git.oblomov.eu Git - linux-2.6/blob - arch/um/kernel/skas/process.c

   1 /*
   2  * Copyright (C) 2002- 2004 Jeff Dike (jdike@addtoit.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <unistd.h>
   9 #include <errno.h>
  10 #include <signal.h>
  11 #include <setjmp.h>
  12 #include <sched.h>
  13 #include <sys/wait.h>
  14 #include <sys/mman.h>
  15 #include <sys/user.h>
  16 #include <sys/time.h>
  17 #include <asm/unistd.h>
  18 #include <asm/types.h>
  19 #include "user.h"
  20 #include "ptrace_user.h"
  21 #include "time_user.h"
  22 #include "sysdep/ptrace.h"
  23 #include "user_util.h"
  24 #include "kern_util.h"
  25 #include "skas.h"
  26 #include "stub-data.h"
  27 #include "mm_id.h"
  28 #include "sysdep/sigcontext.h"
  29 #include "sysdep/stub.h"
  30 #include "os.h"
  31 #include "proc_mm.h"
  32 #include "skas_ptrace.h"
  33 #include "chan_user.h"
  34 #include "signal_user.h"
  35 #include "registers.h"
  36 #include "mem.h"
  37 #include "uml-config.h"
  38 #include "process.h"
  39
  40 int is_skas_winch(int pid, int fd, void *data)
  41 {
  42         if(pid != os_getpgrp())
  43                 return(0);
  44
  45         register_winch_irq(-1, fd, -1, data);
  46         return(1);
  47 }
  48
  49 void wait_stub_done(int pid, int sig, char * fname)
  50 {
  51         int n, status, err;
  52
  53         do {
  54                 if ( sig != -1 ) {
  55                         err = ptrace(PTRACE_CONT, pid, 0, sig);
  56                         if(err)
  57                                 panic("%s : continue failed, errno = %d\n",
  58                                       fname, errno);
  59                 }
  60                 sig = 0;
  61
  62                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
  63         } while((n >= 0) && WIFSTOPPED(status) &&
  64                 ((WSTOPSIG(status) == SIGVTALRM) ||
  65                  /* running UML inside a detached screen can cause
  66                   * SIGWINCHes
  67                   */
  68                  (WSTOPSIG(status) == SIGWINCH)));
  69
  70         if((n < 0) || !WIFSTOPPED(status) ||
  71            (WSTOPSIG(status) != SIGUSR1 && WSTOPSIG(status) != SIGTRAP)){
  72                 unsigned long regs[FRAME_SIZE];
  73                 if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
  74                         printk("Failed to get registers from stub, "
  75                                "errno = %d\n", errno);
  76                 else {
  77                         int i;
  78
  79                         printk("Stub registers -\n");
  80                         for(i = 0; i < FRAME_SIZE; i++)
  81                                 printk("\t%d - %lx\n", i, regs[i]);
  82                 }
  83                 panic("%s : failed to wait for SIGUSR1/SIGTRAP, "
  84                       "pid = %d, n = %d, errno = %d, status = 0x%x\n",
  85                       fname, pid, n, errno, status);
  86         }
  87 }
  88
  89 void get_skas_faultinfo(int pid, struct faultinfo * fi)
  90 {
  91         int err;
  92
  93         if(ptrace_faultinfo){
  94                 err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
  95                 if(err)
  96                         panic("get_skas_faultinfo - PTRACE_FAULTINFO failed, "
  97                               "errno = %d\n", errno);
  98
  99                 /* Special handling for i386, which has different structs */
 100                 if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
 101                         memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
 102                                sizeof(struct faultinfo) -
 103                                sizeof(struct ptrace_faultinfo));
 104         }
 105         else {
 106                 wait_stub_done(pid, SIGSEGV, "get_skas_faultinfo");
 107
 108                 /* faultinfo is prepared by the stub-segv-handler at start of
 109                  * the stub stack page. We just have to copy it.
