Kernel: Don't use MMX memcpy() in the kernel.

I just discovered the hard way that clobbering FPU/MMX/SSE registers in the
kernel makes things very confusing for userspace (and other kernel threads.)

Let's banish all of those things from the kernel to keep things simple.

2 files changed, 6 insertions, 0 deletions

diff --git a/AK/StdLibExtras.cpp b/AK/StdLibExtras.cpp
index b807d5ebb9..ee8aa862d9 100644
--- a/AK/StdLibExtras.cpp
+++ b/AK/StdLibExtras.cpp
@@ -5,6 +5,7 @@
 
 extern "C" {
 
+#ifndef KERNEL
 void* mmx_memcpy(void* dest, const void* src, size_t len)
 {
     ASSERT(len >= 1024);
@@ -51,6 +52,7 @@ void* mmx_memcpy(void* dest, const void* src, size_t len)
         memcpy(dest_ptr, src_ptr, len);
     return dest;
 }
+#endif
 
 #ifdef KERNEL
 
diff --git a/AK/StdLibExtras.h b/AK/StdLibExtras.h
index 04c9ce72d0..6a282b98ab 100644
--- a/AK/StdLibExtras.h
+++ b/AK/StdLibExtras.h
@@ -11,14 +11,18 @@
 
 #include <AK/Types.h>
 
+#ifndef KERNEL
 extern "C" void* mmx_memcpy(void* to, const void* from, size_t);
+#endif
 
 [[gnu::always_inline]] inline void fast_dword_copy(dword* dest, const dword* src, size_t count)
 {
+#ifndef KERNEL
     if (count >= 256) {
         mmx_memcpy(dest, src, count * sizeof(count));
         return;
     }
+#endif
     asm volatile(
         "rep movsl\n"
         : "=S"(src), "=D"(dest), "=c"(count)