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

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  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                 printf("failed to install handler for signal %d - errno = %d\n",
 78                        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                 printf("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         /* Reboot */
188         if (ret) {
189                 printf("\n");
190                 execvp(new_argv[0], new_argv);
191                 perror("Failed to exec kernel");
192                 ret = 1;
193         }
194         printf("\n");
195         return uml_exitcode;
196 }
197 
198 extern void *__real_malloc(int);
199 
200 void *__wrap_malloc(int size)
201 {
202         void *ret;
203 
204         if (!kmalloc_ok)
205                 return __real_malloc(size);
206         else if (size <= UM_KERN_PAGE_SIZE)
207                 /* finding contiguous pages can be hard*/
208                 ret = uml_kmalloc(size, UM_GFP_KERNEL);
209         else ret = vmalloc(size);
210 
211         /*
212          * glibc people insist that if malloc fails, errno should be
213          * set by malloc as well. So we do.
214          */
215         if (ret == NULL)
216                 errno = ENOMEM;
217 
218         return ret;
219 }
220 
221 void *__wrap_calloc(int n, int size)
222 {
223         void *ptr = __wrap_malloc(n * size);
224 
225         if (ptr == NULL)
226                 return NULL;
227         memset(ptr, 0, n * size);
228         return ptr;
229 }
230 
231 extern void __real_free(void *);
232 
233 extern unsigned long high_physmem;
234 
235 void __wrap_free(void *ptr)
236 {
237         unsigned long addr = (unsigned long) ptr;
238 
239         /*
240          * We need to know how the allocation happened, so it can be correctly
241          * freed.  This is done by seeing what region of memory the pointer is
242          * in -
243          *      physical memory - kmalloc/kfree
244          *      kernel virtual memory - vmalloc/vfree
245          *      anywhere else - malloc/free
246          * If kmalloc is not yet possible, then either high_physmem and/or
247          * end_vm are still 0 (as at startup), in which case we call free, or
248          * we have set them, but anyway addr has not been allocated from those
249          * areas. So, in both cases __real_free is called.
250          *
251          * CAN_KMALLOC is checked because it would be bad to free a buffer
252          * with kmalloc/vmalloc after they have been turned off during
253          * shutdown.
254          * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
255          * there is a possibility for memory leaks.
256          */
257 
258         if ((addr >= uml_physmem) && (addr < high_physmem)) {
259                 if (kmalloc_ok)
260                         kfree(ptr);
261         }
262         else if ((addr >= start_vm) && (addr < end_vm)) {
263                 if (kmalloc_ok)
264                         vfree(ptr);
265         }
266         else __real_free(ptr);
267 }
268 

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