arch/i386-pc/kernel/kernel_cpu.c

   1 /*
   2     Copyright © 2011-2015, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: i386 native CPU supplementals for task scheduler
   6     Lang: english
   7 */
   8
   9 #include <exec/lists.h>
  10 #include <exec/tasks.h>
  11 #include <exec/execbase.h>
  12 #include <hardware/intbits.h>
  13 #include <proto/exec.h>
  14
  15 #include "etask.h"
  16
  17 #include "kernel_base.h"
  18 #include "kernel_debug.h"
  19 #include "kernel_intern.h"
  20 #include "kernel_intr.h"
  21 #include "kernel_scheduler.h"
  22
  23 #include "apic.h"
  24
  25 #define D(x)
  26
  27 static inline unsigned long long RDTSC() {
  28    unsigned long long _tsc;
  29    asm volatile (".byte 0x0f, 0x31" : "=A" (_tsc));
  30    return _tsc;
  31 }
  32
  33 void cpu_Dispatch(struct ExceptionContext *regs)
  34 {
  35     struct Task *task;
  36     struct ExceptionContext *ctx;
  37
  38     /*
  39      * Is the list of ready tasks empty? Well, increment the idle switch count and halt CPU.
  40      * It should be extended by some plugin mechanism which would put CPU and whole machine
  41      * into some more sophisticated sleep states (ACPI?)
  42      */
  43     while (!(task = core_Dispatch()))
  44     {
  45         /* Sleep almost forever ;) */
  46         __asm__ __volatile__("sti; hlt; cli");
  47
  48         if (SysBase->SysFlags & SFF_SoftInt)
  49             core_Cause(INTB_SOFTINT, 1l << INTB_SOFTINT);
  50     }
  51
  52     /* TODO: Handle exception
  53     if (task->tc_Flags & TF_EXCEPT)
  54         Exception(); */
  55
  56     /* Get task's context */
  57     ctx = task->tc_UnionETask.tc_ETask->et_RegFrame;
  58     D(bug("[Kernel] Dispatch task %s, context 0x%p\n", task->tc_Node.ln_Name, ctx));
  59
  60     /* Restore GPRs first. CopyMemQuick() may use SSE. */
  61     CopyMemQuick(ctx, regs, offsetof(struct ExceptionContext, FPData));
  62     /* Then FPU */
  63     if (ctx->Flags & ECF_FPX)
  64     {
  65         /*
  66          * We have SSE state, restore it.
  67          * SSE context includes 8087, so we don't have to care about
  68          * it separately after this.
  69          */
  70         asm volatile("fxrstor (%0)"::"r"(ctx->FXData));
  71     }
  72     else if (ctx->Flags & ECF_FPU)
  73     {
  74         /* No SSE, plain 8087 */
  75         asm volatile("frstor (%0)"::"r"(ctx->FPData));
  76     }
  77
  78     /* Store the launch time */
  79     GetIntETask(task)->iet_private1 = RDTSC();
  80 }
  81
  82 void cpu_Switch(struct ExceptionContext *regs)
  83 {
  84     struct Task *task = SysBase->ThisTask;
  85     struct ExceptionContext *ctx = task->tc_UnionETask.tc_ETask->et_RegFrame;
  86
  87     D(bug("[Kernel] cpu_Switch(), task %s\n", task->tc_Node.ln_Name));
  88
  89     /*
  90      * Copy the fpu, mmx, xmm state.
  91      * Do this before CopyMemQuick(), because this function
  92      * can use SSE itself.
  93      */
  94     if (KernelBase->kb_ContextFlags & ECF_FPX)
  95         asm volatile("fxsave (%0)"::"r"(ctx->FXData));
  96     if (KernelBase->kb_ContextFlags & ECF_FPU)
  97         asm volatile("fnsave (%0)"::"r"(ctx->FPData));
  98
  99     /*
 100      * Copy current task's context into the ETask structure. Note that context on stack
 101      * misses SSE data pointer.
 102      */
 103     CopyMemQuick(regs, ctx, offsetof(struct ExceptionContext, FPData));
 104     /* We have the complete data now */
 105     ctx->Flags = ECF_SEGMENTS | KernelBase->kb_ContextFlags;
 106     /* Set task's tc_SPReg */
 107     task->tc_SPReg = (APTR)regs->esp;
 108
 109     /* FIXME */
 110 #if (0)
 111     GetIntETask(task)->iet_CpuTime += (RDTSC() - GetIntETask(task)->iet_private1);
 112 #endif
 113
 114     core_Switch();
 115 }