Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull fpu state cleanups from Ingo Molnar:
 "This tree streamlines further aspects of FPU handling by eliminating
  the prepare_to_copy() complication and moving that logic to
  arch_dup_task_struct().

  It also fixes the FPU dumps in threaded core dumps, removes and old
  (and now invalid) assumption plus micro-optimizes the exit path by
  avoiding an FPU save for dead tasks."

Fixed up trivial add-add conflict in arch/sh/kernel/process.c that came
in because we now do the FPU handling in arch_dup_task_struct() rather
than the legacy (and now gone) prepare_to_copy().

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, fpu: drop the fpu state during thread exit
  x86, xsave: remove thread_has_fpu() bug check in __sanitize_i387_state()
  coredump: ensure the fpu state is flushed for proper multi-threaded core dump
  fork: move the real prepare_to_copy() users to arch_dup_task_struct()

41 files changed, 63 insertions, 149 deletions

diff --git a/arch/alpha/include/asm/processor.h b/arch/alpha/include/asm/processor.h
index 94afe58..e37b887 100644
--- a/arch/alpha/include/asm/processor.h
+++ b/arch/alpha/include/asm/processor.h
@@ -49,9 +49,6 @@ extern void start_thread(struct pt_regs *, unsigned long, unsigned long);
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 /* Create a kernel thread without removing it from tasklists.  */
 extern long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 
diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
index d7038fa..99afa74 100644
--- a/arch/arm/include/asm/processor.h
+++ b/arch/arm/include/asm/processor.h
@@ -77,9 +77,6 @@ struct task_struct;
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 unsigned long get_wchan(struct task_struct *p);
 
 #if __LINUX_ARM_ARCH__ == 6 || defined(CONFIG_ARM_ERRATA_754327)
diff --git a/arch/avr32/include/asm/processor.h b/arch/avr32/include/asm/processor.h
index 108502b..87d8bac 100644
--- a/arch/avr32/include/asm/processor.h
+++ b/arch/avr32/include/asm/processor.h
@@ -145,9 +145,6 @@ extern void release_thread(struct task_struct *);
 /* Create a kernel thread without removing it from tasklists */
 extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk) do { } while(0)
-
 /* Return saved PC of a blocked thread */
 #define thread_saved_pc(tsk)    ((tsk)->thread.cpu_context.pc)
 
diff --git a/arch/blackfin/include/asm/processor.h b/arch/blackfin/include/asm/processor.h
index 8af7772..4ef7cfe 100644
--- a/arch/blackfin/include/asm/processor.h
+++ b/arch/blackfin/include/asm/processor.h
@@ -75,8 +75,6 @@ static inline void release_thread(struct task_struct *dead_task)
 {
 }
 
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern int kernel_thread(int (*fn) (void *), void *arg, unsigned long flags);
 
 /*
diff --git a/arch/c6x/include/asm/processor.h b/arch/c6x/include/asm/processor.h
index 3ff7fab..c50af7e 100644
--- a/arch/c6x/include/asm/processor.h
+++ b/arch/c6x/include/asm/processor.h
@@ -92,9 +92,6 @@ static inline void release_thread(struct task_struct *dead_task)
 {
 }
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 #define copy_segments(tsk, mm)		do { } while (0)
diff --git a/arch/cris/include/asm/processor.h b/arch/cris/include/asm/processor.h
index 8dc56ef..ef4e1bc 100644
--- a/arch/cris/include/asm/processor.h
+++ b/arch/cris/include/asm/processor.h
@@ -49,10 +49,6 @@ struct task_struct;
 #define task_pt_regs(task) user_regs(task_thread_info(task))
 #define current_regs() task_pt_regs(current)
 
-static inline void prepare_to_copy(struct task_struct *tsk)
-{
-}
-
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 unsigned long get_wchan(struct task_struct *p);
diff --git a/arch/frv/include/asm/processor.h b/arch/frv/include/asm/processor.h
index 9b1a92b..a8311d3 100644
--- a/arch/frv/include/asm/processor.h
+++ b/arch/frv/include/asm/processor.h
@@ -103,8 +103,6 @@ do {							\
 	__frame->sp	= (_usp);			\
 } while(0)
 
