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 <stdarg.h>
9#include <unistd.h>
10#include <errno.h>
11#include <fcntl.h>
12#include <sched.h>
13#include <signal.h>
14#include <string.h>
15#include <sys/mman.h>
16#include <sys/stat.h>
17#include <sys/wait.h>
18#include <sys/time.h>
19#include <sys/resource.h>
20#include <asm/unistd.h>
21#include <init.h>
22#include <os.h>
23#include <mem_user.h>
24#include <ptrace_user.h>
25#include <registers.h>
26#include <skas.h>
27
28static void ptrace_child(void)
29{
30	int ret;
31	/* Calling os_getpid because some libcs cached getpid incorrectly */
32	int pid = os_getpid(), ppid = getppid();
33	int sc_result;
34
35	if (change_sig(SIGWINCH, 0) < 0 ||
36	    ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) {
37		perror("ptrace");
38		kill(pid, SIGKILL);
39	}
40	kill(pid, SIGSTOP);
41
42	/*
43	 * This syscall will be intercepted by the parent. Don't call more than
44	 * once, please.
45	 */
46	sc_result = os_getpid();
47
48	if (sc_result == pid)
49		/* Nothing modified by the parent, we are running normally. */
50		ret = 1;
51	else if (sc_result == ppid)
52		/*
53		 * Expected in check_ptrace and check_sysemu when they succeed
54		 * in modifying the stack frame
55		 */
56		ret = 0;
57	else
58		/* Serious trouble! This could be caused by a bug in host 2.6
59		 * SKAS3/2.6 patch before release -V6, together with a bug in
60		 * the UML code itself.
61		 */
62		ret = 2;
63
64	exit(ret);
65}
66
67static void fatal_perror(const char *str)
68{
69	perror(str);
70	exit(1);
71}
72
73static void fatal(char *fmt, ...)
74{
75	va_list list;
76
77	va_start(list, fmt);
78	vfprintf(stderr, fmt, list);
79	va_end(list);
80
81	exit(1);
82}
83
84static void non_fatal(char *fmt, ...)
85{
86	va_list list;
87
88	va_start(list, fmt);
89	vfprintf(stderr, fmt, list);
90	va_end(list);
91}
92
93static int start_ptraced_child(void)
94{
95	int pid, n, status;
96
97	fflush(stdout);
98
99	pid = fork();
100	if (pid == 0)
101		ptrace_child();
102	else if (pid < 0)
103		fatal_perror("start_ptraced_child : fork failed");
104
105	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
106	if (n < 0)
107		fatal_perror("check_ptrace : waitpid failed");
108	if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
109		fatal("check_ptrace : expected SIGSTOP, got status = %d",
110		      status);
111
112	return pid;
113}
114
115/* When testing for SYSEMU support, if it is one of the broken versions, we
116 * must just avoid using sysemu, not panic, but only if SYSEMU features are
117 * broken.
118 * So only for SYSEMU features we test mustpanic, while normal host features
119 * must work anyway!
120 */
121static int stop_ptraced_child(int pid, int exitcode, int mustexit)
122{
123	int status, n, ret = 0;
124
125	if (ptrace(PTRACE_CONT, pid, 0, 0) < 0) {
126		perror("stop_ptraced_child : ptrace failed");
127		return -1;
128	}
129	CATCH_EINTR(n = waitpid(pid, &status, 0));
130	if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
131		int exit_with = WEXITSTATUS(status);
132		if (exit_with == 2)
133			non_fatal("check_ptrace : child exited with status 2. "
134				  "\nDisabling SYSEMU support.\n");
135		non_fatal("check_ptrace : child exited with exitcode %d, while "
136			  "expecting %d; status 0x%x\n", exit_with,
137			  exitcode, status);
138		if (mustexit)
139			exit(1);
140		ret = -1;
141	}
142
143	return ret;
144}
145
146/* Changed only during early boot */
147static int force_sysemu_disabled = 0;
148
149static int __init nosysemu_cmd_param(char *str, int* add)
150{
151	force_sysemu_disabled = 1;
152	return 0;
153}
154
155__uml_setup("nosysemu", nosysemu_cmd_param,
156"nosysemu\n"
157"    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
158"    SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
159"    behaviour of ptrace() and helps reducing host context switch rate.\n"
160"    To make it working, you need a kernel patch for your host, too.\n"
161"    See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
162"    information.\n\n");
163
164static void __init check_sysemu(void)
165{
166	unsigned long regs[MAX_REG_NR];
167	int pid, n, status, count=0;
168
169	non_fatal("Checking syscall emulation patch for ptrace...");
170	sysemu_supported = 0;
171	pid = start_ptraced_child();
172
173	if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
174		goto fail;
175
176	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
177	if (n < 0)
178		fatal_perror("check_sysemu : wait failed");
179	if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
180		fatal("check_sysemu : expected SIGTRAP, got status = %d\n",
181		      status);
182
183	if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
184		fatal_perror("check_sysemu : PTRACE_GETREGS failed");
185	if (PT_SYSCALL_NR(regs) != __NR_getpid) {
186		non_fatal("check_sysemu got system call number %d, "
187			  "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
188		goto fail;
189	}
190
191	n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
192	if (n < 0) {
