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x86_64: implement TSS initialisation and user/kernel stack pointer switching

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max 🍓
2026-02-08 11:34:21 +00:00
parent 564d4f9ba0
commit 4051265876
7 changed files with 178 additions and 6 deletions
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42
arch/x86_64/gdt.c
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@@ -1,5 +1,8 @@
#include <mango/libc/string.h>
#include <arch/gdt.h>
#include <arch/tss.h>
#include <mango/libc/string.h>
#include <mango/types.h>
#include <stddef.h>
static void init_entry(struct gdt_entry *entry, int access, int flags)
{
@@ -15,13 +18,42 @@ int gdt_init(struct gdt *gdt, struct gdt_ptr *gdtp)
{
memset(&gdt->g_entries[0], 0x0, sizeof gdt->g_entries[0]);
init_entry(&gdt->g_entries[1], GDT_A_PRESENT | GDT_A_CODEREAD | GDT_A_CODE, GDT_F_64BIT);
init_entry(&gdt->g_entries[2], GDT_A_PRESENT | GDT_A_DATAWRITE | GDT_A_DATA, GDT_F_64BIT);
init_entry(&gdt->g_entries[3], GDT_A_PRESENT | GDT_A_USER | GDT_A_CODEREAD | GDT_A_CODE, GDT_F_64BIT);
init_entry(&gdt->g_entries[4], GDT_A_PRESENT | GDT_A_USER | GDT_A_DATAWRITE | GDT_A_DATA, GDT_F_64BIT);
init_entry(
&gdt->g_entries[1],
GDT_A_PRESENT | GDT_A_CODEREAD | GDT_A_CODE,
GDT_F_64BIT);
init_entry(
&gdt->g_entries[2],
GDT_A_PRESENT | GDT_A_DATAWRITE | GDT_A_DATA,
GDT_F_64BIT);
init_entry(
&gdt->g_entries[3],
GDT_A_PRESENT | GDT_A_USER | GDT_A_CODEREAD | GDT_A_CODE,
GDT_F_64BIT);
init_entry(
&gdt->g_entries[4],
GDT_A_PRESENT | GDT_A_USER | GDT_A_DATAWRITE | GDT_A_DATA,
GDT_F_64BIT);
gdtp->g_ptr = (uint64_t)gdt;
gdtp->g_limit = sizeof(*gdt) - 1;
return 0;
}
void gdt_write_tss(struct gdt *gdt, struct tss *tss)
{
struct tss_gdt_entry *tss_entry = &gdt->g_tss;
virt_addr_t base = (virt_addr_t)tss;
size_t limit = sizeof *tss;
tss_entry->ge_base_low = (base & 0xFFFF);
tss_entry->ge_base_mid = (base >> 16) & 0xFF;
tss_entry->ge_base_hi = (base >> 24) & 0xFF;
tss_entry->ge_base_ext = (base >> 32) & 0xFFFFFFFF;
tss_entry->ge_limit_low = (limit & 0xFFFF);
tss_entry->ge_gran = (limit >> 16) & 0xF;
tss_entry->ge_access = 0xE9;
tss_entry->ge_reserved = 0;
}