x86/fpu: Change math_error() to use unlazy_fpu(), kill (now) unused save_init_fpu()

math_error() calls save_init_fpu() after conditional_sti(), this means
that the caller can be preempted. If !use_eager_fpu() we can hit the
WARN_ON_ONCE(!__thread_has_fpu(tsk)) and/or save the wrong FPU state.

Change math_error() to use unlazy_fpu() and kill save_init_fpu().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1423252925-14451-4-git-send-email-riel@redhat.com
Signed-off-by: Borislav Petkov <bp@suse.de>

diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h
index e97622f577229e431cd2f49c7b3aa30bb9f31ce8..02f2e0817918452ff28fb581a51e333d617dbd05 100644 (file)
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -517,24 +517,6 @@ static inline void __save_fpu(struct task_struct *tsk)
                fpu_fxsave(&tsk->thread.fpu);
 }
 
-/*
- * These disable preemption on their own and are safe
- */
-static inline void save_init_fpu(struct task_struct *tsk)
-{
-       WARN_ON_ONCE(!__thread_has_fpu(tsk));
-
-       if (use_eager_fpu()) {
-               __save_fpu(tsk);
-               return;
-       }
-
-       preempt_disable();
-       __save_init_fpu(tsk);
-       __thread_fpu_end(tsk);
-       preempt_enable();
-}
-
 /*
  * i387 state interaction
  */

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 88900e288021f23a2f22aebf739e25070f456971..9d889f74e80699066aac279bebe79ee6906e3d6e 100644 (file)
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -663,7 +663,7 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr)
        /*
         * Save the info for the exception handler and clear the error.
         */
-       save_init_fpu(task);
+       unlazy_fpu(task);
        task->thread.trap_nr = trapnr;
        task->thread.error_code = error_code;
        info.si_signo = SIGFPE;