release/src-rt-6.x/linux/linux-2.6/arch/um/os-Linux/start_up.c

   1 /*
   2  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <pty.h>
   7 #include <stdio.h>
   8 #include <stddef.h>
   9 #include <stdarg.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <unistd.h>
  13 #include <signal.h>
  14 #include <sched.h>
  15 #include <fcntl.h>
  16 #include <errno.h>
  17 #include <sys/time.h>
  18 #include <sys/wait.h>
  19 #include <sys/mman.h>
  20 #include <sys/resource.h>
  21 #include <asm/unistd.h>
  22 #include <asm/page.h>
  23 #include <sys/types.h>
  24 #include "kern_util.h"
  25 #include "user.h"
  26 #include "signal_kern.h"
  27 #include "sysdep/ptrace.h"
  28 #include "sysdep/sigcontext.h"
  29 #include "irq_user.h"
  30 #include "ptrace_user.h"
  31 #include "mem_user.h"
  32 #include "init.h"
  33 #include "os.h"
  34 #include "uml-config.h"
  35 #include "choose-mode.h"
  36 #include "mode.h"
  37 #include "tempfile.h"
  38 #include "kern_constants.h"
  39
  40 #ifdef UML_CONFIG_MODE_SKAS
  41 #include "skas.h"
  42 #include "skas_ptrace.h"
  43 #include "registers.h"
  44 #endif
  45
  46 static int ptrace_child(void *arg)
  47 {
  48         int ret;
  49         int pid = os_getpid(), ppid = getppid();
  50         int sc_result;
  51
  52         change_sig(SIGWINCH, 0);
  53         if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
  54                 perror("ptrace");
  55                 os_kill_process(pid, 0);
  56         }
  57         kill(pid, SIGSTOP);
  58
  59         /*This syscall will be intercepted by the parent. Don't call more than
  60          * once, please.*/
  61         sc_result = os_getpid();
  62
  63         if (sc_result == pid)
  64                 ret = 1; /*Nothing modified by the parent, we are running
  65                            normally.*/
  66         else if (sc_result == ppid)
  67                 ret = 0; /*Expected in check_ptrace and check_sysemu when they
  68                            succeed in modifying the stack frame*/
  69         else
  70                 ret = 2; /*Serious trouble! This could be caused by a bug in
  71                            host 2.6 SKAS3/2.6 patch before release -V6, together
  72                            with a bug in the UML code itself.*/
  73         _exit(ret);
  74 }
  75
  76 static void fatal_perror(char *str)
  77 {
  78         perror(str);
  79         exit(1);
  80 }
  81
  82 static void fatal(char *fmt, ...)
  83 {
  84         va_list list;
  85
  86         va_start(list, fmt);
  87         vprintf(fmt, list);
  88         va_end(list);
  89         fflush(stdout);
  90
  91         exit(1);
  92 }
  93
  94 static void non_fatal(char *fmt, ...)
  95 {
  96         va_list list;
  97
  98         va_start(list, fmt);
  99         vprintf(fmt, list);
 100         va_end(list);
 101         fflush(stdout);
 102 }
 103
 104 static int start_ptraced_child(void **stack_out)
 105 {
 106         void *stack;
 107         unsigned long sp;
 108         int pid, n, status;
 109
 110         stack = mmap(NULL, UM_KERN_PAGE_SIZE,
 111                      PROT_READ | PROT_WRITE | PROT_EXEC,
 112                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 113         if(stack == MAP_FAILED)
 114                 fatal_perror("check_ptrace : mmap failed");
 115         sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
 116         pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
 117         if(pid < 0)
 118                 fatal_perror("start_ptraced_child : clone failed");
 119         CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 120         if(n < 0)
 121                 fatal_perror("check_ptrace : clone failed");
 122         if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
 123                 fatal("check_ptrace : expected SIGSTOP, got status = %d",
 124                       status);
 125
 126         *stack_out = stack;
 127         return pid;
 128 }
 129
 130 /* When testing for SYSEMU support, if it is one of the broken versions, we
 131  * must just avoid using sysemu, not panic, but only if SYSEMU features are
 132  * broken.
 133  * So only for SYSEMU features we test mustpanic, while normal host features
 134  * must work anyway!
