x86, fpu: drop_fpu() before restoring new state from sigframe

No need to save the state with unlazy_fpu(), that is about to get overwritten
by the state from the signal frame. Instead use drop_fpu() and continue
to restore the new state.

Also fold the stop_fpu_preload() into drop_fpu().

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-2-git-send-email-suresh.b.siddha@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h
index 4fbb419..78169d1 100644 (file)
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -448,17 +448,12 @@ static inline void save_init_fpu(struct task_struct *tsk)
        preempt_enable();
 }
 
-static inline void stop_fpu_preload(struct task_struct *tsk)
-{
-       tsk->fpu_counter = 0;
-}
-
 static inline void drop_fpu(struct task_struct *tsk)
 {
        /*
         * Forget coprocessor state..
         */
-       stop_fpu_preload(tsk);
+       tsk->fpu_counter = 0;
        preempt_disable();
        __drop_fpu(tsk);
        preempt_enable();

diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index 0923d27..07ddc87 100644 (file)
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -382,16 +382,14 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
                struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
                struct user_i387_ia32_struct env;
 
-               stop_fpu_preload(tsk);
-               unlazy_fpu(tsk);
+               drop_fpu(tsk);
 
                if (__copy_from_user(xsave, buf_fx, state_size) ||
-                   __copy_from_user(&env, buf, sizeof(env))) {
-                       drop_fpu(tsk);
+                   __copy_from_user(&env, buf, sizeof(env)))
                        return -1;
-               }
 
                sanitize_restored_xstate(tsk, &env, xstate_bv, fx_only);
+               set_used_math();
        } else {
                /*
                 * For 64-bit frames and 32-bit fsave frames, restore the user