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/ptrace.h>
  13 #include <sys/wait.h>
  14 #include <asm/unistd.h>
  15 #include "as-layout.h"
  16 #include "chan_user.h"
  17 #include "kern_constants.h"
  18 #include "kern_util.h"
  19 #include "mem.h"
  20 #include "os.h"
  21 #include "process.h"
  22 #include "proc_mm.h"
  23 #include "ptrace_user.h"
  24 #include "registers.h"
  25 #include "skas.h"
  26 #include "skas_ptrace.h"
  27 #include "user.h"
  28 #include "sysdep/stub.h"
  29
  30 int is_skas_winch(int pid, int fd, void *data)
  31 {
  32         if (pid != getpgrp())
  33                 return 0;
  34
  35         register_winch_irq(-1, fd, -1, data, 0);
  36         return 1;
  37 }
  38
  39 static int ptrace_dump_regs(int pid)
  40 {
  41         unsigned long regs[MAX_REG_NR];
  42         int i;
  43
  44         if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
  45                 return -errno;
  46
  47         printk(UM_KERN_ERR "Stub registers -\n");
  48         for (i = 0; i < ARRAY_SIZE(regs); i++)
  49                 printk(UM_KERN_ERR "\t%d - %lx\n", i, regs[i]);
  50
  51         return 0;
  52 }
  53
  54 /*
  55  * Signals that are OK to receive in the stub - we'll just continue it.
  56  * SIGWINCH will happen when UML is inside a detached screen.
  57  */
  58 #define STUB_SIG_MASK (1 << SIGVTALRM)
  59
  60 /* Signals that the stub will finish with - anything else is an error */
  61 #define STUB_DONE_MASK (1 << SIGTRAP)
  62
  63 void wait_stub_done(int pid)
  64 {
  65         int n, status, err;
  66
  67         while (1) {
  68                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
  69                 if ((n < 0) || !WIFSTOPPED(status))
  70                         goto bad_wait;
  71
  72                 if (((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0)
  73                         break;
  74
  75                 err = ptrace(PTRACE_CONT, pid, 0, 0);
  76                 if (err) {
  77                         printk(UM_KERN_ERR "wait_stub_done : continue failed, "
  78                                "errno = %d\n", errno);
  79                         fatal_sigsegv();
  80                 }
  81         }
  82
  83         if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0)
  84                 return;
  85
  86 bad_wait:
  87         err = ptrace_dump_regs(pid);
  88         if (err)
  89                 printk(UM_KERN_ERR "Failed to get registers from stub, "
  90                        "errno = %d\n", -err);
  91         printk(UM_KERN_ERR "wait_stub_done : failed to wait for SIGTRAP, "
  92                "pid = %d, n = %d, errno = %d, status = 0x%x\n", pid, n, errno,
  93                status);
  94         fatal_sigsegv();
  95 }
  96
  97 extern unsigned long current_stub_stack(void);
  98
  99 void get_skas_faultinfo(int pid, struct faultinfo * fi)
 100 {
 101         int err;
 102
 103         if (ptrace_faultinfo) {
 104                 err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
 105                 if (err) {
 106                         printk(UM_KERN_ERR "get_skas_faultinfo - "
 107                                "PTRACE_FAULTINFO failed, errno = %d\n", errno);
 108                         fatal_sigsegv();
 109                 }
 110
 111                 /* Special handling for i386, which has different structs */
 112                 if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
 113                         memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
 114                                sizeof(struct faultinfo) -
 115                                sizeof(struct ptrace_faultinfo));
 116         }
 117         else {
 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 }
 133
 134 static void handle_segv(int pid, struct uml_pt_regs * regs)
 135 {
 136         get_skas_faultinfo(pid, &regs->faultinfo);
 137         segv(regs->faultinfo, 0, 1, NULL);
 138 }
 139
 140 /*
 141  * To use the same value of using_sysemu as the caller, ask it that value
 142  * (in local_using_sysemu
 143  */
 144 static void handle_trap(int pid, struct uml_pt_regs *regs,
 145                         int local_using_sysemu)
 146 {
 147         int err, status;
 148
 149         if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
 150                 fatal_sigsegv();
