syscall.c

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/*
 * 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.
 */

#include <syscall/syscall.h>
#include <arch/syscall.h>
#include <panic.h>
#include <arch/cpu.h>
#include <arch/pm.h>
#include <arch/asm.h>

#include <print.h>
#include <arch/cpu.h>

extern void syscall_entry(void);

void syscall_setup_cpu(void)
{
        /* Enable SYSCALL/SYSRET */
        set_efer_flag(AMD_SCE_FLAG);

        /* 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,
                  ((__u64)(gdtselector(KDATA_DES) | PL_USER)<<48) \
                  | ((__u64)(gdtselector(KTEXT_DES) | PL_KERNEL)<<32));
        write_msr(AMD_MSR_LSTAR, (__u64)syscall_entry);
        /* Mask RFLAGS on syscall 
         * - disable interrupts, until we exchange the stack register
         *   (mask the IE bit)
         */
        write_msr(AMD_MSR_SFMASK, 0x200);
}

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