106 lines
3.6 KiB
ArmAsm
106 lines
3.6 KiB
ArmAsm
/* msr.s - Utilities to read/write the Model Specific Registers (MSRs) */
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/*
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* Copyright (c) 2011-2014 Wind River Systems, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1) Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2) Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3) Neither the name of Wind River Systems nor the names of its contributors
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* may be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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DESCRIPTION
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This module provides the implementation of the _MsrWrite() and _MsrRead()
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utilities.
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*/
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#define _ASMLANGUAGE
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#include <nanokernel/x86/asm.h>
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/* exports (internal APIs) */
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GTEXT(_MsrWrite)
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GTEXT(_MsrRead)
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/*******************************************************************************
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*
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* _MsrWrite - write to a model specific register (MSR)
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*
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* This function is used to write to an MSR.
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*
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* C function prototype:
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*
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* void _MsrWrite (unsigned int msr, uint64_t msrData);
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*
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* The definitions of the so-called "Architectural MSRs" are contained
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* in nanok.h and have the format: IA32_XXX_MSR
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*
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* INTERNAL
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* 1) The 'wrmsr' instruction was introduced in the Pentium processor; executing
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* this instruction on an earlier IA-32 processor will result in an invalid
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* opcode exception.
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* 2) The 'wrmsr' uses the ECX, EDX, and EAX registers which matches the set of
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* volatile registers!
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*
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* RETURNS: N/A
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*/
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SECTION_FUNC(TEXT, _MsrWrite)
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movl SP_ARG1(%esp), %ecx /* load ECX with <msr> */
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movl 0x8(%esp), %eax /* load LS 32-bits of <msrData> */
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movl 0xc(%esp), %edx /* load MS 32-bits of <msrData> */
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wrmsr /* write %edx:%eax to the MSR */
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ret
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/*******************************************************************************
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*
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* _MsrRead - read from a model specific register (MSR)
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*
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* This function is used to read from an MSR.
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*
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* C function prototype:
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*
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* uint64_t _MsrRead (unsigned int msr);
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*
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* The definitions of the so-called "Architectural MSRs" are contained
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* in nanok.h and have the format: IA32_XXX_MSR
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*
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* INTERNAL
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* 1) The 'rdmsr' instruction was introduced in the Pentium processor; executing
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* this instruction on an earlier IA-32 processor will result in an invalid
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* opcode exception.
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* 2) The 'rdmsr' uses the ECX, EDX, and EAX registers which matches the set of
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* volatile registers!
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*
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* RETURNS: N/A
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*/
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SECTION_FUNC(TEXT, _MsrRead)
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movl SP_ARG1(%esp), %ecx /* load ECX with <msr> */
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rdmsr /* read MSR into %edx:%eax */
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ret
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