[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>

1 files changed, 16 insertions, 24 deletions

diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 4178f6cc3d37..dedbb449632e 100644
--- 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;
 }