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