-extern void prepare_to_copy(struct task_struct *tsk);
-
 /* Free all resources held by a thread. */
 static inline void release_thread(struct task_struct *dead_task)
 {
diff --git a/arch/frv/kernel/process.c b/arch/frv/kernel/process.c
index ed09e9e..ff95f50 100644
--- a/arch/frv/kernel/process.c
+++ b/arch/frv/kernel/process.c
@@ -165,17 +165,6 @@ asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
 	return do_fork(clone_flags, newsp, __frame, 0, parent_tidptr, child_tidptr);
 } /* end sys_clone() */
 
-/*****************************************************************************/
-/*
- * This gets called before we allocate a new thread and copy
- * the current task into it.
- */
-void prepare_to_copy(struct task_struct *tsk)
-{
-	//unlazy_fpu(tsk);
-} /* end prepare_to_copy() */
-
-/*****************************************************************************/
 /*
  * set up the kernel stack and exception frames for a new process
  */
diff --git a/arch/h8300/include/asm/processor.h b/arch/h8300/include/asm/processor.h
index 61fabf1..4c9f6f8 100644
--- a/arch/h8300/include/asm/processor.h
+++ b/arch/h8300/include/asm/processor.h
@@ -109,8 +109,6 @@ static inline void release_thread(struct task_struct *dead_task)
 
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
-#define prepare_to_copy(tsk)	do { } while (0)
-
 /*
  * Free current thread data structures etc..
  */
diff --git a/arch/hexagon/include/asm/processor.h b/arch/hexagon/include/asm/processor.h
index 20c5dda..e8ea459 100644
--- a/arch/hexagon/include/asm/processor.h
+++ b/arch/hexagon/include/asm/processor.h
@@ -59,13 +59,6 @@ struct thread_struct {
 #define cpu_relax() __vmyield()
 
 /*
- * "Unlazying all lazy status" occurs here.
- */
-static inline void prepare_to_copy(struct task_struct *tsk)
-{
-}
-
-/*
  * Decides where the kernel will search for a free chunk of vm space during
  * mmaps.
  * See also arch_get_unmapped_area.
diff --git a/arch/ia64/include/asm/processor.h b/arch/ia64/include/asm/processor.h
index f92f67a..5a994ec 100644
--- a/arch/ia64/include/asm/processor.h
+++ b/arch/ia64/include/asm/processor.h
@@ -343,9 +343,6 @@ struct task_struct;
  */
 #define release_thread(dead_task)
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 /*
  * This is the mechanism for creating a new kernel thread.
  *
diff --git a/arch/m32r/include/asm/processor.h b/arch/m32r/include/asm/processor.h
index e1f46d7..da17253 100644
--- a/arch/m32r/include/asm/processor.h
+++ b/arch/m32r/include/asm/processor.h
@@ -118,8 +118,6 @@ struct mm_struct;
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-#define prepare_to_copy(tsk)	do { } while (0)
-
 /*
  * create a kernel thread without removing it from tasklists
  */
diff --git a/arch/m68k/include/asm/processor.h b/arch/m68k/include/asm/processor.h
index 46460fa..f17c42a 100644
--- a/arch/m68k/include/asm/processor.h
+++ b/arch/m68k/include/asm/processor.h
@@ -153,9 +153,6 @@ static inline void release_thread(struct task_struct *dead_task)
 {
 }
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 /*
diff --git a/arch/microblaze/include/asm/processor.h b/arch/microblaze/include/asm/processor.h
index bffb545..af2bb96 100644
--- a/arch/microblaze/include/asm/processor.h
+++ b/arch/microblaze/include/asm/processor.h
@@ -23,7 +23,6 @@ extern const struct seq_operations cpuinfo_op;
 
