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