arch/um/os-Linux/skas/process.c

   1 /*
   2  * Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <stdlib.h>
   7 #include <unistd.h>
   8 #include <sched.h>
   9 #include <errno.h>
  10 #include <string.h>
  11 #include <sys/mman.h>
  12 #include <sys/wait.h>
  13 #include <asm/unistd.h>
  14 #include "as-layout.h"
  15 #include "init.h"
  16 #include "kern_util.h"
  17 #include "mem.h"
  18 #include "os.h"
  19 #include "proc_mm.h"
  20 #include "ptrace_user.h"
  21 #include "registers.h"
  22 #include "skas.h"
  23 #include "skas_ptrace.h"
  24 #include "sysdep/stub.h"
  25
  26 int is_skas_winch(int pid, int fd, void *data)
  27 {
  28         return pid == getpgrp();
  29 }
  30
  31 static int ptrace_dump_regs(int pid)
  32 {
  33         unsigned long regs[MAX_REG_NR];
  34         int i;
  35
  36         if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
  37                 return -errno;
  38
  39         printk(UM_KERN_ERR "Stub registers -\n");
  40         for (i = 0; i < ARRAY_SIZE(regs); i++)
  41                 printk(UM_KERN_ERR "\t%d - %lx\n", i, regs[i]);
  42
  43         return 0;
  44 }
  45
  46 /*
  47  * Signals that are OK to receive in the stub - we'll just continue it.
  48  * SIGWINCH will happen when UML is inside a detached screen.
  49  */
  50 #define STUB_SIG_MASK ((1 << SIGVTALRM) | (1 << SIGWINCH))
  51
  52 /* Signals that the stub will finish with - anything else is an error */
  53 #define STUB_DONE_MASK (1 << SIGTRAP)
  54
  55 void wait_stub_done(int pid)
  56 {
  57         int n, status, err;
  58
  59         while (1) {
  60                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
  61                 if ((n < 0) || !WIFSTOPPED(status))
  62                         goto bad_wait;
  63
  64                 if (((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0)
  65                         break;
  66
  67                 err = ptrace(PTRACE_CONT, pid, 0, 0);
  68                 if (err) {
  69                         printk(UM_KERN_ERR "wait_stub_done : continue failed, "
  70                                "errno = %d\n", errno);
  71                         fatal_sigsegv();
  72                 }
  73         }
  74
  75         if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0)
  76                 return;
  77
  78 bad_wait:
  79         err = ptrace_dump_regs(pid);
  80         if (err)
  81                 printk(UM_KERN_ERR "Failed to get registers from stub, "
  82                        "errno = %d\n", -err);
  83         printk(UM_KERN_ERR "wait_stub_done : failed to wait for SIGTRAP, "
  84                "pid = %d, n = %d, errno = %d, status = 0x%x\n", pid, n, errno,
  85                status);
  86         fatal_sigsegv();
  87 }
  88
  89 extern unsigned long current_stub_stack(void);
  90
  91 static void get_skas_faultinfo(int pid, struct faultinfo *fi)
  92 {
  93         int err;
  94
  95         if (ptrace_faultinfo) {
  96                 err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
  97                 if (err) {
  98                         printk(UM_KERN_ERR "get_skas_faultinfo - "
  99                                "PTRACE_FAULTINFO failed, errno = %d\n", errno);
 100                         fatal_sigsegv();
 101                 }
 102
 103                 /* Special handling for i386, which has different structs */
 104                 if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
 105                         memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
 106                                sizeof(struct faultinfo) -
 107                                sizeof(struct ptrace_faultinfo));
 108         }
 109         else {
 110                 unsigned long fpregs[FP_SIZE];
 111
 112                 err = get_fp_registers(pid, fpregs);
 113                 if (err < 0) {
 114                         printk(UM_KERN_ERR "save_fp_registers returned %d\n",
 115                                err);
 116                         fatal_sigsegv();
 117                 }
 118                 err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
 119                 if (err) {
 120                         printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
 121                                "errno = %d\n", pid, errno);
 122                         fatal_sigsegv();
 123                 }
 124                 wait_stub_done(pid);
 125
 126                 /*
 127                  * faultinfo is prepared by the stub-segv-handler at start of
 128                  * the stub stack page. We just have to copy it.
