1
2
3
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
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
44
45
46 sc_result = os_getpid();
47
48 if (sc_result == pid)
49
50 ret = 1;
51 else if (sc_result == ppid)
52
53
54
55
56 ret = 0;
57 else
58
59
60
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
116
117
118
119
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
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).\n"
158" SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
159" behaviour of ptrace() and helps reduce host context switch rates.\n"
160" To make it work, 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 os_info("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 os_info("OK\n");
203 set_using_sysemu(!force_sysemu_disabled);
204
205 os_info("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 os_info("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 os_info("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 os_info("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 os_info("Core dump limits :\n\tsoft - ");
312 if (lim.rlim_cur == RLIM_INFINITY)
313 os_info("NONE\n");
314 else
315 os_info("%llu\n", (unsigned long long)lim.rlim_cur);
316
317 os_info("\thard - ");
318 if (lim.rlim_max == RLIM_INFINITY)
319 os_info("NONE\n");
320 else
321 os_info("%llu\n", (unsigned long long)lim.rlim_max);
322}
323
324void __init os_early_checks(void)
325{
326 int pid;
327
328
329 check_coredump_limit();
330
331 check_ptrace();
332
333
334
335
336 check_tmpexec();
337
338 pid = start_ptraced_child();
339 if (init_registers(pid))
340 fatal("Failed to initialize default registers");
341 stop_ptraced_child(pid, 1, 1);
342}
343
344int __init parse_iomem(char *str, int *add)
345{
346 struct iomem_region *new;
347 struct stat64 buf;
348 char *file, *driver;
349 int fd, size;
350
351 driver = str;
352 file = strchr(str,',');
353 if (file == NULL) {
354 os_warn("parse_iomem : failed to parse iomem\n");
355 goto out;
356 }
357 *file = '\0';
358 file++;
359 fd = open(file, O_RDWR, 0);
360 if (fd < 0) {
361 perror("parse_iomem - Couldn't open io file");
362 goto out;
363 }
364
365 if (fstat64(fd, &buf) < 0) {
366 perror("parse_iomem - cannot stat_fd file");
367 goto out_close;
368 }
369
370 new = malloc(sizeof(*new));
371 if (new == NULL) {
372 perror("Couldn't allocate iomem_region struct");
373 goto out_close;
374 }
375
376 size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
377
378 *new = ((struct iomem_region) { .next = iomem_regions,
379 .driver = driver,
380 .fd = fd,
381 .size = size,
382 .phys = 0,
383 .virt = 0 });
384 iomem_regions = new;
385 iomem_size += new->size + UM_KERN_PAGE_SIZE;
386
387 return 0;
388 out_close:
389 close(fd);
390 out:
391 return 1;
392}
393
