~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/arch/um/os-Linux/start_up.c

Version: ~ [ linux-5.11-rc3 ] ~ [ linux-5.10.7 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.89 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.167 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.215 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.251 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.251 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.85 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 
 28 static 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 
 67 static void fatal_perror(const char *str)
 68 {
 69         perror(str);
 70         exit(1);
 71 }
 72 
 73 static 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 
 84 static 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 
 93 static 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  */
121 static 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 */
147 static int force_sysemu_disabled = 0;
148 
149 static 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 
164 static 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 
253 fail:
254         stop_ptraced_child(pid, 1, 0);
255 fail_stopped:
256         non_fatal("missing\n");
257 }
258 
259 static 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 
299 extern void check_tmpexec(void);
300 
301 static 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 
322 void __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 
342 int __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 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp