src/runtime/trymap.c

   1 /*
   2  * a utility for experimenting with mmap()-at-absolute-address-ranges
   3  * as a crude way of checking whether it's reasonable for SBCL to
   4  * reserve those address ranges for itself
   5  */
   6
   7 /*
   8  * This software is part of the SBCL system. See the README file for
   9  * more information.
  10  *
  11  * This software is derived from the CMU CL system, which was
  12  * written at Carnegie Mellon University and released into the
  13  * public domain. The software is in the public domain and is
  14  * provided with absolutely no warranty. See the COPYING and CREDITS
  15  * files for more information.
  16  */
  17
  18 #include <stdio.h>
  19 #include <sys/types.h>
  20 #include <sys/mman.h>
  21
  22 long
  23 hexparse(char *s)
  24 {
  25     long result;
  26     if (1 != sscanf(s, "%lx", &result)) {
  27         fprintf(stderr, "can't parse \"%s\" as hexadecimal integer\n", s);
  28         exit(1);
  29     }
  30     return result;
  31 }
  32
  33 int
  34 main(int argc, char *argv[])
  35 {
  36     char *addr;
  37     char *requested_addr;
  38
  39     /* FIXME: It would be nice to make the no-command-line-arguments
  40      * case of this program automatically check all the spaces that
  41      * SBCL likes to map. Then we could execute this program as a
  42      * sanity check in make-target-2.sh before we try to execute sbcl
  43      * itself. */
  44     if (argc != 3) {
  45         fprintf(stderr, "usage: %s $addr $size\n", argv[0]);
  46         exit(1);
  47     }
  48
  49     requested_addr = (char*)hexparse(argv[1]);
  50     addr = mmap(requested_addr,
  51                 hexparse(argv[2]),
  52                 0x7,
  53                 MAP_PRIVATE | MAP_ANON | MAP_FIXED,
  54                 -1,
  55                 0);
  56
  57     /* FIXME: It would be nice to make this a stronger test. E.g.
  58      * besides just trying to mmap() the area, we could check that the
  59      * area is not already mapped (perhaps by checking that attempts
  60      * to reference the to-be-mapped area cause SIGSEGV or SIGBUS).
  61      * (At least on OpenBSD, "A successful mmap deletes any previous
  62      * mapping in the allocated address range.") */
  63     if (addr != requested_addr) {
  64         perror("mmap");
  65     }
  66
  67     exit(0);
  68 }