 135  */
 136 static int stop_ptraced_child(int pid, void *stack, int exitcode,
 137                               int mustexit)
 138 {
 139         int status, n, ret = 0;
 140
 141         if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
 142                 fatal_perror("stop_ptraced_child : ptrace failed");
 143         CATCH_EINTR(n = waitpid(pid, &status, 0));
 144         if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
 145                 int exit_with = WEXITSTATUS(status);
 146                 if (exit_with == 2)
 147                         non_fatal("check_ptrace : child exited with status 2. "
 148                                   "\nDisabling SYSEMU support.\n");
 149                 non_fatal("check_ptrace : child exited with exitcode %d, while "
 150                           "expecting %d; status 0x%x\n", exit_with,
 151                           exitcode, status);
 152                 if (mustexit)
 153                         exit(1);
 154                 ret = -1;
 155         }
 156
 157         if(munmap(stack, UM_KERN_PAGE_SIZE) < 0)
 158                 fatal_perror("check_ptrace : munmap failed");
 159         return ret;
 160 }
 161
 162 /* Changed only during early boot */
 163 int ptrace_faultinfo = 1;
 164 int ptrace_ldt = 1;
 165 int proc_mm = 1;
 166 int skas_needs_stub = 0;
 167
 168 static int __init skas0_cmd_param(char *str, int* add)
 169 {
 170         ptrace_faultinfo = proc_mm = 0;
 171         return 0;
 172 }
 173
 174 /* The two __uml_setup would conflict, without this stupid alias. */
 175
 176 static int __init mode_skas0_cmd_param(char *str, int* add)
 177         __attribute__((alias("skas0_cmd_param")));
 178
 179 __uml_setup("skas0", skas0_cmd_param,
 180                 "skas0\n"
 181                 "    Disables SKAS3 usage, so that SKAS0 is used, unless \n"
 182                 "    you specify mode=tt.\n\n");
 183
 184 __uml_setup("mode=skas0", mode_skas0_cmd_param,
 185                 "mode=skas0\n"
 186                 "    Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
 187                 "    specify mode=tt. Note that this was recently added - on \n"
 188                 "    older kernels you must use simply \"skas0\".\n\n");
 189
 190 /* Changed only during early boot */
 191 static int force_sysemu_disabled = 0;
 192
 193 static int __init nosysemu_cmd_param(char *str, int* add)
 194 {
 195         force_sysemu_disabled = 1;
 196         return 0;
 197 }
 198
 199 __uml_setup("nosysemu", nosysemu_cmd_param,
 200 "nosysemu\n"
 201 "    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
 202 "    SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
 203 "    behaviour of ptrace() and helps reducing host context switch rate.\n"
 204 "    To make it working, you need a kernel patch for your host, too.\n"
 205 "    See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
 206 "    information.\n\n");
 207
 208 static void __init check_sysemu(void)
 209 {
 210         void *stack;
 211         unsigned long regs[MAX_REG_NR];
 212         int pid, n, status, count=0;
 213
 214         non_fatal("Checking syscall emulation patch for ptrace...");
 215         sysemu_supported = 0;
 216         pid = start_ptraced_child(&stack);
 217
 218         if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
 219                 goto fail;
 220
 221         CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 222         if (n < 0)
 223                 fatal_perror("check_sysemu : wait failed");
 224         if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
 225                 fatal("check_sysemu : expected SIGTRAP, got status = %d",
 226                       status);
 227
 228         if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
 229                 fatal_perror("check_sysemu : PTRACE_GETREGS failed");
 230         if(PT_SYSCALL_NR(regs) != __NR_getpid){
 231                 non_fatal("check_sysemu got system call number %d, "
 232                           "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
 233                 goto fail;
 234         }
 235
 236         n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
 237         if(n < 0){
 238                 non_fatal("check_sysemu : failed to modify system call "
 239                           "return");
 240                 goto fail;
 241         }
 242
 243         if (stop_ptraced_child(pid, stack, 0, 0) < 0)
 244                 goto fail_stopped;
 245
 246         sysemu_supported = 1;
 247         non_fatal("OK\n");
 248         set_using_sysemu(!force_sysemu_disabled);
 249
 250         non_fatal("Checking advanced syscall emulation patch for ptrace...");
 251         pid = start_ptraced_child(&stack);
 252
 253         if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
 254                    (void *) PTRACE_O_TRACESYSGOOD) < 0))
 255                 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
 256
 257         while(1){
 258                 count++;
 259                 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
 260                         goto fail;
 261                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 262                 if(n < 0)
