git.oblomov.eu Git - linux-2.6/blob - 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) | (1 << SIGWINCH))
  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                 unsigned long fpregs[FP_SIZE];
 119
 120                 err = get_fp_registers(pid, fpregs);
 121                 if (err < 0) {
 122                         printk(UM_KERN_ERR "save_fp_registers returned %d\n",
 123                                err);
 124                         fatal_sigsegv();
 125                 }
 126                 err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
 127                 if (err) {
 128                         printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
 129                                "errno = %d\n", pid, errno);
 130                         fatal_sigsegv();
 131                 }
 132                 wait_stub_done(pid);
 133
 134                 /*
 135                  * faultinfo is prepared by the stub-segv-handler at start of
 136                  * the stub stack page. We just have to copy it.
 137                  */
 138                 memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
 139
 140                 err = put_fp_registers(pid, fpregs);
 141                 if (err < 0) {
 142                         printk(UM_KERN_ERR "put_fp_registers returned %d\n",
 143                                err);
 144                         fatal_sigsegv();
 145                 }
 146         }
 147 }
 148
 149 static void handle_segv(int pid, struct uml_pt_regs * regs)
 150 {
 151         get_skas_faultinfo(pid, &regs->faultinfo);
 152         segv(regs->faultinfo, 0, 1, NULL);
 153 }
 154
 155 /*
 156  * To use the same value of using_sysemu as the caller, ask it that value
 157  * (in local_using_sysemu
 158  */
 159 static void handle_trap(int pid, struct uml_pt_regs *regs,
 160                         int local_using_sysemu)
 161 {
 162         int err, status;
 163
 164         if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
 165                 fatal_sigsegv();
 166
 167         /* Mark this as a syscall */
 168         UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
 169
 170         if (!local_using_sysemu)
 171         {
 172                 err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
 173                              __NR_getpid);
 174                 if (err < 0) {
 175                         printk(UM_KERN_ERR "handle_trap - nullifying syscall "
 176                                "failed, errno = %d\n", errno);
 177                         fatal_sigsegv();
 178                 }
 179
 180                 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
 181                 if (err < 0) {
 182                         printk(UM_KERN_ERR "handle_trap - continuing to end of "
 183                                "syscall failed, errno = %d\n", errno);
 184                         fatal_sigsegv();
 185                 }
 186
 187                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
 188                 if ((err < 0) || !WIFSTOPPED(status) ||
 189                     (WSTOPSIG(status) != SIGTRAP + 0x80)) {
 190                         err = ptrace_dump_regs(pid);
 191                         if (err)
 192                                 printk(UM_KERN_ERR "Failed to get registers "
 193                                        "from process, errno = %d\n", -err);
 194                         printk(UM_KERN_ERR "handle_trap - failed to wait at "
 195                                "end of syscall, errno = %d, status = %d\n",
 196                                errno, status);
 197                         fatal_sigsegv();
 198                 }
 199         }
 200
 201         handle_syscall(regs);
 202 }
 203
 204 extern int __syscall_stub_start;
 205
 206 static int userspace_tramp(void *stack)
 207 {
 208         void *addr;
 209         int err;
 210
 211         ptrace(PTRACE_TRACEME, 0, 0, 0);
 212
 213         signal(SIGTERM, SIG_DFL);
 214         signal(SIGWINCH, SIG_IGN);
 215         err = set_interval();
 216         if (err) {
 217                 printk(UM_KERN_ERR "userspace_tramp - setting timer failed, "
 218                        "errno = %d\n", err);
 219                 exit(1);
 220         }
 221
 222         if (!proc_mm) {
 223                 /*
 224                  * This has a pte, but it can't be mapped in with the usual
 225                  * tlb_flush mechanism because this is part of that mechanism
 226                  */
 227                 int fd;
 228                 unsigned long long offset;
 229                 fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
 230                 addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
 231                               PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
 232                 if (addr == MAP_FAILED) {
 233                         printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, "
 234                                "errno = %d\n", STUB_CODE, errno);
 235                         exit(1);
 236                 }
 237
 238                 if (stack != NULL) {
 239                         fd = phys_mapping(to_phys(stack), &offset);
 240                         addr = mmap((void *) STUB_DATA,
 241                                     UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
