arch/um/kernel/skas/clone.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
   4  * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   5  */
   6
   7 #include <signal.h>
   8 #include <sched.h>
   9 #include <asm/unistd.h>
  10 #include <sys/time.h>
  11 #include <as-layout.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         remap_stack(data->fd, data->offset);
  40         goto done;
  41
  42  out:
  43         /*
  44          * save current result.
  45          * Parent: pid;
  46          * child: retcode of mmap already saved and it jumps around this
  47          * assignment
  48          */
  49         data->err = err;
  50  done:
  51         trap_myself();
  52 }