 263                         fatal_perror("check_ptrace : wait failed");
 264
 265                 if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){
 266                         if (!count)
 267                                 fatal("check_ptrace : SYSEMU_SINGLESTEP "
 268                                       "doesn't singlestep");
 269                         n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
 270                                    os_getpid());
 271                         if(n < 0)
 272                                 fatal_perror("check_sysemu : failed to modify "
 273                                              "system call return");
 274                         break;
 275                 }
 276                 else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
 277                         count++;
 278                 else
 279                         fatal("check_ptrace : expected SIGTRAP or "
 280                               "(SIGTRAP | 0x80), got status = %d", status);
 281         }
 282         if (stop_ptraced_child(pid, stack, 0, 0) < 0)
 283                 goto fail_stopped;
 284
 285         sysemu_supported = 2;
 286         non_fatal("OK\n");
 287
 288         if ( !force_sysemu_disabled )
 289                 set_using_sysemu(sysemu_supported);
 290         return;
 291
 292 fail:
 293         stop_ptraced_child(pid, stack, 1, 0);
 294 fail_stopped:
 295         non_fatal("missing\n");
 296 }
 297
 298 static void __init check_ptrace(void)
 299 {
 300         void *stack;
 301         int pid, syscall, n, status;
 302
 303         non_fatal("Checking that ptrace can change system call numbers...");
 304         pid = start_ptraced_child(&stack);
 305
 306         if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
 307                    (void *) PTRACE_O_TRACESYSGOOD) < 0))
 308                 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
 309
 310         while(1){
 311                 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
 312                         fatal_perror("check_ptrace : ptrace failed");
 313
 314                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 315                 if(n < 0)
 316                         fatal_perror("check_ptrace : wait failed");
 317
 318                 if(!WIFSTOPPED(status) ||
 319                    (WSTOPSIG(status) != (SIGTRAP | 0x80)))
 320                         fatal("check_ptrace : expected (SIGTRAP|0x80), "
 321                                "got status = %d", status);
 322
 323                 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
 324                                  0);
 325                 if(syscall == __NR_getpid){
 326                         n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
 327                                    __NR_getppid);
 328                         if(n < 0)
 329                                 fatal_perror("check_ptrace : failed to modify "
 330                                              "system call");
 331                         break;
 332                 }
 333         }
 334         stop_ptraced_child(pid, stack, 0, 1);
 335         non_fatal("OK\n");
 336         check_sysemu();
 337 }
 338
 339 extern void check_tmpexec(void);
 340
 341 static void __init check_coredump_limit(void)
 342 {
 343         struct rlimit lim;
 344         int err = getrlimit(RLIMIT_CORE, &lim);
 345
 346         if(err){
 347                 perror("Getting core dump limit");
 348                 return;
 349         }
 350
 351         printf("Core dump limits :\n\tsoft - ");
 352         if(lim.rlim_cur == RLIM_INFINITY)
 353                 printf("NONE\n");
 354         else printf("%lu\n", lim.rlim_cur);
 355
 356         printf("\thard - ");
 357         if(lim.rlim_max == RLIM_INFINITY)
 358                 printf("NONE\n");
 359         else printf("%lu\n", lim.rlim_max);
 360 }
 361
 362 void __init os_early_checks(void)
 363 {
 364         /* Print out the core dump limits early */
 365         check_coredump_limit();
 366
 367         check_ptrace();
 368
 369         /* Need to check this early because mmapping happens before the
 370          * kernel is running.
 371          */
 372         check_tmpexec();
 373 }
 374
 375 static int __init noprocmm_cmd_param(char *str, int* add)
 376 {
 377         proc_mm = 0;
 378         return 0;
 379 }
 380
 381 __uml_setup("noprocmm", noprocmm_cmd_param,
 382 "noprocmm\n"
 383 "    Turns off usage of /proc/mm, even if host supports it.\n"
 384 "    To support /proc/mm, the host needs to be patched using\n"
 385 "    the current skas3 patch.\n\n");
 386
 387 static int __init noptracefaultinfo_cmd_param(char *str, int* add)
 388 {
 389         ptrace_faultinfo = 0;
 390         return 0;
 391 }
 392
 393 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
 394 "noptracefaultinfo\n"
 395 "    Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
 396 "    it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
 397 "    using the current skas3 patch.\n\n");
 398
 399 static int __init noptraceldt_cmd_param(char *str, int* add)
 400 {
 401         ptrace_ldt = 0;
 402         return 0;
 403 }
