summaryrefslogtreecommitdiff
path: root/arch/um/os-Linux/main.c
blob: f1fee2b9123942c117ac1d498027da2f33f004b9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
/*
 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <sys/resource.h>
#include <as-layout.h>
#include <init.h>
#include <kern_util.h>
#include <os.h>
#include <um_malloc.h>

#define PGD_BOUND (4 * 1024 * 1024)
#define STACKSIZE (8 * 1024 * 1024)
#define THREAD_NAME_LEN (256)

long elf_aux_hwcap;

static void set_stklim(void)
{
	struct rlimit lim;

	if (getrlimit(RLIMIT_STACK, &lim) < 0) {
		perror("getrlimit");
		exit(1);
	}
	if ((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)) {
		lim.rlim_cur = STACKSIZE;
		if (setrlimit(RLIMIT_STACK, &lim) < 0) {
			perror("setrlimit");
			exit(1);
		}
	}
}

static void last_ditch_exit(int sig)
{
	uml_cleanup();
	exit(1);
}

static void install_fatal_handler(int sig)
{
	struct sigaction action;

	/* All signals are enabled in this handler ... */
	sigemptyset(&action.sa_mask);

	/*
	 * ... including the signal being handled, plus we want the
	 * handler reset to the default behavior, so that if an exit
	 * handler is hanging for some reason, the UML will just die
	 * after this signal is sent a second time.
	 */
	action.sa_flags = SA_RESETHAND | SA_NODEFER;
	action.sa_restorer = NULL;
	action.sa_handler = last_ditch_exit;
	if (sigaction(sig, &action, NULL) < 0) {
		os_warn("failed to install handler for signal %d "
			"- errno = %d\n", sig, errno);
		exit(1);
	}
}

#define UML_LIB_PATH	":" OS_LIB_PATH "/uml"

static void setup_env_path(void)
{
	char *new_path = NULL;
	char *old_path = NULL;
	int path_len = 0;

	old_path = getenv("PATH");
	/*
	 * if no PATH variable is set or it has an empty value
	 * just use the default + /usr/lib/uml
	 */
	if (!old_path || (path_len = strlen(old_path)) == 0) {
		if (putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH))
			perror("couldn't putenv");
		return;
	}

	/* append /usr/lib/uml to the existing path */
	path_len += strlen("PATH=" UML_LIB_PATH) + 1;
	new_path = malloc(path_len);
	if (!new_path) {
		perror("couldn't malloc to set a new PATH");
		return;
	}
	snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
	if (putenv(new_path)) {
		perror("couldn't putenv to set a new PATH");
		free(new_path);
	}
}

extern void scan_elf_aux( char **envp);

int __init main(int argc, char **argv, char **envp)
{
	char **new_argv;
	int ret, i, err;

	set_stklim();

	setup_env_path();

	setsid();

	new_argv = malloc((argc + 1) * sizeof(char *));
	if (new_argv == NULL) {
		perror("Mallocing argv");
		exit(1);
	}
	for (i = 0; i < argc; i++) {
		new_argv[i] = strdup(argv[i]);
		if (new_argv[i] == NULL) {
			perror("Mallocing an arg");
			exit(1);
		}
	}
	new_argv[argc] = NULL;

	/*
	 * Allow these signals to bring down a UML if all other
	 * methods of control fail.
	 */
	install_fatal_handler(SIGINT);
	install_fatal_handler(SIGTERM);

#ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
	scan_elf_aux(envp);
#endif

	change_sig(SIGPIPE, 0);
	ret = linux_main(argc, argv);

	/*
	 * Disable SIGPROF - I have no idea why libc doesn't do this or turn
	 * off the profiling time, but UML dies with a SIGPROF just before
	 * exiting when profiling is active.
	 */
	change_sig(SIGPROF, 0);

	/*
	 * This signal stuff used to be in the reboot case.  However,
	 * sometimes a timer signal can come in when we're halting (reproducably
	 * when writing out gcov information, presumably because that takes
	 * some time) and cause a segfault.
	 */

	/* stop timers and set timer signal to be ignored */
	os_timer_disable();

	/* disable SIGIO for the fds and set SIGIO to be ignored */
	err = deactivate_all_fds();
	if (err)
		os_warn("deactivate_all_fds failed, errno = %d\n", -err);

	/*
	 * Let any pending signals fire now.  This ensures
	 * that they won't be delivered after the exec, when
	 * they are definitely not expected.
	 */
	unblock_signals();

	os_info("\n");
	/* Reboot */
	if (ret) {
		execvp(new_argv[0], new_argv);
		perror("Failed to exec kernel");
		ret = 1;
	}
	return uml_exitcode;
}

extern void *__real_malloc(int);

void *__wrap_malloc(int size)
{
	void *ret;

	if (!kmalloc_ok)
		return __real_malloc(size);
	else if (size <= UM_KERN_PAGE_SIZE)
		/* finding contiguous pages can be hard*/
		ret = uml_kmalloc(size, UM_GFP_KERNEL);
	else ret = vmalloc(size);

	/*
	 * glibc people insist that if malloc fails, errno should be
	 * set by malloc as well. So we do.
	 */
	if (ret == NULL)
		errno = ENOMEM;

	return ret;
}

void *__wrap_calloc(int n, int size)
{
	void *ptr = __wrap_malloc(n * size);

	if (ptr == NULL)
		return NULL;
	memset(ptr, 0, n * size);
	return ptr;
}

extern void __real_free(void *);

extern unsigned long high_physmem;

void __wrap_free(void *ptr)
{
	unsigned long addr = (unsigned long) ptr;

	/*
	 * We need to know how the allocation happened, so it can be correctly
	 * freed.  This is done by seeing what region of memory the pointer is
	 * in -
	 * 	physical memory - kmalloc/kfree
	 *	kernel virtual memory - vmalloc/vfree
	 * 	anywhere else - malloc/free
	 * If kmalloc is not yet possible, then either high_physmem and/or
	 * end_vm are still 0 (as at startup), in which case we call free, or
	 * we have set them, but anyway addr has not been allocated from those
	 * areas. So, in both cases __real_free is called.
	 *
	 * CAN_KMALLOC is checked because it would be bad to free a buffer
	 * with kmalloc/vmalloc after they have been turned off during
	 * shutdown.
	 * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
	 * there is a possibility for memory leaks.
	 */

	if ((addr >= uml_physmem) && (addr < high_physmem)) {
		if (kmalloc_ok)
			kfree(ptr);
	}
	else if ((addr >= start_vm) && (addr < end_vm)) {
		if (kmalloc_ok)
			vfree(ptr);
	}
	else __real_free(ptr);
}