#include "msr.h"
#include "gdt.h"

void 
msr_read(uint32_t msr, uint32_t *lo, uint32_t *hi)
{
    __asm__ volatile("rdmsr": "=a"(*lo), "=d"(*hi): "c"(msr));
}

void 
msr_write(uint32_t msr, uint32_t lo, uint32_t hi)
{
    __asm__ volatile("wrmsr":: "a"(lo), "c"(msr), "d"(hi));
}

void
msr_set_gs_base(uintptr_t gs)
{
    union msr_gs_base gs_base = { .gs = gs };
    msr_write(MSR_GS_BASE, gs_base.v[0], gs_base.v[1]);
}

uintptr_t
msr_get_gs_base(void)
{
    union msr_gs_base gs_base;
    msr_read(MSR_GS_BASE, &gs_base.v[0], &gs_base.v[1]);
    return gs_base.gs;
}

void
msr_enable_sce(void)
{
    uint32_t efer[2];
    msr_read(MSR_EFER, &efer[0], &efer[1]);

    efer[0] |= MSR_EFER_SCE;
    msr_write(MSR_EFER, efer[0], efer[1]);

    union msr_star star;
    star.kcs = GDT_OFFSET(GDT_KERNEL_CODE);
    star.ucs = GDT_OFFSET(GDT_USER_CODE);
    msr_write(MSR_STAR, star.v[0], star.v[1]);
}

void
msr_set_lstar(void *lstar_value)
{
    union msr_lstar lstar;
    lstar.rip = lstar_value;
    msr_write(MSR_LSTAR, lstar.v[0], lstar.v[1]);
}