/*

   * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)

   * Copyright 2003 PathScale, Inc.
   * Licensed under the GPL
   */

  #include <linux/stddef.h>
  #include <linux/err.h>
  #include <linux/hardirq.h>

  #include <linux/mm.h>

  #include <linux/module.h>

  #include <linux/personality.h>
  #include <linux/proc_fs.h>
  #include <linux/ptrace.h>
  #include <linux/random.h>

  #include <linux/slab.h>

  #include <linux/sched.h>

  #include <linux/seq_file.h>

  #include <linux/tick.h>
  #include <linux/threads.h>
  #include <asm/current.h>
  #include <asm/pgtable.h>

  #include <asm/mmu_context.h>

  #include <asm/uaccess.h>

  #include "as-layout.h"

  #include "kern_util.h"

  #include "os.h"

  #include "skas.h"

  /*
   * This is a per-cpu array.  A processor only modifies its entry and it only

   * cares about its entry, so it's OK if another processor is modifying its
   * entry.
   */
  struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };

  static inline int external_pid(void)

  {

  	/* FIXME: Need to look up userspace_pid by cpu */

  	return userspace_pid[0];

  }
  
  int pid_to_processor_id(int pid)
  {
  	int i;

  	for (i = 0; i < ncpus; i++) {

  		if (cpu_tasks[i].pid == pid)

  			return i;

  	}

  	return -1;

  }
  
  void free_stack(unsigned long stack, int order)
  {
  	free_pages(stack, order);
  }
  
  unsigned long alloc_stack(int order, int atomic)
  {
  	unsigned long page;

  	gfp_t flags = GFP_KERNEL;

  	if (atomic)
  		flags = GFP_ATOMIC;

  	page = __get_free_pages(flags, order);

  	return page;

  }
  
  int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
  {
  	int pid;
  
  	current->thread.request.u.thread.proc = fn;
  	current->thread.request.u.thread.arg = arg;

  	pid = do_fork(CLONE_VM | CLONE_UNTRACED | flags, 0,
  		      &current->thread.regs, 0, NULL, NULL);

  	return pid;

  }

  EXPORT_SYMBOL(kernel_thread);

  static inline void set_current(struct task_struct *task)

  {

  	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)

  		{ external_pid(), task });

  }

  extern void arch_switch_to(struct task_struct *to);

  void *_switch_to(void *prev, void *next, void *last)
  {

  	struct task_struct *from = prev;

  	struct task_struct *to = next;

  	to->thread.prev_sched = from;
  	set_current(to);

  	do {

  		current->thread.saved_task = NULL;

  		switch_threads(&from->thread.switch_buf,
  			       &to->thread.switch_buf);

  		arch_switch_to(current);

  		if (current->thread.saved_task)

  			show_regs(&(current->thread.regs));

  		to = current->thread.saved_task;
  		from = current;

  	} while (current->thread.saved_task);

  	return current->thread.prev_sched;

  }
  
  void interrupt_end(void)
  {

  	if (need_resched())

  		schedule();

  	if (test_tsk_thread_flag(current, TIF_SIGPENDING))

  		do_signal();

  }

  void exit_thread(void)
  {

  }

  void *get_current(void)
  {

  	return current;

  }

  /*
   * This is called magically, by its address being stuffed in a jmp_buf

   * and being longjmp-d to.
   */
  void new_thread_handler(void)
  {
  	int (*fn)(void *), n;
  	void *arg;

  	if (current->thread.prev_sched != NULL)

  		schedule_tail(current->thread.prev_sched);
  	current->thread.prev_sched = NULL;
  
  	fn = current->thread.request.u.thread.proc;
  	arg = current->thread.request.u.thread.arg;

  	/*
  	 * The return value is 1 if the kernel thread execs a process,

  	 * 0 if it just exits
  	 */
  	n = run_kernel_thread(fn, arg, &current->thread.exec_buf);

  	if (n == 1) {

  		/* Handle any immediate reschedules or signals */
  		interrupt_end();
  		userspace(&current->thread.regs.regs);
  	}
  	else do_exit(0);
  }
  
