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Linux/arch/um/os-Linux/main.c

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  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 = uml_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 }
262 

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