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  1. /*
  2.  * Copyright (c) 2006 Ondrej Palkovsky
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup amd64
  30.  * @{
  31.  */
  32. /** @file
  33.  */
  34.  
  35. #include <syscall/syscall.h>
  36. #include <arch/syscall.h>
  37. #include <panic.h>
  38. #include <arch/cpu.h>
  39. #include <arch/pm.h>
  40. #include <arch/asm.h>
  41.  
  42. #include <print.h>
  43. #include <arch/cpu.h>
  44.  
  45. extern void syscall_entry(void);
  46.  
  47. /** Enable & setup support for SYSCALL/SYSRET */
  48. void syscall_setup_cpu(void)
  49. {
  50.     /* Enable SYSCALL/SYSRET */
  51.     set_efer_flag(AMD_SCE_FLAG);
  52.  
  53.     /* Setup syscall entry address */
  54.    
  55.     /* This is _mess_ - the 64-bit CS is argument + 16,
  56.      * the SS is argument + 8. The order is:
  57.      * +0(KDATA_DES), +8(UDATA_DES), +16(UTEXT_DES)
  58.      */
  59.     write_msr(AMD_MSR_STAR,
  60.         ((uint64_t)(gdtselector(KDATA_DES) | PL_USER) << 48) |
  61.         ((uint64_t)(gdtselector(KTEXT_DES) | PL_KERNEL) << 32));
  62.     write_msr(AMD_MSR_LSTAR, (uint64_t)syscall_entry);
  63.     /* Mask RFLAGS on syscall
  64.      * - disable interrupts, until we exchange the stack register
  65.      *   (mask the IF bit)
  66.      * - clear DF so that the string instructions operate in
  67.      *   the right direction
  68.      */
  69.     write_msr(AMD_MSR_SFMASK, RFLAGS_IF | RFLAGS_DF);
  70. }
  71.  
  72. /** @}
  73.  */
  74.