 129                  */
 130                 memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
 131
 132                 err = put_fp_registers(pid, fpregs);
 133                 if (err < 0) {
 134                         printk(UM_KERN_ERR "put_fp_registers returned %d\n",
 135                                err);
 136                         fatal_sigsegv();
 137                 }
 138         }
 139 }
 140
 141 static void handle_segv(int pid, struct uml_pt_regs * regs)
 142 {
 143         get_skas_faultinfo(pid, &regs->faultinfo);
 144         segv(regs->faultinfo, 0, 1, NULL);
 145 }
 146
 147 /*
 148  * To use the same value of using_sysemu as the caller, ask it that value
 149  * (in local_using_sysemu
 150  */
 151 static void handle_trap(int pid, struct uml_pt_regs *regs,
 152                         int local_using_sysemu)
 153 {
 154         int err, status;
 155
 156         if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
 157                 fatal_sigsegv();
 158
 159         /* Mark this as a syscall */
 160         UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
 161
 162         if (!local_using_sysemu)
 163         {
 164                 err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
 165                              __NR_getpid);
 166                 if (err < 0) {
 167                         printk(UM_KERN_ERR "handle_trap - nullifying syscall "
 168                                "failed, errno = %d\n", errno);
 169                         fatal_sigsegv();
 170                 }
 171
 172                 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
 173                 if (err < 0) {
 174                         printk(UM_KERN_ERR "handle_trap - continuing to end of "
 175                                "syscall failed, errno = %d\n", errno);
 176                         fatal_sigsegv();
 177                 }
 178
 179                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
 180                 if ((err < 0) || !WIFSTOPPED(status) ||
 181                     (WSTOPSIG(status) != SIGTRAP + 0x80)) {
 182                         err = ptrace_dump_regs(pid);
 183                         if (err)
 184                                 printk(UM_KERN_ERR "Failed to get registers "
 185                                        "from process, errno = %d\n", -err);
 186                         printk(UM_KERN_ERR "handle_trap - failed to wait at "
 187                                "end of syscall, errno = %d, status = %d\n",
 188                                errno, status);
 189                         fatal_sigsegv();
 190                 }
 191         }
 192
 193         handle_syscall(regs);
 194 }
 195
 196 extern int __syscall_stub_start;
 197
 198 static int userspace_tramp(void *stack)
 199 {
 200         void *addr;
 201         int err;
 202
 203         ptrace(PTRACE_TRACEME, 0, 0, 0);
 204
 205         signal(SIGTERM, SIG_DFL);
 206         signal(SIGWINCH, SIG_IGN);
 207         err = set_interval();
 208         if (err) {
 209                 printk(UM_KERN_ERR "userspace_tramp - setting timer failed, "
 210                        "errno = %d\n", err);
 211                 exit(1);
 212         }
 213
 214         if (!proc_mm) {
 215                 /*
 216                  * This has a pte, but it can't be mapped in with the usual
 217                  * tlb_flush mechanism because this is part of that mechanism
 218                  */
 219                 int fd;
 220                 unsigned long long offset;
 221                 fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
 222                 addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
 223                               PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
 224                 if (addr == MAP_FAILED) {
 225                         printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, "
 226                                "errno = %d\n", STUB_CODE, errno);
 227                         exit(1);
 228                 }
 229
 230                 if (stack != NULL) {
 231                         fd = phys_mapping(to_phys(stack), &offset);
 232                         addr = mmap((void *) STUB_DATA,
 233                                     UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
 234                                     MAP_FIXED | MAP_SHARED, fd, offset);
 235                         if (addr == MAP_FAILED) {
 236                                 printk(UM_KERN_ERR "mapping segfault stack "
 237                                        "at 0x%lx failed, errno = %d\n",
 238                                        STUB_DATA, errno);
 239                                 exit(1);
 240                         }
 241                 }
 242         }
 243         if (!ptrace_faultinfo && (stack != NULL)) {
