Diff markup

Differences between /userland/myprog14.c (Article 7.5) and /userland/myprog14.c (Article 9.5)

 /* Copyright (C) 2005 David Decotigny              /* Copyright (C) 2005 David Decotigny
                                                    
    This program is free software; you can redi        This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU Genera        modify it under the terms of the GNU General Public License
    as published by the Free Software Foundatio        as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any lat        of the License, or (at your option) any later version.
                                                       
    This program is distributed in the hope tha        This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the         but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details        GNU General Public License for more details.
                                                       
    You should have received a copy of the GNU         You should have received a copy of the GNU General Public License
    along with this program; if not, write to t        along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 3        Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    USA.                                               USA. 
 */                                                 */
                                                    
 #include <crt.h>                                   #include <crt.h>
 #include <libc.h>                                  #include <libc.h>
 #include <stdarg.h>                                #include <stdarg.h>
 #include <debug.h>                                 #include <debug.h>
                                                    
 /**                                                /**
  * @file myprog14.c                                 * @file myprog14.c
  *                                                  *
  * uaccess tests. Demonstrate that a page faul      * uaccess tests. Demonstrate that a page fault in kernel during
  * userspace access (with uaccess.c functions)      * userspace access (with uaccess.c functions) is NEVER (or at least
  * should not be) fatal:                            * should not be) fatal:
  *  - licit page faults are resolved as usual       *  - licit page faults are resolved as usual (COW, page_in, ...)
  *  - illicit page faults are caught and the u      *  - illicit page faults are caught and the uaccess functions tolerate
  *    and report it                                 *    and report it
  *                                                  *
  * We use the temporary syscall 4012 (hexdump)      * We use the temporary syscall 4012 (hexdump) to force the kernel to
  * call user_memcpy and do some page faults.        * call user_memcpy and do some page faults.
  */                                                 */
                                                    
 int main()                                     !!  int main(void)
 {                                                  {
   char * zoup;                                       char * zoup;
                                                   >>    int fd;
                                                    
                                                   >>    fd = open("/dev/zero", O_RDWR);
   zoup = mmap(0, 8192,                               zoup = mmap(0, 8192,
               PROT_READ | PROT_WRITE,                            PROT_READ | PROT_WRITE,
               MAP_SHARED,                                        MAP_SHARED,
               "/dev/zero", 34);                !!                fd, 34);
                                                   >>    close(fd);
                                                   >>  
   bochs_printf("mapped @%x\n", (unsigned)zoup)       bochs_printf("mapped @%x\n", (unsigned)zoup);
                                                    
   /* Do some forks to complicate things */           /* Do some forks to complicate things */
   fork();                                            fork();
   fork();                                            fork();
                                                    
   /* Force the first page of the mapping to be       /* Force the first page of the mapping to be allocated */
   *zoup = 'a';                                       *zoup = 'a';
                                                    
   _sos_syscall2(4012, (unsigned)zoup, 16384);        _sos_syscall2(4012, (unsigned)zoup, 16384);
   /*                                                 /*
    * all 3 cases are handled here:                    * all 3 cases are handled here:
    *  - [zoup, zoup + 4kB[: no page fault at a        *  - [zoup, zoup + 4kB[: no page fault at all (page already mapped)
    *  - [zoup+4kB, zoup + 8kB[: page fault =>         *  - [zoup+4kB, zoup + 8kB[: page fault => /dev/zero page_in() called
    *  - [zoup+8kB, ...[: page fault => illegal        *  - [zoup+8kB, ...[: page fault => illegal user address =>
    *    user_memcpy reports that only 8kB out         *    user_memcpy reports that only 8kB out of the 16kB could be
    *    hexdumped                                     *    hexdumped
    */                                                 */
                                                    
   return 0;                                          return 0;
 }                                                  }