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_util.h>
  16 #include <os.h>
  17 #include <um_malloc.h>
  18
  19 #define PGD_BOUND (4 * 1024 * 1024)
  20 #define STACKSIZE (8 * 1024 * 1024)
  21 #define THREAD_NAME_LEN (256)
  22
  23 long elf_aux_hwcap;
  24
  25 static void set_stklim(void)
  26 {
  27         struct rlimit lim;
  28
  29         if (getrlimit(RLIMIT_STACK, &lim) < 0) {
  30                 perror("getrlimit");
  31                 exit(1);
  32         }
  33         if ((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)) {
  34                 lim.rlim_cur = STACKSIZE;
  35                 if (setrlimit(RLIMIT_STACK, &lim) < 0) {
  36                         perror("setrlimit");
  37                         exit(1);
  38                 }
  39         }
  40 }
  41
  42 static __init void do_uml_initcalls(void)
  43 {
  44         initcall_t *call;
  45
  46         call = &__uml_initcall_start;
  47         while (call < &__uml_initcall_end) {
  48                 (*call)();
  49                 call++;
  50         }
  51 }
  52
  53 static void last_ditch_exit(int sig)
  54 {
  55         uml_cleanup();
  56         exit(1);
  57 }
  58
  59 static void install_fatal_handler(int sig)
  60 {
  61         struct sigaction action;
  62
  63         /* All signals are enabled in this handler ... */
  64         sigemptyset(&action.sa_mask);
  65
  66         /*
  67          * ... including the signal being handled, plus we want the
  68          * handler reset to the default behavior, so that if an exit
  69          * handler is hanging for some reason, the UML will just die
  70          * after this signal is sent a second time.
  71          */
  72         action.sa_flags = SA_RESETHAND | SA_NODEFER;
  73         action.sa_restorer = NULL;
  74         action.sa_handler = last_ditch_exit;
  75         if (sigaction(sig, &action, NULL) < 0) {
  76                 printf("failed to install handler for signal %d - errno = %d\n",
  77                        sig, errno);
  78                 exit(1);
  79         }
  80 }
  81
  82 #define UML_LIB_PATH    ":" OS_LIB_PATH "/uml"
  83
  84 static void setup_env_path(void)
  85 {
  86         char *new_path = NULL;
  87         char *old_path = NULL;
  88         int path_len = 0;
  89
  90         old_path = getenv("PATH");
  91         /*
  92          * if no PATH variable is set or it has an empty value
  93          * just use the default + /usr/lib/uml
  94          */
  95         if (!old_path || (path_len = strlen(old_path)) == 0) {
  96                 if (putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH))
  97                         perror("couldn't putenv");
  98                 return;
  99         }
 100
 101         /* append /usr/lib/uml to the existing path */
 102         path_len += strlen("PATH=" UML_LIB_PATH) + 1;
 103         new_path = malloc(path_len);
 104         if (!new_path) {
 105                 perror("couldn't malloc to set a new PATH");
 106                 return;
 107         }
 108         snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
 109         if (putenv(new_path)) {
 110                 perror("couldn't putenv to set a new PATH");
 111                 free(new_path);
 112         }
 113 }
 114
 115 extern void scan_elf_aux( char **envp);
 116
 117 int __init main(int argc, char **argv, char **envp)
 118 {
 119         char **new_argv;
 120         int ret, i, err;
 121
 122         set_stklim();
 123
 124         setup_env_path();
 125
 126         setsid();
 127
 128         new_argv = malloc((argc + 1) * sizeof(char *));
 129         if (new_argv == NULL) {
 130                 perror("Mallocing argv");
 131                 exit(1);
 132         }
 133         for (i = 0; i < argc; i++) {
 134                 new_argv[i] = strdup(argv[i]);
 135                 if (new_argv[i] == NULL) {
 136                         perror("Mallocing an arg");
 137                         exit(1);
 138                 }
 139         }
 140         new_argv[argc] = NULL;
 141
 142         /*
 143          * Allow these signals to bring down a UML if all other
 144          * methods of control fail.
