/*
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   *
   * Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
   * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
   * Copyright 1999 Hewlett Packard Co.
   *
   */
  
  #include <linux/mm.h>
  #include <linux/ptrace.h>
  #include <linux/sched.h>
  #include <linux/interrupt.h>
  #include <linux/module.h>
  
  #include <asm/uaccess.h>
  #include <asm/traps.h>
  
  /* Various important other fields */
  #define bit22set(x)		(x & 0x00000200)
  #define bits23_25set(x)		(x & 0x000001c0)
  #define isGraphicsFlushRead(x)	((x & 0xfc003fdf) == 0x04001a80)
  				/* extended opcode is 0x6a */
  
  #define BITSSET		0x1c0	/* for identifying LDCW */
  
  
  DEFINE_PER_CPU(struct exception_data, exception_data);
  
  int show_unhandled_signals = 1;
  
  /*
   * parisc_acctyp(unsigned int inst) --
   *    Given a PA-RISC memory access instruction, determine if the
   *    the instruction would perform a memory read or memory write
   *    operation.
   *
   *    This function assumes that the given instruction is a memory access
   *    instruction (i.e. you should really only call it if you know that
   *    the instruction has generated some sort of a memory access fault).
   *
   * Returns:
   *   VM_READ  if read operation
   *   VM_WRITE if write operation
   *   VM_EXEC  if execute operation
   */
  static unsigned long
  parisc_acctyp(unsigned long code, unsigned int inst)
  {
  	if (code == 6 || code == 16)
  	    return VM_EXEC;
  
  	switch (inst & 0xf0000000) {
  	case 0x40000000: /* load */
  	case 0x50000000: /* new load */
  		return VM_READ;
  
  	case 0x60000000: /* store */
  	case 0x70000000: /* new store */
  		return VM_WRITE;
  
  	case 0x20000000: /* coproc */
  	case 0x30000000: /* coproc2 */
  		if (bit22set(inst))
  			return VM_WRITE;
  
  	case 0x0: /* indexed/memory management */
  		if (bit22set(inst)) {
  			/*
  			 * Check for the 'Graphics Flush Read' instruction.
  			 * It resembles an FDC instruction, except for bits
  			 * 20 and 21. Any combination other than zero will
  			 * utilize the block mover functionality on some
  			 * older PA-RISC platforms.  The case where a block
  			 * move is performed from VM to graphics IO space
  			 * should be treated as a READ.
  			 *
  			 * The significance of bits 20,21 in the FDC
  			 * instruction is:
  			 *
  			 *   00  Flush data cache (normal instruction behavior)
  			 *   01  Graphics flush write  (IO space -> VM)
  			 *   10  Graphics flush read   (VM -> IO space)
  			 *   11  Graphics flush read/write (VM <-> IO space)
  			 */
  			if (isGraphicsFlushRead(inst))
  				return VM_READ;
  			return VM_WRITE;
  		} else {
  			/*
  			 * Check for LDCWX and LDCWS (semaphore instructions).
  			 * If bits 23 through 25 are all 1's it is one of
  			 * the above two instructions and is a write.
  			 *
  			 * Note: With the limited bits we are looking at,
  			 * this will also catch PROBEW and PROBEWI. However,
  			 * these should never get in here because they don't
  			 * generate exceptions of the type:
  			 *   Data TLB miss fault/data page fault
  			 *   Data memory protection trap
  			 */
  			if (bits23_25set(inst) == BITSSET)
  				return VM_WRITE;
  		}
  		return VM_READ; /* Default */
  	}
  	return VM_READ; /* Default */
  }
  
  #undef bit22set
  #undef bits23_25set
  #undef isGraphicsFlushRead
  #undef BITSSET
  
  
  #if 0
  /* This is the treewalk to find a vma which is the highest that has
   * a start < addr.  We're using find_vma_prev instead right now, but
   * we might want to use this at some point in the future.  Probably
   * not, but I want it committed to CVS so I don't lose it :-)
   */
  			while (tree != vm_avl_empty) {
  				if (tree->vm_start > addr) {
  					tree = tree->vm_avl_left;
  				} else {
  					prev = tree;
  					if (prev->vm_next == NULL)
  						break;
  					if (prev->vm_next->vm_start > addr)
  						break;
  					tree = tree->vm_avl_right;
  				}
  			}
  #endif
  
  int fixup_exception(struct pt_regs *regs)
  {
  	const struct exception_table_entry *fix;
  
  	/* If we only stored 32bit addresses in the exception table we can drop
  	 * out if we faulted on a 64bit address. */
  	if ((sizeof(regs->iaoq[0]) > sizeof(fix->insn))
  		&& (regs->iaoq[0] >> 32))
  			return 0;
  
  	fix = search_exception_tables(regs->iaoq[0]);
  	if (fix) {
  		struct exception_data *d;
  		d = &__get_cpu_var(exception_data);
  		d->fault_ip = regs->iaoq[0];
  		d->fault_space = regs->isr;
  		d->fault_addr = regs->ior;
  
  		regs->iaoq[0] = ((fix->fixup) & ~3);
  		/*
  		 * NOTE: In some cases the faulting instruction
  		 * may be in the delay slot of a branch. We
  		 * don't want to take the branch, so we don't
  		 * increment iaoq[1], instead we set it to be
  		 * iaoq[0]+4, and clear the B bit in the PSW
  		 */
  		regs->iaoq[1] = regs->iaoq[0] + 4;
  		regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
  
