1 files changed, 43 insertions, 0 deletions
diff --git a/src/bits64/controlregs.rs b/src/bits64/controlregs.rs
new file mode 100644
index 0000000..c243caf
--- /dev/null
+++ b/src/bits64/controlregs.rs
@@ -0,0 +1,43 @@
+//! Functions to read and write control registers.
+
+pub unsafe fn cr0() -> u64 {
+    let ret: u64;
+    asm!("mov %cr0, $0" : "=r" (ret));
+    ret
+}
+
+/// Write cr0.
+pub unsafe fn cr0_write(val: u64) {
+    asm!("mov $0, %cr0" :: "r" (val) : "memory");
+}
+
+/// Contains page-fault linear address.
+pub unsafe fn cr2() -> u64 {
+    let ret: u64;
+    asm!("mov %cr2, $0" : "=r" (ret));
+    ret
+}
+
+/// Contains page-table root pointer.
+pub unsafe fn cr3() -> u64 {
+    let ret: u64;
+    asm!("mov %cr3, $0" : "=r" (ret));
+    ret
+}
+
+/// Switch page-table PML4 pointer.
+pub unsafe fn cr3_write(val: u64) {
+    asm!("mov $0, %cr3" :: "r" (val) : "memory");
+}
+
+/// Contains various flags to control operations in protected mode.
+pub unsafe fn cr4() -> u64 {
+    let ret: u64;
+    asm!("mov %cr4, $0" : "=r" (ret));
+    ret
+}
+
+/// Write cr4.
+pub unsafe fn cr4_write(val: u64) {
+    asm!("mov $0, %cr4" :: "r" (val) : "memory");
+}