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803 palkovsky 1
/*
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 * Copyright (C) 2006 Ondrej Palkovsky
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 * All rights reserved.
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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
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#include <syscall/syscall.h>
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#include <arch/syscall.h>
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#include <panic.h>
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#include <arch/cpu.h>
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#include <arch/pm.h>
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#include <arch/asm.h>
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#include <print.h>
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#include <arch/cpu.h>
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extern void syscall_entry(void);
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/** Enable & setup support for SYSCALL/SYSRET */
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void syscall_setup_cpu(void)
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{
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    /* Enable SYSCALL/SYSRET */
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    set_efer_flag(AMD_SCE_FLAG);
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    /* Setup syscall entry address */
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    /* This is _mess_ - the 64-bit CS is argument+16,
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     * the SS is argument+8. The order is:
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     * +0(KDATA_DES), +8(UDATA_DES), +16(UTEXT_DES)
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     */
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    write_msr(AMD_MSR_STAR,
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          ((__u64)(gdtselector(KDATA_DES) | PL_USER)<<48) \
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          | ((__u64)(gdtselector(KTEXT_DES) | PL_KERNEL)<<32));
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    write_msr(AMD_MSR_LSTAR, (__u64)syscall_entry);
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    /* Mask RFLAGS on syscall
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     * - disable interrupts, until we exchange the stack register
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     *   (mask the IE bit)
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     */
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    write_msr(AMD_MSR_SFMASK, 0x200);
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}