arch/um/kernel/skas/clone.c

   1 #include <sched.h>
   2 #include <signal.h>
   3 #include <sys/mman.h>
   4 #include <sys/time.h>
   5 #include <asm/unistd.h>
   6 #include <asm/page.h>
   7 #include "ptrace_user.h"
   8 #include "skas.h"
   9 #include "stub-data.h"
  10 #include "uml-config.h"
  11 #include "sysdep/stub.h"
  12 #include "kern_constants.h"
  13
  14 /* This is in a separate file because it needs to be compiled with any
  15  * extraneous gcc flags (-pg, -fprofile-arcs, -ftest-coverage) disabled
  16  *
  17  * Use UM_KERN_PAGE_SIZE instead of PAGE_SIZE because that calls getpagesize
  18  * on some systems.
  19  */
  20
  21 #define STUB_DATA(field) (((struct stub_data *) UML_CONFIG_STUB_DATA)->field)
  22
  23 void __attribute__ ((__section__ (".__syscall_stub")))
  24 stub_clone_handler(void)
  25 {
  26         long err;
  27
  28         err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD,
  29                             UML_CONFIG_STUB_DATA + UM_KERN_PAGE_SIZE / 2 -
  30                             sizeof(void *));
  31         if(err != 0)
  32                 goto out;
  33
  34         err = stub_syscall4(__NR_ptrace, PTRACE_TRACEME, 0, 0, 0);
  35         if(err)
  36                 goto out;
  37
  38         err = stub_syscall3(__NR_setitimer, ITIMER_VIRTUAL,
  39                             (long) &STUB_DATA(timer), 0);
  40         if(err)
  41                 goto out;
  42
  43         err = stub_syscall6(STUB_MMAP_NR, UML_CONFIG_STUB_DATA,
  44                             UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
  45                             MAP_FIXED | MAP_SHARED, STUB_DATA(fd),
  46                             STUB_DATA(offset));
  47  out:
  48         /* save current result. Parent: pid; child: retcode of mmap */
  49         STUB_DATA(err) = err;
  50         trap_myself();
  51 }