arch/um/os-Linux/main.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 <sys/resource.h>
  13 #include "as-layout.h"
  14 #include "init.h"
  15 #include "kern_constants.h"
  16 #include "kern_util.h"
  17 #include "os.h"
  18 #include "um_malloc.h"
  19
  20 #define PGD_BOUND (4 * 1024 * 1024)
  21 #define STACKSIZE (8 * 1024 * 1024)
  22 #define THREAD_NAME_LEN (256)
  23
  24 static void set_stklim(void)
  25 {
  26         struct rlimit lim;
  27
  28         if (getrlimit(RLIMIT_STACK, &lim) < 0) {
  29                 perror("getrlimit");
  30                 exit(1);
  31         }
  32         if ((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)) {
  33                 lim.rlim_cur = STACKSIZE;
  34                 if (setrlimit(RLIMIT_STACK, &lim) < 0) {
  35                         perror("setrlimit");
  36                         exit(1);
  37                 }
  38         }
  39 }
  40
  41 static __init void do_uml_initcalls(void)
  42 {
  43         initcall_t *call;
  44
  45         call = &__uml_initcall_start;
  46         while (call < &__uml_initcall_end) {
  47                 (*call)();
  48                 call++;
  49         }
  50 }
  51
  52 static void last_ditch_exit(int sig)
  53 {
  54         uml_cleanup();
  55         exit(1);
  56 }
  57
  58 static void install_fatal_handler(int sig)
  59 {
  60         struct sigaction action;
  61
  62         /* All signals are enabled in this handler ... */
  63         sigemptyset(&action.sa_mask);
  64
  65         /*
  66          * ... including the signal being handled, plus we want the
  67          * handler reset to the default behavior, so that if an exit
  68          * handler is hanging for some reason, the UML will just die
  69          * after this signal is sent a second time.
  70          */
  71         action.sa_flags = SA_RESETHAND | SA_NODEFER;
  72         action.sa_restorer = NULL;
  73         action.sa_handler = last_ditch_exit;
  74         if (sigaction(sig, &action, NULL) < 0) {
  75                 printf("failed to install handler for signal %d - errno = %d\n",
  76                        errno);
  77                 exit(1);
  78         }
  79 }
  80
  81 #define UML_LIB_PATH    ":/usr/lib/uml"
  82
  83 static void setup_env_path(void)
  84 {
  85         char *new_path = NULL;
  86         char *old_path = NULL;
  87         int path_len = 0;
  88
  89         old_path = getenv("PATH");
  90         /*
  91          * if no PATH variable is set or it has an empty value
  92          * just use the default + /usr/lib/uml
  93          */
  94         if (!old_path || (path_len = strlen(old_path)) == 0) {
  95                 putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH);
  96                 return;
  97         }
  98
  99         /* append /usr/lib/uml to the existing path */
 100         path_len += strlen("PATH=" UML_LIB_PATH) + 1;
 101         new_path = malloc(path_len);
 102         if (!new_path) {
 103                 perror("coudn't malloc to set a new PATH");
 104                 return;
 105         }
 106         snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
 107         putenv(new_path);
 108 }
 109
 110 extern int uml_exitcode;
 111
 112 extern void scan_elf_aux( char **envp);
 113
 114 int __init main(int argc, char **argv, char **envp)
 115 {
 116         char **new_argv;
 117         int ret, i, err;
 118
 119         set_stklim();
 120
 121         setup_env_path();
 122
 123         new_argv = malloc((argc + 1) * sizeof(char *));
 124         if (new_argv == NULL) {
 125                 perror("Mallocing argv");
 126                 exit(1);
 127         }
 128         for (i = 0; i < argc; i++) {
 129                 new_argv[i] = strdup(argv[i]);
 130                 if (new_argv[i] == NULL) {
 131                         perror("Mallocing an arg");
 132                         exit(1);
 133                 }
 134         }
 135         new_argv[argc] = NULL;
 136
 137         /*
 138          * Allow these signals to bring down a UML if all other
 139          * methods of control fail.
