arch/um/os-Linux/util.c

   1 /*
   2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <unistd.h>
   9 #include <errno.h>
  10 #include <signal.h>
  11 #include <string.h>
  12 #include <termios.h>
  13 #include <wait.h>
  14 #include <sys/mman.h>
  15 #include <sys/utsname.h>
  16 #include "kern_constants.h"
  17 #include "os.h"
  18 #include "user.h"
  19
  20 void stack_protections(unsigned long address)
  21 {
  22         if (mprotect((void *) address, UM_THREAD_SIZE,
  23                     PROT_READ | PROT_WRITE | PROT_EXEC) < 0)
  24                 panic("protecting stack failed, errno = %d", errno);
  25 }
  26
  27 int raw(int fd)
  28 {
  29         struct termios tt;
  30         int err;
  31
  32         CATCH_EINTR(err = tcgetattr(fd, &tt));
  33         if (err < 0)
  34                 return -errno;
  35
  36         cfmakeraw(&tt);
  37
  38         CATCH_EINTR(err = tcsetattr(fd, TCSADRAIN, &tt));
  39         if (err < 0)
  40                 return -errno;
  41
  42         /*
  43          * XXX tcsetattr could have applied only some changes
  44          * (and cfmakeraw() is a set of changes)
  45          */
  46         return 0;
  47 }
  48
  49 void setup_machinename(char *machine_out)
  50 {
  51         struct utsname host;
  52
  53         uname(&host);
  54 #ifdef UML_CONFIG_UML_X86
  55 # ifndef UML_CONFIG_64BIT
  56         if (!strcmp(host.machine, "x86_64")) {
  57                 strcpy(machine_out, "i686");
  58                 return;
  59         }
  60 # else
  61         if (!strcmp(host.machine, "i686")) {
  62                 strcpy(machine_out, "x86_64");
  63                 return;
  64         }
  65 # endif
  66 #endif
  67         strcpy(machine_out, host.machine);
  68 }
  69
  70 void setup_hostinfo(char *buf, int len)
  71 {
  72         struct utsname host;
  73
  74         uname(&host);
  75         snprintf(buf, len, "%s %s %s %s %s", host.sysname, host.nodename,
  76                  host.release, host.version, host.machine);
  77 }
  78
  79 /*
  80  * We cannot use glibc's abort(). It makes use of tgkill() which
  81  * has no effect within UML's kernel threads.
  82  * After that glibc would execute an invalid instruction to kill
  83  * the calling process and UML crashes with SIGSEGV.
  84  */
  85 static inline void __attribute__ ((noreturn)) uml_abort(void)
  86 {
  87         sigset_t sig;
  88
  89         fflush(NULL);
  90
  91         if (!sigemptyset(&sig) && !sigaddset(&sig, SIGABRT))
  92                 sigprocmask(SIG_UNBLOCK, &sig, 0);
  93
  94         for (;;)
  95                 if (kill(getpid(), SIGABRT) < 0)
  96                         exit(127);
  97 }
  98
  99 void os_dump_core(void)
 100 {
 101         int pid;
 102
 103         signal(SIGSEGV, SIG_DFL);
 104
 105         /*
 106          * We are about to SIGTERM this entire process group to ensure that
 107          * nothing is around to run after the kernel exits.  The
 108          * kernel wants to abort, not die through SIGTERM, so we
 109          * ignore it here.
 110          */
 111
 112         signal(SIGTERM, SIG_IGN);
 113         kill(0, SIGTERM);
 114         /*
 115          * Most of the other processes associated with this UML are
 116          * likely sTopped, so give them a SIGCONT so they see the
 117          * SIGTERM.
 118          */
 119         kill(0, SIGCONT);
 120
 121         /*
 122          * Now, having sent signals to everyone but us, make sure they
 123          * die by ptrace.  Processes can survive what's been done to
 124          * them so far - the mechanism I understand is receiving a
 125          * SIGSEGV and segfaulting immediately upon return.  There is
 126          * always a SIGSEGV pending, and (I'm guessing) signals are
 127          * processed in numeric order so the SIGTERM (signal 15 vs
 128          * SIGSEGV being signal 11) is never handled.
 129          *
 130          * Run a waitpid loop until we get some kind of error.
 131          * Hopefully, it's ECHILD, but there's not a lot we can do if
 132          * it's something else.  Tell os_kill_ptraced_process not to
 133          * wait for the child to report its death because there's
 134          * nothing reasonable to do if that fails.
 135          */
 136
 137         while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0)
 138                 os_kill_ptraced_process(pid, 0);
 139
 140         uml_abort();
 141 }
 142
 143 void um_early_printk(const char *s, unsigned int n)
 144 {
 145         printf("%.*s", n, s);
 146 }