 110                  */
 111                 memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
 112         }
 113 }
 114
 115 static void handle_segv(int pid, union uml_pt_regs * regs)
 116 {
 117         get_skas_faultinfo(pid, &regs->skas.faultinfo);
 118         segv(regs->skas.faultinfo, 0, 1, NULL);
 119 }
 120
 121 /*To use the same value of using_sysemu as the caller, ask it that value (in local_using_sysemu)*/
 122 static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu)
 123 {
 124         int err, status;
 125
 126         /* Mark this as a syscall */
 127         UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->skas.regs);
 128
 129         if (!local_using_sysemu)
 130         {
 131                 err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, __NR_getpid);
 132                 if(err < 0)
 133                         panic("handle_trap - nullifying syscall failed errno = %d\n",
 134                               errno);
 135
 136                 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
 137                 if(err < 0)
 138                         panic("handle_trap - continuing to end of syscall failed, "
 139                               "errno = %d\n", errno);
 140
 141                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
 142                 if((err < 0) || !WIFSTOPPED(status) ||
 143                    (WSTOPSIG(status) != SIGTRAP + 0x80))
 144                         panic("handle_trap - failed to wait at end of syscall, "
 145                               "errno = %d, status = %d\n", errno, status);
 146         }
 147
 148         handle_syscall(regs);
 149 }
 150
 151 extern int __syscall_stub_start;
 152 int stub_code_fd = -1;
 153 __u64 stub_code_offset;
 154
 155 static int userspace_tramp(void *stack)
 156 {
 157         void *addr;
 158
 159         ptrace(PTRACE_TRACEME, 0, 0, 0);
 160
 161         init_new_thread_signals(1);
 162         enable_timer();
 163
 164         if(!proc_mm){
 165                 /* This has a pte, but it can't be mapped in with the usual
 166                  * tlb_flush mechanism because this is part of that mechanism
 167                  */
 168                 addr = mmap64((void *) UML_CONFIG_STUB_CODE, page_size(),
 169                               PROT_EXEC, MAP_FIXED | MAP_PRIVATE,
 170                               stub_code_fd, stub_code_offset);
 171                 if(addr == MAP_FAILED){
 172                         printk("mapping stub code failed, errno = %d\n",
 173                                errno);
 174                         exit(1);
 175                 }
 176
 177                 if(stack != NULL){
 178                         int fd;
 179                         __u64 offset;
 180
 181                         fd = phys_mapping(to_phys(stack), &offset);
 182                         addr = mmap((void *) UML_CONFIG_STUB_DATA, page_size(),
 183                                     PROT_READ | PROT_WRITE,
 184                                     MAP_FIXED | MAP_SHARED, fd, offset);
 185                         if(addr == MAP_FAILED){
 186                                 printk("mapping stub stack failed, "
 187                                        "errno = %d\n", errno);
 188                                 exit(1);
 189                         }
 190                 }
 191         }
 192         if(!ptrace_faultinfo){
 193                 unsigned long v = UML_CONFIG_STUB_CODE +
 194                                   (unsigned long) stub_segv_handler -
 195                                   (unsigned long) &__syscall_stub_start;
 196
 197                 set_sigstack((void *) UML_CONFIG_STUB_DATA, page_size());
 198                 set_handler(SIGSEGV, (void *) v, SA_ONSTACK,
 199                             SIGIO, SIGWINCH, SIGALRM, SIGVTALRM,
 200                             SIGUSR1, -1);
 201         }
 202
 203         os_stop_process(os_getpid());
 204         return(0);
 205 }
 206
 207 /* Each element set once, and only accessed by a single processor anyway */
 208 #undef NR_CPUS
 209 #define NR_CPUS 1
 210 int userspace_pid[NR_CPUS];
 211
 212 int start_userspace(unsigned long stub_stack)
 213 {
 214         void *stack;
 215         unsigned long sp;
 216         int pid, status, n, flags;
 217
 218         if ( stub_code_fd == -1 )
 219                 stub_code_fd = phys_mapping(to_phys(&__syscall_stub_start),
 220                                             &stub_code_offset);
 221
 222         stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
 223                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 224         if(stack == MAP_FAILED)
 225                 panic("start_userspace : mmap failed, errno = %d", errno);
 226         sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
 227
 228         flags = CLONE_FILES | SIGCHLD;
 229         if(proc_mm) flags |= CLONE_VM;
 230         pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
 231         if(pid < 0)
 232                 panic("start_userspace : clone failed, errno = %d", errno);
 233
 234         do {
 235                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 236                 if(n < 0)
 237                         panic("start_userspace : wait failed, errno = %d",
 238                               errno);
 239         } while(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
 240
 241         if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
