diff options
| -rw-r--r-- | kernel/gdt.c | 21 | ||||
| -rw-r--r-- | platform/boot.s | 10 |
2 files changed, 22 insertions, 9 deletions
diff --git a/kernel/gdt.c b/kernel/gdt.c index b76e441..b0d6320 100644 --- a/kernel/gdt.c +++ b/kernel/gdt.c @@ -43,7 +43,6 @@ static struct lgdt_arg lgdt_arg; // probably doesn't need to be global static void gdt_prepare(); static void gdt_load(); -static void gdt_check(); static void gdt_prepare() { @@ -96,23 +95,27 @@ static void gdt_prepare() { GDT[SEG_TSS].base_high = (((uint32_t) &TSS) >> 24) & 0xff; } +void change_cs(int seg); // temporary + static void gdt_load() { lgdt_arg.limit = sizeof(GDT) - 1; lgdt_arg.base = (uint32_t) &GDT; - asm("lgdt (%0)" : : "r" (&lgdt_arg) : "memory"); - - asm("ltr %%ax" : : "a" (SEG_TSS << 3 | 3) : "memory"); -} + asm("lgdt (%0)" + : : "r" (&lgdt_arg) : "memory"); + asm("ltr %%ax" + : : "a" (SEG_TSS << 3 | 3) : "memory"); -static void gdt_check() { - // note: this only checks the r0data segment, - // it's far from a comprehensive test + // update all segment registers + change_cs(SEG_r0code << 3); asm("mov %0, %%ds;" + "mov %0, %%ss;" + "mov %0, %%es;" + "mov %0, %%fs;" + "mov %0, %%gs;" : : "r" (SEG_r0data << 3) : "memory"); } void gdt_init() { gdt_prepare(); gdt_load(); - gdt_check(); } diff --git a/platform/boot.s b/platform/boot.s index c2a06c3..d5bfda5 100644 --- a/platform/boot.s +++ b/platform/boot.s @@ -34,4 +34,14 @@ halt_cpu: 1: hlt jmp 1b +// temporary, will be moved to another file soon +.global change_cs +.type change_cs, @function +change_cs: + /* retf pops off the return address and code segment off the stack. + * it turns out that in the i386 cdecl calling convention they're in + * the correct place already. + */ + retf + .size _start, . - _start |