  /* Called magically, see new_thread_handler above */
  void fork_handler(void)
  {
  	force_flush_all();

  
  	schedule_tail(current->thread.prev_sched);

  	/*
  	 * XXX: if interrupt_end() calls schedule, this call to

  	 * arch_switch_to isn't needed. We could want to apply this to

  	 * improve performance. -bb
  	 */

  	arch_switch_to(current);

  
  	current->thread.prev_sched = NULL;
  
  	/* Handle any immediate reschedules or signals */
  	interrupt_end();
  
  	userspace(&current->thread.regs.regs);
  }

  int copy_thread(unsigned long clone_flags, unsigned long sp,

  		unsigned long stack_top, struct task_struct * p,

  		struct pt_regs *regs)
  {

  	void (*handler)(void);
  	int ret = 0;

  	p->thread = (struct thread_struct) INIT_THREAD;

  	if (current->thread.forking) {

  	  	memcpy(&p->thread.regs.regs, &regs->regs,
  		       sizeof(p->thread.regs.regs));

  		REGS_SET_SYSCALL_RETURN(p->thread.regs.regs.gp, 0);

  		if (sp != 0)

  			REGS_SP(p->thread.regs.regs.gp) = sp;

  		handler = fork_handler;

  		arch_copy_thread(&current->thread.arch, &p->thread.arch);
  	}
  	else {

  		get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);

  		p->thread.request.u.thread = current->thread.request.u.thread;
  		handler = new_thread_handler;
  	}
  
  	new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
  
  	if (current->thread.forking) {
  		clear_flushed_tls(p);
  
  		/*
  		 * Set a new TLS for the child thread?
  		 */
  		if (clone_flags & CLONE_SETTLS)
  			ret = arch_copy_tls(p);
  	}

  	return ret;

  }
  
  void initial_thread_cb(void (*proc)(void *), void *arg)
  {
  	int save_kmalloc_ok = kmalloc_ok;
  
  	kmalloc_ok = 0;

  	initial_thread_cb_skas(proc, arg);

  	kmalloc_ok = save_kmalloc_ok;
  }

  void default_idle(void)
  {

  	unsigned long long nsecs;

  	while (1) {

  		/* endless idle loop with no priority at all */

  
  		/*
  		 * although we are an idle CPU, we do not want to
  		 * get into the scheduler unnecessarily.
  		 */

  		if (need_resched())

  			schedule();

  		tick_nohz_idle_enter();
  		rcu_idle_enter();

  		nsecs = disable_timer();
  		idle_sleep(nsecs);

  		rcu_idle_exit();
  		tick_nohz_idle_exit();

  	}
  }
  
  void cpu_idle(void)
  {

  	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();

  	default_idle();

  }

  int __cant_sleep(void) {
  	return in_atomic() || irqs_disabled() || in_interrupt();
  	/* Is in_interrupt() really needed? */

  }

  int user_context(unsigned long sp)
  {
  	unsigned long stack;
  
  	stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);

  	return stack != (unsigned long) current_thread_info();

  }

  extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
  
  void do_uml_exitcalls(void)
  {
  	exitcall_t *call;
  
  	call = &__uml_exitcall_end;
  	while (--call >= &__uml_exitcall_begin)
  		(*call)();
  }

  char *uml_strdup(const char *string)

  {

  	return kstrdup(string, GFP_KERNEL);

  }

  EXPORT_SYMBOL(uml_strdup);

  int copy_to_user_proc(void __user *to, void *from, int size)
  {

  	return copy_to_user(to, from, size);

  }
  
  int copy_from_user_proc(void *to, void __user *from, int size)
  {

  	return copy_from_user(to, from, size);

