x86: fix broken math-emu with lazy allocation of fpu area
[linux-2.6.git] / arch / x86 / kernel / i387.c
index 8f8102d..eb9ddd8 100644 (file)
 #endif
 
 static unsigned int            mxcsr_feature_mask __read_mostly = 0xffffffffu;
+unsigned int xstate_size;
+static struct i387_fxsave_struct fx_scratch __cpuinitdata;
 
-void mxcsr_feature_mask_init(void)
+void __cpuinit mxcsr_feature_mask_init(void)
 {
        unsigned long mask = 0;
 
        clts();
        if (cpu_has_fxsr) {
-               memset(&current->thread.i387.fxsave, 0,
-                      sizeof(struct i387_fxsave_struct));
-               asm volatile("fxsave %0" : : "m" (current->thread.i387.fxsave));
-               mask = current->thread.i387.fxsave.mxcsr_mask;
+               memset(&fx_scratch, 0, sizeof(struct i387_fxsave_struct));
+               asm volatile("fxsave %0" : : "m" (fx_scratch));
+               mask = fx_scratch.mxcsr_mask;
                if (mask == 0)
                        mask = 0x0000ffbf;
        }
@@ -53,6 +54,21 @@ void mxcsr_feature_mask_init(void)
        stts();
 }
 
+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
+       else
+               xstate_size = sizeof(struct i387_fsave_struct);
+#endif
+}
+
 #ifdef CONFIG_X86_64
 /*
  * Called at bootup to set up the initial FPU state that is later cloned
@@ -61,10 +77,6 @@ void mxcsr_feature_mask_init(void)
 void __cpuinit fpu_init(void)
 {
        unsigned long oldcr0 = read_cr0();
-       extern void __bad_fxsave_alignment(void);
-
-       if (offsetof(struct task_struct, thread.i387.fxsave) & 15)
-               __bad_fxsave_alignment();
 
        set_in_cr4(X86_CR4_OSFXSR);
        set_in_cr4(X86_CR4_OSXMMEXCPT);
@@ -84,32 +96,53 @@ void __cpuinit fpu_init(void)
  * value at reset if we support XMM instructions and then
  * remeber the current task has used the FPU.
  */
-void init_fpu(struct task_struct *tsk)
+int init_fpu(struct task_struct *tsk)
 {
        if (tsk_used_math(tsk)) {
-               if (tsk == current)
+               if (HAVE_HWFP && tsk == current)
                        unlazy_fpu(tsk);
-               return;
+               return 0;
+       }
+
+       /*
+        * Memory allocation at the first usage of the FPU and other state.
+        */
+       if (!tsk->thread.xstate) {
+               tsk->thread.xstate = kmem_cache_alloc(task_xstate_cachep,
+                                                     GFP_KERNEL);
+               if (!tsk->thread.xstate)
+                       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) {
-               memset(&tsk->thread.i387.fxsave, 0,
-                      sizeof(struct i387_fxsave_struct));
-               tsk->thread.i387.fxsave.cwd = 0x37f;
+               struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave;
+
+               memset(fx, 0, xstate_size);
+               fx->cwd = 0x37f;
                if (cpu_has_xmm)
-                       tsk->thread.i387.fxsave.mxcsr = MXCSR_DEFAULT;
+                       fx->mxcsr = MXCSR_DEFAULT;
        } else {
-               memset(&tsk->thread.i387.fsave, 0,
-                      sizeof(struct i387_fsave_struct));
-               tsk->thread.i387.fsave.cwd = 0xffff037fu;
-               tsk->thread.i387.fsave.swd = 0xffff0000u;
-               tsk->thread.i387.fsave.twd = 0xffffffffu;
-               tsk->thread.i387.fsave.fos = 0xffff0000u;
+               struct i387_fsave_struct *fp = &tsk->thread.xstate->fsave;
+               memset(fp, 0, xstate_size);
+               fp->cwd = 0xffff037fu;
+               fp->swd = 0xffff0000u;
+               fp->twd = 0xffffffffu;
+               fp->fos = 0xffff0000u;
        }
        /*
         * Only the device not available exception or ptrace can call init_fpu.
         */
        set_stopped_child_used_math(tsk);
+       return 0;
 }
 
 int fpregs_active(struct task_struct *target, const struct user_regset *regset)
@@ -126,13 +159,17 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
                unsigned int pos, unsigned int count,
                void *kbuf, void __user *ubuf)
 {
+       int ret;
+
        if (!cpu_has_fxsr)
                return -ENODEV;
 
-       init_fpu(target);
+       ret = init_fpu(target);
+       if (ret)
+               return ret;
 
        return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-                                  &target->thread.i387.fxsave, 0, -1);
+                                  &target->thread.xstate->fxsave, 0, -1);
 }
 
 int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
@@ -144,16 +181,19 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
        if (!cpu_has_fxsr)
                return -ENODEV;
 