 242                                     MAP_FIXED | MAP_SHARED, fd, offset);
 243                         if (addr == MAP_FAILED) {
 244                                 printk(UM_KERN_ERR "mapping segfault stack "
 245                                        "at 0x%lx failed, errno = %d\n",
 246                                        STUB_DATA, errno);
 247                                 exit(1);
 248                         }
 249                 }
 250         }
 251         if (!ptrace_faultinfo && (stack != NULL)) {
 252                 struct sigaction sa;
 253
 254                 unsigned long v = STUB_CODE +
 255                                   (unsigned long) stub_segv_handler -
 256                                   (unsigned long) &__syscall_stub_start;
 257
 258                 set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
 259                 sigemptyset(&sa.sa_mask);
 260                 sa.sa_flags = SA_ONSTACK | SA_NODEFER;
 261                 sa.sa_handler = (void *) v;
 262                 sa.sa_restorer = NULL;
 263                 if (sigaction(SIGSEGV, &sa, NULL) < 0) {
 264                         printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "
 265                                "handler failed - errno = %d\n", errno);
 266                         exit(1);
 267                 }
 268         }
 269
 270         kill(os_getpid(), SIGSTOP);
 271         return 0;
 272 }
 273
 274 /* Each element set once, and only accessed by a single processor anyway */
 275 #undef NR_CPUS
 276 #define NR_CPUS 1
 277 int userspace_pid[NR_CPUS];
 278
 279 int start_userspace(unsigned long stub_stack)
 280 {
 281         void *stack;
 282         unsigned long sp;
 283         int pid, status, n, flags, err;
 284
 285         stack = mmap(NULL, UM_KERN_PAGE_SIZE,
 286                      PROT_READ | PROT_WRITE | PROT_EXEC,
 287                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 288         if (stack == MAP_FAILED) {
 289                 err = -errno;
 290                 printk(UM_KERN_ERR "start_userspace : mmap failed, "
 291                        "errno = %d\n", errno);
 292                 return err;
 293         }
 294
 295         sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
 296
 297         flags = CLONE_FILES;
 298         if (proc_mm)
 299                 flags |= CLONE_VM;
 300         else
 301                 flags |= SIGCHLD;
 302
 303         pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
 304         if (pid < 0) {
 305                 err = -errno;
 306                 printk(UM_KERN_ERR "start_userspace : clone failed, "
 307                        "errno = %d\n", errno);
 308                 return err;
 309         }
 310
 311         do {
 312                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
 313                 if (n < 0) {
 314                         err = -errno;
 315                         printk(UM_KERN_ERR "start_userspace : wait failed, "
 316                                "errno = %d\n", errno);
 317                         goto out_kill;
 318                 }
 319         } while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
 320
 321         if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
 322                 err = -EINVAL;
 323                 printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got "
 324                        "status = %d\n", status);
 325                 goto out_kill;
 326         }
 327
 328         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
 329                    (void *) PTRACE_O_TRACESYSGOOD) < 0) {
 330                 err = -errno;
 331                 printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS "
 332                        "failed, errno = %d\n", errno);
 333                 goto out_kill;
 334         }
 335
 336         if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
 337                 err = -errno;
 338                 printk(UM_KERN_ERR "start_userspace : munmap failed, "
 339                        "errno = %d\n", errno);
 340                 goto out_kill;
 341         }
 342
 343         return pid;
 344
 345  out_kill:
 346         os_kill_ptraced_process(pid, 1);
 347         return err;
 348 }
 349
 350 void userspace(struct uml_pt_regs *regs)
 351 {
 352         struct itimerval timer;
 353         unsigned long long nsecs, now;
 354         int err, status, op, pid = userspace_pid[0];
 355         /* To prevent races if using_sysemu changes under us.*/
 356         int local_using_sysemu;
 357
 358         if (getitimer(ITIMER_VIRTUAL, &timer))
 359                 printk(UM_KERN_ERR "Failed to get itimer, errno = %d\n", errno);
 360         nsecs = timer.it_value.tv_sec * UM_NSEC_PER_SEC +
 361                 timer.it_value.tv_usec * UM_NSEC_PER_USEC;
 362         nsecs += os_nsecs();
 363
 364         while (1) {
 365                 /*
 366                  * This can legitimately fail if the process loads a
 367                  * bogus value into a segment register.  It will
 368                  * segfault and PTRACE_GETREGS will read that value
 369                  * out of the process.  However, PTRACE_SETREGS will
 370                  * fail.  In this case, there is nothing to do but
 371                  * just kill the process.
