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[213.99.162.212]) by smtp.gmail.com with ESMTPSA id a16sm9022470wmd.11.2019.11.08.05.58.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Nov 2019 05:58:03 -0800 (PST) From: Richard Henderson X-Google-Original-From: Richard Henderson To: linux-arm-kernel@lists.infradead.org Cc: linux-crypto@vger.kernel.org, mark.rutland@arm.com, ard.biesheuvel@linaro.org, Richard Henderson Subject: [PATCH v5] arm64: Implement archrandom.h for ARMv8.5-RNG Date: Fri, 8 Nov 2019 14:57:51 +0100 Message-Id: <20191108135751.3218-1-rth@twiddle.net> X-Mailer: git-send-email 2.17.1 Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org From: Richard Henderson Expose the ID_AA64ISAR0.RNDR field to userspace, as the RNG system registers are always available at EL0. Signed-off-by: Richard Henderson --- v2: 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. v3: Keep arch_get_random{,_seed}_long in sync. v4: Use __cpus_have_const_cap before falling back to this_cpu_has_cap. v5: Improve commentary; fix some checkpatch warnings. --- Documentation/arm64/cpu-feature-registers.rst | 2 + arch/arm64/include/asm/archrandom.h | 35 ++++++++ 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 | 82 +++++++++++++++++++ arch/arm64/Kconfig | 12 +++ arch/arm64/kernel/Makefile | 1 + drivers/char/Kconfig | 4 +- 9 files changed, 153 insertions(+), 3 deletions(-) create mode 100644 arch/arm64/include/asm/archrandom.h create mode 100644 arch/arm64/kernel/random.c -- 2.17.1 diff --git a/Documentation/arm64/cpu-feature-registers.rst b/Documentation/arm64/cpu-feature-registers.rst index 2955287e9acc..78d6f5c6e824 100644 --- a/Documentation/arm64/cpu-feature-registers.rst +++ b/Documentation/arm64/cpu-feature-registers.rst @@ -117,6 +117,8 @@ infrastructure: +------------------------------+---------+---------+ | Name | bits | visible | +------------------------------+---------+---------+ + | RNDR | [63-60] | y | + +------------------------------+---------+---------+ | TS | [55-52] | y | +------------------------------+---------+---------+ | FHM | [51-48] | y | diff --git a/arch/arm64/include/asm/archrandom.h b/arch/arm64/include/asm/archrandom.h new file mode 100644 index 000000000000..e796a6de7421 --- /dev/null +++ b/arch/arm64/include/asm/archrandom.h @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_ARCHRANDOM_H +#define _ASM_ARCHRANDOM_H + +#ifdef CONFIG_ARCH_RANDOM + +bool __must_check arch_get_random_long(unsigned long *v); +bool __must_check arch_get_random_seed_long(unsigned long *v); + +static inline bool __must_check arch_get_random_int(unsigned int *v) +{ + unsigned long val; + + if (arch_get_random_long(&val)) { + *v = val; + return true; + } + + return false; +} + +static inline bool __must_check arch_get_random_seed_int(unsigned int *v) +{ + unsigned long val; + + if (arch_get_random_seed_long(&val)) { + *v = val; + return true; + } + + return false; +} + +#endif /* CONFIG_ARCH_RANDOM */ +#endif /* _ASM_ARCHRANDOM_H */ diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index ac1dbca3d0cd..1dd7644bc59a 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -54,7 +54,8 @@ #define ARM64_WORKAROUND_1463225 44 #define ARM64_WORKAROUND_CAVIUM_TX2_219_TVM 45 #define ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM 46 +#define ARM64_HAS_RNG 47 -#define ARM64_NCAPS 47 +#define ARM64_NCAPS 48 #endif /* __ASM_CPUCAPS_H */ diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 6e919fafb43d..5e718f279469 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -365,6 +365,9 @@ #define SYS_CTR_EL0 sys_reg(3, 3, 0, 0, 1) #define SYS_DCZID_EL0 sys_reg(3, 3, 0, 0, 7) +#define SYS_RNDR_EL0 sys_reg(3, 3, 2, 4, 0) +#define SYS_RNDRRS_EL0 sys_reg(3, 3, 2, 4, 1) + #define SYS_PMCR_EL0 sys_reg(3, 3, 9, 12, 0) #define SYS_PMCNTENSET_EL0 sys_reg(3, 3, 9, 12, 1) #define SYS_PMCNTENCLR_EL0 sys_reg(3, 3, 9, 12, 2) @@ -539,6 +542,7 @@ ENDIAN_SET_EL1 | SCTLR_EL1_UCI | SCTLR_EL1_RES1) /* id_aa64isar0 */ +#define ID_AA64ISAR0_RNDR_SHIFT 60 #define ID_AA64ISAR0_TS_SHIFT 52 #define ID_AA64ISAR0_FHM_SHIFT 48 #define ID_AA64ISAR0_DP_SHIFT 44 diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 80f459ad0190..456d5c461cbf 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -119,6 +119,7 @@ static void cpu_enable_cnp(struct arm64_cpu_capabilities const *cap); * sync with the documentation