 151
 152         /* Mark this as a syscall */
 153         UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
 154
 155         if (!local_using_sysemu)
 156         {
 157                 err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
 158                              __NR_getpid);
 159                 if (err < 0) {
 160                         printk(UM_KERN_ERR "handle_trap - nullifying syscall "
 161                                "failed, errno = %d\n", errno);
 162                         fatal_sigsegv();
 163                 }
 164
 165                 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
 166                 if (err < 0) {
 167                         printk(UM_KERN_ERR "handle_trap - continuing to end of "
 168                                "syscall failed, errno = %d\n", errno);
 169                         fatal_sigsegv();
 170                 }
 171
 172                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
 173                 if ((err < 0) || !WIFSTOPPED(status) ||
 174                     (WSTOPSIG(status) != SIGTRAP + 0x80)) {
 175                         err = ptrace_dump_regs(pid);
 176                         if (err)
 177                                 printk(UM_KERN_ERR "Failed to get registers "
 178                                        "from process, errno = %d\n", -err);
 179                         printk(UM_KERN_ERR "handle_trap - failed to wait at "
 180                                "end of syscall, errno = %d, status = %d\n",
 181                                errno, status);
 182                         fatal_sigsegv();
 183                 }
 184         }
 185
 186         handle_syscall(regs);
 187 }
 188
 189 extern int __syscall_stub_start;
 190
 191 static int userspace_tramp(void *stack)
 192 {
 193         void *addr;
 194         int err;
 195
 196         ptrace(PTRACE_TRACEME, 0, 0, 0);
 197
 198         signal(SIGTERM, SIG_DFL);
 199         signal(SIGWINCH, SIG_IGN);
 200         err = set_interval();
 201         if (err) {
 202                 printk(UM_KERN_ERR "userspace_tramp - setting timer failed, "
 203                        "errno = %d\n", err);
 204                 exit(1);
 205         }
 206
 207         if (!proc_mm) {
 208                 /*
 209                  * This has a pte, but it can't be mapped in with the usual
 210                  * tlb_flush mechanism because this is part of that mechanism
 211                  */
 212                 int fd;
 213                 unsigned long long offset;
 214                 fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
 215                 addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
 216                               PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
 217                 if (addr == MAP_FAILED) {
 218                         printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, "
 219                                "errno = %d\n", STUB_CODE, errno);
 220                         exit(1);
 221                 }
 222
 223                 if (stack != NULL) {
 224                         fd = phys_mapping(to_phys(stack), &offset);
 225                         addr = mmap((void *) STUB_DATA,
 226                                     UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
 227                                     MAP_FIXED | MAP_SHARED, fd, offset);
 228                         if (addr == MAP_FAILED) {
 229                                 printk(UM_KERN_ERR "mapping segfault stack "
 230                                        "at 0x%lx failed, errno = %d\n",
 231                                        STUB_DATA, errno);
 232                                 exit(1);
 233                         }
 234                 }
 235         }
 236         if (!ptrace_faultinfo && (stack != NULL)) {
 237                 struct sigaction sa;
 238
 239                 unsigned long v = STUB_CODE +
 240                                   (unsigned long) stub_segv_handler -
 241                                   (unsigned long) &__syscall_stub_start;
 242
 243                 set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
 244                 sigemptyset(&sa.sa_mask);
 245                 sa.sa_flags = SA_ONSTACK | SA_NODEFER;
 246                 sa.sa_handler = (void *) v;
