x86: fix broken math-emu with lazy allocation of fpu area
[linux-2.6.git] / arch / x86 / kernel / i387.c
index db6839b..eb9ddd8 100644 (file)
@@ -56,6 +56,11 @@ void __cpuinit mxcsr_feature_mask_init(void)
 
 void __init init_thread_xstate(void)
 {
+       if (!HAVE_HWFP) {
+               xstate_size = sizeof(struct i387_soft_struct);
+               return;
+       }
+
        if (cpu_has_fxsr)
                xstate_size = sizeof(struct i387_fxsave_struct);
 #ifdef CONFIG_X86_32
@@ -94,7 +99,7 @@ void __cpuinit fpu_init(void)
 int init_fpu(struct task_struct *tsk)
 {
        if (tsk_used_math(tsk)) {
-               if (tsk == current)
+               if (HAVE_HWFP && tsk == current)
                        unlazy_fpu(tsk);
                return 0;
        }
@@ -109,6 +114,15 @@ int init_fpu(struct task_struct *tsk)
                        return -ENOMEM;
        }
 
+#ifdef CONFIG_X86_32
+       if (!HAVE_HWFP) {
+               memset(tsk->thread.xstate, 0, xstate_size);
+               finit();
+               set_stopped_child_used_math(tsk);
+               return 0;
+       }
+#endif
+
        if (cpu_has_fxsr) {
                struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave;
 
@@ -330,13 +344,13 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
        struct user_i387_ia32_struct env;
        int ret;
 
-       if (!HAVE_HWFP)
-               return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
-
        ret = init_fpu(target);
        if (ret)
                return ret;
 
+       if (!HAVE_HWFP)
+               return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
+
        if (!cpu_has_fxsr) {
                return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                                           &target->thread.xstate->fsave, 0,
@@ -360,15 +374,15 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
        struct user_i387_ia32_struct env;
        int ret;
 
-       if (!HAVE_HWFP)
-               return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
-
        ret = init_fpu(target);
        if (ret)
                return ret;
 
        set_stopped_child_used_math(target);
 
+       if (!HAVE_HWFP)
+               return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
+
        if (!cpu_has_fxsr) {
                return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                                          &target->thread.xstate->fsave, 0, -1);
@@ -450,7 +464,6 @@ static inline int restore_i387_fsave(struct _fpstate_ia32 __user *buf)
 {
        struct task_struct *tsk = current;
 
-       clear_fpu(tsk);
        return __copy_from_user(&tsk->thread.xstate->fsave, buf,
                                sizeof(struct i387_fsave_struct));
 }
@@ -461,7 +474,6 @@ static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf)
        struct user_i387_ia32_struct env;
        int err;
 
-       clear_fpu(tsk);
        err = __copy_from_user(&tsk->thread.xstate->fxsave, &buf->_fxsr_env[0],
                               sizeof(struct i387_fxsave_struct));
        /* mxcsr reserved bits must be masked to zero for security reasons */
@@ -476,6 +488,16 @@ static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf)
 int restore_i387_ia32(struct _fpstate_ia32 __user *buf)
 {
        int err;
+       struct task_struct *tsk = current;
+
+       if (HAVE_HWFP)
+               clear_fpu(tsk);
+
+       if (!used_math()) {
+               err = init_fpu(tsk);
+               if (err)
+                       return err;
+       }
 
        if (HAVE_HWFP) {
                if (cpu_has_fxsr)