 # define cpu_relax()		barrier()
 # define cpu_sleep()		do {} while (0)
-# define prepare_to_copy(tsk)	do {} while (0)
 
 #define task_pt_regs(tsk) \
 		(((struct pt_regs *)(THREAD_SIZE + task_stack_page(tsk))) - 1)
diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h
index 20e9dcf..5e33fab 100644
--- a/arch/mips/include/asm/processor.h
+++ b/arch/mips/include/asm/processor.h
@@ -310,9 +310,6 @@ struct task_struct;
 /* Free all resources held by a thread. */
 #define release_thread(thread) do { } while(0)
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern long kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 extern unsigned long thread_saved_pc(struct task_struct *tsk);
diff --git a/arch/mn10300/include/asm/processor.h b/arch/mn10300/include/asm/processor.h
index f7b3c9a..247928c 100644
--- a/arch/mn10300/include/asm/processor.h
+++ b/arch/mn10300/include/asm/processor.h
@@ -139,9 +139,6 @@ static inline void start_thread(struct pt_regs *regs,
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-extern void prepare_to_copy(struct task_struct *tsk);
-
 /*
  * create a kernel thread without removing it from tasklists
  */
diff --git a/arch/mn10300/kernel/process.c b/arch/mn10300/kernel/process.c
index 14707f2..7dab0cd 100644
--- a/arch/mn10300/kernel/process.c
+++ b/arch/mn10300/kernel/process.c
@@ -208,12 +208,14 @@ void copy_segments(struct task_struct *p, struct mm_struct *new_mm)
 }
 
 /*
- * this gets called before we allocate a new thread and copy the current task
- * into it so that we can store lazy state into memory
+ * this gets called so that we can store lazy state into memory and copy the
+ * current task into the new thread.
  */
-void prepare_to_copy(struct task_struct *tsk)
+int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
-	unlazy_fpu(tsk);
+	unlazy_fpu(src);
+	*dst = *src;
+	return 0;
 }
 
 /*
diff --git a/arch/openrisc/include/asm/processor.h b/arch/openrisc/include/asm/processor.h
index f7516fa..30462f1 100644
--- a/arch/openrisc/include/asm/processor.h
+++ b/arch/openrisc/include/asm/processor.h
@@ -72,10 +72,6 @@ struct thread_struct {
 #define task_pt_regs(task) user_regs(task_thread_info(task))
 #define current_regs() user_regs(current_thread_info())
 
-extern inline void prepare_to_copy(struct task_struct *tsk)
-{
-}
-
 #define INIT_SP         (sizeof(init_stack) + (unsigned long) &init_stack)
 
 #define INIT_THREAD  { }
diff --git a/arch/parisc/include/asm/processor.h b/arch/parisc/include/asm/processor.h
index acdf4ca..0e8b7b8 100644
--- a/arch/parisc/include/asm/processor.h
+++ b/arch/parisc/include/asm/processor.h
@@ -328,9 +328,6 @@ struct mm_struct;
 extern void release_thread(struct task_struct *);
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern void map_hpux_gateway_page(struct task_struct *tsk, struct mm_struct *mm);
 
 extern unsigned long get_wchan(struct task_struct *p);
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 48a26d3..55e8563 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -74,9 +74,6 @@ struct task_struct;
 void start_thread(struct pt_regs *regs, unsigned long fdptr, unsigned long sp);
 void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-extern void prepare_to_copy(struct task_struct *tsk);
-
 /* Create a new kernel thread. */
 extern long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 7f8ec1d..710f400 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -711,18 +711,21 @@ release_thread(struct task_struct *t)
 }
 
 /*
- * This gets called before we allocate a new thread and copy
- * the current task into it.
+ * this gets called so that we can store coprocessor state into memory and
+ * copy the current task into the new thread.
  */
-void prepare_to_copy(struct task_struct *tsk)
+int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
-	flush_fp_to_thread(current);
-	flush_altivec_to_thread(current);
-	flush_vsx_to_thread(current);
-	flush_spe_to_thread(current);
+	flush_fp_to_thread(src);
+	flush_altivec_to_thread(src);
+	flush_vsx_to_thread(src);
+	flush_spe_to_thread(src);
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
-	flush_ptrace_hw_breakpoint(tsk);
+	flush_ptrace_hw_breakpoint(src);
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
+
+	*dst = *src;
+	return 0;
 }
 
