1 files changed, 52 insertions, 0 deletions
diff --git a/arch/x86_64/hal/msr.c b/arch/x86_64/hal/msr.c
new file mode 100644
index 0000000..f27e303
--- /dev/null
+++ b/arch/x86_64/hal/msr.c
@@ -0,0 +1,52 @@
+#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]);
+}