 242                 panic("start_userspace : expected SIGSTOP, got status = %d",
 243                       status);
 244
 245         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, (void *)PTRACE_O_TRACESYSGOOD) < 0)
 246                 panic("start_userspace : PTRACE_SETOPTIONS failed, errno=%d\n",
 247                       errno);
 248
 249         if(munmap(stack, PAGE_SIZE) < 0)
 250                 panic("start_userspace : munmap failed, errno = %d\n", errno);
 251
 252         return(pid);
 253 }
 254
 255 void userspace(union uml_pt_regs *regs)
 256 {
 257         int err, status, op, pid = userspace_pid[0];
 258         int local_using_sysemu; /*To prevent races if using_sysemu changes under us.*/
 259
 260         while(1){
 261                 restore_registers(pid, regs);
 262
 263                 /* Now we set local_using_sysemu to be used for one loop */
 264                 local_using_sysemu = get_using_sysemu();
 265
 266                 op = SELECT_PTRACE_OPERATION(local_using_sysemu, singlestepping(NULL));
 267
 268                 err = ptrace(op, pid, 0, 0);
 269                 if(err)
 270                         panic("userspace - could not resume userspace process, "
 271                               "pid=%d, ptrace operation = %d, errno = %d\n",
 272                               op, errno);
 273
 274                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
 275                 if(err < 0)
 276                         panic("userspace - waitpid failed, errno = %d\n",
 277                               errno);
 278
 279                 regs->skas.is_user = 1;
 280                 save_registers(pid, regs);
 281                 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
 282
 283                 if(WIFSTOPPED(status)){
 284                         switch(WSTOPSIG(status)){
 285                         case SIGSEGV:
 286                                 if(PTRACE_FULL_FAULTINFO || !ptrace_faultinfo)
 287                                         user_signal(SIGSEGV, regs, pid);
 288                                 else handle_segv(pid, regs);
 289                                 break;
 290                         case SIGTRAP + 0x80:
 291                                 handle_trap(pid, regs, local_using_sysemu);
 292                                 break;
 293                         case SIGTRAP:
 294                                 relay_signal(SIGTRAP, regs);
 295                                 break;
 296                         case SIGIO:
 297                         case SIGVTALRM:
 298                         case SIGILL:
 299                         case SIGBUS:
 300                         case SIGFPE:
 301                         case SIGWINCH:
 302                                 user_signal(WSTOPSIG(status), regs, pid);
 303                                 break;
 304                         default:
 305                                 printk("userspace - child stopped with signal "
 306                                        "%d\n", WSTOPSIG(status));
 307                         }
 308                         pid = userspace_pid[0];
 309                         interrupt_end();
 310
 311                         /* Avoid -ERESTARTSYS handling in host */
 312                         PT_SYSCALL_NR(regs->skas.regs) = -1;
 313                 }
 314         }
 315 }
 316 #define INIT_JMP_NEW_THREAD 0
 317 #define INIT_JMP_REMOVE_SIGSTACK 1
 318 #define INIT_JMP_CALLBACK 2
 319 #define INIT_JMP_HALT 3
 320 #define INIT_JMP_REBOOT 4
 321
 322
 323 int copy_context_skas0(unsigned long new_stack, int pid)
 324 {
 325         int err;
 326         unsigned long regs[MAX_REG_NR];
 327         unsigned long current_stack = current_stub_stack();
 328         struct stub_data *data = (struct stub_data *) current_stack;
 329         struct stub_data *child_data = (struct stub_data *) new_stack;
 330         __u64 new_offset;
 331         int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
 332
 333         /* prepare offset and fd of child's stack as argument for parent's
 334          * and child's mmap2 calls
 335          */
 336         *data = ((struct stub_data) { .offset   = MMAP_OFFSET(new_offset),
 337                                       .fd       = new_fd,
 338                                       .timer    = ((struct itimerval)
 339                                                    { { 0, 1000000 / hz() },
 340                                                      { 0, 1000000 / hz() }})});
 341         get_safe_registers(regs);
 342
 343         /* Set parent's instruction pointer to start of clone-stub */
 344         regs[REGS_IP_INDEX] = UML_CONFIG_STUB_CODE +
 345                                 (unsigned long) stub_clone_handler -
 346                                 (unsigned long) &__syscall_stub_start;
 347         regs[REGS_SP_INDEX] = UML_CONFIG_STUB_DATA + PAGE_SIZE -
 348                 sizeof(void *);
 349         err = ptrace_setregs(pid, regs);
 350         if(err < 0)
 351                 panic("copy_context_skas0 : PTRACE_SETREGS failed, "
 352                       "pid = %d, errno = %d\n", pid, errno);
 353
 354         /* set a well known return code for detection of child write failure */
 355         child_data->err = 12345678;
 356
 357         /* Wait, until parent has finished its work: read child's pid from
 358          * parent's stack, and check, if bad result.
