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Kernel: Add a more expressive API for getting random bytes

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We now have these API's in <Kernel/Random.h>:

    - get_fast_random_bytes(u8* buffer, size_t buffer_size)
    - get_good_random_bytes(u8* buffer, size_t buffer_size)
    - get_fast_random<T>()
    - get_good_random<T>()

Internally they both use x86 RDRAND if available, otherwise they fall
back to the same LCG we had in RandomDevice all along.

The main purpose of this patch is to give kernel code a way to better
express its needs for random data.

Randomness is something that will require a lot more work, but this is
hopefully a step in the right direction.
This commit is contained in:
Andreas Kling 2020-01-03 12:36:30 +01:00
parent 24cc67d199
commit 9026598999
11 changed files with 87 additions and 48 deletions
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2
Kernel/Arch/i386/CPU.cpp
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@ -524,6 +524,7 @@ void sse_init()
bool g_cpu_supports_nx;
bool g_cpu_supports_pae;
bool g_cpu_supports_pge;
bool g_cpu_supports_rdrand;
bool g_cpu_supports_smep;
bool g_cpu_supports_sse;
bool g_cpu_supports_tsc;
@ -536,6 +537,7 @@ void detect_cpu_features()
g_cpu_supports_pge = (processor_info.edx() & (1 << 13));
g_cpu_supports_sse = (processor_info.edx() & (1 << 25));
g_cpu_supports_tsc = (processor_info.edx() & (1 << 4));
g_cpu_supports_rdrand = (processor_info.ecx() & (1 << 30));
CPUID extended_processor_info(0x80000001);
g_cpu_supports_nx = (extended_processor_info.edx() & (1 << 20));