arch/um/os-Linux/main.c

   1 /*
   2  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
   3  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   4  * Licensed under the GPL
   5  */
   6
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <unistd.h>
  10 #include <errno.h>
  11 #include <signal.h>
  12 #include <string.h>
  13 #include <sys/resource.h>
  14 #include <as-layout.h>
  15 #include <init.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 long elf_aux_hwcap;
  25
  26 static void set_stklim(void)
  27 {
  28         struct rlimit lim;
  29
  30         if (getrlimit(RLIMIT_STACK, &lim) < 0) {
  31                 perror("getrlimit");
  32                 exit(1);
  33         }
  34         if ((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)) {
  35                 lim.rlim_cur = STACKSIZE;
  36                 if (setrlimit(RLIMIT_STACK, &lim) < 0) {
  37                         perror("setrlimit");
  38                         exit(1);
  39                 }
  40         }
  41 }
  42
  43 static __init void do_uml_initcalls(void)
  44 {
  45         initcall_t *call;
  46
  47         call = &__uml_initcall_start;
  48         while (call < &__uml_initcall_end) {
  49                 (*call)();
  50                 call++;
  51         }
  52 }
  53
  54 static void last_ditch_exit(int sig)
  55 {
  56         uml_cleanup();
  57         exit(1);
  58 }
  59
  60 static void install_fatal_handler(int sig)
  61 {
  62         struct sigaction action;
  63
  64         /* All signals are enabled in this handler ... */
  65         sigemptyset(&action.sa_mask);
  66
  67         /*
  68          * ... including the signal being handled, plus we want the
  69          * handler reset to the default behavior, so that if an exit
  70          * handler is hanging for some reason, the UML will just die
  71          * after this signal is sent a second time.
  72          */
  73         action.sa_flags = SA_RESETHAND | SA_NODEFER;
  74         action.sa_restorer = NULL;
  75         action.sa_handler = last_ditch_exit;
  76         if (sigaction(sig, &action, NULL) < 0) {
  77                 os_warn("failed to install handler for signal %d "
  78                         "- errno = %d\n", sig, errno);
  79                 exit(1);
  80         }
  81 }
  82
  83 #define UML_LIB_PATH    ":" OS_LIB_PATH "/uml"
  84
  85 static void setup_env_path(void)
  86 {
  87         char *new_path = NULL;
  88         char *old_path = NULL;
  89         int path_len = 0;
  90
  91         old_path = getenv("PATH");
  92         /*
  93          * if no PATH variable is set or it has an empty value
  94          * just use the default + /usr/lib/uml
  95          */
  96         if (!old_path || (path_len = strlen(old_path)) == 0) {
  97                 if (putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH))
  98                         perror("couldn't putenv");
  99                 return;
 100         }
 101
 102         /* append /usr/lib/uml to the existing path */
 103         path_len += strlen("PATH=" UML_LIB_PATH) + 1;
 104         new_path = malloc(path_len);
 105         if (!new_path) {
 106                 perror("couldn't malloc to set a new PATH");
 107                 return;
 108         }
 109         snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
 110         if (putenv(new_path)) {
 111                 perror("couldn't putenv to set a new PATH");
 112                 free(new_path);
 113         }
 114 }
 115
 116 extern void scan_elf_aux( char **envp);
 117
 118 int __init main(int argc, char **argv, char **envp)
 119 {
 120         char **new_argv;
 121         int ret, i, err;
 122
 123         set_stklim();
 124
 125         setup_env_path();
 126
 127         setsid();
 128
 129         new_argv = malloc((argc + 1) * sizeof(char *));
 130         if (new_argv == NULL) {
 131                 perror("Mallocing argv");
 132                 exit(1);
 133         }
 134         for (i = 0; i < argc; i++) {
 135                 new_argv[i] = strdup(argv[i]);
 136                 if (new_argv[i] == NULL) {
 137                         perror("Mallocing an arg");
 138                         exit(1);
 139                 }
 140         }
 141         new_argv[argc] = NULL;
 142
 143         /*
 144          * Allow these signals to bring down a UML if all other
 145          * methods of control fail.
 146          */
 147         install_fatal_handler(SIGINT);
 148         install_fatal_handler(SIGTERM);
 149
 150 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 151         scan_elf_aux(envp);
 152 #endif
 153
 154         do_uml_initcalls();
 155         change_sig(SIGPIPE, 0);
 156         ret = linux_main(argc, argv);
 157
 158         /*
 159          * Disable SIGPROF - I have no idea why libc doesn't do this or turn
 160          * off the profiling time, but UML dies with a SIGPROF just before
 161          * exiting when profiling is active.
 162          */
 163         change_sig(SIGPROF, 0);
 164
 165         /*
 166          * This signal stuff used to be in the reboot case.  However,
 167          * sometimes a timer signal can come in when we're halting (reproducably
 168          * when writing out gcov information, presumably because that takes
 169          * some time) and cause a segfault.
 170          */
 171
 172         /* stop timers and set timer signal to be ignored */
 173         os_timer_disable();
 174
 175         /* disable SIGIO for the fds and set SIGIO to be ignored */
 176         err = deactivate_all_fds();
 177         if (err)
 178                 os_warn("deactivate_all_fds failed, errno = %d\n", -err);
 179
 180         /*
 181          * Let any pending signals fire now.  This ensures
 182          * that they won't be delivered after the exec, when
 183          * they are definitely not expected.
 184          */
 185         unblock_signals();
 186
 187         os_info("\n");
 188         /* Reboot */
 189         if (ret) {
 190                 execvp(new_argv[0], new_argv);
 191                 perror("Failed to exec kernel");
 192                 ret = 1;
 193         }
 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 }