arch/i386-all/kernel/createcontext.c

   1 /*
   2     Copyright © 1995-2014, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include <aros/kernel.h>
   7 #include <aros/libcall.h>
   8 #include <aros/i386/cpucontext.h>
   9
  10 #include <kernel_base.h>
  11 #include <kernel_objects.h>
  12
  13 #ifndef SIZEOF_8087_FRAME
  14 #define SIZEOF_8087_FRAME sizeof(struct FPUContext)
  15 #endif
  16
  17 AROS_LH0(void *, KrnCreateContext,
  18           struct KernelBase *, KernelBase, 18, Kernel)
  19
  20 {
  21     AROS_LIBFUNC_INIT
  22
  23     struct ExceptionContext *ctx;
  24
  25     /*
  26      * Allocate common data block and FPU data block in one chunk.
  27      * On native ports AROSCPUContext can be simply #define'd to ExceptionContext,
  28      * so we refer struct AROSCPUContext only for size calculation.
  29      */
  30     ctx = krnAllocCPUContext();
  31     if (ctx)
  32     {
  33         IPTR fpdata = (IPTR)ctx + sizeof(struct AROSCPUContext);
  34
  35         ctx->Flags  = KernelBase->kb_ContextFlags;      /* kb_ContextFlags on i386 hold only FPU bits */
  36         ctx->eflags = 0x3202;                           /* Set up default values for some registers */
  37
  38 /* These definitions may come from machine-specific kernel_cpu.h */
  39 #ifdef USER_CS
  40         ctx->Flags |= ECF_SEGMENTS;
  41         ctx->cs     = USER_CS;
  42         ctx->ds     = USER_DS;
  43         ctx->es     = USER_DS;
  44         ctx->fs     = USER_DS;
  45         ctx->gs     = USER_DS;
  46         ctx->ss     = USER_DS;
  47 #endif
  48
  49         if (!KernelBase->kb_ContextFlags)
  50         {
  51             /* Don't do any of the following if we don't support FPU at all */
  52             return ctx;
  53         }
  54
  55         if (ctx->Flags & ECF_FPU)
  56         {
  57             ctx->FPData = (struct FPUContext *)fpdata;
  58             fpdata += SIZEOF_8087_FRAME;
  59         }
  60
  61         if (ctx->Flags & ECF_FPX)
  62         {
  63             UBYTE current_xmm[512+15];
  64             UBYTE *curr = (UBYTE *)(((IPTR)current_xmm + 15) & ~15);
  65
  66             fpdata = (fpdata + 15) & ~15;
  67             ctx->FXData = (struct FPXContext *)fpdata;
  68
  69             asm volatile(
  70                 "       fxsave (%0)\n"
  71                 "       fninit\n"
  72                 "       fwait\n"
  73                 "       fxsave (%1)\n"
  74                 "       andl %2, %2\n"
  75                 "       je 1f\n"
  76                 "       fnsave (%2)\n"
  77                 "1:     fxrstor (%0)\n"
  78                 ::"r"(curr), "r"(ctx->FXData), "r"(ctx->FPData):"cc");
  79         }
  80         else if (ctx->Flags & ECF_FPU)
  81         {
  82             UBYTE curr[112];
  83
  84             /* fnsave implies fninit, so we don't need to do it explicitly */
  85             asm volatile(
  86                 "       fnsave (%0)\n"
  87                 "       fnsave (%1)\n"
  88                 "       frstor (%0)\n"
  89                 ::"r"(curr), "r"(ctx->FPData):"cc");
  90         }
  91     }
  92
  93     return ctx;
  94
  95     AROS_LIBFUNC_EXIT
  96 }