x86: Avoid unnecessary __clear_user() and xrstor in signal handling

[pandora-kernel.git] / arch / x86 / kernel / xsave.c

diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index 37e68fc..6e73db1 100644 (file)
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -91,14 +91,6 @@ int save_i387_xstate(void __user *buf)
                return 0;
 
        if (task_thread_info(tsk)->status & TS_USEDFPU) {
-               /*
-                * Start with clearing the user buffer. This will present a
-                * clean context for the bytes not touched by the fxsave/xsave.
-                */
-               err = __clear_user(buf, sig_xstate_size);
-               if (err)
-                       return err;
-
                if (use_xsave())
                        err = xsave_user(buf);
                else
@@ -184,8 +176,8 @@ static int restore_user_xstate(void __user *buf)
         * init the state skipped by the user.
         */
        mask = pcntxt_mask & ~mask;
-
-       xrstor_state(init_xstate_buf, mask);
+       if (unlikely(mask))
+               xrstor_state(init_xstate_buf, mask);
 
        return 0;