From: Richard Henderson <richard.henderson@linaro.org>
Date: Tue, 21 Jan 2020 12:58:52 +0000
Subject: arm64: Implement archrandom.h for ARMv8.5-RNG
Git-commit: 1a50ec0b3b2e9a83f1b1245ea37a853aac2f741c
Patch-mainline: v5.6-rc1
References: jsc#SLE-16574 jsc#SLE-13718
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>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
---
Documentation/arm64/cpu-feature-registers.rst | 2
Documentation/arm64/elf_hwcaps.rst | 4 +
arch/arm64/Kconfig | 12 ++++
arch/arm64/include/asm/archrandom.h | 67 ++++++++++++++++++++++++++
arch/arm64/include/asm/cpucaps.h | 3 -
arch/arm64/include/asm/hwcap.h | 1
arch/arm64/include/asm/sysreg.h | 4 +
arch/arm64/include/uapi/asm/hwcap.h | 1
arch/arm64/kernel/cpufeature.c | 14 +++++
arch/arm64/kernel/cpuinfo.c | 1
10 files changed, 108 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/include/asm/archrandom.h
--- 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 |
--- a/Documentation/arm64/elf_hwcaps.rst
+++ b/Documentation/arm64/elf_hwcaps.rst
@@ -60,6 +60,10 @@ Other hwcaps may indicate the presence o
described by ID registers alone. These may be described without
reference to ID registers, and may refer to other documentation.
+HWCAP2_RNG
+
+ Functionality implied by ID_AA64ISAR0_EL1.RNDR == 0b0001.
+
3. The hwcaps exposed in AT_HWCAP
---------------------------------
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1434,6 +1434,18 @@ 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
--- /dev/null
+++ b/arch/arm64/include/asm/archrandom.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ARCHRANDOM_H
+#define _ASM_ARCHRANDOM_H
+
+#ifdef CONFIG_ARCH_RANDOM
+
+#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;
+}
+
+#else
+
+static inline bool __arm64_rndr(unsigned long *v) { return false; }
+
+#endif /* CONFIG_ARCH_RANDOM */
+#endif /* _ASM_ARCHRANDOM_H */
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -55,7 +55,8 @@
#define ARM64_WORKAROUND_CAVIUM_TX2_219_TVM 45
#define ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM 46
#define ARM64_WORKAROUND_1542419 47
+#define ARM64_HAS_RNG 48
-#define ARM64_NCAPS 48
+#define ARM64_NCAPS 49
#endif /* __ASM_CPUCAPS_H */
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -86,6 +86,7 @@
#define KERNEL_HWCAP_SVESM4 __khwcap2_feature(SVESM4)
#define KERNEL_HWCAP_FLAGM2 __khwcap2_feature(FLAGM2)
#define KERNEL_HWCAP_FRINT __khwcap2_feature(FRINT)
+#define KERNEL_HWCAP_RNG __khwcap2_feature(RNG)
#define KERNEL_HWCAP_SVEI8MM __khwcap2_feature(SVEI8MM)
#define KERNEL_HWCAP_SVEF32MM __khwcap2_feature(SVEF32MM)
#define KERNEL_HWCAP_SVEF64MM __khwcap2_feature(SVEF64MM)
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -366,6 +366,9 @@
#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)
@@ -540,6 +543,7 @@
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
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -65,6 +65,7 @@
#define HWCAP2_SVESM4 (1 << 6)
#define HWCAP2_FLAGM2 (1 << 7)
#define HWCAP2_FRINT (1 << 8)
+#define HWCAP2_RNG (1 << 9)
#define HWCAP2_SVEI8MM (1 << 9)
#define HWCAP2_SVEF32MM (1 << 10)
#define HWCAP2_SVEF64MM (1 << 11)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -118,6 +118,7 @@ static void cpu_enable_cnp(struct arm64_
* 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),
@@ -1595,6 +1596,18 @@ static const struct arm64_cpu_capabiliti
.min_field_value = 1,
},
#endif
+#ifdef CONFIG_ARCH_RANDOM
+ {
+ .desc = "Random Number Generator",
+ .capability = ARM64_HAS_RNG,
+ .type = ARM64_CPUCAP_SYSTEM_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
{},
};
@@ -1672,6 +1685,7 @@ static const struct arm64_cpu_capabiliti
HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_FHM_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_ASIMDFHM),
HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_TS_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FLAGM),
HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_TS_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, KERNEL_HWCAP_FLAGM2),
+ HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_RNDR_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_RNG),
HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_FP_SHIFT, FTR_SIGNED, 0, CAP_HWCAP, KERNEL_HWCAP_FP),
HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_FP_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FPHP),
HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_ASIMD_SHIFT, FTR_SIGNED, 0, CAP_HWCAP, KERNEL_HWCAP_ASIMD),
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -84,6 +84,7 @@ static const char *const hwcap_str[] = {
"svesm4",
"flagm2",
"frint",
+ "rng",
"svei8mm",
"svef32mm",
"svef64mm",