60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
#include <arch/gdt.h>
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#include <arch/tss.h>
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#include <mango/libc/string.h>
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#include <mango/types.h>
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#include <stddef.h>
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static void init_entry(struct gdt_entry *entry, int access, int flags)
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{
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entry->ge_limit_low = 0xFFFF;
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entry->ge_base_low = 0x00;
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entry->ge_base_mid = 0x00;
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entry->ge_access = access;
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entry->ge_gran = flags;
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entry->ge_base_hi = 0x00;
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}
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int gdt_init(struct gdt *gdt, struct gdt_ptr *gdtp)
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{
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memset(&gdt->g_entries[0], 0x0, sizeof gdt->g_entries[0]);
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init_entry(
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&gdt->g_entries[1],
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GDT_A_PRESENT | GDT_A_CODEREAD | GDT_A_CODE,
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GDT_F_64BIT);
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init_entry(
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&gdt->g_entries[2],
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GDT_A_PRESENT | GDT_A_DATAWRITE | GDT_A_DATA,
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GDT_F_64BIT);
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init_entry(
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&gdt->g_entries[3],
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GDT_A_PRESENT | GDT_A_USER | GDT_A_CODEREAD | GDT_A_CODE,
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GDT_F_64BIT);
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init_entry(
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&gdt->g_entries[4],
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GDT_A_PRESENT | GDT_A_USER | GDT_A_DATAWRITE | GDT_A_DATA,
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GDT_F_64BIT);
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gdtp->g_ptr = (uint64_t)gdt;
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gdtp->g_limit = sizeof(*gdt) - 1;
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return 0;
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}
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void gdt_write_tss(struct gdt *gdt, struct tss *tss)
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{
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struct tss_gdt_entry *tss_entry = &gdt->g_tss;
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virt_addr_t base = (virt_addr_t)tss;
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size_t limit = sizeof *tss;
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tss_entry->ge_base_low = (base & 0xFFFF);
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tss_entry->ge_base_mid = (base >> 16) & 0xFF;
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tss_entry->ge_base_hi = (base >> 24) & 0xFF;
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tss_entry->ge_base_ext = (base >> 32) & 0xFFFFFFFF;
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tss_entry->ge_limit_low = (limit & 0xFFFF);
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tss_entry->ge_gran = (limit >> 16) & 0xF;
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tss_entry->ge_access = 0xE9;
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tss_entry->ge_reserved = 0;
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}
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