/*
   * This file handles the architecture dependent parts of process handling.
   *
   *    Copyright IBM Corp. 1999, 2009
   *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
   *		 Hartmut Penner <hp@de.ibm.com>,
   *		 Denis Joseph Barrow,
   */
  
  #include <linux/compiler.h>
  #include <linux/cpu.h>
  #include <linux/sched.h>
  #include <linux/kernel.h>
  #include <linux/mm.h>
  #include <linux/elfcore.h>
  #include <linux/smp.h>
  #include <linux/slab.h>
  #include <linux/interrupt.h>
  #include <linux/tick.h>
  #include <linux/personality.h>
  #include <linux/syscalls.h>
  #include <linux/compat.h>
  #include <linux/kprobes.h>
  #include <linux/random.h>
  #include <linux/module.h>
  #include <asm/io.h>
  #include <asm/processor.h>
  #include <asm/vtimer.h>
  #include <asm/exec.h>
  #include <asm/irq.h>
  #include <asm/nmi.h>
  #include <asm/smp.h>
  #include <asm/switch_to.h>
  #include <asm/runtime_instr.h>
  #include "entry.h"
  
  asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  
  /*
   * Return saved PC of a blocked thread. used in kernel/sched.
   * resume in entry.S does not create a new stack frame, it
   * just stores the registers %r6-%r15 to the frame given by
   * schedule. We want to return the address of the caller of
   * schedule, so we have to walk the backchain one time to
   * find the frame schedule() store its return address.
   */
  unsigned long thread_saved_pc(struct task_struct *tsk)
  {
  	struct stack_frame *sf, *low, *high;
  
  	if (!tsk || !task_stack_page(tsk))
  		return 0;
  	low = task_stack_page(tsk);
  	high = (struct stack_frame *) task_pt_regs(tsk);
  	sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
  	if (sf <= low || sf > high)
  		return 0;
  	sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
  	if (sf <= low || sf > high)
  		return 0;
  	return sf->gprs[8];
  }
  
  void arch_cpu_idle(void)
  {
  	local_mcck_disable();
  	if (test_thread_flag(TIF_MCCK_PENDING)) {
  		local_mcck_enable();
  		local_irq_enable();
  		return;
  	}
  	/* Halt the cpu and keep track of cpu time accounting. */
  	vtime_stop_cpu();
  	local_irq_enable();
  }
  
  void arch_cpu_idle_exit(void)
  {
  	if (test_thread_flag(TIF_MCCK_PENDING))
  		s390_handle_mcck();
  }
  
  void arch_cpu_idle_dead(void)
  {
  	cpu_die();
  }
  
  extern void __kprobes kernel_thread_starter(void);
  
  /*
   * Free current thread data structures etc..
   */
  void exit_thread(void)
  {
  	exit_thread_runtime_instr();
  }
  
  void flush_thread(void)
  {
  }
  
  void release_thread(struct task_struct *dead_task)
  {
  }
  
  int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
  		unsigned long arg, struct task_struct *p)
  {
  	struct thread_info *ti;
  	struct fake_frame
  	{
  		struct stack_frame sf;
  		struct pt_regs childregs;
  	} *frame;
  
  	frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
  	p->thread.ksp = (unsigned long) frame;
  	/* Save access registers to new thread structure. */
  	save_access_regs(&p->thread.acrs[0]);
  	/* start new process with ar4 pointing to the correct address space */
  	p->thread.mm_segment = get_fs();
  	/* Don't copy debug registers */
  	memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
  	memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
  	clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
  	clear_tsk_thread_flag(p, TIF_PER_TRAP);
  	/* Initialize per thread user and system timer values */
  	ti = task_thread_info(p);
  	ti->user_timer = 0;
  	ti->system_timer = 0;
  
  	frame->sf.back_chain = 0;
  	/* new return point is ret_from_fork */
  	frame->sf.gprs[8] = (unsigned long) ret_from_fork;
  	/* fake return stack for resume(), don't go back to schedule */
  	frame->sf.gprs[9] = (unsigned long) frame;
  
  	/* Store access registers to kernel stack of new process. */
  	if (unlikely(p->flags & PF_KTHREAD)) {
  		/* kernel thread */
  		memset(&frame->childregs, 0, sizeof(struct pt_regs));
  		frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
  				PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
  		frame->childregs.psw.addr = PSW_ADDR_AMODE |
  				(unsigned long) kernel_thread_starter;
  		frame->childregs.gprs[9] = new_stackp; /* function */
  		frame->childregs.gprs[10] = arg;
  		frame->childregs.gprs[11] = (unsigned long) do_exit;
  		frame->childregs.orig_gpr2 = -1;
  
  		return 0;
  	}
  	frame->childregs = *current_pt_regs();
  	frame->childregs.gprs[2] = 0;	/* child returns 0 on fork. */
  	if (new_stackp)
  		frame->childregs.gprs[15] = new_stackp;
  