of the CPU feature register ABI. */ static const struct arm64_ftr_bits ftr_id_aa64isar0[] = { + ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_RNDR_SHIFT, 4, 0), ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_TS_SHIFT, 4, 0), ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_FHM_SHIFT, 4, 0), ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_DP_SHIFT, 4, 0), @@ -1565,6 +1566,18 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .sign = FTR_UNSIGNED, .min_field_value = 1, }, +#endif +#ifdef CONFIG_ARCH_RANDOM + { + .desc = "Random Number Generator", + .capability = ARM64_HAS_RNG, + .type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE, + .matches = has_cpuid_feature, + .sys_reg = SYS_ID_AA64ISAR0_EL1, + .field_pos = ID_AA64ISAR0_RNDR_SHIFT, + .sign = FTR_UNSIGNED, + .min_field_value = 1, + }, #endif {}, }; diff --git a/arch/arm64/kernel/random.c b/arch/arm64/kernel/random.c new file mode 100644 index 000000000000..e7ff29dd637c --- /dev/null +++ b/arch/arm64/kernel/random.c @@ -0,0 +1,82 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Random number generation using ARMv8.5-RNG. + */ + +#include +#include +#include +#include +#include + +static inline bool has_random(void) +{ + /* + * We "have" RNG if either + * (1) every cpu in the system has RNG, or + * (2) in a non-preemptible context, current cpu has RNG. + * + * Case 1 is the expected case when RNG is deployed, but + * case 2 is present as a backup. Case 2 has two effects: + * (A) rand_initialize() is able to use the instructions + * when present in the boot cpu, which happens before + * secondary cpus are enabled and before features are + * resolved for the full system. + * (B) add_interrupt_randomness() is able to use the + * instructions when present on the current cpu, in case + * some big/little system only has RNG on big cpus. + * + * We can use __cpus_have_const_cap because we then fall + * back to checking the current cpu. + */ + return __cpus_have_const_cap(ARM64_HAS_RNG) || + (!preemptible() && this_cpu_has_cap(ARM64_HAS_RNG)); +} + +bool arch_get_random_long(unsigned long *v) +{ + bool ok; + + if (!has_random()) + return false; + + /* + * 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"); + + if (unlikely(!ok)) + pr_warn_ratelimited("cpu%d: sys_rndr failed\n", + read_cpuid_id()); + return ok; +} + +bool arch_get_random_seed_long(unsigned long *v) +{ + bool ok; + + if (!has_random()) + return false; + + /* + * 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"); + + if (unlikely(!ok)) + pr_warn_ratelimited("cpu%d: sys_rndrrs failed\n", + read_cpuid_id()); + return ok; +} diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 3f047afb982c..5bc88601f07b 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1438,6 +1438,18 @@ config ARM64_PTR_AUTH endmenu +menu "ARMv8.5 architectural features" + +config ARCH_RANDOM + bool "Enable support for random number generation" + default y + help + Random number generation (part of the ARMv8.5 Extensions) + provides a high bandwidth, cryptographically secure + hardware random number generator. + +endmenu + config ARM64_SVE bool "ARM Scalable Vector Extension support" default y diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 478491f07b4f..a47c2b984da7 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -63,6 +63,7 @@ obj-$(CONFIG_CRASH_CORE) += crash_core.o obj-$(CONFIG_ARM_SDE_INTERFACE) += sdei.o obj-$(CONFIG_ARM64_SSBD) += ssbd.o obj-$(CONFIG_ARM64_PTR_AUTH) += pointer_auth.o +obj-$(CONFIG_ARCH_RANDOM) += random.o obj-y += vdso/ probes/ obj-$(CONFIG_COMPAT_VDSO) += vdso32/ diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig index df0fc997dc3e..f26a0a8cc0d0 100644 --- a/drivers/char/Kconfig +++ b/drivers/char/Kconfig @@ -539,7 +539,7 @@ endmenu config RANDOM_TRUST_CPU bool "Trust the CPU manufacturer to initialize Linux's CRNG" - depends on X86 || S390 || PPC + depends on X86 || S390 || PPC || ARM64 default n help Assume that CPU manufacturer (e.g., Intel or AMD for RDSEED or @@ -559,4 +559,4 @@ config RANDOM_TRUST_BOOTLOADER device randomness. Say Y here to assume the entropy provided by the booloader is trustworthy so it will be added to the kernel's entropy pool. Otherwise, say N here so it will be regarded as device input that - only mixes the entropy pool. \ No newline at end of file + only mixes the entropy pool.