  		return 1;
  	}
  
  	return 0;
  }
  
  /*
   * Print out info about fatal segfaults, if the show_unhandled_signals
   * sysctl is set:
   */
  static inline void
  show_signal_msg(struct pt_regs *regs, unsigned long code,
  		unsigned long address, struct task_struct *tsk,
  		struct vm_area_struct *vma)
  {
  	if (!unhandled_signal(tsk, SIGSEGV))
  		return;
  
  	if (!printk_ratelimit())
  		return;
  
  	pr_warn("
  ");
  	pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx",
  	    tsk->comm, code, address);
  	print_vma_addr(KERN_CONT " in ", regs->iaoq[0]);
  	if (vma)
  		pr_warn(" vm_start = 0x%08lx, vm_end = 0x%08lx
  ",
  				vma->vm_start, vma->vm_end);
  
  	show_regs(regs);
  }
  
  void do_page_fault(struct pt_regs *regs, unsigned long code,
  			      unsigned long address)
  {
  	struct vm_area_struct *vma, *prev_vma;
  	struct task_struct *tsk;
  	struct mm_struct *mm;
  	unsigned long acc_type;
  	int fault;
  	unsigned int flags;
  
  	if (in_atomic())
  		goto no_context;
  
  	tsk = current;
  	mm = tsk->mm;
  	if (!mm)
  		goto no_context;
  
  	flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
  	if (user_mode(regs))
  		flags |= FAULT_FLAG_USER;
  
  	acc_type = parisc_acctyp(code, regs->iir);
  	if (acc_type & VM_WRITE)
  		flags |= FAULT_FLAG_WRITE;
  retry:
  	down_read(&mm->mmap_sem);
  	vma = find_vma_prev(mm, address, &prev_vma);
  	if (!vma || address < vma->vm_start)
  		goto check_expansion;
  /*
   * Ok, we have a good vm_area for this memory access. We still need to
   * check the access permissions.
   */
  
  good_area:
  
  	if ((vma->vm_flags & acc_type) != acc_type)
  		goto bad_area;
  
  	/*
  	 * If for any reason at all we couldn't handle the fault, make
  	 * sure we exit gracefully rather than endlessly redo the
  	 * fault.
  	 */
  
  	fault = handle_mm_fault(mm, vma, address, flags);
  
  	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
  		return;
  
  	if (unlikely(fault & VM_FAULT_ERROR)) {
  		/*
  		 * We hit a shared mapping outside of the file, or some
  		 * other thing happened to us that made us unable to
  		 * handle the page fault gracefully.
  		 */
  		if (fault & VM_FAULT_OOM)
  			goto out_of_memory;
  		else if (fault & VM_FAULT_SIGBUS)
  			goto bad_area;
  		BUG();
  	}
  	if (flags & FAULT_FLAG_ALLOW_RETRY) {
  		if (fault & VM_FAULT_MAJOR)
  			current->maj_flt++;
  		else
  			current->min_flt++;
  		if (fault & VM_FAULT_RETRY) {
  			flags &= ~FAULT_FLAG_ALLOW_RETRY;
  
  			/*
  			 * No need to up_read(&mm->mmap_sem) as we would
  			 * have already released it in __lock_page_or_retry
  			 * in mm/filemap.c.
  			 */
  
  			goto retry;
  		}
  	}
  	up_read(&mm->mmap_sem);
  	return;
  
  check_expansion:
  	vma = prev_vma;
  	if (vma && (expand_stack(vma, address) == 0))
  		goto good_area;
  
  /*
   * Something tried to access memory that isn't in our memory map..
   */
  bad_area:
  	up_read(&mm->mmap_sem);
  
  	if (user_mode(regs)) {
  		struct siginfo si;
  
  		show_signal_msg(regs, code, address, tsk, vma);
  
  		switch (code) {
  		case 15:	/* Data TLB miss fault/Data page fault */
  			/* send SIGSEGV when outside of vma */
  			if (!vma ||
  			    address < vma->vm_start || address > vma->vm_end) {
  				si.si_signo = SIGSEGV;
  				si.si_code = SEGV_MAPERR;
  				break;
  			}
  
  			/* send SIGSEGV for wrong permissions */
  			if ((vma->vm_flags & acc_type) != acc_type) {
  				si.si_signo = SIGSEGV;
  				si.si_code = SEGV_ACCERR;
  				break;
  			}
  
  			/* probably address is outside of mapped file */
  			/* fall through */
  		case 17:	/* NA data TLB miss / page fault */
  		case 18:	/* Unaligned access - PCXS only */
  			si.si_signo = SIGBUS;
  			si.si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR;
  			break;
  		case 16:	/* Non-access instruction TLB miss fault */
  		case 26:	/* PCXL: Data memory access rights trap */
  		default:
  			si.si_signo = SIGSEGV;
  			si.si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR;
  			break;
  		}
  		si.si_errno = 0;
  		si.si_addr = (void __user *) address;
  		force_sig_info(si.si_signo, &si, current);
  		return;
  	}
  
  no_context:
  
  	if (!user_mode(regs) && fixup_exception(regs)) {
  		return;
  	}
  
  	parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
  
    out_of_memory:
  	up_read(&mm->mmap_sem);
  	if (!user_mode(regs))
  		goto no_context;
  	pagefault_out_of_memory();
  }