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 <asm/page.h>
  16 #include "kern_util.h"
  17 #include "as-layout.h"
  18 #include "mem_user.h"
  19 #include "irq_user.h"
  20 #include "user.h"
  21 #include "init.h"
  22 #include "mode.h"
  23 #include "choose-mode.h"
  24 #include "uml-config.h"
  25 #include "os.h"
  26 #include "um_malloc.h"
  27
  28 /* Set in main, unchanged thereafter */
  29 char *linux_prog;
  30
  31 #define PGD_BOUND (4 * 1024 * 1024)
  32 #define STACKSIZE (8 * 1024 * 1024)
  33 #define THREAD_NAME_LEN (256)
  34
  35 static void set_stklim(void)
  36 {
  37         struct rlimit lim;
  38
  39         if(getrlimit(RLIMIT_STACK, &lim) < 0){
  40                 perror("getrlimit");
  41                 exit(1);
  42         }
  43         if((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)){
  44                 lim.rlim_cur = STACKSIZE;
  45                 if(setrlimit(RLIMIT_STACK, &lim) < 0){
  46                         perror("setrlimit");
  47                         exit(1);
  48                 }
  49         }
  50 }
  51
  52 static __init void do_uml_initcalls(void)
  53 {
  54         initcall_t *call;
  55
  56         call = &__uml_initcall_start;
  57         while (call < &__uml_initcall_end){
  58                 (*call)();
  59                 call++;
  60         }
  61 }
  62
  63 static void last_ditch_exit(int sig)
  64 {
  65         uml_cleanup();
  66         exit(1);
  67 }
  68
  69 static void install_fatal_handler(int sig)
  70 {
  71         struct sigaction action;
  72
  73         /* All signals are enabled in this handler ... */
  74         sigemptyset(&action.sa_mask);
  75
  76         /* ... including the signal being handled, plus we want the
  77          * handler reset to the default behavior, so that if an exit
  78          * handler is hanging for some reason, the UML will just die
  79          * after this signal is sent a second time.
  80          */
  81         action.sa_flags = SA_RESETHAND | SA_NODEFER;
  82         action.sa_restorer = NULL;
  83         action.sa_handler = last_ditch_exit;
  84         if(sigaction(sig, &action, NULL) < 0){
  85                 printf("failed to install handler for signal %d - errno = %d\n",
  86                        errno);
  87                 exit(1);
  88         }
  89 }
  90
  91 #define UML_LIB_PATH    ":/usr/lib/uml"
  92
  93 static void setup_env_path(void)
  94 {
  95         char *new_path = NULL;
  96         char *old_path = NULL;
  97         int path_len = 0;
  98
  99         old_path = getenv("PATH");
 100         /* if no PATH variable is set or it has an empty value
 101          * just use the default + /usr/lib/uml
 102          */
 103         if (!old_path || (path_len = strlen(old_path)) == 0) {
 104                 putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH);
 105                 return;
 106         }
 107
 108         /* append /usr/lib/uml to the existing path */
 109         path_len += strlen("PATH=" UML_LIB_PATH) + 1;
 110         new_path = malloc(path_len);
 111         if (!new_path) {
 112                 perror("coudn't malloc to set a new PATH");
 113                 return;
 114         }
 115         snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
 116         putenv(new_path);
 117 }
 118
 119 extern int uml_exitcode;
 120
 121 extern void scan_elf_aux( char **envp);
 122
 123 int __init main(int argc, char **argv, char **envp)
 124 {
 125         char **new_argv;
 126         int ret, i, err;
 127
 128 #ifdef UML_CONFIG_CMDLINE_ON_HOST
 129         /* Allocate memory for thread command lines */
 130         if(argc < 2 || strlen(argv[1]) < THREAD_NAME_LEN - 1){
 131
 132                 char padding[THREAD_NAME_LEN] = {
 133                         [ 0 ...  THREAD_NAME_LEN - 2] = ' ', '\0'
 134                 };
 135
 136                 new_argv = malloc((argc + 2) * sizeof(char*));
 137                 if(!new_argv) {
 138                         perror("Allocating extended argv");
 139                         exit(1);
 140                 }
 141
 142                 new_argv[0] = argv[0];
 143                 new_argv[1] = padding;
 144
 145                 for(i = 2; i <= argc; i++)
 146                         new_argv[i] = argv[i - 1];
 147                 new_argv[argc + 1] = NULL;
 148
 149                 execvp(new_argv[0], new_argv);
 150                 perror("execing with extended args");
 151                 exit(1);
 152         }
 153 #endif
 154
 155         linux_prog = argv[0];
 156
 157         set_stklim();
 158
 159         setup_env_path();
 160
 161         new_argv = malloc((argc + 1) * sizeof(char *));
 162         if(new_argv == NULL){
 163                 perror("Mallocing argv");
 164                 exit(1);
 165         }
 166         for(i=0;i<argc;i++){
 167                 new_argv[i] = strdup(argv[i]);
 168                 if(new_argv[i] == NULL){
 169                         perror("Mallocing an arg");
 170                         exit(1);
 171                 }
 172         }
 173         new_argv[argc] = NULL;
 174
 175         /* Allow these signals to bring down a UML if all other
 176          * methods of control fail.
