arch/um/kernel/skas/clone.c

   1 /*
   2  * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <signal.h>
   7 #include <sched.h>
   8 #include <asm/unistd.h>
   9 #include <sys/time.h>
  10 #include "as-layout.h"
  11 #include "kern_constants.h"
  12 #include "ptrace_user.h"
  13 #include "stub-data.h"
  14 #include "sysdep/stub.h"
  15
  16 /*
  17  * This is in a separate file because it needs to be compiled with any
  18  * extraneous gcc flags (-pg, -fprofile-arcs, -ftest-coverage) disabled
  19  *
  20  * Use UM_KERN_PAGE_SIZE instead of PAGE_SIZE because that calls getpagesize
  21  * on some systems.
  22  */
  23
  24 void __attribute__ ((__section__ (".__syscall_stub")))
  25 stub_clone_handler(void)
  26 {
  27         struct stub_data *data = (struct stub_data *) STUB_DATA;
  28         long err;
  29
  30         err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD,
  31                             STUB_DATA + UM_KERN_PAGE_SIZE / 2 - sizeof(void *));
  32         if (err != 0)
  33                 goto out;
  34
  35         err = stub_syscall4(__NR_ptrace, PTRACE_TRACEME, 0, 0, 0);
  36         if (err)
  37                 goto out;
  38
  39         err = stub_syscall3(__NR_setitimer, ITIMER_VIRTUAL,
  40                             (long) &data->timer, 0);
  41         if (err)
  42                 goto out;
  43
  44         remap_stack(data->fd, data->offset);
  45         goto done;
  46
  47  out:
  48         /*
  49          * save current result.
  50          * Parent: pid;
  51          * child: retcode of mmap already saved and it jumps around this
  52          * assignment
  53          */
  54         data->err = err;
  55  done:
  56         trap_myself();
  57 }