 /*
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index d499b30..6cbf313 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -141,9 +141,6 @@ struct seq_file;
 extern void release_thread(struct task_struct *);
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 /*
  * Return saved PC of a blocked thread.
  */
diff --git a/arch/score/include/asm/processor.h b/arch/score/include/asm/processor.h
index 7e22f21..ab3aceb 100644
--- a/arch/score/include/asm/processor.h
+++ b/arch/score/include/asm/processor.h
@@ -26,7 +26,6 @@ extern unsigned long get_wchan(struct task_struct *p);
 
 #define cpu_relax()		barrier()
 #define release_thread(thread)	do {} while (0)
-#define prepare_to_copy(tsk)	do {} while (0)
 
 /*
  * User space process size: 2GB. This is hardcoded into a few places,
diff --git a/arch/sh/include/asm/processor_32.h b/arch/sh/include/asm/processor_32.h
index 900f8d7..b6311fd 100644
--- a/arch/sh/include/asm/processor_32.h
+++ b/arch/sh/include/asm/processor_32.h
@@ -126,9 +126,6 @@ extern void start_thread(struct pt_regs *regs, unsigned long new_pc, unsigned lo
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-void prepare_to_copy(struct task_struct *tsk);
-
 /*
  * create a kernel thread without removing it from tasklists
  */
diff --git a/arch/sh/include/asm/processor_64.h b/arch/sh/include/asm/processor_64.h
index 740e268..cd6029f 100644
--- a/arch/sh/include/asm/processor_64.h
+++ b/arch/sh/include/asm/processor_64.h
@@ -169,7 +169,6 @@ extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 #define copy_segments(p, mm)	do { } while (0)
 #define release_segments(mm)	do { } while (0)
 #define forget_segments()	do { } while (0)
-#define prepare_to_copy(tsk)	do { } while (0)
 /*
  * FPU lazy state save handling.
  */
diff --git a/arch/sh/kernel/process.c b/arch/sh/kernel/process.c
index e77feaf..9b7a459 100644
--- a/arch/sh/kernel/process.c
+++ b/arch/sh/kernel/process.c
@@ -13,8 +13,15 @@ unsigned long __stack_chk_guard __read_mostly;
 EXPORT_SYMBOL(__stack_chk_guard);
 #endif
 
+/*
+ * this gets called so that we can store lazy state into memory and copy the
+ * current task into the new thread.
+ */
 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
+#ifdef CONFIG_SUPERH32
+	unlazy_fpu(src, task_pt_regs(src));
+#endif
 	*dst = *src;
 
 	if (src->thread.xstate) {
diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c
index f78cc42..59521e8 100644
--- a/arch/sh/kernel/process_32.c
+++ b/arch/sh/kernel/process_32.c
@@ -156,15 +156,6 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 }
 EXPORT_SYMBOL(dump_fpu);
 
-/*
- * This gets called before we allocate a new thread and copy
- * the current task into it.
- */
-void prepare_to_copy(struct task_struct *tsk)
-{
-	unlazy_fpu(tsk, task_pt_regs(tsk));
-}
-
 asmlinkage void ret_from_fork(void);
 
 int copy_thread(unsigned long clone_flags, unsigned long usp,
diff --git a/arch/sparc/include/asm/processor_32.h b/arch/sparc/include/asm/processor_32.h
index 9cbd854..f74ac9e 100644
--- a/arch/sparc/include/asm/processor_32.h
+++ b/arch/sparc/include/asm/processor_32.h
@@ -108,9 +108,6 @@ static inline void start_thread(struct pt_regs * regs, unsigned long pc,
 #define release_thread(tsk)		do { } while(0)
 extern pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern unsigned long get_wchan(struct task_struct *);
 
