@@ -58,6 +58,16 @@ static inline bool __arm64_rndrrs(unsigned long *v)
return ok;
}
+static __always_inline bool __cpu_has_rng(void)
+{
+ if (!system_capabilities_finalized() && early_boot_irqs_disabled) {
+ /* 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_EL1_RNDR_SHIFT) & 0xf;
+ }
+ return cpus_have_const_cap(ARM64_HAS_RNG);
+}
+
static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
{
/*
@@ -66,7 +76,7 @@ static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t
* 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))
+ if (max_longs && __cpu_has_rng() && __arm64_rndr(v))
return 1;
return 0;
}
@@ -108,53 +118,10 @@ static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, s
* 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_rndrrs(v))
- return 1;
-
- 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_EL1_RNDR_SHIFT) & 0xf;
-}
-
-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;
-
- 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) {
- 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))
+ if (__cpu_has_rng() && __arm64_rndrrs(v))
return 1;
return 0;
}
-#define arch_get_random_seed_longs_early arch_get_random_seed_longs_early
#endif /* _ASM_ARCHRANDOM_H */
@@ -813,13 +813,13 @@ void __init random_init_early(const char *command_line)
#endif
for (i = 0, arch_bits = sizeof(entropy) * 8; i < ARRAY_SIZE(entropy);) {
- longs = arch_get_random_seed_longs_early(entropy, ARRAY_SIZE(entropy) - i);
+ longs = arch_get_random_seed_longs(entropy, ARRAY_SIZE(entropy) - i);
if (longs) {
_mix_pool_bytes(entropy, sizeof(*entropy) * longs);
i += longs;
continue;
}
- longs = arch_get_random_longs_early(entropy, ARRAY_SIZE(entropy) - i);
+ longs = arch_get_random_longs(entropy, ARRAY_SIZE(entropy) - i);
if (longs) {
_mix_pool_bytes(entropy, sizeof(*entropy) * longs);
i += longs;
@@ -153,26 +153,6 @@ declare_get_random_var_wait(long, unsigned long)
#include <asm/archrandom.h>
-/*
- * Called from the boot CPU during startup; not valid to call once
- * secondary CPUs are up and preemption is possible.
- */
-#ifndef arch_get_random_seed_longs_early
-static inline size_t __init arch_get_random_seed_longs_early(unsigned long *v, size_t max_longs)
-{
- WARN_ON(system_state != SYSTEM_BOOTING);
- return arch_get_random_seed_longs(v, max_longs);
-}
-#endif
-
-#ifndef arch_get_random_longs_early
-static inline bool __init arch_get_random_longs_early(unsigned long *v, size_t max_longs)
-{
- WARN_ON(system_state != SYSTEM_BOOTING);
- return arch_get_random_longs(v, max_longs);
-}
-#endif
-
#ifdef CONFIG_SMP
int random_prepare_cpu(unsigned int cpu);
int random_online_cpu(unsigned int cpu);
The arch_get_random*_early() abstraction is not completely useful and adds complexity, because it's not a given that there will be no calls to arch_get_random*() between random_init_early(), which uses arch_get_random*_early(), and init_cpu_features(). During that gap, crng_reseed() might be called, which uses arch_get_random*(), since it's mostly not init code. Instead we can test whether we're in the early phase in arch_get_random*() itself, and in doing so avoid all ambiguity about where we are. Fortunately, the only architecture that currently implements arch_get_random*_early() also has an alternatives-based cpu feature system, one flag of which determines whether the other flags have been initialized. This makes it possible to do the early check with zero cost once the system is initialized. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Jean-Philippe Brucker <jean-philippe@linaro.org> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> --- Changes v1->v2: - Also check early_boot_irqs_disabled, to make sure that the raw capability check only runs during an early stage when we're only running on the boot CPU and with IRQs off. This check disappears once the system is up, because system_capabilities_finalized() is a static branch. Catalin - Though this touches arm64's archrandom.h, I intend to take this through the random.git tree, if that's okay. I have other patches that will build off of this one. -Jason arch/arm64/include/asm/archrandom.h | 57 ++++++----------------------- drivers/char/random.c | 4 +- include/linux/random.h | 20 ---------- 3 files changed, 14 insertions(+), 67 deletions(-)