linux/arch/um/os-Linux/skas/process.c
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   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
  30int 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
  39static 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
  63void 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
  86bad_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
  97extern unsigned long current_stub_stack(void);
  98
  99static 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
 149static 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 */
 159static 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
 204extern int __syscall_stub_start;
 205
 206static 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
 277int userspace_pid[NR_CPUS];
 278
 279int 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
 350void 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
 459static unsigned long thread_regs[MAX_REG_NR];
 460
 461static 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
 478int 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 */
 562int 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
 618void 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
 630void switch_threads(jmp_buf *me, jmp_buf *you)
 631{
 632        if (UML_SETJMP(me) == 0)
 633                UML_LONGJMP(you, 1);
 634}
 635
 636static jmp_buf initial_jmpbuf;
 637
 638/* XXX Make these percpu */
 639static void (*cb_proc)(void *arg);
 640static void *cb_arg;
 641static jmp_buf *cb_back;
 642
 643int 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
 683void 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
 701void halt_skas(void)
 702{
 703        block_signals();
 704        UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
 705}
 706
 707void reboot_skas(void)
 708{
 709        block_signals();
 710        UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
 711}
 712
 713void __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}
 729
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