 244                 struct sigaction sa;
 245
 246                 unsigned long v = STUB_CODE +
 247                                   (unsigned long) stub_segv_handler -
 248                                   (unsigned long) &__syscall_stub_start;
 249
 250                 set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
 251                 sigemptyset(&sa.sa_mask);
 252                 sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO;
 253                 sa.sa_sigaction = (void *) v;
 254                 sa.sa_restorer = NULL;
 255                 if (sigaction(SIGSEGV, &sa, NULL) < 0) {
 256                         printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "
 257                                "handler failed - errno = %d\n", errno);
 258                         exit(1);
 259                 }
 260         }
 261
 262         kill(os_getpid(), SIGSTOP);
 263         return 0;
 264 }
 265
 266 /* Each element set once, and only accessed by a single processor anyway */
 267 #undef NR_CPUS
 268 #define NR_CPUS 1
 269 int userspace_pid[NR_CPUS];
 270
 271 int start_userspace(unsigned long stub_stack)
 272 {
 273         void *stack;
 274         unsigned long sp;
 275         int pid, status, n, flags, err;
 276
 277         stack = mmap(NULL, UM_KERN_PAGE_SIZE,
 278                      PROT_READ | PROT_WRITE | PROT_EXEC,
 279                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 280         if (stack == MAP_FAILED) {
 281                 err = -errno;
 282                 printk(UM_KERN_ERR "start_userspace : mmap failed, "
 283                        "errno = %d\n", errno);
 284                 return err;
 285         }
 286
 287         sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
 288
 289         flags = CLONE_FILES;
 290         if (proc_mm)
 291                 flags |= CLONE_VM;
 292         else
 293                 flags |= SIGCHLD;
 294
 295         pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
 296         if (pid < 0) {
 297                 err = -errno;
 298                 printk(UM_KERN_ERR "start_userspace : clone failed, "
 299                        "errno = %d\n", errno);
 300                 return err;
 301         }
 302
 303         do {
 304                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
 305                 if (n < 0) {
 306                         err = -errno;
 307                         printk(UM_KERN_ERR "start_userspace : wait failed, "
 308                                "errno = %d\n", errno);
 309                         goto out_kill;
 310                 }
 311         } while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
 312
 313         if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
 314                 err = -EINVAL;
 315                 printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got "
 316                        "status = %d\n", status);
 317                 goto out_kill;
 318         }
 319
 320         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
 321                    (void *) PTRACE_O_TRACESYSGOOD) < 0) {
 322                 err = -errno;
 323                 printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS "
 324                        "failed, errno = %d\n", errno);
 325                 goto out_kill;
 326         }
 327
 328         if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
 329                 err = -errno;
 330                 printk(UM_KERN_ERR "start_userspace : munmap failed, "
 331                        "errno = %d\n", errno);
 332                 goto out_kill;
 333         }
 334
 335         return pid;
 336
 337  out_kill:
 338         os_kill_ptraced_process(pid, 1);
 339         return err;
 340 }
 341
 342 void userspace(struct uml_pt_regs *regs)
 343 {
 344         struct itimerval timer;
 345         unsigned long long nsecs, now;
 346         int err, status, op, pid = userspace_pid[0];
 347         /* To prevent races if using_sysemu changes under us.*/
 348         int local_using_sysemu;
 349
 350         if (getitimer(ITIMER_VIRTUAL, &timer))
 351                 printk(UM_KERN_ERR "Failed to get itimer, errno = %d\n", errno);
 352         nsecs = timer.it_value.tv_sec * UM_NSEC_PER_SEC +
 353                 timer.it_value.tv_usec * UM_NSEC_PER_USEC;
 354         nsecs += os_nsecs();
 355
 356         while (1) {
 357                 /*
 358                  * This can legitimately fail if the process loads a
 359                  * bogus value into a segment register.  It will
 360                  * segfault and PTRACE_GETREGS will read that value
 361                  * out of the process.  However, PTRACE_SETREGS will
 362                  * fail.  In this case, there is nothing to do but
 363                  * just kill the process.