 145          */
 146         install_fatal_handler(SIGINT);
 147         install_fatal_handler(SIGTERM);
 148
 149 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 150         scan_elf_aux(envp);
 151 #endif
 152
 153         do_uml_initcalls();
 154         change_sig(SIGPIPE, 0);
 155         ret = linux_main(argc, argv);
 156
 157         /*
 158          * Disable SIGPROF - I have no idea why libc doesn't do this or turn
 159          * off the profiling time, but UML dies with a SIGPROF just before
 160          * exiting when profiling is active.
 161          */
 162         change_sig(SIGPROF, 0);
 163
 164         /*
 165          * This signal stuff used to be in the reboot case.  However,
 166          * sometimes a SIGVTALRM can come in when we're halting (reproducably
 167          * when writing out gcov information, presumably because that takes
 168          * some time) and cause a segfault.
 169          */
 170
 171         /* stop timers and set SIGVTALRM to be ignored */
 172         disable_timer();
 173
 174         /* disable SIGIO for the fds and set SIGIO to be ignored */
 175         err = deactivate_all_fds();
 176         if (err)
 177                 printf("deactivate_all_fds failed, errno = %d\n", -err);
 178
 179         /*
 180          * Let any pending signals fire now.  This ensures
 181          * that they won't be delivered after the exec, when
 182          * they are definitely not expected.
 183          */
 184         unblock_signals();
 185
 186         /* Reboot */
 187         if (ret) {
 188                 printf("\n");
 189                 execvp(new_argv[0], new_argv);
 190                 perror("Failed to exec kernel");
 191                 ret = 1;
 192         }
 193         printf("\n");
 194         return uml_exitcode;
 195 }
 196
 197 extern void *__real_malloc(int);
 198
 199 void *__wrap_malloc(int size)
 200 {
 201         void *ret;
 202
 203         if (!kmalloc_ok)
 204                 return __real_malloc(size);
 205         else if (size <= UM_KERN_PAGE_SIZE)
 206                 /* finding contiguous pages can be hard*/
 207                 ret = uml_kmalloc(size, UM_GFP_KERNEL);
 208         else ret = vmalloc(size);
 209
 210         /*
 211          * glibc people insist that if malloc fails, errno should be
 212          * set by malloc as well. So we do.
 213          */
 214         if (ret == NULL)
 215                 errno = ENOMEM;
 216
 217         return ret;
 218 }
 219
 220 void *__wrap_calloc(int n, int size)
 221 {
 222         void *ptr = __wrap_malloc(n * size);
 223
 224         if (ptr == NULL)
 225                 return NULL;
 226         memset(ptr, 0, n * size);
 227         return ptr;
 228 }
 229
 230 extern void __real_free(void *);
 231
 232 extern unsigned long high_physmem;
 233
 234 void __wrap_free(void *ptr)
 235 {
 236         unsigned long addr = (unsigned long) ptr;
 237
 238         /*
 239          * We need to know how the allocation happened, so it can be correctly
 240          * freed.  This is done by seeing what region of memory the pointer is
 241          * in -
 242          *      physical memory - kmalloc/kfree
 243          *      kernel virtual memory - vmalloc/vfree
 244          *      anywhere else - malloc/free
 245          * If kmalloc is not yet possible, then either high_physmem and/or
 246          * end_vm are still 0 (as at startup), in which case we call free, or
 247          * we have set them, but anyway addr has not been allocated from those
 248          * areas. So, in both cases __real_free is called.
 249          *
 250          * CAN_KMALLOC is checked because it would be bad to free a buffer
 251          * with kmalloc/vmalloc after they have been turned off during
 252          * shutdown.
 253          * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
 254          * there is a possibility for memory leaks.
 255          */
 256
 257         if ((addr >= uml_physmem) && (addr < high_physmem)) {
 258                 if (kmalloc_ok)
 259                         kfree(ptr);
 260         }
 261         else if ((addr >= start_vm) && (addr < end_vm)) {
 262                 if (kmalloc_ok)
 263                         vfree(ptr);
 264         }
 265         else __real_free(ptr);
 266 }