arch/i386-all/kernel/createcontext.c

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