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                        sig, 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                 if (putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH))
  96                         perror("couldn't putenv");
  97                 return;
  98         }
  99
 100         /* append /usr/lib/uml to the existing path */
 101         path_len += strlen("PATH=" UML_LIB_PATH) + 1;
 102         new_path = malloc(path_len);
 103         if (!new_path) {
 104                 perror("couldn't malloc to set a new PATH");
 105                 return;
 106         }
 107         snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
 108         if (putenv(new_path)) {
 109                 perror("couldn't putenv to set a new PATH");
 110                 free(new_path);
 111         }
 112 }
 113
 114 extern void scan_elf_aux( char **envp);
 115
 116 int __init main(int argc, char **argv, char **envp)
 117 {
 118         char **new_argv;
 119         int ret, i, err;
 120
 121         set_stklim();
 122
 123         setup_env_path();
 124
 125         new_argv = malloc((argc + 1) * sizeof(char *));
 126         if (new_argv == NULL) {
 127                 perror("Mallocing argv");
 128                 exit(1);
 129         }
 130         for (i = 0; i < argc; i++) {
 131                 new_argv[i] = strdup(argv[i]);
 132                 if (new_argv[i] == NULL) {
 133                         perror("Mallocing an arg");
 134                         exit(1);
 135                 }
 136         }
 137         new_argv[argc] = NULL;
 138
 139         /*
 140          * Allow these signals to bring down a UML if all other
 141          * methods of control fail.
 142          */
 143         install_fatal_handler(SIGINT);
 144         install_fatal_handler(SIGTERM);
 145         install_fatal_handler(SIGHUP);
 146
 147         scan_elf_aux(envp);
 148
 149         do_uml_initcalls();
 150         ret = linux_main(argc, argv);
 151
 152         /*
 153          * Disable SIGPROF - I have no idea why libc doesn't do this or turn
 154          * off the profiling time, but UML dies with a SIGPROF just before
 155          * exiting when profiling is active.
 156          */
 157         change_sig(SIGPROF, 0);
 158
 159         /*
 160          * This signal stuff used to be in the reboot case.  However,
 161          * sometimes a SIGVTALRM can come in when we're halting (reproducably
 162          * when writing out gcov information, presumably because that takes
 163          * some time) and cause a segfault.
 164          */
 165
 166         /* stop timers and set SIGVTALRM to be ignored */
 167         disable_timer();
 168
 169         /* disable SIGIO for the fds and set SIGIO to be ignored */
 170         err = deactivate_all_fds();
 171         if (err)
 172                 printf("deactivate_all_fds failed, errno = %d\n", -err);
 173
 174         /*
 175          * Let any pending signals fire now.  This ensures
 176          * that they won't be delivered after the exec, when
 177          * they are definitely not expected.
 178          */
 179         unblock_signals();
 180
 181         /* Reboot */
 182         if (ret) {
 183                 printf("\n");
 184                 execvp(new_argv[0], new_argv);
 185                 perror("Failed to exec kernel");
 186                 ret = 1;
 187         }
 188         printf("\n");
 189         return uml_exitcode;
 190 }
 191
 192 extern void *__real_malloc(int);
 193
 194 void *__wrap_malloc(int size)
 195 {
 196         void *ret;
 197
 198         if (!kmalloc_ok)
 199                 return __real_malloc(size);
 200         else if (size <= UM_KERN_PAGE_SIZE)
 201                 /* finding contiguous pages can be hard*/
 202                 ret = kmalloc(size, UM_GFP_KERNEL);
 203         else ret = vmalloc(size);
 204
 205         /*
 206          * glibc people insist that if malloc fails, errno should be
 207          * set by malloc as well. So we do.
 208          */
 209         if (ret == NULL)
 210                 errno = ENOMEM;
 211
 212         return ret;
 213 }
 214
 215 void *__wrap_calloc(int n, int size)
 216 {
 217         void *ptr = __wrap_malloc(n * size);
 218
 219         if (ptr == NULL)
 220                 return NULL;
 221         memset(ptr, 0, n * size);
 222         return ptr;
 223 }
 224
 225 extern void __real_free(void *);
 226
 227 extern unsigned long high_physmem;
 228
 229 void __wrap_free(void *ptr)
 230 {
 231         unsigned long addr = (unsigned long) ptr;
 232
 233         /*
 234          * We need to know how the allocation happened, so it can be correctly
 235          * freed.  This is done by seeing what region of memory the pointer is
 236          * in -
 237          *      physical memory - kmalloc/kfree
 238          *      kernel virtual memory - vmalloc/vfree
 239          *      anywhere else - malloc/free
 240          * If kmalloc is not yet possible, then either high_physmem and/or
 241          * end_vm are still 0 (as at startup), in which case we call free, or
 242          * we have set them, but anyway addr has not been allocated from those
 243          * areas. So, in both cases __real_free is called.
 244          *
 245          * CAN_KMALLOC is checked because it would be bad to free a buffer
 246          * with kmalloc/vmalloc after they have been turned off during
 247          * shutdown.
 248          * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
 249          * there is a possibility for memory leaks.
 250          */
 251
 252         if ((addr >= uml_physmem) && (addr < high_physmem)) {
 253                 if (kmalloc_ok)
 254                         kfree(ptr);
 255         }
 256         else if ((addr >= start_vm) && (addr < end_vm)) {
 257                 if (kmalloc_ok)
 258                         vfree(ptr);
 259         }
 260         else __real_free(ptr);
 261 }