/* windows.c: Routines to deal with register window management
   *            at the C-code level.
   *
   * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   */
  
  #include <linux/kernel.h>
  #include <linux/sched.h>
  #include <linux/string.h>
  #include <linux/mm.h>
  #include <linux/smp.h>

  
  #include <asm/uaccess.h>
  
  /* Do save's until all user register windows are out of the cpu. */
  void flush_user_windows(void)
  {
  	register int ctr asm("g5");
  
  	ctr = 0;
  	__asm__ __volatile__(
  		"
  1:
  \t"
  		"ld	[%%g6 + %2], %%g4
  \t"
  		"orcc	%%g0, %%g4, %%g0
  \t"
  		"add	%0, 1, %0
  \t"
  		"bne	1b
  \t"
  		" save	%%sp, -64, %%sp
  "
  		"2:
  \t"
  		"subcc	%0, 1, %0
  \t"
  		"bne	2b
  \t"
  		" restore %%g0, %%g0, %%g0
  "
  	: "=&r" (ctr)
  	: "0" (ctr),
  	  "i" ((const unsigned long)TI_UWINMASK)
  	: "g4", "cc");
  }
  
  static inline void shift_window_buffer(int first_win, int last_win, struct thread_info *tp)
  {
  	int i;
  
  	for(i = first_win; i < last_win; i++) {
  		tp->rwbuf_stkptrs[i] = tp->rwbuf_stkptrs[i+1];

  		memcpy(&tp->reg_window[i], &tp->reg_window[i+1], sizeof(struct reg_window32));

  	}
  }
  
  /* Place as many of the user's current register windows 
   * on the stack that we can.  Even if the %sp is unaligned
   * we still copy the window there, the only case that we don't
   * succeed is if the %sp points to a bum mapping altogether.
   * setup_frame() and do_sigreturn() use this before shifting
   * the user stack around.  Future instruction and hardware
   * bug workaround routines will need this functionality as
   * well.
   */
  void synchronize_user_stack(void)
  {
  	struct thread_info *tp = current_thread_info();
  	int window;
  
  	flush_user_windows();
  	if(!tp->w_saved)
  		return;
  
  	/* Ok, there is some dirty work to do. */
  	for(window = tp->w_saved - 1; window >= 0; window--) {
  		unsigned long sp = tp->rwbuf_stkptrs[window];
  
  		/* Ok, let it rip. */
  		if (copy_to_user((char __user *) sp, &tp->reg_window[window],

  				 sizeof(struct reg_window32)))

  			continue;
  
  		shift_window_buffer(window, tp->w_saved - 1, tp);
  		tp->w_saved--;
  	}
  }
  
  #if 0
  /* An optimization. */
  static inline void copy_aligned_window(void *dest, const void *src)
  {
  	__asm__ __volatile__("ldd [%1], %%g2
  \t"
  			     "ldd [%1 + 0x8], %%g4
  \t"
  			     "std %%g2, [%0]
  \t"
  			     "std %%g4, [%0 + 0x8]
  \t"
  			     "ldd [%1 + 0x10], %%g2
  \t"
  			     "ldd [%1 + 0x18], %%g4
  \t"
  			     "std %%g2, [%0 + 0x10]
  \t"
  			     "std %%g4, [%0 + 0x18]
  \t"
  			     "ldd [%1 + 0x20], %%g2
  \t"
  			     "ldd [%1 + 0x28], %%g4
  \t"
  			     "std %%g2, [%0 + 0x20]
  \t"
  			     "std %%g4, [%0 + 0x28]
  \t"
  			     "ldd [%1 + 0x30], %%g2
  \t"
  			     "ldd [%1 + 0x38], %%g4
  \t"
  			     "std %%g2, [%0 + 0x30]
  \t"
  			     "std %%g4, [%0 + 0x38]
  \t" : :
  			     "r" (dest), "r" (src) :
  			     "g2", "g3", "g4", "g5");
  }
  #endif
  
  /* Try to push the windows in a threads window buffer to the
   * user stack.  Unaligned %sp's are not allowed here.
   */
  
  void try_to_clear_window_buffer(struct pt_regs *regs, int who)
  {
  	struct thread_info *tp = current_thread_info();
  	int window;

  	flush_user_windows();
  	for(window = 0; window < tp->w_saved; window++) {
  		unsigned long sp = tp->rwbuf_stkptrs[window];
  
  		if ((sp & 7) ||
  		    copy_to_user((char __user *) sp, &tp->reg_window[window],

  				 sizeof(struct reg_window32)))

  			do_exit(SIGILL);
  	}
  	tp->w_saved = 0;

  }