  	/* Don't copy runtime instrumentation info */
  	p->thread.ri_cb = NULL;
  	p->thread.ri_signum = 0;
  	frame->childregs.psw.mask &= ~PSW_MASK_RI;
  
  #ifndef CONFIG_64BIT
  	/*
  	 * save fprs to current->thread.fp_regs to merge them with
  	 * the emulated registers and then copy the result to the child.
  	 */
  	save_fp_ctl(&current->thread.fp_regs.fpc);
  	save_fp_regs(current->thread.fp_regs.fprs);
  	memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
  	       sizeof(s390_fp_regs));
  	/* Set a new TLS ?  */
  	if (clone_flags & CLONE_SETTLS)
  		p->thread.acrs[0] = frame->childregs.gprs[6];
  #else /* CONFIG_64BIT */
  	/* Save the fpu registers to new thread structure. */
  	save_fp_ctl(&p->thread.fp_regs.fpc);
  	save_fp_regs(p->thread.fp_regs.fprs);
  	p->thread.fp_regs.pad = 0;
  	/* Set a new TLS ?  */
  	if (clone_flags & CLONE_SETTLS) {
  		unsigned long tls = frame->childregs.gprs[6];
  		if (is_compat_task()) {
  			p->thread.acrs[0] = (unsigned int)tls;
  		} else {
  			p->thread.acrs[0] = (unsigned int)(tls >> 32);
  			p->thread.acrs[1] = (unsigned int)tls;
  		}
  	}
  #endif /* CONFIG_64BIT */
  	return 0;
  }
  
  asmlinkage void execve_tail(void)
  {
  	current->thread.fp_regs.fpc = 0;
  	if (MACHINE_HAS_IEEE)
  		asm volatile("sfpc %0,%0" : : "d" (0));
  }
  
  /*
   * fill in the FPU structure for a core dump.
   */
  int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
  {
  #ifndef CONFIG_64BIT
  	/*
  	 * save fprs to current->thread.fp_regs to merge them with
  	 * the emulated registers and then copy the result to the dump.
  	 */
  	save_fp_ctl(&current->thread.fp_regs.fpc);
  	save_fp_regs(current->thread.fp_regs.fprs);
  	memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
  #else /* CONFIG_64BIT */
  	save_fp_ctl(&fpregs->fpc);
  	save_fp_regs(fpregs->fprs);
  #endif /* CONFIG_64BIT */
  	return 1;
  }
  EXPORT_SYMBOL(dump_fpu);
  
  unsigned long get_wchan(struct task_struct *p)
  {
  	struct stack_frame *sf, *low, *high;
  	unsigned long return_address;
  	int count;
  
  	if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
  		return 0;
  	low = task_stack_page(p);
  	high = (struct stack_frame *) task_pt_regs(p);
  	sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
  	if (sf <= low || sf > high)
  		return 0;
  	for (count = 0; count < 16; count++) {
  		sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
  		if (sf <= low || sf > high)
  			return 0;
  		return_address = sf->gprs[8] & PSW_ADDR_INSN;
  		if (!in_sched_functions(return_address))
  			return return_address;
  	}
  	return 0;
  }
  
  unsigned long arch_align_stack(unsigned long sp)
  {
  	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
  		sp -= get_random_int() & ~PAGE_MASK;
  	return sp & ~0xf;
  }
  
  static inline unsigned long brk_rnd(void)
  {
  	/* 8MB for 32bit, 1GB for 64bit */
  	if (is_32bit_task())
  		return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
  	else
  		return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
  }
  
  unsigned long arch_randomize_brk(struct mm_struct *mm)
  {
  	unsigned long ret;
  
  	ret = PAGE_ALIGN(mm->brk + brk_rnd());
  	return (ret > mm->brk) ? ret : mm->brk;
  }
  
  unsigned long randomize_et_dyn(unsigned long base)
  {
  	unsigned long ret;
  
  	if (!(current->flags & PF_RANDOMIZE))
  		return base;
  	ret = PAGE_ALIGN(base + brk_rnd());
  	return (ret > base) ? ret : base;
  }