75 lines
1.3 KiB
C
75 lines
1.3 KiB
C
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#include "gdt.h"
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static struct gdt gdt = { 0 };
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static void create_kernel_ds()
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{
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}
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static void create_kernel_cs()
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{
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}
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static void create_gdt()
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{
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create_kernel_ds();
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create_kernel_cs();
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}
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static void load_gdt()
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{
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struct gdt_r gdtr;
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gdtr.addr = (uint32_t)&gdt;
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gdtr.limit = GDT_SIZE - 1;
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asm volatile("lgdt %0\n"
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:
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: "m" (gdtr)
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: "memory");
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}
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static void load_ds()
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{
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struct segment_selector selector;
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selector.index = KERNEL_DS_INDEX;
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selector.table_indicator = 0;
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selector.rpl = 0;
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asm volatile("movw %0, %%ax\n"
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"movw %%ax, %%ds\n"
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"movw %%ax, %%fs\n"
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"movw %%ax, %%gs\n"
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"movw %%ax, %%ss\n"
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:
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: "m" (selector)
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: "ax");
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}
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static void load_cs()
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{
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struct segment_selector selector;
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selector.index = KERNEL_CS_INDEX;
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selector.table_indicator = 0;
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selector.rpl = 0;
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asm volatile("pushl %0\n"
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"pushl $1f\n"
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"lret\n"
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"1:\n"
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:
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: "m" (selector));
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}
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static void reload_segment_selectors()
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{
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load_ds();
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load_cs();
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}
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void init_gdt()
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{
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create_gdt();
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load_gdt();
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reload_segment_selectors();
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}
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