 #define task_pt_regs(tsk) ((tsk)->thread.kregs)
diff --git a/arch/sparc/include/asm/processor_64.h b/arch/sparc/include/asm/processor_64.h
index e713db2..67df5cc 100644
--- a/arch/sparc/include/asm/processor_64.h
+++ b/arch/sparc/include/asm/processor_64.h
@@ -186,9 +186,6 @@ do { \
 /* Free all resources held by a thread. */
 #define release_thread(tsk)		do { } while (0)
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 extern unsigned long get_wchan(struct task_struct *task);
diff --git a/arch/tile/include/asm/processor.h b/arch/tile/include/asm/processor.h
index 34c1e01..15cd8a4 100644
--- a/arch/tile/include/asm/processor.h
+++ b/arch/tile/include/asm/processor.h
@@ -210,9 +210,6 @@ static inline void release_thread(struct task_struct *dead_task)
 	/* Nothing for now */
 }
 
-/* Prepare to copy thread state - unlazy all lazy status. */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 
 extern int do_work_pending(struct pt_regs *regs, u32 flags);
diff --git a/arch/um/include/asm/processor-generic.h b/arch/um/include/asm/processor-generic.h
index 7827394..69f1c57 100644
--- a/arch/um/include/asm/processor-generic.h
+++ b/arch/um/include/asm/processor-generic.h
@@ -74,11 +74,6 @@ static inline void release_thread(struct task_struct *task)
 
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
-static inline void prepare_to_copy(struct task_struct *tsk)
-{
-}
-
-
 extern unsigned long thread_saved_pc(struct task_struct *t);
 
 static inline void mm_copy_segments(struct mm_struct *from_mm,
diff --git a/arch/unicore32/include/asm/processor.h b/arch/unicore32/include/asm/processor.h
index f0d780a..14382cb 100644
--- a/arch/unicore32/include/asm/processor.h
+++ b/arch/unicore32/include/asm/processor.h
@@ -68,9 +68,6 @@ struct task_struct;
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 unsigned long get_wchan(struct task_struct *p);
 
 #define cpu_relax()			barrier()
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index ccbb1ea..7745b25 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -579,9 +579,6 @@ extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy state */
-extern void prepare_to_copy(struct task_struct *tsk);
-
 unsigned long get_wchan(struct task_struct *p);
 
 /*
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index f2e8c0f..735279e 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -56,10 +56,16 @@ EXPORT_SYMBOL_GPL(idle_notifier_unregister);
 struct kmem_cache *task_xstate_cachep;
 EXPORT_SYMBOL_GPL(task_xstate_cachep);
 
+/*
+ * this gets called so that we can store lazy state into memory and copy the
+ * current task into the new thread.
+ */
 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
 	int ret;
 
+	unlazy_fpu(src);
+
 	*dst = *src;
 	if (fpu_allocated(&src->thread.fpu)) {
 		memset(&dst->thread.fpu, 0, sizeof(dst->thread.fpu));
@@ -89,6 +95,16 @@ void arch_task_cache_init(void)
 				  SLAB_PANIC | SLAB_NOTRACK, NULL);
 }
 
+static inline void drop_fpu(struct task_struct *tsk)
+{
+	/*
+	 * Forget coprocessor state..
+	 */
+	tsk->fpu_counter = 0;
+	clear_fpu(tsk);
+	clear_used_math();
+}
+
 /*
  * Free current thread data structures etc..
  */
@@ -111,6 +127,8 @@ void exit_thread(void)
 		put_cpu();
 		kfree(bp);
 	}
+
+	drop_fpu(me);
 }
 
 void show_regs_common(void)
@@ -145,12 +163,7 @@ void flush_thread(void)
 
 	flush_ptrace_hw_breakpoint(tsk);
 	memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
-	/*
-	 * Forget coprocessor state..
-	 */
-	tsk->fpu_counter = 0;
-	clear_fpu(tsk);
-	clear_used_math();
+	drop_fpu(tsk);
 }
 
 static void hard_disable_TSC(void)
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 01d8d40..516fa18 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -126,15 +126,6 @@ void release_thread(struct task_struct *dead_task)
 	release_vm86_irqs(dead_task);
 }
 
