[ARM] Optimise VFP thread notify function a little

The common case for the thread notifier is a context switch.  Tell
gcc that this is the most likely condition so it can optimise the
function for this case.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 4178f6c..dedbb44 100644 (file)
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -40,10 +40,19 @@ unsigned int VFP_arch;
 static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
 {
        struct thread_info *thread = v;
-       union vfp_state *vfp = &thread->vfpstate;
+       union vfp_state *vfp;
 
-       switch (cmd) {
-       case THREAD_NOTIFY_FLUSH:
+       if (likely(cmd == THREAD_NOTIFY_SWITCH)) {
+               /*
+                * Always disable VFP so we can lazily save/restore the
+                * old state.
+                */
+               fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
+               return NOTIFY_DONE;
+       }
+
+       vfp = &thread->vfpstate;
+       if (cmd == THREAD_NOTIFY_FLUSH) {
                /*
                 * Per-thread VFP initialisation.
                 */
@@ -56,29 +65,12 @@ static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
                 * Disable VFP to ensure we initialise it first.
                 */
                fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
-
-               /*
-                * FALLTHROUGH: Ensure we don't try to overwrite our newly
-                * initialised state information on the first fault.
-                */
-
-       case THREAD_NOTIFY_RELEASE:
-               /*
-                * Per-thread VFP cleanup.
-                */
-               if (last_VFP_context == vfp)
-                       last_VFP_context = NULL;
-               break;
-
-       case THREAD_NOTIFY_SWITCH:
-               /*
-                * Always disable VFP so we can lazily save/restore the
-                * old state.
-                */
-               fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
-               break;
        }
 
+       /* flush and release case: Per-thread VFP cleanup. */
+       if (last_VFP_context == vfp)
+               last_VFP_context = NULL;
+
        return NOTIFY_DONE;
 }