 364                  */
 365                 if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp))
 366                         fatal_sigsegv();
 367
 368                 if (put_fp_registers(pid, regs->fp))
 369                         fatal_sigsegv();
 370
 371                 /* Now we set local_using_sysemu to be used for one loop */
 372                 local_using_sysemu = get_using_sysemu();
 373
 374                 op = SELECT_PTRACE_OPERATION(local_using_sysemu,
 375                                              singlestepping(NULL));
 376
 377                 if (ptrace(op, pid, 0, 0)) {
 378                         printk(UM_KERN_ERR "userspace - ptrace continue "
 379                                "failed, op = %d, errno = %d\n", op, errno);
 380                         fatal_sigsegv();
 381                 }
 382
 383                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
 384                 if (err < 0) {
 385                         printk(UM_KERN_ERR "userspace - wait failed, "
 386                                "errno = %d\n", errno);
 387                         fatal_sigsegv();
 388                 }
 389
 390                 regs->is_user = 1;
 391                 if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
 392                         printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, "
 393                                "errno = %d\n", errno);
 394                         fatal_sigsegv();
 395                 }
 396
 397                 if (get_fp_registers(pid, regs->fp)) {
 398                         printk(UM_KERN_ERR "userspace -  get_fp_registers failed, "
 399                                "errno = %d\n", errno);
 400                         fatal_sigsegv();
 401                 }
 402
 403                 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
 404
 405                 if (WIFSTOPPED(status)) {
 406                         int sig = WSTOPSIG(status);
 407                         switch (sig) {
 408                         case SIGSEGV:
 409                                 if (PTRACE_FULL_FAULTINFO ||
 410                                     !ptrace_faultinfo) {
 411                                         get_skas_faultinfo(pid,
 412                                                            &regs->faultinfo);
 413                                         (*sig_info[SIGSEGV])(SIGSEGV, regs);
 414                                 }
 415                                 else handle_segv(pid, regs);
 416                                 break;
 417                         case SIGTRAP + 0x80:
 418                                 handle_trap(pid, regs, local_using_sysemu);
 419                                 break;
 420                         case SIGTRAP:
 421                                 relay_signal(SIGTRAP, regs);
 422                                 break;
 423                         case SIGVTALRM:
 424                                 now = os_nsecs();
 425                                 if (now < nsecs)
 426                                         break;
 427                                 block_signals();
 428                                 (*sig_info[sig])(sig, regs);
 429                                 unblock_signals();
 430                                 nsecs = timer.it_value.tv_sec *
 431                                         UM_NSEC_PER_SEC +
 432                                         timer.it_value.tv_usec *
 433                                         UM_NSEC_PER_USEC;
 434                                 nsecs += os_nsecs();
 435                                 break;
 436                         case SIGIO:
 437                         case SIGILL:
 438                         case SIGBUS:
 439                         case SIGFPE:
 440                         case SIGWINCH:
 441                                 block_signals();
 442                                 (*sig_info[sig])(sig, regs);
 443                                 unblock_signals();
 444                                 break;
 445                         default:
 446                                 printk(UM_KERN_ERR "userspace - child stopped "
 447                                        "with signal %d\n", sig);
 448                                 fatal_sigsegv();
 449                         }
 450                         pid = userspace_pid[0];
 451                         interrupt_end();
 452
 453                         /* Avoid -ERESTARTSYS handling in host */
 454                         if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
 455                                 PT_SYSCALL_NR(regs->gp) = -1;
 456                 }
 457         }
 458 }
 459
 460 static unsigned long thread_regs[MAX_REG_NR];
 461 static unsigned long thread_fp_regs[FP_SIZE];
 462
 463 static int __init init_thread_regs(void)
 464 {
 465         get_safe_registers(thread_regs, thread_fp_regs);
 466         /* Set parent's instruction pointer to start of clone-stub */
 467         thread_regs[REGS_IP_INDEX] = STUB_CODE +
 468                                 (unsigned long) stub_clone_handler -
 469                                 (unsigned long) &__syscall_stub_start;