-/*
- * This gets called before we allocate a new thread and copy
- * the current task into it.
- */
-void prepare_to_copy(struct task_struct *tsk)
-{
-	unlazy_fpu(tsk);
-}
-
 int copy_thread(unsigned long clone_flags, unsigned long sp,
 	unsigned long unused,
 	struct task_struct *p, struct pt_regs *regs)
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 28e8102..61cdf7f 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -145,15 +145,6 @@ static inline u32 read_32bit_tls(struct task_struct *t, int tls)
 	return get_desc_base(&t->thread.tls_array[tls]);
 }
 
-/*
- * This gets called before we allocate a new thread and copy
- * the current task into it.
- */
-void prepare_to_copy(struct task_struct *tsk)
-{
-	unlazy_fpu(tsk);
-}
-
 int copy_thread(unsigned long clone_flags, unsigned long sp,
 		unsigned long unused,
 	struct task_struct *p, struct pt_regs *regs)
diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index e62728e..bd18149 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -48,8 +48,6 @@ void __sanitize_i387_state(struct task_struct *tsk)
 	if (!fx)
 		return;
 
-	BUG_ON(__thread_has_fpu(tsk));
-
 	xstate_bv = tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv;
 
 	/*
diff --git a/arch/xtensa/include/asm/processor.h b/arch/xtensa/include/asm/processor.h
index 3acb26e..5c371d8 100644
--- a/arch/xtensa/include/asm/processor.h
+++ b/arch/xtensa/include/asm/processor.h
@@ -168,9 +168,6 @@ struct mm_struct;
 /* Free all resources held by a thread. */
 #define release_thread(thread) do { } while(0)
 
-/* Prepare to copy thread state - unlazy all lazy status */
-extern void prepare_to_copy(struct task_struct*);
-
 /* Create a kernel thread without removing it from tasklists */
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 6a2d6ed..9b306e5 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -140,13 +140,16 @@ void flush_thread(void)
 }
 
 /*
- * This is called before the thread is copied. 
+ * this gets called so that we can store coprocessor state into memory and
+ * copy the current task into the new thread.
  */
-void prepare_to_copy(struct task_struct *tsk)
+int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
 #if XTENSA_HAVE_COPROCESSORS
-	coprocessor_flush_all(task_thread_info(tsk));
+	coprocessor_flush_all(task_thread_info(src));
 #endif
+	*dst = *src;
+	return 0;
 }
 
 /*
diff --git a/fs/exec.c b/fs/exec.c
index d038968..1e8efdc 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1938,8 +1938,21 @@ static int coredump_wait(int exit_code, struct core_state *core_state)
 		core_waiters = zap_threads(tsk, mm, core_state, exit_code);
 	up_write(&mm->mmap_sem);
 
-	if (core_waiters > 0)
+	if (core_waiters > 0) {
+		struct core_thread *ptr;
+
 		wait_for_completion(&core_state->startup);
+		/*
+		 * Wait for all the threads to become inactive, so that
+		 * all the thread context (extended register state, like
+		 * fpu etc) gets copied to the memory.
+		 */
+		ptr = core_state->dumper.next;
+		while (ptr != NULL) {
+			wait_task_inactive(ptr->task, 0);
+			ptr = ptr->next;
+		}
+	}
 
 	return core_waiters;
 }
diff --git a/kernel/fork.c b/kernel/fork.c
index ad54c83..05c813d 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -292,8 +292,6 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 	int node = tsk_fork_get_node(orig);
 	int err;
 
-	prepare_to_copy(orig);
-
 	tsk = alloc_task_struct_node(node);
 	if (!tsk)
 		return NULL;