 177          */
 178         install_fatal_handler(SIGINT);
 179         install_fatal_handler(SIGTERM);
 180         install_fatal_handler(SIGHUP);
 181
 182         scan_elf_aux( envp);
 183
 184         do_uml_initcalls();
 185         ret = linux_main(argc, argv);
 186
 187         /* Disable SIGPROF - I have no idea why libc doesn't do this or turn
 188          * off the profiling time, but UML dies with a SIGPROF just before
 189          * exiting when profiling is active.
 190          */
 191         change_sig(SIGPROF, 0);
 192
 193         /* This signal stuff used to be in the reboot case.  However,
 194          * sometimes a SIGVTALRM can come in when we're halting (reproducably
 195          * when writing out gcov information, presumably because that takes
 196          * some time) and cause a segfault.
 197          */
 198
 199         /* stop timers and set SIG*ALRM to be ignored */
 200         disable_timer();
 201
 202         /* disable SIGIO for the fds and set SIGIO to be ignored */
 203         err = deactivate_all_fds();
 204         if(err)
 205                 printf("deactivate_all_fds failed, errno = %d\n", -err);
 206
 207         /* Let any pending signals fire now.  This ensures
 208          * that they won't be delivered after the exec, when
 209          * they are definitely not expected.
 210          */
 211         unblock_signals();
 212
 213         /* Reboot */
 214         if(ret){
 215                 printf("\n");
 216                 execvp(new_argv[0], new_argv);
 217                 perror("Failed to exec kernel");
 218                 ret = 1;
 219         }
 220         printf("\n");
 221         return uml_exitcode;
 222 }
 223
 224 #define CAN_KMALLOC() \
 225         (kmalloc_ok && CHOOSE_MODE((os_getpid() != tracing_pid), 1))
 226
 227 extern void *__real_malloc(int);
 228
 229 void *__wrap_malloc(int size)
 230 {
 231         void *ret;
 232
 233         if(!CAN_KMALLOC())
 234                 return __real_malloc(size);
 235         else if(size <= PAGE_SIZE) /* finding contiguos pages can be hard*/
 236                 ret = um_kmalloc(size);
 237         else ret = um_vmalloc(size);
 238
 239         /* glibc people insist that if malloc fails, errno should be
 240          * set by malloc as well. So we do.
 241          */
 242         if(ret == NULL)
 243                 errno = ENOMEM;
 244
 245         return ret;
 246 }
 247
 248 void *__wrap_calloc(int n, int size)
 249 {
 250         void *ptr = __wrap_malloc(n * size);
 251
 252         if(ptr == NULL)
 253                 return NULL;
 254         memset(ptr, 0, n * size);
 255         return ptr;
 256 }
 257
 258 extern void __real_free(void *);
 259
 260 extern unsigned long high_physmem;
 261
 262 void __wrap_free(void *ptr)
 263 {
 264         unsigned long addr = (unsigned long) ptr;
 265
 266         /* We need to know how the allocation happened, so it can be correctly
 267          * freed.  This is done by seeing what region of memory the pointer is
 268          * in -
 269          *      physical memory - kmalloc/kfree
 270          *      kernel virtual memory - vmalloc/vfree
 271          *      anywhere else - malloc/free
 272          * If kmalloc is not yet possible, then either high_physmem and/or
 273          * end_vm are still 0 (as at startup), in which case we call free, or
 274          * we have set them, but anyway addr has not been allocated from those
 275          * areas. So, in both cases __real_free is called.
 276          *
 277          * CAN_KMALLOC is checked because it would be bad to free a buffer
 278          * with kmalloc/vmalloc after they have been turned off during
 279          * shutdown.
 280          * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
 281          * there is a possibility for memory leaks.
 282          */
 283
 284         if((addr >= uml_physmem) && (addr < high_physmem)){
 285                 if(CAN_KMALLOC())
 286                         kfree(ptr);
 287         }
 288         else if((addr >= start_vm) && (addr < end_vm)){
 289                 if(CAN_KMALLOC())
 290                         vfree(ptr);
 291         }
 292         else __real_free(ptr);
 293 }