Changes in kernel/arch/amd64/src/cpu/cpu.c [811770c:49e6c6b4] in mainline

File:

• kernel/arch/amd64/src/cpu/cpu.c (modified) (2 diffs)

kernel/arch/amd64/src/cpu/cpu.c

@@ -76 +76 @@
 void cpu_setup_fpu(void)
 {
-        write_cr0((read_cr0() & ~CR0_EM) | CR0_MP);
-        write_cr4(read_cr4() | CR4_OSFXSR);
+        asm volatile (
+                "movq %%cr0, %%rax\n"
+                "btsq $1, %%rax\n"  /* cr0.mp */
+                "btrq $2, %%rax\n"  /* cr0.em */
+                "movq %%rax, %%cr0\n"
+                
+                "movq %%cr4, %%rax\n"
+                "bts $9, %%rax\n"   /* cr4.osfxsr */
+                "movq %%rax, %%cr4\n"
+                ::: "%rax"
+        );
 }
 
@@ -88 +97 @@
 void fpu_disable(void)
 {
-        write_cr0(read_cr0() | CR0_TS);
+        asm volatile (
+                "mov %%cr0, %%rax\n"
+                "bts $3, %%rax\n"
+                "mov %%rax, %%cr0\n"
+                ::: "%rax"
+        );
 }
 
 void fpu_enable(void)
 {
-        write_cr0(read_cr0() & ~CR0_TS);
+        asm volatile (
+                "mov %%cr0, %%rax\n"
+                "btr $3, %%rax\n"
+                "mov %%rax, %%cr0\n"
+                ::: "%rax"
+        );
 }