146 lines
3.7 KiB
C
Executable File
146 lines
3.7 KiB
C
Executable File
/* GDB support for an sbrk-like function that uses mmap.
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Copyright 1992 Free Software Foundation, Inc.
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Contributed by Cygnus Support, using pieces from other GDB modules.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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#include <stdio.h>
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#include "defs.h"
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#ifdef HAVE_MMAP
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#include <fcntl.h>
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#include <sys/mman.h>
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#ifdef i386
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#define MMAP_BASE ((caddr_t) 0x81000000)
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#define MMAP_PGSZ 0x00002000 /* Must be multiple of real page size */
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#else
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#define MMAP_BASE ((caddr_t) 0xC2000000)
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#define MMAP_PGSZ 0x00002000 /* Must be multiple of real page size */
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#endif
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#define PAGE_ALIGN(addr) (caddr_t) (((long)(addr) + MMAP_PGSZ - 1) & \
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~(MMAP_PGSZ - 1))
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static caddr_t mbase = MMAP_BASE; /* Current base of mmap'd region */
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static caddr_t mbreak = MMAP_BASE; /* Current "break" address */
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static caddr_t mtop = MMAP_BASE; /* Current top of mmap'd region */
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static int fd = -1; /* Open fd for /dev/zero */
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/* Provide a utility routine for other modules to obtain compatible
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page alignment. */
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PTR
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mmap_page_align (addr)
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PTR addr;
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{
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return (PAGE_ALIGN (addr));
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}
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/* Return the base address of the start of the mmap'd region. Note that
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we can find the end of the region at anytime by calling mmap_sbrk(0) */
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PTR
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mmap_base ()
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{
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return (mbase);
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}
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/* Works like sbrk(), but uses mmap to add to or subtract from a
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memory region. */
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PTR
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mmap_sbrk (size)
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int size;
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{
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PTR result = NULL;
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int minc;
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caddr_t moveto;
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if (size == 0)
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{
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/* Just return the current "break" value. */
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result = mbreak;
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}
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else if (size < 0)
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{
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/* We are deallocating memory. If the amount requested would cause
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us to try to deallocate back past the base of the mmap'd region
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then do nothing, and return NULL. Otherwise, deallocate the
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memory and return the old break value. */
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if (mbreak + size >= mbase)
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{
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result = (PTR) mbreak;
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mbreak += size;
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moveto = PAGE_ALIGN (mbreak);
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munmap (moveto, (size_t) (mtop - moveto));
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mtop = moveto;
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}
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}
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else
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{
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/* We are allocating memory. Make sure we have an open file
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descriptor and then go on to get the memory. */
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if ((fd == -1) && (fd = open ("/dev/zero", O_RDONLY)) < 0)
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{
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result = NULL;
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}
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else if (mbreak + size > mtop)
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{
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/* The request would move us past the end of the currently
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mapped memory, so map in enough more memory to satisfy
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the request. */
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moveto = PAGE_ALIGN (mbreak + size);
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if (mmap (mtop, moveto - mtop, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_FIXED, fd, 0) == mtop)
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{
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mtop = moveto;
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result = (PTR) mbreak;
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mbreak += size;
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}
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}
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else
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{
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result = (PTR) mbreak;
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mbreak += size;
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}
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}
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return (result);
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}
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PTR
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mmap_remap (base, mapsize, fd, foffset)
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PTR base;
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long mapsize;
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int fd;
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long foffset;
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{
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/* FIXME: Quick hack, needs error checking and other attention. */
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munmap (mbase, (size_t) (mtop - mbase));
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mbase = base;
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mtop = mbase + mapsize;
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base = mmap (base, mapsize, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_FIXED, dup (fd), foffset);
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return (base);
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}
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#endif /* HAVE_MMAP */
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