/*
* Copyright (c) 2006 Ondrej Palkovsky
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup kernel_amd64
* @{
*/
/** @file
*/
#include <syscall/syscall.h>
#include <arch/syscall.h>
#include <panic.h>
#include <arch/cpu.h>
#include <arch/pm.h>
#include <arch/asm.h>
extern void syscall_entry(void);
/** Enable & setup support for SYSCALL/SYSRET */
void syscall_setup_cpu(void)
{
/* Enable SYSCALL/SYSRET */
write_msr(AMD_MSR_EFER, read_msr(AMD_MSR_EFER) | AMD_SCE);
/* Setup syscall entry address */
/*
* This is _mess_ - the 64-bit CS is argument + 16,
* the SS is argument + 8. The order is:
* +0(KDATA_DES), +8(UDATA_DES), +16(UTEXT_DES)
*/
write_msr(AMD_MSR_STAR,
((uint64_t) (GDT_SELECTOR(KDATA_DES) | PL_USER) << 48) |
((uint64_t) (GDT_SELECTOR(KTEXT_DES) | PL_KERNEL) << 32));
write_msr(AMD_MSR_LSTAR, (uint64_t)syscall_entry);
/*
* Mask RFLAGS on syscall
* - disable interrupts, until we exchange the stack register
* (mask the IF bit)
* - clear DF so that the string instructions operate in
* the right direction
* - clear NT to prevent a #GP should the flag proliferate to an IRET
* - clear TF to prevent an immediate #DB if TF is set
*/
write_msr(AMD_MSR_SFMASK,
RFLAGS_IF | RFLAGS_DF | RFLAGS_NT | RFLAGS_TF);
}
/** @}
*/