 470         thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
 471                 sizeof(void *);
 472 #ifdef __SIGNAL_FRAMESIZE
 473         thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
 474 #endif
 475         return 0;
 476 }
 477
 478 __initcall(init_thread_regs);
 479
 480 int copy_context_skas0(unsigned long new_stack, int pid)
 481 {
 482         struct timeval tv = { .tv_sec = 0, .tv_usec = UM_USEC_PER_SEC / UM_HZ };
 483         int err;
 484         unsigned long current_stack = current_stub_stack();
 485         struct stub_data *data = (struct stub_data *) current_stack;
 486         struct stub_data *child_data = (struct stub_data *) new_stack;
 487         unsigned long long new_offset;
 488         int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
 489
 490         /*
 491          * prepare offset and fd of child's stack as argument for parent's
 492          * and child's mmap2 calls
 493          */
 494         *data = ((struct stub_data) { .offset   = MMAP_OFFSET(new_offset),
 495                                       .fd       = new_fd,
 496                                       .timer    = ((struct itimerval)
 497                                                    { .it_value = tv,
 498                                                      .it_interval = tv }) });
 499
 500         err = ptrace_setregs(pid, thread_regs);
 501         if (err < 0) {
 502                 err = -errno;
 503                 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS "
 504                        "failed, pid = %d, errno = %d\n", pid, -err);
 505                 return err;
 506         }
 507
 508         err = put_fp_registers(pid, thread_fp_regs);
 509         if (err < 0) {
 510                 printk(UM_KERN_ERR "copy_context_skas0 : put_fp_registers "
 511                        "failed, pid = %d, err = %d\n", pid, err);
 512                 return err;
 513         }
 514
 515         /* set a well known return code for detection of child write failure */
 516         child_data->err = 12345678;
 517
 518         /*
 519          * Wait, until parent has finished its work: read child's pid from
 520          * parent's stack, and check, if bad result.
 521          */
 522         err = ptrace(PTRACE_CONT, pid, 0, 0);
 523         if (err) {
 524                 err = -errno;
 525                 printk(UM_KERN_ERR "Failed to continue new process, pid = %d, "
 526                        "errno = %d\n", pid, errno);
 527                 return err;
 528         }
 529
 530         wait_stub_done(pid);
 531
 532         pid = data->err;
 533         if (pid < 0) {
 534                 printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
 535                        "error %d\n", -pid);
 536                 return pid;
 537         }
 538
 539         /*
 540          * Wait, until child has finished too: read child's result from
 541          * child's stack and check it.
 542          */
 543         wait_stub_done(pid);
 544         if (child_data->err != STUB_DATA) {
 545                 printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports "
 546                        "error %ld\n", child_data->err);
 547                 err = child_data->err;
 548                 goto out_kill;
 549         }
 550
 551         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
 552                    (void *)PTRACE_O_TRACESYSGOOD) < 0) {
 553                 err = -errno;
 554                 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS "
 555                        "failed, errno = %d\n", errno);
 556                 goto out_kill;
 557         }
 558
 559         return pid;
 560
 561  out_kill:
 562         os_kill_ptraced_process(pid, 1);
 563         return err;
 564 }
 565
 566 /*
 567  * This is used only, if stub pages are needed, while proc_mm is
 568  * available. Opening /proc/mm creates a new mm_context, which lacks
 569  * the stub-pages. Thus, we map them using /proc/mm-fd
 570  */
 571 int map_stub_pages(int fd, unsigned long code, unsigned long data,
 572                    unsigned long stack)
 573 {
 574         struct proc_mm_op mmop;
 575         int n;
 576         unsigned long long code_offset;
 577         int code_fd = phys_mapping(to_phys((void *) &__syscall_stub_start),
 578                                    &code_offset);
 579
 580         mmop = ((struct proc_mm_op) { .op        = MM_MMAP,
 581                                       .u         =
 582                                       { .mmap    =
 583                                         { .addr    = code,
 584                                           .len     = UM_KERN_PAGE_SIZE,
 585                                           .prot    = PROT_EXEC,
 586                                           .flags   = MAP_FIXED | MAP_PRIVATE,
 587                                           .fd      = code_fd,
 588                                           .offset  = code_offset
 589         } } });
 590         CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
 591         if (n != sizeof(mmop)) {
 592                 n = errno;