 372                  */
 373                 if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp))
 374                         fatal_sigsegv();
 375
 376                 /* Now we set local_using_sysemu to be used for one loop */
 377                 local_using_sysemu = get_using_sysemu();
 378
 379                 op = SELECT_PTRACE_OPERATION(local_using_sysemu,
 380                                              singlestepping(NULL));
 381
 382                 if (ptrace(op, pid, 0, 0)) {
 383                         printk(UM_KERN_ERR "userspace - ptrace continue "
 384                                "failed, op = %d, errno = %d\n", op, errno);
 385                         fatal_sigsegv();
 386                 }
 387
 388                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
 389                 if (err < 0) {
 390                         printk(UM_KERN_ERR "userspace - wait failed, "
 391                                "errno = %d\n", errno);
 392                         fatal_sigsegv();
 393                 }
 394
 395                 regs->is_user = 1;
 396                 if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
 397                         printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, "
 398                                "errno = %d\n", errno);
 399                         fatal_sigsegv();
 400                 }
 401
 402                 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
 403
 404                 if (WIFSTOPPED(status)) {
 405                         int sig = WSTOPSIG(status);
 406                         switch (sig) {
 407                         case SIGSEGV:
 408                                 if (PTRACE_FULL_FAULTINFO ||
 409                                     !ptrace_faultinfo) {
 410                                         get_skas_faultinfo(pid,
 411                                                            &regs->faultinfo);
 412                                         (*sig_info[SIGSEGV])(SIGSEGV, regs);
 413                                 }
 414                                 else handle_segv(pid, regs);
 415                                 break;
 416                         case SIGTRAP + 0x80:
 417                                 handle_trap(pid, regs, local_using_sysemu);
 418                                 break;
 419                         case SIGTRAP:
 420                                 relay_signal(SIGTRAP, regs);
 421                                 break;
 422                         case SIGVTALRM:
 423                                 now = os_nsecs();
 424                                 if (now < nsecs)
 425                                         break;
 426                                 block_signals();
 427                                 (*sig_info[sig])(sig, regs);
 428                                 unblock_signals();
 429                                 nsecs = timer.it_value.tv_sec *
 430                                         UM_NSEC_PER_SEC +
 431                                         timer.it_value.tv_usec *
 432                                         UM_NSEC_PER_USEC;
 433                                 nsecs += os_nsecs();
 434                                 break;
 435                         case SIGIO:
 436                         case SIGILL:
 437                         case SIGBUS:
 438                         case SIGFPE:
 439                         case SIGWINCH:
 440                                 block_signals();
 441                                 (*sig_info[sig])(sig, regs);
 442                                 unblock_signals();
 443                                 break;
 444                         default:
 445                                 printk(UM_KERN_ERR "userspace - child stopped "
 446                                        "with signal %d\n", sig);
 447                                 fatal_sigsegv();
 448                         }
 449                         pid = userspace_pid[0];
 450                         interrupt_end();
 451
 452                         /* Avoid -ERESTARTSYS handling in host */
 453                         if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
 454                                 PT_SYSCALL_NR(regs->gp) = -1;
 455                 }
 456         }
 457 }
 458
 459 static unsigned long thread_regs[MAX_REG_NR];
 460
 461 static int __init init_thread_regs(void)
 462 {
 463         get_safe_registers(thread_regs);
 464         /* Set parent's instruction pointer to start of clone-stub */
 465         thread_regs[REGS_IP_INDEX] = STUB_CODE +
 466                                 (unsigned long) stub_clone_handler -
 467                                 (unsigned long) &__syscall_stub_start;
 468         thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
 469                 sizeof(void *);
 470 #ifdef __SIGNAL_FRAMESIZE
 471         thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
 472 #endif
