2,8 +2,6 @@ #ifndef _ASM_ARCHRANDOM_H #define _ASM_ARCHRANDOM_H -#ifdef CONFIG_ARCH_RANDOM - #include <linux/arm-smccc.h> #include <linux/bug.h> #include <linux/kernel.h> @@ -42,19 +40,41 @@ static inline bool __arm64_rndr(unsigned long *v) return ok; } -static inline bool __must_check arch_get_random_long(unsigned long *v) +static inline bool __arm64_rndrrs(unsigned long *v) { - return false; + bool ok; + + /* + * Reads of RNDRRS set PSTATE.NZCV to 0b0000 on success, + * and set PSTATE.NZCV to 0b0100 otherwise. + */ + asm volatile( + __mrs_s("%0", SYS_RNDRRS_EL0) "\n" + " cset %w1, ne\n" + : "=r" (*v), "=r" (ok) + : + : "cc"); + + return ok; } -static inline bool __must_check arch_get_random_int(unsigned int *v) +static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs) { - return false; + /* + * 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 (max_longs && cpus_have_const_cap(ARM64_HAS_RNG) && __arm64_rndr(v)) + return 1; + return 0; } -static inline bool __must_check arch_get_random_seed_long(unsigned long *v) +static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs) { - struct arm_smccc_res res; + if (!max_longs) + return 0; /* * We prefer the SMCCC call, since its semantics (return actual @@ -63,83 +83,78 @@ static inline bool __must_check arch_get_random_seed_long(unsigned long *v) * (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); + struct arm_smccc_res res; + + max_longs = min_t(size_t, 3, max_longs); + arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, max_longs * 64, &res); if ((int)res.a0 >= 0) { - *v = res.a3; - return true; + switch (max_longs) { + case 3: + *v++ = res.a1; + fallthrough; + case 2: + *v++ = res.a2; + fallthrough; + case 1: + *v++ = res.a3; + break; + } + return max_longs; } } /* - * 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. + * RNDRRS is not backed by an entropy source but by a DRBG that is + * reseeded after each invocation. This is not a 100% fit but good + * enough to implement this API if no other entropy source exists. */ - if (cpus_have_const_cap(ARM64_HAS_RNG) && __arm64_rndr(v)) - return true; - - return false; -} - -static inline bool __must_check arch_get_random_seed_int(unsigned int *v) -{ - struct arm_smccc_res res; - unsigned long val; - - 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; - } - } + if (cpus_have_const_cap(ARM64_HAS_RNG) && __arm64_rndrrs(v)) + return 1; - return false; + return 0; } 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; + return (ftr >> ID_AA64ISAR0_EL1_RNDR_SHIFT) & 0xf; } -static inline bool __init __must_check -arch_get_random_seed_long_early(unsigned long *v) +static inline size_t __init __must_check +arch_get_random_seed_longs_early(unsigned long *v, size_t max_longs) { WARN_ON(system_state != SYSTEM_BOOTING); + if (!max_longs) + return 0; + if (smccc_trng_available) { struct arm_smccc_res res; - arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, 64, &res); + max_longs = min_t(size_t, 3, max_longs); + arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, max_longs * 64, &res); if ((int)res.a0 >= 0) { - *v = res.a3; - return true; + switch (max_longs) { + case 3: + *v++ = res.a1; + fallthrough; + case 2: + *v++ = res.a2; + fallthrough; + case 1: + *v++ = res.a3; + break; + } + return max_longs; } } if (__early_cpu_has_rndr() && __arm64_rndr(v)) - return true; + return 1; - 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; + return 0; } +#define arch_get_random_seed_longs_early arch_get_random_seed_longs_early -#endif /* CONFIG_ARCH_RANDOM */ #endif /* _ASM_ARCHRANDOM_H */ |