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Diffstat (limited to 'gdb/mmap-sbrk.c')
| -rwxr-xr-x | gdb/mmap-sbrk.c | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/gdb/mmap-sbrk.c b/gdb/mmap-sbrk.c new file mode 100755 index 0000000..fe9c072 --- /dev/null +++ b/gdb/mmap-sbrk.c @@ -0,0 +1,145 @@ +/* GDB support for an sbrk-like function that uses mmap. + Copyright 1992 Free Software Foundation, Inc. + Contributed by Cygnus Support, using pieces from other GDB modules. + +This file is part of GDB. + +This program is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or +(at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program; if not, write to the Free Software +Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ + +#include <stdio.h> +#include "defs.h" + +#ifdef HAVE_MMAP + +#include <fcntl.h> +#include <sys/mman.h> + +#ifdef i386 +#define MMAP_BASE ((caddr_t) 0x81000000) +#define MMAP_PGSZ 0x00002000 /* Must be multiple of real page size */ +#else +#define MMAP_BASE ((caddr_t) 0xC2000000) +#define MMAP_PGSZ 0x00002000 /* Must be multiple of real page size */ +#endif + +#define PAGE_ALIGN(addr) (caddr_t) (((long)(addr) + MMAP_PGSZ - 1) & \ + ~(MMAP_PGSZ - 1)) + +static caddr_t mbase = MMAP_BASE; /* Current base of mmap'd region */ +static caddr_t mbreak = MMAP_BASE; /* Current "break" address */ +static caddr_t mtop = MMAP_BASE; /* Current top of mmap'd region */ + +static int fd = -1; /* Open fd for /dev/zero */ + + +/* Provide a utility routine for other modules to obtain compatible + page alignment. */ + +PTR +mmap_page_align (addr) + PTR addr; +{ + return (PAGE_ALIGN (addr)); +} + +/* Return the base address of the start of the mmap'd region. Note that + we can find the end of the region at anytime by calling mmap_sbrk(0) */ + +PTR +mmap_base () +{ + return (mbase); +} + +/* Works like sbrk(), but uses mmap to add to or subtract from a + memory region. */ + +PTR +mmap_sbrk (size) + int size; +{ + PTR result = NULL; + int minc; + caddr_t moveto; + + if (size == 0) + { + /* Just return the current "break" value. */ + result = mbreak; + } + else if (size < 0) + { + /* We are deallocating memory. If the amount requested would cause + us to try to deallocate back past the base of the mmap'd region + then do nothing, and return NULL. Otherwise, deallocate the + memory and return the old break value. */ + if (mbreak + size >= mbase) + { + result = (PTR) mbreak; + mbreak += size; + moveto = PAGE_ALIGN (mbreak); + munmap (moveto, (size_t) (mtop - moveto)); + mtop = moveto; + } + } + else + { + /* We are allocating memory. Make sure we have an open file + descriptor and then go on to get the memory. */ + if ((fd == -1) && (fd = open ("/dev/zero", O_RDONLY)) < 0) + { + result = NULL; + } + else if (mbreak + size > mtop) + { + /* The request would move us past the end of the currently + mapped memory, so map in enough more memory to satisfy + the request. */ + moveto = PAGE_ALIGN (mbreak + size); + if (mmap (mtop, moveto - mtop, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_FIXED, fd, 0) == mtop) + { + mtop = moveto; + result = (PTR) mbreak; + mbreak += size; + } + } + else + { + result = (PTR) mbreak; + mbreak += size; + } + } + return (result); +} + +PTR +mmap_remap (base, mapsize, fd, foffset) + PTR base; + long mapsize; + int fd; + long foffset; +{ + /* FIXME: Quick hack, needs error checking and other attention. */ + munmap (mbase, (size_t) (mtop - mbase)); + mbase = base; + mtop = mbase + mapsize; + base = mmap (base, mapsize, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_FIXED, dup (fd), foffset); + return (base); +} + + +#endif /* HAVE_MMAP */ |