 247                 sa.sa_restorer = NULL;
 248                 if (sigaction(SIGSEGV, &sa, NULL) < 0) {
 249                         printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "
 250                                "handler failed - errno = %d\n", errno);
 251                         exit(1);
 252                 }
 253         }
 254
 255         kill(os_getpid(), SIGSTOP);
 256         return 0;
 257 }
 258
 259 /* Each element set once, and only accessed by a single processor anyway */
 260 #undef NR_CPUS
 261 #define NR_CPUS 1
 262 int userspace_pid[NR_CPUS];
 263
 264 int start_userspace(unsigned long stub_stack)
 265 {
 266         void *stack;
 267         unsigned long sp;
 268         int pid, status, n, flags, err;
 269
 270         stack = mmap(NULL, UM_KERN_PAGE_SIZE,
 271                      PROT_READ | PROT_WRITE | PROT_EXEC,
 272                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 273         if (stack == MAP_FAILED) {
 274                 err = -errno;
 275                 printk(UM_KERN_ERR "start_userspace : mmap failed, "
 276                        "errno = %d\n", errno);
 277                 return err;
 278         }
 279
 280         sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
 281
 282         flags = CLONE_FILES;
 283         if (proc_mm)
 284                 flags |= CLONE_VM;
 285         else
 286                 flags |= SIGCHLD;
 287
 288         pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
 289         if (pid < 0) {
 290                 err = -errno;
 291                 printk(UM_KERN_ERR "start_userspace : clone failed, "
 292                        "errno = %d\n", errno);
 293                 return err;
 294         }
 295
 296         do {
 297                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
 298                 if (n < 0) {
 299                         err = -errno;
 300                         printk(UM_KERN_ERR "start_userspace : wait failed, "
 301                                "errno = %d\n", errno);
 302                         goto out_kill;
 303                 }
 304         } while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
 305
 306         if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
 307                 err = -EINVAL;
 308                 printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got "
 309                        "status = %d\n", status);
 310                 goto out_kill;
 311         }
 312
 313         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
 314                    (void *) PTRACE_O_TRACESYSGOOD) < 0) {
 315                 err = -errno;
 316                 printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS "
 317                        "failed, errno = %d\n", errno);
 318                 goto out_kill;
 319         }
 320
 321         if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
 322                 err = -errno;
 323                 printk(UM_KERN_ERR "start_userspace : munmap failed, "
 324                        "errno = %d\n", errno);
 325                 goto out_kill;
 326         }
 327
 328         return pid;
 329
 330  out_kill:
 331         os_kill_ptraced_process(pid, 1);
 332         return err;
 333 }
 334
 335 void userspace(struct uml_pt_regs *regs)
 336 {
 337         struct itimerval timer;
 338         unsigned long long nsecs, now;
 339         int err, status, op, pid = userspace_pid[0];
 340         /* To prevent races if using_sysemu changes under us.*/
 341         int local_using_sysemu;
 342
 343         if (getitimer(ITIMER_VIRTUAL, &timer))
 344                 printk("Failed to get itimer, errno = %d\n", errno);
 345         nsecs = timer.it_value.tv_sec * UM_NSEC_PER_SEC +
 346                 timer.it_value.tv_usec * UM_NSEC_PER_USEC;
 347         nsecs += os_nsecs();
 348
 349         while (1) {
 350                 /*
 351                  * This can legitimately fail if the process loads a
 352                  * bogus value into a segment register.  It will
 353                  * segfault and PTRACE_GETREGS will read that value
 354                  * out of the process.  However, PTRACE_SETREGS will
 355                  * fail.  In this case, there is nothing to do but
 356                  * just kill the process.
