Changes in kernel/arch/amd64/src/amd64.c [811770c:af9dd1e] in mainline

File:

• kernel/arch/amd64/src/amd64.c (modified) (3 diffs)

kernel/arch/amd64/src/amd64.c

@@ -64 +64 @@
 #endif
 
+/** Disable I/O on non-privileged levels
+ *
+ * Clean IOPL(12,13) and NT(14) flags in EFLAGS register
+ */
+static void clean_IOPL_NT_flags(void)
+{
+        asm volatile (
+                "pushfq\n"
+                "pop %%rax\n"
+                "and $~(0x7000), %%rax\n"
+                "pushq %%rax\n"
+                "popfq\n"
+                ::: "%rax"
+        );
+}
+
+/** Disable alignment check
+ *
+ * Clean AM(18) flag in CR0 register 
+ */
+static void clean_AM_flag(void)
+{
+        asm volatile (
+                "mov %%cr0, %%rax\n"
+                "and $~(0x40000), %%rax\n"
+                "mov %%rax, %%cr0\n"
+                ::: "%rax"
+        );
+}
+
 /** Perform amd64-specific initialization before main_bsp() is called.
  *
@@ -86 +116 @@
 {
         /* Enable no-execute pages */
-        write_msr(AMD_MSR_EFER, read_msr(AMD_MSR_EFER) | AMD_NXE);
+        set_efer_flag(AMD_NXE_FLAG);
         /* Enable FPU */
         cpu_setup_fpu();
@@ -93 +123 @@
         pm_init();
         
-        /* Disable I/O on nonprivileged levels, clear the nested-thread flag */
-        write_rflags(read_rflags() & ~(RFLAGS_IOPL | RFLAGS_NT));
+        /* Disable I/O on nonprivileged levels
+         * clear the NT (nested-thread) flag 
+         */
+        clean_IOPL_NT_flags();
         /* Disable alignment check */
-        write_cr0(read_cr0() & ~CR0_AM);
+        clean_AM_flag();
         
         if (config.cpu_active == 1) {