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db_memrw.c revision 1.5 
      1 /*	$NetBSD: db_memrw.c,v 1.5 1994/12/02 18:18:44 gwr Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1994 Gordon W. Ross
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. The name of the author may not be used to endorse or promote products
     16  *    derived from this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     28  */
     29 
     30 /*
     31  * Interface to the debugger for virtual memory read/write.
     32  * To write in the text segment, we have to first make
     33  * the page writable, do the write, then restore the PTE.
     34  * For writes outside the text segment, and all reads,
     35  * just do the access -- if it causes a fault, the debugger
     36  * will recover with a longjmp to an appropriate place.
     37  */
     38 
     39 #include <sys/param.h>
     40 #include <sys/proc.h>
     41 
     42 #include <vm/vm.h>
     43 
     44 #include <machine/db_machdep.h>
     45 #include <machine/pte.h>
     46 
     47 /*
     48  * Read bytes from kernel address space for debugger.
     49  * This used to check for valid PTEs, but now that
     50  * traps in DDB work correctly, "Just Do It!"
     51  */
     52 void
     53 db_read_bytes(addr, size, data)
     54 	vm_offset_t	addr;
     55 	register int	size;
     56 	register char	*data;
     57 {
     58 	register char	*src;
     59 
     60 	src = (char *)addr;
     61 	while (--size >= 0)
     62 		*data++ = *src++;
     63 }
     64 
     65 /*
     66  * Write one byte somewhere in kernel text.
     67  * It does not matter if this is slow. -gwr
     68  */
     69 static void
     70 db_write_text(dst, ch)
     71 	char *dst;
     72 	int ch;
     73 {
     74 	int		oldpte, tmppte;
     75 	vm_offset_t pgva;
     76 
     77 	pgva = sun3_trunc_page((long)dst);
     78 	oldpte = get_pte(pgva);
     79 
     80 	if ((oldpte & PG_VALID) == 0) {
     81 		db_printf(" address 0x%x not a valid page\n", dst);
     82 		return;
     83 	}
     84 
     85 	tmppte = oldpte | PG_WRITE;
     86 	set_pte(pgva, tmppte);
     87 
     88 	*dst = (char) ch;
     89 
     90 	set_pte(pgva, oldpte);
     91 }
     92 
     93 /*
     94  * Write bytes to kernel address space for debugger.
     95  */
     96 void
     97 db_write_bytes(addr, size, data)
     98 	vm_offset_t	addr;
     99 	int	size;
    100 	char	*data;
    101 {
    102 	extern char	start[], etext[] ;
    103 	char	*dst;
    104 
    105 	dst = (char *)addr;
    106 	while (--size >= 0) {
    107 		if ((dst >= start) && (dst < etext))
    108 			db_write_text(dst, *data);
    109 		else
    110 			*dst = *data;
    111 		dst++; data++;
    112 	}
    113 }
    114