 357                  */
 358                 if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp))
 359                         fatal_sigsegv();
 360
 361                 /* Now we set local_using_sysemu to be used for one loop */
 362                 local_using_sysemu = get_using_sysemu();
 363
 364                 op = SELECT_PTRACE_OPERATION(local_using_sysemu,
 365                                              singlestepping(NULL));
 366
 367                 if (ptrace(op, pid, 0, 0)) {
 368                         printk(UM_KERN_ERR "userspace - ptrace continue "
 369                                "failed, op = %d, errno = %d\n", op, errno);
 370                         fatal_sigsegv();
 371                 }
 372
 373                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
 374                 if (err < 0) {
 375                         printk(UM_KERN_ERR "userspace - wait failed, "
 376                                "errno = %d\n", errno);
 377                         fatal_sigsegv();
 378                 }
 379
 380                 regs->is_user = 1;
 381                 if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
 382                         printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, "
 383                                "errno = %d\n", errno);
 384                         fatal_sigsegv();
 385                 }
 386
 387                 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
 388
 389                 if (WIFSTOPPED(status)) {
 390                         int sig = WSTOPSIG(status);
 391                         switch(sig) {
 392                         case SIGSEGV:
 393                                 if (PTRACE_FULL_FAULTINFO ||
 394                                     !ptrace_faultinfo) {
 395                                         get_skas_faultinfo(pid,
 396                                                            &regs->faultinfo);
 397                                         (*sig_info[SIGSEGV])(SIGSEGV, regs);
 398                                 }
 399                                 else handle_segv(pid, regs);
 400                                 break;
 401                         case SIGTRAP + 0x80:
 402                                 handle_trap(pid, regs, local_using_sysemu);
 403                                 break;
 404                         case SIGTRAP:
 405                                 relay_signal(SIGTRAP, regs);
 406                                 break;
 407                         case SIGVTALRM:
 408                                 now = os_nsecs();
 409                                 if (now < nsecs)
 410                                         break;
 411                                 block_signals();
 412                                 (*sig_info[sig])(sig, regs);
 413                                 unblock_signals();
 414                                 nsecs = timer.it_value.tv_sec *
 415                                         UM_NSEC_PER_SEC +
 416                                         timer.it_value.tv_usec *
 417                                         UM_NSEC_PER_USEC;
 418                                 nsecs += os_nsecs();
 419                                 break;
 420                         case SIGIO:
 421                         case SIGILL:
 422                         case SIGBUS:
 423                         case SIGFPE:
 424                         case SIGWINCH:
 425                                 block_signals();
 426                                 (*sig_info[sig])(sig, regs);
 427                                 unblock_signals();
 428                                 break;
 429                         default:
 430                                 printk(UM_KERN_ERR "userspace - child stopped "
 431                                        "with signal %d\n", sig);
 432                                 fatal_sigsegv();
 433                         }
 434                         pid = userspace_pid[0];
 435                         interrupt_end();
 436
 437                         /* Avoid -ERESTARTSYS handling in host */
 438                         if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
 439                                 PT_SYSCALL_NR(regs->gp) = -1;
 440                 }
 441         }
 442 }
 443
 444 static unsigned long thread_regs[MAX_REG_NR];
 445
 446 static int __init init_thread_regs(void)
 447 {
 448         get_safe_registers(thread_regs);
 449         /* Set parent's instruction pointer to start of clone-stub */
 450         thread_regs[REGS_IP_INDEX] = STUB_CODE +
 451                                 (unsigned long) stub_clone_handler -
 452                                 (unsigned long) &__syscall_stub_start;
 453         thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
 454                 sizeof(void *);
 455 #ifdef __SIGNAL_FRAMESIZE
 456         thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
 457 #endif
 458         return 0;
 459 }
 460
 461 __initcall(init_thread_regs);
 462
 463 int copy_context_skas0(unsigned long new_stack, int pid)
 464 {
 465         struct timeval tv = { .tv_sec = 0, .tv_usec = UM_USEC_PER_SEC / UM_HZ };
 466         int err;
 467         unsigned long current_stack = current_stub_stack();
 468         struct stub_data *data = (struct stub_data *) current_stack;
 469         struct stub_data *child_data = (struct stub_data *) new_stack;
 470         unsigned long long new_offset;
 471         int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
 472
 473         /*
 474          * prepare offset and fd of child's stack as argument for parent's
 475          * and child's mmap2 calls
 476          */
 477         *data = ((struct stub_data) { .offset   = MMAP_OFFSET(new_offset),
 478                                       .fd       = new_fd,
 479                                       .timer    = ((struct itimerval)
 480                                                    { .it_value = tv,
 481                                                      .it_interval = tv }) });
 482
 483         err = ptrace_setregs(pid, thread_regs);
 484         if (err < 0) {
 485                 err = -errno;
 486                 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS "
 487                        "failed, pid = %d, errno = %d\n", pid, -err);
 488                 return err;
 489         }
 490
 491         /* set a well known return code for detection of child write failure */
 492         child_data->err = 12345678;
 493
 494         /*
 495          * Wait, until parent has finished its work: read child's pid from
 496          * parent's stack, and check, if bad result.
