preparing for multitasking

1 files changed, 29 insertions, 0 deletions

diff --git a/kc/core/cpu/msr.c b/kc/core/cpu/msr.c
new file mode 100644
index 0000000..2efdd7d
--- /dev/null
+++ b/kc/core/cpu/msr.c
@@ -0,0 +1,29 @@
+#include "msr.h"
+
+uint64_t msr_read(uint32_t index)
+{
+    uint32_t low;
+    uint32_t high;
+
+    __asm__ volatile
+        (
+         "rdmsr\n\t"
+         : "=a"(low), "=d"(high)
+         : "c"(index)
+        );
+
+    return ((uint64_t)high << 32)|low;
+}
+
+void msr_write(uint32_t index, uint64_t value)
+{
+    uint32_t low = value & 0xffffffff;
+    uint32_t high = value >> 32;
+
+    __asm__ volatile
+        (
+         "wrmsr\n\t"
+         :: "a"(low), "d"(high), "c"(index)
+        );
+}
+