 473         return 0;
 474 }
 475
 476 __initcall(init_thread_regs);
 477
 478 int copy_context_skas0(unsigned long new_stack, int pid)
 479 {
 480         struct timeval tv = { .tv_sec = 0, .tv_usec = UM_USEC_PER_SEC / UM_HZ };
 481         int err;
 482         unsigned long current_stack = current_stub_stack();
 483         struct stub_data *data = (struct stub_data *) current_stack;
 484         struct stub_data *child_data = (struct stub_data *) new_stack;
 485         unsigned long long new_offset;
 486         int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
 487
 488         /*
 489          * prepare offset and fd of child's stack as argument for parent's
 490          * and child's mmap2 calls
 491          */
 492         *data = ((struct stub_data) { .offset   = MMAP_OFFSET(new_offset),
 493                                       .fd       = new_fd,
 494                                       .timer    = ((struct itimerval)
 495                                                    { .it_value = tv,
 496                                                      .it_interval = tv }) });
 497
 498         err = ptrace_setregs(pid, thread_regs);
 499         if (err < 0) {
 500                 err = -errno;
 501                 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS "
 502                        "failed, pid = %d, errno = %d\n", pid, -err);
 503                 return err;
 504         }
 505
 506         /* set a well known return code for detection of child write failure */
 507         child_data->err = 12345678;
 508
 509         /*
 510          * Wait, until parent has finished its work: read child's pid from
 511          * parent's stack, and check, if bad result.
 512          */
 513         err = ptrace(PTRACE_CONT, pid, 0, 0);
 514         if (err) {
 515                 err = -errno;
 516                 printk(UM_KERN_ERR "Failed to continue new process, pid = %d, "
 517                        "errno = %d\n", pid, errno);
 518                 return err;
 519         }
 520
 521         wait_stub_done(pid);
 522
 523         pid = data->err;
 524         if (pid < 0) {
 525                 printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
 526                        "error %d\n", -pid);
 527                 return pid;
 528         }
 529
 530         /*
 531          * Wait, until child has finished too: read child's result from
 532          * child's stack and check it.
 533          */
 534         wait_stub_done(pid);
 535         if (child_data->err != STUB_DATA) {
 536                 printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports "
 537                        "error %ld\n", child_data->err);
 538                 err = child_data->err;
 539                 goto out_kill;
 540         }
 541
 542         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
 543                    (void *)PTRACE_O_TRACESYSGOOD) < 0) {
 544                 err = -errno;
 545                 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS "
 546                        "failed, errno = %d\n", errno);
 547                 goto out_kill;
 548         }
 549
 550         return pid;
 551
 552  out_kill:
 553         os_kill_ptraced_process(pid, 1);
 554         return err;
 555 }
 556
 557 /*
 558  * This is used only, if stub pages are needed, while proc_mm is
 559  * available. Opening /proc/mm creates a new mm_context, which lacks
 560  * the stub-pages. Thus, we map them using /proc/mm-fd
 561  */
 562 int map_stub_pages(int fd, unsigned long code, unsigned long data,
 563                    unsigned long stack)
 564 {
 565         struct proc_mm_op mmop;
 566         int n;
 567         unsigned long long code_offset;
 568         int code_fd = phys_mapping(to_phys((void *) &__syscall_stub_start),
 569                                    &code_offset);
 570
 571         mmop = ((struct proc_mm_op) { .op        = MM_MMAP,
 572                                       .u         =
 573                                       { .mmap    =
 574                                         { .addr    = code,
 575                                           .len     = UM_KERN_PAGE_SIZE,
 576                                           .prot    = PROT_EXEC,
 577                                           .flags   = MAP_FIXED | MAP_PRIVATE,
 578                                           .fd      = code_fd,
 579                                           .offset  = code_offset
 580         } } });
 581         CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
 582         if (n != sizeof(mmop)) {
 583                 n = errno;
 584                 printk(UM_KERN_ERR "mmap args - addr = 0x%lx, fd = %d, "
 585                        "offset = %llx\n", code, code_fd,
 586                        (unsigned long long) code_offset);
 587                 printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for code "
 588                        "failed, err = %d\n", n);