 497          */
 498         err = ptrace(PTRACE_CONT, pid, 0, 0);
 499         if (err) {
 500                 err = -errno;
 501                 printk(UM_KERN_ERR "Failed to continue new process, pid = %d, "
 502                        "errno = %d\n", pid, errno);
 503                 return err;
 504         }
 505
 506         wait_stub_done(pid);
 507
 508         pid = data->err;
 509         if (pid < 0) {
 510                 printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
 511                        "error %d\n", -pid);
 512                 return pid;
 513         }
 514
 515         /*
 516          * Wait, until child has finished too: read child's result from
 517          * child's stack and check it.
 518          */
 519         wait_stub_done(pid);
 520         if (child_data->err != STUB_DATA) {
 521                 printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports "
 522                        "error %ld\n", child_data->err);
 523                 err = child_data->err;
 524                 goto out_kill;
 525         }
 526
 527         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
 528                    (void *)PTRACE_O_TRACESYSGOOD) < 0) {
 529                 err = -errno;
 530                 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS "
 531                        "failed, errno = %d\n", errno);
 532                 goto out_kill;
 533         }
 534
 535         return pid;
 536
 537  out_kill:
 538         os_kill_ptraced_process(pid, 1);
 539         return err;
 540 }
 541
 542 /*
 543  * This is used only, if stub pages are needed, while proc_mm is
 544  * available. Opening /proc/mm creates a new mm_context, which lacks
 545  * the stub-pages. Thus, we map them using /proc/mm-fd
 546  */
 547 int map_stub_pages(int fd, unsigned long code, unsigned long data,
 548                    unsigned long stack)
 549 {
 550         struct proc_mm_op mmop;
 551         int n;
 552         unsigned long long code_offset;
 553         int code_fd = phys_mapping(to_phys((void *) &__syscall_stub_start),
 554                                    &code_offset);
 555
 556         mmop = ((struct proc_mm_op) { .op        = MM_MMAP,
 557                                       .u         =
 558                                       { .mmap    =
 559                                         { .addr    = code,
 560                                           .len     = UM_KERN_PAGE_SIZE,
 561                                           .prot    = PROT_EXEC,
 562                                           .flags   = MAP_FIXED | MAP_PRIVATE,
 563                                           .fd      = code_fd,
 564                                           .offset  = code_offset
 565         } } });
 566         CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
 567         if (n != sizeof(mmop)) {
 568                 n = errno;
 569                 printk(UM_KERN_ERR "mmap args - addr = 0x%lx, fd = %d, "
 570                        "offset = %llx\n", code, code_fd,
 571                        (unsigned long long) code_offset);
 572                 printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for code "
 573                        "failed, err = %d\n", n);
 574                 return -n;
 575         }
 576
 577         if (stack) {
 578                 unsigned long long map_offset;
 579                 int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
 580                 mmop = ((struct proc_mm_op)
 581                                 { .op        = MM_MMAP,
 582                                   .u         =
 583                                   { .mmap    =
 584                                     { .addr    = data,
 585                                       .len     = UM_KERN_PAGE_SIZE,
 586                                       .prot    = PROT_READ | PROT_WRITE,
 587                                       .flags   = MAP_FIXED | MAP_SHARED,
 588                                       .fd      = map_fd,
 589                                       .offset  = map_offset
 590                 } } });