 404
 405 __uml_setup("noptraceldt", noptraceldt_cmd_param,
 406 "noptraceldt\n"
 407 "    Turns off usage of PTRACE_LDT, even if host supports it.\n"
 408 "    To support PTRACE_LDT, the host needs to be patched using\n"
 409 "    the current skas3 patch.\n\n");
 410
 411 #ifdef UML_CONFIG_MODE_SKAS
 412 static inline void check_skas3_ptrace_faultinfo(void)
 413 {
 414         struct ptrace_faultinfo fi;
 415         void *stack;
 416         int pid, n;
 417
 418         non_fatal("  - PTRACE_FAULTINFO...");
 419         pid = start_ptraced_child(&stack);
 420
 421         n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
 422         if (n < 0) {
 423                 ptrace_faultinfo = 0;
 424                 if(errno == EIO)
 425                         non_fatal("not found\n");
 426                 else
 427                         perror("not found");
 428         }
 429         else {
 430                 if (!ptrace_faultinfo)
 431                         non_fatal("found but disabled on command line\n");
 432                 else
 433                         non_fatal("found\n");
 434         }
 435
 436         init_registers(pid);
 437         stop_ptraced_child(pid, stack, 1, 1);
 438 }
 439
 440 static inline void check_skas3_ptrace_ldt(void)
 441 {
 442 #ifdef PTRACE_LDT
 443         void *stack;
 444         int pid, n;
 445         unsigned char ldtbuf[40];
 446         struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
 447                 .func = 2, /* read default ldt */
 448                 .ptr = ldtbuf,
 449                 .bytecount = sizeof(ldtbuf)};
 450
 451         non_fatal("  - PTRACE_LDT...");
 452         pid = start_ptraced_child(&stack);
 453
 454         n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
 455         if (n < 0) {
 456                 if(errno == EIO)
 457                         non_fatal("not found\n");
 458                 else {
 459                         perror("not found");
 460                 }
 461                 ptrace_ldt = 0;
 462         }
 463         else {
 464                 if(ptrace_ldt)
 465                         non_fatal("found\n");
 466                 else
 467                         non_fatal("found, but use is disabled\n");
 468         }
 469
 470         stop_ptraced_child(pid, stack, 1, 1);
 471 #else
 472         /* PTRACE_LDT might be disabled via cmdline option.
 473          * We want to override this, else we might use the stub
 474          * without real need
 475          */
 476         ptrace_ldt = 1;
 477 #endif
 478 }
 479
 480 static inline void check_skas3_proc_mm(void)
 481 {
 482         non_fatal("  - /proc/mm...");
 483         if (access("/proc/mm", W_OK) < 0) {
 484                 proc_mm = 0;
 485                 perror("not found");
 486         }
 487         else {
 488                 if (!proc_mm)
 489                         non_fatal("found but disabled on command line\n");
 490                 else
 491                         non_fatal("found\n");
 492         }
 493 }
 494
 495 int can_do_skas(void)
 496 {
 497         non_fatal("Checking for the skas3 patch in the host:\n");
 498
 499         check_skas3_proc_mm();
 500         check_skas3_ptrace_faultinfo();
 501         check_skas3_ptrace_ldt();
 502
 503         if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
 504                 skas_needs_stub = 1;
 505
 506         return 1;
 507 }
 508 #else
 509 int can_do_skas(void)
 510 {
 511         return 0;
 512 }
 513 #endif
 514
 515 int __init parse_iomem(char *str, int *add)
 516 {
 517         struct iomem_region *new;
 518         struct stat64 buf;
 519         char *file, *driver;
 520         int fd, size;
 521
 522         driver = str;
 523         file = strchr(str,',');
 524         if(file == NULL){
 525                 printf("parse_iomem : failed to parse iomem\n");
 526                 goto out;
 527         }
 528         *file = '\0';
 529         file++;
 530         fd = open(file, O_RDWR, 0);
 531         if(fd < 0){
 532                 os_print_error(fd, "parse_iomem - Couldn't open io file");
 533                 goto out;
 534         }
 535
 536         if(fstat64(fd, &buf) < 0){
 537                 perror("parse_iomem - cannot stat_fd file");
 538                 goto out_close;
 539         }
 540
 541         new = malloc(sizeof(*new));
 542         if(new == NULL){
 543                 perror("Couldn't allocate iomem_region struct");
 544                 goto out_close;
 545         }
 546
 547         size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
 548
 549         *new = ((struct iomem_region) { .next           = iomem_regions,
 550                                         .driver         = driver,
 551                                         .fd             = fd,
 552                                         .size           = size,
 553                                         .phys           = 0,
 554                                         .virt           = 0 });
 555         iomem_regions = new;
 556         iomem_size += new->size + UM_KERN_PAGE_SIZE;
 557
 558         return 0;
 559  out_close:
 560         close(fd);
 561  out:
 562         return 1;
 563 }