 359          */
 360         wait_stub_done(pid, 0, "copy_context_skas0");
 361
 362         pid = data->err;
 363         if(pid < 0)
 364                 panic("copy_context_skas0 - stub-parent reports error %d\n",
 365                       pid);
 366
 367         /* Wait, until child has finished too: read child's result from
 368          * child's stack and check it.
 369          */
 370         wait_stub_done(pid, -1, "copy_context_skas0");
 371         if (child_data->err != UML_CONFIG_STUB_DATA)
 372                 panic("copy_context_skas0 - stub-child reports error %d\n",
 373                       child_data->err);
 374
 375         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
 376                    (void *)PTRACE_O_TRACESYSGOOD) < 0)
 377                 panic("copy_context_skas0 : PTRACE_SETOPTIONS failed, "
 378                       "errno = %d\n", errno);
 379
 380         return pid;
 381 }
 382
 383 /*
 384  * This is used only, if stub pages are needed, while proc_mm is
 385  * availabl. Opening /proc/mm creates a new mm_context, which lacks
 386  * the stub-pages. Thus, we map them using /proc/mm-fd
 387  */
 388 void map_stub_pages(int fd, unsigned long code,
 389                     unsigned long data, unsigned long stack)
 390 {
 391         struct proc_mm_op mmop;
 392         int n;
 393
 394         mmop = ((struct proc_mm_op) { .op        = MM_MMAP,
 395                                       .u         =
 396                                       { .mmap    =
 397                                         { .addr    = code,
 398                                           .len     = PAGE_SIZE,
 399                                           .prot    = PROT_EXEC,
 400                                           .flags   = MAP_FIXED | MAP_PRIVATE,
 401                                           .fd      = stub_code_fd,
 402                                           .offset  = stub_code_offset
 403         } } });
 404         n = os_write_file(fd, &mmop, sizeof(mmop));
 405         if(n != sizeof(mmop))
 406                 panic("map_stub_pages : /proc/mm map for code failed, "
 407                       "err = %d\n", -n);
 408
 409         if ( stack ) {
 410                 __u64 map_offset;
 411                 int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
 412                 mmop = ((struct proc_mm_op)
 413                                 { .op        = MM_MMAP,
 414                                   .u         =
 415                                   { .mmap    =
 416                                     { .addr    = data,
 417                                       .len     = PAGE_SIZE,
 418                                       .prot    = PROT_READ | PROT_WRITE,
 419                                       .flags   = MAP_FIXED | MAP_SHARED,
 420                                       .fd      = map_fd,
 421                                       .offset  = map_offset
 422                 } } });
 423                 n = os_write_file(fd, &mmop, sizeof(mmop));
 424                 if(n != sizeof(mmop))
 425                         panic("map_stub_pages : /proc/mm map for data failed, "
 426                               "err = %d\n", -n);
 427         }
 428 }
 429
 430 void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
 431                 void (*handler)(int))
 432 {
 433         unsigned long flags;
 434         sigjmp_buf switch_buf, fork_buf;
 435
 436         *switch_buf_ptr = &switch_buf;
 437         *fork_buf_ptr = &fork_buf;
 438
 439         /* Somewhat subtle - siglongjmp restores the signal mask before doing
 440          * the longjmp.  This means that when jumping from one stack to another
 441          * when the target stack has interrupts enabled, an interrupt may occur
 442          * on the source stack.  This is bad when starting up a process because
 443          * it's not supposed to get timer ticks until it has been scheduled.
 444          * So, we disable interrupts around the sigsetjmp to ensure that
 445          * they can't happen until we get back here where they are safe.
