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  1. /*
  2.  * Copyright (C) 2001-2004 Jakub Jermar
  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. #include <arch/pm.h>
  30. #include <config.h>
  31. #include <arch/types.h>
  32. #include <typedefs.h>
  33. #include <arch/interrupt.h>
  34. #include <arch/asm.h>
  35. #include <arch/context.h>
  36. #include <panic.h>
  37.  
  38. /*
  39.  * Early i386 configuration functions and data structures.
  40.  */
  41.  
  42. /*
  43.  * We have no use for segmentation so we set up flat mode. In this
  44.  * mode, we use, for each privilege level, two segments spanning the
  45.  * whole memory. One is for code and one is for data.
  46.  */
  47. struct descriptor gdt[GDT_ITEMS] = {
  48.     /* NULL descriptor */
  49.     { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  50.     /* KTEXT descriptor */
  51.     { 0xffff, 0, 0, AR_PRESENT | AR_CODE | DPL_KERNEL, 0xf, 0, 0, 1, 1, 0 },
  52.     /* KDATA descriptor */
  53.     { 0xffff, 0, 0, AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_KERNEL, 0xf, 0, 0, 1, 1, 0 },
  54.     /* UTEXT descriptor */
  55.     { 0xffff, 0, 0, AR_PRESENT | AR_CODE | DPL_USER, 0xf, 0, 0, 1, 1, 0 },
  56.     /* UDATA descriptor */
  57.     { 0xffff, 0, 0, AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_USER, 0xf, 0, 0, 1, 1, 0 },
  58.     /* TSS descriptor - set up will be completed later */
  59.     { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
  60. };
  61.  
  62. static struct idescriptor idt[IDT_ITEMS];
  63.  
  64. static struct tss tss;
  65.  
  66. struct tss *tss_p = NULL;
  67.  
  68. /* gdtr changes everytime new CPU is initialized */
  69. struct ptr_16_32 gdtr = { .limit = sizeof(gdt), .base = (__address) gdt };
  70. struct ptr_16_32 idtr = { .limit = sizeof(idt), .base = (__address) idt };
  71.  
  72. void gdt_setbase(struct descriptor *d, __address base)
  73. {
  74.         d->base_0_15 = base & 0xffff;
  75.         d->base_16_23 = (base >> 16) & 0xff;
  76.         d->base_24_31 = (base >> 24) & 0xff;
  77. }
  78.  
  79. void gdt_setlimit(struct descriptor *d, __address limit)
  80. {
  81.         d->limit_0_15 = limit & 0xffff;
  82.         d->limit_16_19 = (limit >> 16) & 0xf;
  83. }
  84.  
  85. void idt_setoffset(struct idescriptor *d, __address offset)
  86. {
  87.     d->offset_0_15 = offset & 0xffff;
  88.     d->offset_16_31 = offset >> 16;
  89. }
  90.  
  91. void tss_initialize(struct tss *t)
  92. {
  93.     memsetb((__address) t, sizeof(struct tss), 0);
  94. }
  95.  
  96. /*
  97.  * This function takes care of proper setup of IDT and IDTR.
  98.  */
  99. void idt_init(void)
  100. {
  101.     struct idescriptor *d;
  102.     int i;
  103.    
  104.     for (i = 0; i < IDT_ITEMS; i++) {
  105.         d = &idt[i];
  106.  
  107.         d->unused = 0;
  108.         d->selector = selector(KTEXT_DES);
  109.  
  110.         d->access = AR_PRESENT | AR_INTERRUPT;  /* masking interrupt */
  111.  
  112.         if (i == VECTOR_SYSCALL) {
  113.             /*
  114.              * The syscall interrupt gate must be calleable from userland.
  115.              */
  116.             d->access |= DPL_USER;
  117.         }
  118.        
  119.         idt_setoffset(d, ((__address) interrupt_handlers) + i*interrupt_handler_size);
  120.         trap_register(i, null_interrupt);
  121.     }
  122.     trap_register(13, gp_fault);
  123. }
  124.  
  125.  
  126. void pm_init(void)
  127. {
  128.     struct descriptor *gdt_p = (struct descriptor *) gdtr.base;
  129.  
  130.     /*
  131.      * Each CPU has its private GDT and TSS.
  132.      * All CPUs share one IDT.
  133.      */
  134.  
  135.     if (config.cpu_active == 1) {
  136.         idt_init();
  137.         /*
  138.          * NOTE: bootstrap CPU has statically allocated TSS, because
  139.          * the heap hasn't been initialized so far.
  140.          */
  141.         tss_p = &tss;
  142.     }
  143.     else {
  144.         tss_p = (struct tss *) malloc(sizeof(struct tss));
  145.         if (!tss_p)
  146.             panic(PANIC "could not allocate TSS\n");
  147.     }
  148.  
  149.     tss_initialize(tss_p);
  150.    
  151.     gdt_p[TSS_DES].access = AR_PRESENT | AR_TSS | DPL_KERNEL;
  152.     gdt_p[TSS_DES].special = 1;
  153.     gdt_p[TSS_DES].granularity = 1;
  154.    
  155.     gdt_setbase(&gdt_p[TSS_DES], (__address) tss_p);
  156.     gdt_setlimit(&gdt_p[TSS_DES], sizeof(struct tss) - 1);
  157.  
  158.     /*
  159.      * As of this moment, the current CPU has its own GDT pointing
  160.      * to its own TSS. We just need to load the TR register.
  161.      */
  162.     __asm__("ltr %0" : : "r" ((__u16) selector(TSS_DES)));
  163. }
  164.