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nuclear@54
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1 #define ASM
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2 #include "segm.h"
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3
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4 .data
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5 .align 4
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6 .short 0
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7 /* memory reserved for set_idt */
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8 lim:.short 0
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9 addr:.long 0
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10
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11 .text
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12 /* set_idt(uint32_t addr, uint16_t limit)
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13 * loads the IDTR with the new address and limit for the IDT */
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14 .globl set_idt
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15 set_idt:
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16 movl 4(%esp), %eax
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17 movl %eax, (addr)
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18 movw 8(%esp), %ax
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19 movw %ax, (lim)
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20 lidt (lim)
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21 ret
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22
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23 /* get_intr_state()
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24 * returns 1 if interrutps are enabled, 0 if disabled */
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25 .globl get_intr_state
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26 get_intr_state:
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27 pushf
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28 popl %eax
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29 shr $9, %eax /* bit 9 of eflags is IF */
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30 andl $1, %eax
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31 ret
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32
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33 /* set_intr_state(int state)
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34 * enables interrupts if the argument is non-zero, disables them otherwise */
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35 .globl set_intr_state
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36 set_intr_state:
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37 cmpl $0, 4(%esp)
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38 jz 0f
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39 sti
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40 ret
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41 0: cli
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42 ret
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43
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44
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45 /* interrupt entry with error code macro
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46 * this macro generates an interrupt entry point for the
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47 * exceptions which include error codes in the stack frame
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48 */
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49 .macro ientry_err n name
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50 .globl intr_entry_\name
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51 intr_entry_\name:
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52 pushl $\n
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53 jmp intr_entry_common
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54 .endm
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55
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56 /* interrupt entry without error code macro
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57 * this macro generates an interrupt entry point for the interrupts
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58 * and exceptions which do not include error codes in the stack frame
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59 * it pushes a dummy error code (0), to make the stack frame identical
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60 */
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61 .macro ientry_noerr n name
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62 .globl intr_entry_\name
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63 intr_entry_\name:
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64 pushl $0
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65 pushl $\n
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66 jmp intr_entry_common
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67 .endm
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68
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69 /* common code used by all entry points. calls dispatch_intr()
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70 * defined in intr.c
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71 */
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72 .extern dispatch_intr
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73 intr_entry_common:
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74 /* save the current data segment selectors */
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75 pushl %gs
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76 pushl %fs
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77 pushl %es
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78 pushl %ds
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79 /* save general purpose registers */
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80 pusha
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81 /* if we entered from userspace ss and cs is set correctly, but
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82 * we must make sure all the other selectors are set to the
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83 * kernel data segment */
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84 mov $SEGM_KDATA, %ds
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85 mov $SEGM_KDATA, %es
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86 mov $SEGM_KDATA, %fs
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87 mov $SEGM_KDATA, %gs
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88 call dispatch_intr
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89 intr_ret_local:
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90 /* restore general purpose registers */
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91 popa
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92 /* restore data segment selectors */
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93 popl %ds
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94 popl %es
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95 popl %fs
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96 popl %gs
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97 /* remove error code and intr num from stack */
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98 add $8, %esp
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99 iret
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100
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101 /* intr_ret is called by context_switch to return from the kernel
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102 * to userspace. The argument is a properly formed intr_frame
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103 * structure with the saved context of the new task.
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104 *
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105 * First thing to do is remove the return address pointing back
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106 * to context_switch, which then leaves us with a proper interrupt
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107 * stack frame, so we can jump right in the middle of the regular
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108 * interrupt return code above.
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109 */
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110 .globl intr_ret
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111 intr_ret:
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112 add $4, %esp
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113 jmp intr_ret_local
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114
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115 /* by including interrupts.h with ASM defined, the macros above
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116 * are expanded to generate all required interrupt entry points
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117 */
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118 #include <interrupts.h>
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