-       init_fpu(target);
+       ret = init_fpu(target);
+       if (ret)
+               return ret;
+
        set_stopped_child_used_math(target);
 
        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
-                                &target->thread.i387.fxsave, 0, -1);
+                                &target->thread.xstate->fxsave, 0, -1);
 
        /*
         * mxcsr reserved bits must be masked to zero for security reasons.
         */
-       target->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
+       target->thread.xstate->fxsave.mxcsr &= mxcsr_feature_mask;
 
        return ret;
 }
@@ -233,7 +273,7 @@ static inline u32 twd_fxsr_to_i387(struct i387_fxsave_struct *fxsave)
 static void
 convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
 {
-       struct i387_fxsave_struct *fxsave = &tsk->thread.i387.fxsave;
+       struct i387_fxsave_struct *fxsave = &tsk->thread.xstate->fxsave;
        struct _fpreg *to = (struct _fpreg *) &env->st_space[0];
        struct _fpxreg *from = (struct _fpxreg *) &fxsave->st_space[0];
        int i;
@@ -273,7 +313,7 @@ static void convert_to_fxsr(struct task_struct *tsk,
                            const struct user_i387_ia32_struct *env)
 
 {
-       struct i387_fxsave_struct *fxsave = &tsk->thread.i387.fxsave;
+       struct i387_fxsave_struct *fxsave = &tsk->thread.xstate->fxsave;
        struct _fpreg *from = (struct _fpreg *) &env->st_space[0];
        struct _fpxreg *to = (struct _fpxreg *) &fxsave->st_space[0];
        int i;
@@ -302,15 +342,19 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
               void *kbuf, void __user *ubuf)
 {
        struct user_i387_ia32_struct env;
+       int ret;
+
+       ret = init_fpu(target);
+       if (ret)
+               return ret;
 
        if (!HAVE_HWFP)
                return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
 
-       init_fpu(target);
-
        if (!cpu_has_fxsr) {
                return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-                                          &target->thread.i387.fsave, 0, -1);
+                                          &target->thread.xstate->fsave, 0,
+                                          -1);
        }
 
        if (kbuf && pos == 0 && count == sizeof(env)) {
@@ -330,15 +374,18 @@ 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;
 
-       init_fpu(target);
        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.i387.fsave, 0, -1);
+                                         &target->thread.xstate->fsave, 0, -1);
        }
 
        if (pos > 0 || count < sizeof(env))
@@ -358,11 +405,11 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
 static inline int save_i387_fsave(struct _fpstate_ia32 __user *buf)
 {
        struct task_struct *tsk = current;
+       struct i387_fsave_struct *fp = &tsk->thread.xstate->fsave;
 
        unlazy_fpu(tsk);
-       tsk->thread.i387.fsave.status = tsk->thread.i387.fsave.swd;
-       if (__copy_to_user(buf, &tsk->thread.i387.fsave,
-                          sizeof(struct i387_fsave_struct)))
+       fp->status = fp->swd;
+       if (__copy_to_user(buf, fp, sizeof(struct i387_fsave_struct)))
                return -1;
        return 1;
 }
@@ -370,6 +417,7 @@ static inline int save_i387_fsave(struct _fpstate_ia32 __user *buf)
 static int save_i387_fxsave(struct _fpstate_ia32 __user *buf)
 {
        struct task_struct *tsk = current;
+       struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave;
        struct user_i387_ia32_struct env;
        int err = 0;
 
@@ -379,12 +427,12 @@ static int save_i387_fxsave(struct _fpstate_ia32 __user *buf)
        if (__copy_to_user(buf, &env, sizeof(env)))
                return -1;
 
-       err |= __put_user(tsk->thread.i387.fxsave.swd, &buf->status);
+       err |= __put_user(fx->swd, &buf->status);
        err |= __put_user(X86_FXSR_MAGIC, &buf->magic);
        if (err)
                return -1;
 
-       if (__copy_to_user(&buf->_fxsr_env[0], &tsk->thread.i387.fxsave,
+       if (__copy_to_user(&buf->_fxsr_env[0], fx,
                           sizeof(struct i387_fxsave_struct)))
                return -1;
        return 1;
@@ -416,8 +464,7 @@ 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.i387.fsave, buf,
+       return __copy_from_user(&tsk->thread.xstate->fsave, buf,
                                sizeof(struct i387_fsave_struct));
 }
 
@@ -427,11 +474,10 @@ 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.i387.fxsave, &buf->_fxsr_env[0],
+       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 */
-       tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
+       tsk->thread.xstate->fxsave.mxcsr &= mxcsr_feature_mask;
        if (err || __copy_from_user(&env, buf, sizeof(env)))
                return 1;
        convert_to_fxsr(tsk, &env);
@@ -442,6 +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)