193		non_fatal("check_sysemu : failed to modify system call "
194			  "return");
195		goto fail;
196	}
197
198	if (stop_ptraced_child(pid, 0, 0) < 0)
199		goto fail_stopped;
200
201	sysemu_supported = 1;
202	non_fatal("OK\n");
203	set_using_sysemu(!force_sysemu_disabled);
204
205	non_fatal("Checking advanced syscall emulation patch for ptrace...");
206	pid = start_ptraced_child();
207
208	if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
209		   (void *) PTRACE_O_TRACESYSGOOD) < 0))
210		fatal_perror("check_sysemu: PTRACE_OLDSETOPTIONS failed");
211
212	while (1) {
213		count++;
214		if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
215			goto fail;
216		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
217		if (n < 0)
218			fatal_perror("check_sysemu: wait failed");
219
220		if (WIFSTOPPED(status) &&
221		    (WSTOPSIG(status) == (SIGTRAP|0x80))) {
222			if (!count) {
223				non_fatal("check_sysemu: SYSEMU_SINGLESTEP "
224					  "doesn't singlestep");
225				goto fail;
226			}
227			n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET,
228				   os_getpid());
229			if (n < 0)
230				fatal_perror("check_sysemu : failed to modify "
231					     "system call return");
232			break;
233		}
234		else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
235			count++;
236		else {
237			non_fatal("check_sysemu: expected SIGTRAP or "
238				  "(SIGTRAP | 0x80), got status = %d\n",
239				  status);
240			goto fail;
241		}
242	}
243	if (stop_ptraced_child(pid, 0, 0) < 0)
244		goto fail_stopped;
245
246	sysemu_supported = 2;
247	non_fatal("OK\n");
248
249	if (!force_sysemu_disabled)
250		set_using_sysemu(sysemu_supported);
251	return;
252
253fail:
254	stop_ptraced_child(pid, 1, 0);
255fail_stopped:
256	non_fatal("missing\n");
257}
258
259static void __init check_ptrace(void)
260{
261	int pid, syscall, n, status;
262
263	non_fatal("Checking that ptrace can change system call numbers...");
264	pid = start_ptraced_child();
265
266	if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
267		   (void *) PTRACE_O_TRACESYSGOOD) < 0))
268		fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
269
270	while (1) {
271		if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
272			fatal_perror("check_ptrace : ptrace failed");
273
274		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
275		if (n < 0)
276			fatal_perror("check_ptrace : wait failed");
277
278		if (!WIFSTOPPED(status) ||
279		   (WSTOPSIG(status) != (SIGTRAP | 0x80)))
280			fatal("check_ptrace : expected (SIGTRAP|0x80), "
281			       "got status = %d", status);
282
283		syscall = ptrace(PTRACE_PEEKUSER, pid, PT_SYSCALL_NR_OFFSET,
284				 0);
285		if (syscall == __NR_getpid) {
286			n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
287				   __NR_getppid);
288			if (n < 0)
289				fatal_perror("check_ptrace : failed to modify "
290					     "system call");
291			break;
292		}
293	}
294	stop_ptraced_child(pid, 0, 1);
295	non_fatal("OK\n");
296	check_sysemu();
297}
298
299extern void check_tmpexec(void);
300
301static void __init check_coredump_limit(void)
302{
303	struct rlimit lim;
304	int err = getrlimit(RLIMIT_CORE, &lim);
305
306	if (err) {
307		perror("Getting core dump limit");
308		return;
309	}
310
311	printf("Core dump limits :\n\tsoft - ");
312	if (lim.rlim_cur == RLIM_INFINITY)
313		printf("NONE\n");
314	else printf("%lu\n", lim.rlim_cur);
315
316	printf("\thard - ");
317	if (lim.rlim_max == RLIM_INFINITY)
318		printf("NONE\n");
319	else printf("%lu\n", lim.rlim_max);
320}
321
322void __init os_early_checks(void)
323{
324	int pid;
325
326	/* Print out the core dump limits early */
327	check_coredump_limit();
328
329	check_ptrace();
330
331	/* Need to check this early because mmapping happens before the
332	 * kernel is running.
333	 */
334	check_tmpexec();
335
336	pid = start_ptraced_child();
337	if (init_registers(pid))
338		fatal("Failed to initialize default registers");
339	stop_ptraced_child(pid, 1, 1);
340}
341
342int __init parse_iomem(char *str, int *add)
343{
344	struct iomem_region *new;
345	struct stat64 buf;
346	char *file, *driver;
347	int fd, size;
348
349	driver = str;
350	file = strchr(str,',');
351	if (file == NULL) {
352		fprintf(stderr, "parse_iomem : failed to parse iomem\n");
353		goto out;
354	}
355	*file = '\0';
356	file++;
357	fd = open(file, O_RDWR, 0);
358	if (fd < 0) {
359		perror("parse_iomem - Couldn't open io file");
360		goto out;
361	}
362
363	if (fstat64(fd, &buf) < 0) {
364		perror("parse_iomem - cannot stat_fd file");
365		goto out_close;
366	}
367
368	new = malloc(sizeof(*new));
369	if (new == NULL) {
370		perror("Couldn't allocate iomem_region struct");
371		goto out_close;
372	}
373
374	size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
375
376	*new = ((struct iomem_region) { .next		= iomem_regions,
377					.driver		= driver,
378					.fd		= fd,
379					.size		= size,
380					.phys		= 0,
381					.virt		= 0 });
382	iomem_regions = new;
383	iomem_size += new->size + UM_KERN_PAGE_SIZE;
384
385	return 0;
386 out_close:
387	close(fd);
388 out:
389	return 1;
390}
391