62 lines
1.6 KiB
C
62 lines
1.6 KiB
C
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#ifndef __ARCH_DESC_H
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#define __ARCH_DESC_H
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struct desc_struct {
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unsigned long a,b;
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};
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extern struct desc_struct gdt_table[];
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extern struct desc_struct *idt, *gdt;
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struct Xgt_desc_struct {
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unsigned short size;
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unsigned long address __attribute__((packed));
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};
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#define idt_descr (*(struct Xgt_desc_struct *)((char *)&idt - 2))
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#define gdt_descr (*(struct Xgt_desc_struct *)((char *)&gdt - 2))
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/*
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* Entry into gdt where to find first TSS. GDT layout:
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* 0 - null
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* 1 - not used
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* 2 - kernel code segment
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* 3 - kernel data segment
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* 4 - user code segment
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* 5 - user data segment
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* 6 - not used
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* 7 - not used
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* 8 - APM BIOS support
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* 9 - APM BIOS support
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* 10 - APM BIOS support
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* 11 - APM BIOS support
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* 12 - TSS #0
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* 13 - LDT #0
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* 14 - TSS #1
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* 15 - LDT #1
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*/
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#define FIRST_TSS_ENTRY 12
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#define FIRST_LDT_ENTRY (FIRST_TSS_ENTRY+1)
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#define _TSS(n) ((((unsigned long) n)<<4)+(FIRST_TSS_ENTRY<<3))
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#define _LDT(n) ((((unsigned long) n)<<4)+(FIRST_LDT_ENTRY<<3))
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#define load_TR(n) __asm__ __volatile__("ltr %%ax": /* no output */ :"a" (_TSS(n)))
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#define load_ldt(n) __asm__ __volatile__("lldt %%ax": /* no output */ :"a" (_LDT(n)))
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#define store_TR(n) \
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__asm__("str %%ax\n\t" \
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"subl %2,%%eax\n\t" \
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"shrl $4,%%eax" \
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:"=a" (n) \
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:"0" (0),"i" (FIRST_TSS_ENTRY<<3))
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extern void set_intr_gate(unsigned int irq, void * addr);
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extern void set_ldt_desc(unsigned int n, void *addr, unsigned int size);
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extern void set_tss_desc(unsigned int n, void *addr);
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/*
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* This is the ldt that every process will get unless we need
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* something other than this.
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*/
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extern struct desc_struct default_ldt;
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#endif
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