 593                 printk(UM_KERN_ERR "mmap args - addr = 0x%lx, fd = %d, "
 594                        "offset = %llx\n", code, code_fd,
 595                        (unsigned long long) code_offset);
 596                 printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for code "
 597                        "failed, err = %d\n", n);
 598                 return -n;
 599         }
 600
 601         if (stack) {
 602                 unsigned long long map_offset;
 603                 int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
 604                 mmop = ((struct proc_mm_op)
 605                                 { .op        = MM_MMAP,
 606                                   .u         =
 607                                   { .mmap    =
 608                                     { .addr    = data,
 609                                       .len     = UM_KERN_PAGE_SIZE,
 610                                       .prot    = PROT_READ | PROT_WRITE,
 611                                       .flags   = MAP_FIXED | MAP_SHARED,
 612                                       .fd      = map_fd,
 613                                       .offset  = map_offset
 614                 } } });
 615                 CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
 616                 if (n != sizeof(mmop)) {
 617                         n = errno;
 618                         printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for "
 619                                "data failed, err = %d\n", n);
 620                         return -n;
 621                 }
 622         }
 623
 624         return 0;
 625 }
 626
 627 void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
 628 {
 629         (*buf)[0].JB_IP = (unsigned long) handler;
 630         (*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
 631                 sizeof(void *);
 632 }
 633
 634 #define INIT_JMP_NEW_THREAD 0
 635 #define INIT_JMP_CALLBACK 1
 636 #define INIT_JMP_HALT 2
 637 #define INIT_JMP_REBOOT 3
 638
 639 void switch_threads(jmp_buf *me, jmp_buf *you)
 640 {
 641         if (UML_SETJMP(me) == 0)
 642                 UML_LONGJMP(you, 1);
 643 }
 644
 645 static jmp_buf initial_jmpbuf;
 646
 647 /* XXX Make these percpu */
 648 static void (*cb_proc)(void *arg);
 649 static void *cb_arg;
 650 static jmp_buf *cb_back;
 651
 652 int start_idle_thread(void *stack, jmp_buf *switch_buf)
 653 {
 654         int n;
 655
 656         set_handler(SIGWINCH);
 657
 658         /*
 659          * Can't use UML_SETJMP or UML_LONGJMP here because they save
 660          * and restore signals, with the possible side-effect of
 661          * trying to handle any signals which came when they were
 662          * blocked, which can't be done on this stack.
 663          * Signals must be blocked when jumping back here and restored
 664          * after returning to the jumper.
 665          */
 666         n = setjmp(initial_jmpbuf);
 667         switch (n) {
 668         case INIT_JMP_NEW_THREAD:
 669                 (*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
 670                 (*switch_buf)[0].JB_SP = (unsigned long) stack +
 671                         UM_THREAD_SIZE - sizeof(void *);
 672                 break;
 673         case INIT_JMP_CALLBACK:
 674                 (*cb_proc)(cb_arg);
 675                 longjmp(*cb_back, 1);
 676                 break;
 677         case INIT_JMP_HALT:
 678                 kmalloc_ok = 0;
 679                 return 0;
 680         case INIT_JMP_REBOOT:
 681                 kmalloc_ok = 0;
 682                 return 1;
 683         default:
 684                 printk(UM_KERN_ERR "Bad sigsetjmp return in "
 685                        "start_idle_thread - %d\n", n);
 686                 fatal_sigsegv();
 687         }
 688         longjmp(*switch_buf, 1);
 689 }
 690
 691 void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 692 {
 693         jmp_buf here;
 694
 695         cb_proc = proc;
 696         cb_arg = arg;
 697         cb_back = &here;
 698
 699         block_signals();
 700         if (UML_SETJMP(&here) == 0)
 701                 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
 702         unblock_signals();
 703
 704         cb_proc = NULL;
 705         cb_arg = NULL;
 706         cb_back = NULL;
 707 }
 708
 709 void halt_skas(void)
 710 {
 711         block_signals();
 712         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
 713 }
 714
 715 void reboot_skas(void)
 716 {
 717         block_signals();
 718         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
 719 }
 720
 721 void __switch_mm(struct mm_id *mm_idp)
 722 {
 723         int err;
 724
 725         /* FIXME: need cpu pid in __switch_mm */
 726         if (proc_mm) {
 727                 err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
 728                              mm_idp->u.mm_fd);
 729                 if (err) {
 730                         printk(UM_KERN_ERR "__switch_mm - PTRACE_SWITCH_MM "
 731                                "failed, errno = %d\n", errno);
 732                         fatal_sigsegv();
 733                 }
 734         }
 735         else userspace_pid[0] = mm_idp->u.pid;
 736 }