Kernel: Always inline stac(), clac() and SmapDisabler

Let's not be paying the function call overhead for these tiny ops.
Maybe there's an argument for having fewer gadgets in the kernel but
for now we're actually seeing stac() in profiles so let's put
that above theoretical security issues.

2 files changed, 17 insertions, 20 deletions

diff --git a/Kernel/Arch/i386/CPU.cpp b/Kernel/Arch/i386/CPU.cpp
index 11909c4cfb..affd7705d1 100644
--- a/Kernel/Arch/i386/CPU.cpp
+++ b/Kernel/Arch/i386/CPU.cpp
@@ -734,22 +734,6 @@ void cpu_detect()
     g_cpu_supports_umip = (extended_features.ecx() & (1 << 2));
 }
 
-void stac()
-{
-    if (!g_cpu_supports_smap)
-        return;
-    asm volatile("stac" ::
-                     : "cc");
-}
-
-void clac()
-{
-    if (!g_cpu_supports_smap)
-        return;
-    asm volatile("clac" ::
-                     : "cc");
-}
-
 void cpu_setup()
 {
     cpu_detect();
diff --git a/Kernel/Arch/i386/CPU.h b/Kernel/Arch/i386/CPU.h
index 6cc85461b3..9b6e771be0 100644
--- a/Kernel/Arch/i386/CPU.h
+++ b/Kernel/Arch/i386/CPU.h
@@ -584,18 +584,31 @@ extern bool g_cpu_supports_sse;
 extern bool g_cpu_supports_tsc;
 extern bool g_cpu_supports_umip;
 
-void stac();
-void clac();
+ALWAYS_INLINE void stac()
+{
+    if (!g_cpu_supports_smap)
+        return;
+    asm volatile("stac" ::
+                     : "cc");
+}
+
+ALWAYS_INLINE void clac()
+{
+    if (!g_cpu_supports_smap)
+        return;
+    asm volatile("clac" ::
+                     : "cc");
+}
 
 class SmapDisabler {
 public:
-    SmapDisabler()
+    ALWAYS_INLINE SmapDisabler()
     {
         m_flags = cpu_flags();
         stac();
     }
 
-    ~SmapDisabler()
+    ALWAYS_INLINE ~SmapDisabler()
     {
         if (!(m_flags & 0x40000))
             clac();