arch/x86_64-all/exec/newstackswap.c

   1 /*
   2     Copyright © 1995-2014, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: NewStackSwap() - Call a function with swapped stack, x86-64 version
   6     Lang: english
   7 */
   8
   9 #include <aros/config.h>
  10 #include <aros/debug.h>
  11 #include <exec/tasks.h>
  12 #include <proto/exec.h>
  13
  14 #define _PUSH(sp, val) *--sp = (IPTR)val
  15
  16 AROS_LH3(IPTR, NewStackSwap,
  17         AROS_LHA(struct StackSwapStruct *,  sss, A0),
  18         AROS_LHA(LONG_FUNC, entry, A1),
  19         AROS_LHA(struct StackSwapArgs *, args, A2),
  20         struct ExecBase *, SysBase, 134, Exec)
  21 {
  22     AROS_LIBFUNC_INIT
  23
  24     volatile struct Task *t = FindTask(NULL);
  25     volatile IPTR *sp = sss->stk_Pointer;
  26     volatile APTR spreg = t->tc_SPReg;
  27     volatile APTR splower = t->tc_SPLower;
  28     volatile APTR spupper = t->tc_SPUpper;
  29     IPTR ret;
  30
  31     if (args != NULL)
  32     {
  33         /* Only last two arguments are put to stack in x86-64 */
  34         _PUSH(sp, args->Args[7]);
  35         _PUSH(sp, args->Args[6]);
  36     }
  37     else
  38     {
  39         /* Dummy args to be put in registers below */
  40         args = splower;
  41     }
  42
  43     if (t->tc_Flags & TF_STACKCHK)
  44     {
  45         UBYTE* startfill = sss->stk_Lower;
  46
  47         while (startfill < (UBYTE *)sp)
  48             *startfill++ = 0xE1;
  49     }
  50
  51     /*
  52      * We need to Disable() before changing limits and SP, otherwise
  53      * stack check will fail if we get interrupted in the middle of this
  54      */
  55     D(bug("[NewStackSwap] SP 0x%p, entry point 0x%p\n", sp, entry));
  56     Disable();
  57
  58     /* Change limits. The rest is done in asm below */
  59     t->tc_SPReg = (APTR)sp;
  60     t->tc_SPLower = sss->stk_Lower;
  61     t->tc_SPUpper = sss->stk_Upper;
  62
  63     asm volatile(
  64     /* Save original RSP */
  65     "push %%rbp\n\t"
  66     "movq %%rsp, %%rbp\n\t"
  67     /* Actually change the stack */
  68     "movq %2, %%rsp\n\t"
  69
  70     /* Enable(). It preserves all registers by convention. */
  71     "call *-168(%%rdi)\n\t"
  72
  73     /* Call our function with its arguments */
  74     "movq 0(%3), %%rdi\n\t"
  75     "movq 8(%3), %%rsi\n\t"
  76     "movq 16(%3), %%rdx\n\t"
  77     "movq 24(%3), %%rcx\n\t"
  78     "movq 32(%3), %%r8\n\t"
  79     "movq 40(%3), %%r9\n\t"
  80     "call *%1\n\t"
  81
  82     /* Disable(). Also preserves registers. */
  83     "movabsq $SysBase, %%rdi\n\t"
  84     "movq (%%rdi), %%rdi\n\t"
  85     "call *-160(%%rdi)\n\t"
  86
  87     /* Restore original RSP. Function's return value is in RAX. */
  88     "movq %%rbp, %%rsp\n\t"
  89     "popq %%rbp\n"
  90     : "=a"(ret)
  91     : "r"(entry), "r"(sp), "r"(args), "D"(SysBase)
  92     : "rsi", "rdx", "rcx", "r8", "r9", "cc");
  93
  94     /* Change limits back and return */
  95     t->tc_SPReg = spreg;
  96     t->tc_SPLower = splower;
  97     t->tc_SPUpper = spupper;
  98     Enable();
  99
 100     D(bug("[NewStackSwap] Returning 0x%p\n", ret));
 101     return ret;
 102
 103     AROS_LIBFUNC_EXIT
 104 } /* NewStackSwap() */