 591                 CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
 592                 if (n != sizeof(mmop)) {
 593                         n = errno;
 594                         printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for "
 595                                "data failed, err = %d\n", n);
 596                         return -n;
 597                 }
 598         }
 599
 600         return 0;
 601 }
 602
 603 void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
 604 {
 605         (*buf)[0].JB_IP = (unsigned long) handler;
 606         (*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
 607                 sizeof(void *);
 608 }
 609
 610 #define INIT_JMP_NEW_THREAD 0
 611 #define INIT_JMP_CALLBACK 1
 612 #define INIT_JMP_HALT 2
 613 #define INIT_JMP_REBOOT 3
 614
 615 void switch_threads(jmp_buf *me, jmp_buf *you)
 616 {
 617         if (UML_SETJMP(me) == 0)
 618                 UML_LONGJMP(you, 1);
 619 }
 620
 621 static jmp_buf initial_jmpbuf;
 622
 623 /* XXX Make these percpu */
 624 static void (*cb_proc)(void *arg);
 625 static void *cb_arg;
 626 static jmp_buf *cb_back;
 627
 628 int start_idle_thread(void *stack, jmp_buf *switch_buf)
 629 {
 630         int n;
 631
 632         set_handler(SIGWINCH, (__sighandler_t) sig_handler,
 633                     SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGVTALRM, -1);
 634
 635         /*
 636          * Can't use UML_SETJMP or UML_LONGJMP here because they save
 637          * and restore signals, with the possible side-effect of
 638          * trying to handle any signals which came when they were
 639          * blocked, which can't be done on this stack.
 640          * Signals must be blocked when jumping back here and restored
 641          * after returning to the jumper.
 642          */
 643         n = setjmp(initial_jmpbuf);
 644         switch(n) {
 645         case INIT_JMP_NEW_THREAD:
 646                 (*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
 647                 (*switch_buf)[0].JB_SP = (unsigned long) stack +
 648                         UM_THREAD_SIZE - sizeof(void *);
 649                 break;
 650         case INIT_JMP_CALLBACK:
 651                 (*cb_proc)(cb_arg);
 652                 longjmp(*cb_back, 1);
 653                 break;
 654         case INIT_JMP_HALT:
 655                 kmalloc_ok = 0;
 656                 return 0;
 657         case INIT_JMP_REBOOT:
 658                 kmalloc_ok = 0;
 659                 return 1;
 660         default:
 661                 printk(UM_KERN_ERR "Bad sigsetjmp return in "
 662                        "start_idle_thread - %d\n", n);
 663                 fatal_sigsegv();
 664         }
 665         longjmp(*switch_buf, 1);
 666 }
 667
 668 void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 669 {
 670         jmp_buf here;
 671
 672         cb_proc = proc;
 673         cb_arg = arg;
 674         cb_back = &here;
 675
 676         block_signals();
 677         if (UML_SETJMP(&here) == 0)
 678                 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
 679         unblock_signals();
 680
 681         cb_proc = NULL;
 682         cb_arg = NULL;
 683         cb_back = NULL;
 684 }
 685
 686 void halt_skas(void)
 687 {
 688         block_signals();
 689         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
 690 }
 691
 692 void reboot_skas(void)
 693 {
 694         block_signals();
 695         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
 696 }
 697
 698 void __switch_mm(struct mm_id *mm_idp)
 699 {
 700         int err;
 701
 702         /* FIXME: need cpu pid in __switch_mm */
 703         if (proc_mm) {
 704                 err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
 705                              mm_idp->u.mm_fd);
 706                 if (err) {
 707                         printk(UM_KERN_ERR "__switch_mm - PTRACE_SWITCH_MM "
 708                                "failed, errno = %d\n", errno);
 709                         fatal_sigsegv();
 710                 }
 711         }
 712         else userspace_pid[0] = mm_idp->u.pid;
 713 }