109 lines
2.9 KiB
C
109 lines
2.9 KiB
C
#include <amd64/debug.h>
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#include <amd64/init.h>
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#include <amd64/intr.h>
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#include <amd64/tss.h>
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#include <libk/std.h>
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#include <libk/string.h>
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#define GDT_KCODE 0x08
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#define GDT_KDATA 0x10
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#define GDT_UCODE 0x18
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#define GDT_UDATA 0x20
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#define GDT_TSS 0x28
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#define TSS 0x80
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#define TSS_PRESENT 0x89
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#define KSTACK_SIZE (8 * 1024)
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struct gdt_entry {
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uint16_t limitlow;
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uint16_t baselow;
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uint8_t basemid;
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uint8_t access;
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uint8_t gran;
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uint8_t basehigh;
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} __attribute__ ((packed));
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struct gdt_ptr {
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uint16_t limit;
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uint64_t base;
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} __attribute__ ((packed));
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struct gdt_extended {
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struct gdt_entry old[5];
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struct gdt_entry tsslow;
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struct gdt_entry tsshigh;
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} __attribute__ ((packed));
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/* clang-format off */
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__attribute__ ((aligned (16))) static volatile uint8_t kernel_stack[KSTACK_SIZE];
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__attribute__ ((aligned (16))) static volatile struct gdt_extended gdt;
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/* clang-format on */
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static void amd64_gdt_set (volatile struct gdt_entry* ent, uint32_t base,
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uint32_t limit, uint8_t acc, uint8_t gran) {
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ent->baselow = (base & 0xFFFF);
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ent->basemid = (base >> 16) & 0xFF;
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ent->basehigh = (base >> 24) & 0xFF;
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ent->limitlow = (limit & 0xFFFF);
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ent->gran = ((limit >> 16) & 0x0F) | (gran & 0xF0);
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ent->access = acc;
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}
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static void amd64_gdt_init (void) {
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volatile struct tss* tss = amd64_get_tss ();
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memset ((void*)&gdt, 0, sizeof (gdt));
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memset ((void*)kernel_stack, 0, sizeof (kernel_stack));
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memset ((void*)tss, 0, sizeof (*tss));
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tss->iopb_off = sizeof (*tss);
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tss->rsp0 = (uint64_t)((uintptr_t)kernel_stack + sizeof (kernel_stack));
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uint64_t tssbase = (uint64_t)&tss;
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uint64_t tsslimit = sizeof (*tss) - 1;
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amd64_gdt_set (&gdt.old[0], 0, 0, 0, 0);
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amd64_gdt_set (&gdt.old[1], 0, 0xFFFFF, 0x9A, 0xA0);
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amd64_gdt_set (&gdt.old[2], 0, 0xFFFFF, 0x92, 0xC0);
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amd64_gdt_set (&gdt.old[3], 0, 0xFFFFF, 0xFA, 0xA0);
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amd64_gdt_set (&gdt.old[4], 0, 0xFFFFF, 0xF2, 0xC0);
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amd64_gdt_set (
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&gdt.tsslow, (tssbase & 0xFFFFFFFF), tsslimit, TSS_PRESENT | TSS, 0);
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uint32_t tssbasehigh = (tssbase >> 32);
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gdt.tsshigh.limitlow = (tssbasehigh & 0xFFFF);
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gdt.tsshigh.baselow = (tssbasehigh >> 16) & 0xFFFF;
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gdt.tsshigh.basemid = 0;
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gdt.tsshigh.basehigh = 0;
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gdt.tsshigh.access = 0;
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gdt.tsshigh.gran = 0;
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struct gdt_ptr gdtr;
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gdtr.limit = sizeof (gdt) - 1;
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gdtr.base = (uint64_t)&gdt;
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__asm__ volatile ("lgdt %0" ::"m"(gdtr) : "memory");
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__asm__ volatile ("pushq %[kcode]\n"
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"lea 1f(%%rip), %%rax\n"
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"pushq %%rax\n"
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"lretq\n"
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"1:\n"
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"movw %[kdata], %%ax\n"
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"movw %%ax, %%ds\n"
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"movw %%ax, %%es\n"
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"movw %%ax, %%ss\n"
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:
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: [kcode] "i"(GDT_KCODE), [kdata] "i"(GDT_KDATA)
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: "rax", "memory");
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__asm__ volatile ("ltr %0" ::"r"((uint16_t)GDT_TSS));
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}
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void amd64_init (void) {
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amd64_gdt_init ();
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amd64_debug_init ();
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amd64_intr_init ();
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}
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