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Kernel: Use RDSEED assembly snippet to seed RNG on Aarch64

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There’s similar RDRAND register (encoded as ‘s3_3_c2_c4_0ʼ) to be
added if needed. RNG CPU feature on Aarch64 guarantees existence of both
RDSEED and RDRAND registers simultaneously—in contrast to x86-64, where
respective instructions are independent of each other.
This commit is contained in:
konrad 2023-01-08 05:30:40 +01:00 • committed by Jelle Raaijmakers
parent 7c8e61f4d1
commit e1c50b83e1
3 changed files with 26 additions and 0 deletions
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11
Kernel/Random.cpp
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@ -10,6 +10,8 @@
#if ARCH(X86_64)
# include <Kernel/Arch/x86_64/Time/HPET.h>
# include <Kernel/Arch/x86_64/Time/RTC.h>
#elif ARCH(AARCH64)
# include <Kernel/Arch/aarch64/ASM_wrapper.h>
#endif
#include <Kernel/Devices/RandomDevice.h>
#include <Kernel/Random.h>
@ -59,6 +61,15 @@ UNMAP_AFTER_INIT KernelRng::KernelRng()
current_time += 0x40b2u;
}
}
#elif ARCH(AARCH64)
if (Processor::current().has_feature(CPUFeature::RNG)) {
dmesgln("KernelRng: Using RNDRRS as entropy source");
for (size_t i = 0; i < pool_count * reseed_threshold; ++i) {
add_random_event(Aarch64::Asm::read_rndrrs(), i % 32);
}
} else {
dmesgln("KernelRng: No entropy source available!");
}
#else
dmesgln("KernelRng: No entropy source available!");
#endif