diff options
Diffstat (limited to 'kernel/drivers/gdt.c')
| -rw-r--r-- | kernel/drivers/gdt.c | 34 |
1 files changed, 21 insertions, 13 deletions
diff --git a/kernel/drivers/gdt.c b/kernel/drivers/gdt.c index 8209eaf..693f25f 100644 --- a/kernel/drivers/gdt.c +++ b/kernel/drivers/gdt.c @@ -21,6 +21,12 @@ static struct tss_entry tss = { 0 }; PROTECTED static struct gdt_ptr gp = { 0 }; +CONST u8 gdt_offset(u8 gate) +{ + assert(gate && gate < COUNT(gdt)); + return ((u32)&gdt[gate] - (u32)gdt) & 0xff; +} + CLEAR static void gdt_set_gate(u32 num, u32 base, u32 limit, u8 access, u8 gran) { // Set descriptor base address @@ -48,13 +54,14 @@ CLEAR static void tss_write(u32 num, u16 ss0, u32 esp0) tss.ss0 = ss0; tss.esp0 = esp0; - tss.cs = 0x0b; - tss.ss = tss.ds = tss.es = tss.fs = tss.gs = 0x13; + tss.cs = GDT_SUPER_CODE_OFFSET | 3; + tss.ss = tss.ds = tss.es = tss.fs = tss.gs = GDT_SUPER_DATA_OFFSET | 3; + tss.iomap_base = U16_MAX; } CLEAR static void tss_flush(void) { - __asm__ volatile("ltr %0" ::"r"((u16)((u32)&gdt[5] - (u32)gdt))); + __asm__ volatile("ltr %0" ::"r"((u16)(GDT_TSS_OFFSET | 3))); } CLEAR static void gdt_flush(void) @@ -73,36 +80,35 @@ CLEAR void gdt_install(u32 esp) { // Set GDT pointer and limit gp.limit = sizeof(gdt) - 1; - gp.base = &gdt; + gp.base = gdt; // NULL descriptor gdt_set_gate(0, 0, 0, 0, 0); // Code segment - gdt_set_gate(1, 0, 0xffffffff, + gdt_set_gate(GDT_ROOT_CODE_GATE, 0, U32_MAX, GDT_PRESENT | GDT_DESCRIPTOR | GDT_EXECUTABLE | GDT_READWRITE, GDT_GRANULARITY | GDT_SIZE); // Data segment - gdt_set_gate(2, 0, 0xffffffff, GDT_PRESENT | GDT_DESCRIPTOR | GDT_READWRITE, + gdt_set_gate(GDT_ROOT_DATA_GATE, 0, U32_MAX, GDT_PRESENT | GDT_DESCRIPTOR | GDT_READWRITE, GDT_GRANULARITY | GDT_SIZE); // User mode code segment - gdt_set_gate(3, 0, 0xffffffff, + gdt_set_gate(GDT_USER_CODE_GATE, 0, U32_MAX, GDT_PRESENT | GDT_RING3 | GDT_DESCRIPTOR | GDT_EXECUTABLE | GDT_READWRITE, GDT_GRANULARITY | GDT_SIZE); // User mode data segment - gdt_set_gate(4, 0, 0xffffffff, GDT_PRESENT | GDT_RING3 | GDT_DESCRIPTOR | GDT_READWRITE, + gdt_set_gate(GDT_USER_DATA_GATE, 0, U32_MAX, + GDT_PRESENT | GDT_RING3 | GDT_DESCRIPTOR | GDT_READWRITE, GDT_GRANULARITY | GDT_SIZE); // Write TSS - tss_write(5, GDT_SUPER_DATA_OFFSET, esp); + tss_write(GDT_TSS_GATE, GDT_SUPER_DATA_OFFSET, esp); // Remove old GDT and install the new changes! gdt_flush(); - tss_flush(); - __asm__ volatile("mov %%ax, %%ds\n" "mov %%ax, %%es\n" "mov %%ax, %%fs\n" @@ -110,6 +116,8 @@ CLEAR void gdt_install(u32 esp) "mov %%ax, %%ss\n" ::"a"(GDT_SUPER_DATA_OFFSET) : "memory"); - __asm__ volatile("ljmpl $" STRINGIFY(GDT_SUPER_CODE_OFFSET) ", $code\n" - "code:\n"); + __asm__ volatile("ljmpl $0x08 , $code\n" + "code:\n"); + + tss_flush(); } |