53 lines
1.6 KiB
C++
53 lines
1.6 KiB
C++
/*
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* Copyright (c) 2012, 2013 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* x86-family/pat.cpp
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* Tests whether PAT is available and initializes it.
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*/
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#include <msr.h>
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#include <stdint.h>
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#include <sortix/kernel/cpuid.h>
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#include <sortix/kernel/kernel.h>
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#include <sortix/kernel/pat.h>
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#include "memorymanagement.h"
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namespace Sortix {
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static const uint32_t bit_PAT = 0x00010000U;
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bool IsPATSupported()
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{
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if ( !IsCPUIdSupported() )
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return false;
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uint32_t eax, ebx, ecx, edx;
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cpuid(1, eax, ebx, ecx, edx);
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uint32_t features = edx;
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return features & bit_PAT;
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}
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void InitializePAT()
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{
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using namespace Sortix::Memory;
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const uint32_t LOW = PA[0] << 0 | PA[1] << 8 | PA[2] << 16 | PA[3] << 24;
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const uint32_t HIGH = PA[4] << 0 | PA[5] << 8 | PA[6] << 16 | PA[7] << 24;
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const int PAT_REG = 0x0277;
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wrmsr(PAT_REG, (uint64_t) LOW << 0 | (uint64_t) HIGH << 32);
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}
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} // namespace Sortix
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