 446          */
 447         flags = get_signals();
 448         block_signals();
 449         if(sigsetjmp(fork_buf, 1) == 0)
 450                 new_thread_proc(stack, handler);
 451
 452         remove_sigstack();
 453
 454         set_signals(flags);
 455 }
 456
 457 void thread_wait(void *sw, void *fb)
 458 {
 459         sigjmp_buf buf, **switch_buf = sw, *fork_buf;
 460
 461         *switch_buf = &buf;
 462         fork_buf = fb;
 463         if(sigsetjmp(buf, 1) == 0)
 464                 siglongjmp(*fork_buf, INIT_JMP_REMOVE_SIGSTACK);
 465 }
 466
 467 void switch_threads(void *me, void *next)
 468 {
 469         sigjmp_buf my_buf, **me_ptr = me, *next_buf = next;
 470
 471         *me_ptr = &my_buf;
 472         if(sigsetjmp(my_buf, 1) == 0)
 473                 siglongjmp(*next_buf, 1);
 474 }
 475
 476 static sigjmp_buf initial_jmpbuf;
 477
 478 /* XXX Make these percpu */
 479 static void (*cb_proc)(void *arg);
 480 static void *cb_arg;
 481 static sigjmp_buf *cb_back;
 482
 483 int start_idle_thread(void *stack, void *switch_buf_ptr, void **fork_buf_ptr)
 484 {
 485         sigjmp_buf **switch_buf = switch_buf_ptr;
 486         int n;
 487
 488         set_handler(SIGWINCH, (__sighandler_t) sig_handler,
 489                     SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGALRM,
 490                     SIGVTALRM, -1);
 491
 492         *fork_buf_ptr = &initial_jmpbuf;
 493         n = sigsetjmp(initial_jmpbuf, 1);
 494         switch(n){
 495         case INIT_JMP_NEW_THREAD:
 496                 new_thread_proc((void *) stack, new_thread_handler);
 497                 break;
 498         case INIT_JMP_REMOVE_SIGSTACK:
 499                 remove_sigstack();
 500                 break;
 501         case INIT_JMP_CALLBACK:
 502                 (*cb_proc)(cb_arg);
 503                 siglongjmp(*cb_back, 1);
 504                 break;
 505         case INIT_JMP_HALT:
 506                 kmalloc_ok = 0;
 507                 return(0);
 508         case INIT_JMP_REBOOT:
 509                 kmalloc_ok = 0;
 510                 return(1);
 511         default:
 512                 panic("Bad sigsetjmp return in start_idle_thread - %d\n", n);
 513         }
 514         siglongjmp(**switch_buf, 1);
 515 }
 516
 517 void remove_sigstack(void)
 518 {
 519         stack_t stack = ((stack_t) { .ss_flags  = SS_DISABLE,
 520                                      .ss_sp     = NULL,
 521                                      .ss_size   = 0 });
 522
 523         if(sigaltstack(&stack, NULL) != 0)
 524                 panic("disabling signal stack failed, errno = %d\n", errno);
 525 }
 526
 527 void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 528 {
 529         sigjmp_buf here;
 530
 531         cb_proc = proc;
 532         cb_arg = arg;
 533         cb_back = &here;
 534
 535         block_signals();
 536         if(sigsetjmp(here, 1) == 0)
 537                 siglongjmp(initial_jmpbuf, INIT_JMP_CALLBACK);
 538         unblock_signals();
 539
 540         cb_proc = NULL;
 541         cb_arg = NULL;
 542         cb_back = NULL;
 543 }
 544
 545 void halt_skas(void)
 546 {
 547         block_signals();
 548         siglongjmp(initial_jmpbuf, INIT_JMP_HALT);
 549 }
 550
 551 void reboot_skas(void)
 552 {
 553         block_signals();
 554         siglongjmp(initial_jmpbuf, INIT_JMP_REBOOT);
 555 }
 556
 557 void switch_mm_skas(struct mm_id *mm_idp)
 558 {
 559         int err;
 560
 561 #warning need cpu pid in switch_mm_skas
 562         if(proc_mm){
 563                 err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
 564                              mm_idp->u.mm_fd);
 565                 if(err)
 566                         panic("switch_mm_skas - PTRACE_SWITCH_MM failed, "
 567                               "errno = %d\n", errno);
 568         }
 569         else userspace_pid[0] = mm_idp->u.pid;
 570 }
 571
 572 /*
 573  * Overrides for Emacs so that we follow Linus's tabbing style.
 574  * Emacs will notice this stuff at the end of the file and automatically
 575  * adjust the settings for this buffer only.  This must remain at the end
 576  * of the file.
 577  * ---------------------------------------------------------------------------
 578  * Local variables:
 579  * c-file-style: "linux"
 580  * End:
 581  */