 140          */
 141         install_fatal_handler(SIGINT);
 142         install_fatal_handler(SIGTERM);
 143         install_fatal_handler(SIGHUP);
 144
 145         scan_elf_aux(envp);
 146
 147         do_uml_initcalls();
 148         ret = linux_main(argc, argv);
 149
 150         /*
 151          * Disable SIGPROF - I have no idea why libc doesn't do this or turn
 152          * off the profiling time, but UML dies with a SIGPROF just before
 153          * exiting when profiling is active.
 154          */
 155         change_sig(SIGPROF, 0);
 156
 157         /*
 158          * This signal stuff used to be in the reboot case.  However,
 159          * sometimes a SIGVTALRM can come in when we're halting (reproducably
 160          * when writing out gcov information, presumably because that takes
 161          * some time) and cause a segfault.
 162          */
 163
 164         /* stop timers and set SIGVTALRM to be ignored */
 165         disable_timer();
 166
 167         /* disable SIGIO for the fds and set SIGIO to be ignored */
 168         err = deactivate_all_fds();
 169         if (err)
 170                 printf("deactivate_all_fds failed, errno = %d\n", -err);
 171
 172         /*
 173          * Let any pending signals fire now.  This ensures
 174          * that they won't be delivered after the exec, when
 175          * they are definitely not expected.
 176          */
 177         unblock_signals();
 178
 179         /* Reboot */
 180         if (ret) {
 181                 printf("\n");
 182                 execvp(new_argv[0], new_argv);
 183                 perror("Failed to exec kernel");
 184                 ret = 1;
 185         }
 186         printf("\n");
 187         return uml_exitcode;
 188 }
 189
 190 extern void *__real_malloc(int);
 191
 192 void *__wrap_malloc(int size)
 193 {
 194         void *ret;
 195
 196         if (!kmalloc_ok)
 197                 return __real_malloc(size);
 198         else if (size <= UM_KERN_PAGE_SIZE)
 199                 /* finding contiguous pages can be hard*/
 200                 ret = kmalloc(size, UM_GFP_KERNEL);
 201         else ret = vmalloc(size);
 202
 203         /*
 204          * glibc people insist that if malloc fails, errno should be
 205          * set by malloc as well. So we do.
 206          */
 207         if (ret == NULL)
 208                 errno = ENOMEM;
 209
 210         return ret;
 211 }
 212
 213 void *__wrap_calloc(int n, int size)
 214 {
 215         void *ptr = __wrap_malloc(n * size);
 216
 217         if (ptr == NULL)
 218                 return NULL;
 219         memset(ptr, 0, n * size);
 220         return ptr;
 221 }
 222
 223 extern void __real_free(void *);
 224
 225 extern unsigned long high_physmem;
 226
 227 void __wrap_free(void *ptr)
 228 {
 229         unsigned long addr = (unsigned long) ptr;
 230
 231         /*
 232          * We need to know how the allocation happened, so it can be correctly
 233          * freed.  This is done by seeing what region of memory the pointer is
 234          * in -
 235          *      physical memory - kmalloc/kfree
 236          *      kernel virtual memory - vmalloc/vfree
 237          *      anywhere else - malloc/free
 238          * If kmalloc is not yet possible, then either high_physmem and/or
 239          * end_vm are still 0 (as at startup), in which case we call free, or
 240          * we have set them, but anyway addr has not been allocated from those
 241          * areas. So, in both cases __real_free is called.
 242          *
 243          * CAN_KMALLOC is checked because it would be bad to free a buffer
 244          * with kmalloc/vmalloc after they have been turned off during
 245          * shutdown.
 246          * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
 247          * there is a possibility for memory leaks.
 248          */
 249
 250         if ((addr >= uml_physmem) && (addr < high_physmem)) {
 251                 if (kmalloc_ok)
 252                         kfree(ptr);
 253         }
 254         else if ((addr >= start_vm) && (addr < end_vm)) {
 255                 if (kmalloc_ok)
 256                         vfree(ptr);
 257         }
 258         else __real_free(ptr);
 259 }