  }
  
  int clear_user_proc(void __user *buf, int size)
  {

  	return clear_user(buf, size);

  }
  
  int strlen_user_proc(char __user *str)
  {

  	return strlen_user(str);

  }
  
  int smp_sigio_handler(void)
  {
  #ifdef CONFIG_SMP

  	int cpu = current_thread_info()->cpu;

  	IPI_handler(cpu);

  	if (cpu != 0)

  		return 1;

  #endif

  	return 0;

  }

  int cpu(void)
  {

  	return current_thread_info()->cpu;

  }
  
  static atomic_t using_sysemu = ATOMIC_INIT(0);
  int sysemu_supported;
  
  void set_using_sysemu(int value)
  {
  	if (value > sysemu_supported)
  		return;
  	atomic_set(&using_sysemu, value);
  }
  
  int get_using_sysemu(void)
  {
  	return atomic_read(&using_sysemu);
  }

  static int sysemu_proc_show(struct seq_file *m, void *v)

  {

  	seq_printf(m, "%d
  ", get_using_sysemu());
  	return 0;
  }

  static int sysemu_proc_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, sysemu_proc_show, NULL);

  }

  static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
  				 size_t count, loff_t *pos)

  {
  	char tmp[2];
  
  	if (copy_from_user(tmp, buf, 1))
  		return -EFAULT;
  
  	if (tmp[0] >= '0' && tmp[0] <= '2')
  		set_using_sysemu(tmp[0] - '0');

  	/* We use the first char, but pretend to write everything */
  	return count;

  }

  static const struct file_operations sysemu_proc_fops = {
  	.owner		= THIS_MODULE,
  	.open		= sysemu_proc_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  	.write		= sysemu_proc_write,
  };

  int __init make_proc_sysemu(void)
  {
  	struct proc_dir_entry *ent;
  	if (!sysemu_supported)
  		return 0;

  	ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);

  
  	if (ent == NULL)
  	{

  		printk(KERN_WARNING "Failed to register /proc/sysemu
  ");

  		return 0;

  	}

  	return 0;
  }
  
  late_initcall(make_proc_sysemu);
  
  int singlestepping(void * t)
  {
  	struct task_struct *task = t ? t : current;

  	if (!(task->ptrace & PT_DTRACE))

  		return 0;

  
  	if (task->thread.singlestep_syscall)

  		return 1;

  
  	return 2;
  }

  /*
   * Only x86 and x86_64 have an arch_align_stack().
   * All other arches have "#define arch_align_stack(x) (x)"
   * in their asm/system.h
   * As this is included in UML from asm-um/system-generic.h,
   * we can use it to behave as the subarch does.
   */
  #ifndef arch_align_stack

  unsigned long arch_align_stack(unsigned long sp)
  {

  	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)

  		sp -= get_random_int() % 8192;
  	return sp & ~0xf;
  }

  #endif

  
  unsigned long get_wchan(struct task_struct *p)
  {
  	unsigned long stack_page, sp, ip;
  	bool seen_sched = 0;
  
  	if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
  		return 0;
  
  	stack_page = (unsigned long) task_stack_page(p);
  	/* Bail if the process has no kernel stack for some reason */
  	if (stack_page == 0)
  		return 0;
  
  	sp = p->thread.switch_buf->JB_SP;
  	/*
  	 * Bail if the stack pointer is below the bottom of the kernel
  	 * stack for some reason
  	 */
  	if (sp < stack_page)
  		return 0;
  
  	while (sp < stack_page + THREAD_SIZE) {
  		ip = *((unsigned long *) sp);
  		if (in_sched_functions(ip))
  			/* Ignore everything until we're above the scheduler */
  			seen_sched = 1;
  		else if (kernel_text_address(ip) && seen_sched)
  			return ip;
  
  		sp += sizeof(unsigned long);
  	}
  
  	return 0;
  }

  
  int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
  {
  	int cpu = current_thread_info()->cpu;
  
  	return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
  }