sortix--sortix/libc/include/msr.h

/*
 * Copyright (c) 2013 Jonas 'Sortie' Termansen.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * msr.h
 * High-level access to the rdmsr and wrmsr instructions for accessing and
 * modifying machine specific registers.
 */

#ifndef INCLUDE_MSR_H
#define INCLUDE_MSR_H

#include <sys/cdefs.h>

#include <stdint.h>

#if defined(__i386__) || defined(__x86_64__)

#ifdef __cplusplus
extern "C" {
#endif

#define MSRID_FSBASE __UINT32_C(0xC0000100)
#define MSRID_GSBASE __UINT32_C(0xC0000101)

__attribute__((unused))
static __inline uint64_t rdmsr_instruction(uint32_t msrid)
{
	uint32_t low;
	uint32_t high;
	__asm__ __volatile__ ("rdmsr" : "=a"(low), "=d"(high) : "c"(msrid));
	return (uint64_t) low << 0 | (uint64_t) high << 32;
}

__attribute__((unused))
static __inline uint64_t wrmsr_instruction(uint32_t msrid, uint64_t value)
{
	uint32_t low = value >> 0 & 0xFFFFFFFF;
	uint32_t high = value >> 32 & 0xFFFFFFFF;
	__asm__ __volatile__ ("wrmsr" : : "a"(low), "d"(high), "c"(msrid) : "memory");
	return value;
}

#if __STDC_HOSTED__

uint64_t rdmsr(uint32_t msrid);
uint64_t wrmsr(uint32_t msrid, uint64_t value);

#else

__attribute__((unused))
static __inline uint64_t rdmsr(uint32_t msrid)
{
	return rdmsr_instruction(msrid);
}

__attribute__((unused))
static __inline uint64_t wrmsr(uint32_t msrid, uint64_t value)
{
	return wrmsr_instruction(msrid, value);
}

#endif

__attribute__((unused))
static __inline void rdmsr_split(uint32_t msrid, uint32_t* low, uint32_t* high)
{
	uint64_t result = rdmsr(msrid);
	*low = result >> 0 & 0xFFFFFFFF;
	*high = result >> 32 & 0xFFFFFFFF;
}

__attribute__((unused))
static __inline void wrmsr_split(uint32_t msrid, uint32_t low, uint32_t high)
{
	wrmsr(msrid, (uint64_t) low << 0 | (uint64_t) high << 32);
}

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif

#endif