arch/um/os-Linux/main.c

   1 /*
   2  * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <unistd.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <signal.h>
  11 #include <errno.h>
  12 #include <sys/resource.h>
  13 #include <sys/mman.h>
  14 #include <sys/user.h>
  15 #include "kern_util.h"
  16 #include "as-layout.h"
  17 #include "mem_user.h"
  18 #include "irq_user.h"
  19 #include "user.h"
  20 #include "init.h"
  21 #include "mode.h"
  22 #include "choose-mode.h"
  23 #include "uml-config.h"
  24 #include "os.h"
  25 #include "um_malloc.h"
  26 #include "kern_constants.h"
  27
  28 #define PGD_BOUND (4 * 1024 * 1024)
  29 #define STACKSIZE (8 * 1024 * 1024)
  30 #define THREAD_NAME_LEN (256)
  31
  32 static void set_stklim(void)
  33 {
  34         struct rlimit lim;
  35
  36         if(getrlimit(RLIMIT_STACK, &lim) < 0){
  37                 perror("getrlimit");
  38                 exit(1);
  39         }
  40         if((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)){
  41                 lim.rlim_cur = STACKSIZE;
  42                 if(setrlimit(RLIMIT_STACK, &lim) < 0){
  43                         perror("setrlimit");
  44                         exit(1);
  45                 }
  46         }
  47 }
  48
  49 static __init void do_uml_initcalls(void)
  50 {
  51         initcall_t *call;
  52
  53         call = &__uml_initcall_start;
  54         while (call < &__uml_initcall_end){
  55                 (*call)();
  56                 call++;
  57         }
  58 }
  59
  60 static void last_ditch_exit(int sig)
  61 {
  62         uml_cleanup();
  63         exit(1);
  64 }
  65
  66 static void install_fatal_handler(int sig)
  67 {
  68         struct sigaction action;
  69
  70         /* All signals are enabled in this handler ... */
  71         sigemptyset(&action.sa_mask);
  72
  73         /* ... including the signal being handled, plus we want the
  74          * handler reset to the default behavior, so that if an exit
  75          * handler is hanging for some reason, the UML will just die
  76          * after this signal is sent a second time.
  77          */
  78         action.sa_flags = SA_RESETHAND | SA_NODEFER;
  79         action.sa_restorer = NULL;
  80         action.sa_handler = last_ditch_exit;
  81         if(sigaction(sig, &action, NULL) < 0){
  82                 printf("failed to install handler for signal %d - errno = %d\n",
  83                        errno);
  84                 exit(1);
  85         }
  86 }
  87
  88 #define UML_LIB_PATH    ":/usr/lib/uml"
  89
  90 static void setup_env_path(void)
  91 {
  92         char *new_path = NULL;
  93         char *old_path = NULL;
  94         int path_len = 0;
  95
  96         old_path = getenv("PATH");
  97         /* if no PATH variable is set or it has an empty value
  98          * just use the default + /usr/lib/uml
  99          */
 100         if (!old_path || (path_len = strlen(old_path)) == 0) {
 101                 putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH);
 102                 return;
 103         }
 104
 105         /* append /usr/lib/uml to the existing path */
 106         path_len += strlen("PATH=" UML_LIB_PATH) + 1;
 107         new_path = malloc(path_len);
 108         if (!new_path) {
 109                 perror("coudn't malloc to set a new PATH");
 110                 return;
 111         }
 112         snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
 113         putenv(new_path);
 114 }
 115
 116 extern int uml_exitcode;
 117
 118 extern void scan_elf_aux( char **envp);
 119
 120 int __init main(int argc, char **argv, char **envp)
 121 {
 122         char **new_argv;
 123         int ret, i, err;
 124
 125         set_stklim();
 126
 127         setup_env_path();
 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         /* 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         install_fatal_handler(SIGHUP);
 149
 150         scan_elf_aux( envp);
 151
 152         do_uml_initcalls();
 153         ret = linux_main(argc, argv);
 154
 155         /* Disable SIGPROF - I have no idea why libc doesn't do this or turn
 156          * off the profiling time, but UML dies with a SIGPROF just before
 157          * exiting when profiling is active.
 158          */
 159         change_sig(SIGPROF, 0);
 160
 161         /* This signal stuff used to be in the reboot case.  However,
 162          * sometimes a SIGVTALRM can come in when we're halting (reproducably
 163          * when writing out gcov information, presumably because that takes
 164          * some time) and cause a segfault.
 165          */
 166
 167         /* stop timers and set SIG*ALRM to be ignored */
 168         disable_timer();
 169
 170         /* disable SIGIO for the fds and set SIGIO to be ignored */
 171         err = deactivate_all_fds();
 172         if(err)
 173                 printf("deactivate_all_fds failed, errno = %d\n", -err);
 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 #define CAN_KMALLOC() \
 193         (kmalloc_ok && CHOOSE_MODE((os_getpid() != tracing_pid), 1))
 194
 195 extern void *__real_malloc(int);
 196
 197 void *__wrap_malloc(int size)
 198 {
 199         void *ret;
 200
 201         if(!CAN_KMALLOC())
 202                 return __real_malloc(size);
 203         else if(size <= UM_KERN_PAGE_SIZE)
 204                 /* finding contiguous pages can be hard*/
 205                 ret = kmalloc(size, UM_GFP_KERNEL);
 206         else ret = vmalloc(size);
 207
 208         /* glibc people insist that if malloc fails, errno should be
 209          * set by malloc as well. So we do.
 210          */
 211         if(ret == NULL)
 212                 errno = ENOMEM;
 213
 214         return ret;
 215 }
 216
 217 void *__wrap_calloc(int n, int size)
 218 {
 219         void *ptr = __wrap_malloc(n * size);
 220
 221         if(ptr == NULL)
 222                 return NULL;
 223         memset(ptr, 0, n * size);
 224         return ptr;
 225 }
 226
 227 extern void __real_free(void *);
 228
 229 extern unsigned long high_physmem;
 230
 231 void __wrap_free(void *ptr)
 232 {
 233         unsigned long addr = (unsigned long) ptr;
 234
 235         /* We need to know how the allocation happened, so it can be correctly
 236          * freed.  This is done by seeing what region of memory the pointer is
 237          * in -
 238          *      physical memory - kmalloc/kfree
 239          *      kernel virtual memory - vmalloc/vfree
 240          *      anywhere else - malloc/free
 241          * If kmalloc is not yet possible, then either high_physmem and/or
 242          * end_vm are still 0 (as at startup), in which case we call free, or
 243          * we have set them, but anyway addr has not been allocated from those
 244          * areas. So, in both cases __real_free is called.
 245          *
 246          * CAN_KMALLOC is checked because it would be bad to free a buffer
 247          * with kmalloc/vmalloc after they have been turned off during
 248          * shutdown.
 249          * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
 250          * there is a possibility for memory leaks.
 251          */
 252
 253         if((addr >= uml_physmem) && (addr < high_physmem)){
 254                 if(CAN_KMALLOC())
 255                         kfree(ptr);
 256         }
 257         else if((addr >= start_vm) && (addr < end_vm)){
 258                 if(CAN_KMALLOC())
 259                         vfree(ptr);
 260         }
 261         else __real_free(ptr);
 262 }