 589                 return -n;
 590         }
 591
 592         if (stack) {
 593                 unsigned long long map_offset;
 594                 int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
 595                 mmop = ((struct proc_mm_op)
 596                                 { .op        = MM_MMAP,
 597                                   .u         =
 598                                   { .mmap    =
 599                                     { .addr    = data,
 600                                       .len     = UM_KERN_PAGE_SIZE,
 601                                       .prot    = PROT_READ | PROT_WRITE,
 602                                       .flags   = MAP_FIXED | MAP_SHARED,
 603                                       .fd      = map_fd,
 604                                       .offset  = map_offset
 605                 } } });
 606                 CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
 607                 if (n != sizeof(mmop)) {
 608                         n = errno;
 609                         printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for "
 610                                "data failed, err = %d\n", n);
 611                         return -n;
 612                 }
 613         }
 614
 615         return 0;
 616 }
 617
 618 void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
 619 {
 620         (*buf)[0].JB_IP = (unsigned long) handler;
 621         (*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
 622                 sizeof(void *);
 623 }
 624
 625 #define INIT_JMP_NEW_THREAD 0
 626 #define INIT_JMP_CALLBACK 1
 627 #define INIT_JMP_HALT 2
 628 #define INIT_JMP_REBOOT 3
 629
 630 void switch_threads(jmp_buf *me, jmp_buf *you)
 631 {
 632         if (UML_SETJMP(me) == 0)
 633                 UML_LONGJMP(you, 1);
 634 }
 635
 636 static jmp_buf initial_jmpbuf;
 637
 638 /* XXX Make these percpu */
 639 static void (*cb_proc)(void *arg);
 640 static void *cb_arg;
 641 static jmp_buf *cb_back;
 642
 643 int start_idle_thread(void *stack, jmp_buf *switch_buf)
 644 {
 645         int n;
 646
 647         set_handler(SIGWINCH, (__sighandler_t) sig_handler,
 648                     SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGVTALRM, -1);
 649
 650         /*
 651          * Can't use UML_SETJMP or UML_LONGJMP here because they save
 652          * and restore signals, with the possible side-effect of
 653          * trying to handle any signals which came when they were
 654          * blocked, which can't be done on this stack.
 655          * Signals must be blocked when jumping back here and restored
 656          * after returning to the jumper.
 657          */
 658         n = setjmp(initial_jmpbuf);
 659         switch (n) {
 660         case INIT_JMP_NEW_THREAD:
 661                 (*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
 662                 (*switch_buf)[0].JB_SP = (unsigned long) stack +
 663                         UM_THREAD_SIZE - sizeof(void *);
 664                 break;
 665         case INIT_JMP_CALLBACK:
 666                 (*cb_proc)(cb_arg);
 667                 longjmp(*cb_back, 1);
 668                 break;
 669         case INIT_JMP_HALT:
 670                 kmalloc_ok = 0;
 671                 return 0;
 672         case INIT_JMP_REBOOT:
 673                 kmalloc_ok = 0;
 674                 return 1;
 675         default:
 676                 printk(UM_KERN_ERR "Bad sigsetjmp return in "
 677                        "start_idle_thread - %d\n", n);
 678                 fatal_sigsegv();
 679         }
 680         longjmp(*switch_buf, 1);
 681 }
 682
 683 void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 684 {
 685         jmp_buf here;
 686
 687         cb_proc = proc;
 688         cb_arg = arg;
 689         cb_back = &here;
 690
 691         block_signals();
 692         if (UML_SETJMP(&here) == 0)
 693                 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
 694         unblock_signals();
 695
 696         cb_proc = NULL;
 697         cb_arg = NULL;
 698         cb_back = NULL;
 699 }
 700
 701 void halt_skas(void)
 702 {
 703         block_signals();
 704         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
 705 }
 706
 707 void reboot_skas(void)
 708 {
 709         block_signals();
 710         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
 711 }
 712
 713 void __switch_mm(struct mm_id *mm_idp)
 714 {
 715         int err;
 716
 717         /* FIXME: need cpu pid in __switch_mm */
 718         if (proc_mm) {
 719                 err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
 720                              mm_idp->u.mm_fd);
 721                 if (err) {
 722                         printk(UM_KERN_ERR "__switch_mm - PTRACE_SWITCH_MM "
 723                                "failed, errno = %d\n", errno);
 724                         fatal_sigsegv();
 725                 }
 726         }
 727         else userspace_pid[0] = mm_idp->u.pid;
 728 }