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 #include "as-layout.h"
  38
  39 int is_skas_winch(int pid, int fd, void *data)
  40 {
  41         if(pid != os_getpgrp())
  42                 return(0);
  43
  44         register_winch_irq(-1, fd, -1, data);
  45         return(1);
  46 }
  47
  48 static int ptrace_dump_regs(int pid)
  49 {
  50         unsigned long regs[MAX_REG_NR];
  51         int i;
  52
  53         if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
  54                 return -errno;
  55         else {
  56                 printk("Stub registers -\n");
  57                 for(i = 0; i < ARRAY_SIZE(regs); i++)
  58                         printk("\t%d - %lx\n", i, regs[i]);
  59         }
  60
  61         return 0;
  62 }
  63
  64 /*
  65  * Signals that are OK to receive in the stub - we'll just continue it.
  66  * SIGWINCH will happen when UML is inside a detached screen.
  67  */
  68 #define STUB_SIG_MASK ((1 << SIGVTALRM) | (1 << SIGWINCH))
  69
  70 /* Signals that the stub will finish with - anything else is an error */
  71 #define STUB_DONE_MASK ((1 << SIGUSR1) | (1 << SIGTRAP))
  72
  73 void wait_stub_done(int pid)
  74 {
  75         int n, status, err;
  76
  77         while(1){
  78                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
  79                 if((n < 0) || !WIFSTOPPED(status))
  80                         goto bad_wait;
  81
  82                 if(((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0)
  83                         break;
  84
  85                 err = ptrace(PTRACE_CONT, pid, 0, 0);
  86                 if(err)
  87                         panic("wait_stub_done : continue failed, errno = %d\n",
  88                               errno);
  89         }
  90
  91         if(((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0)
  92                 return;
  93
  94 bad_wait:
  95         err = ptrace_dump_regs(pid);
  96         if(err)
  97                 printk("Failed to get registers from stub, errno = %d\n", -err);
  98         panic("wait_stub_done : failed to wait for SIGUSR1/SIGTRAP, pid = %d, "
  99               "n = %d, errno = %d, status = 0x%x\n", pid, n, errno, status);
 100 }
 101
 102 extern unsigned long current_stub_stack(void);
 103
 104 void get_skas_faultinfo(int pid, struct faultinfo * fi)
 105 {
 106         int err;
 107
 108         if(ptrace_faultinfo){
 109                 err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
 110                 if(err)
 111                         panic("get_skas_faultinfo - PTRACE_FAULTINFO failed, "
 112                               "errno = %d\n", errno);
 113
 114                 /* Special handling for i386, which has different structs */
 115                 if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
 116                         memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
 117                                sizeof(struct faultinfo) -
 118                                sizeof(struct ptrace_faultinfo));
 119         }
 120         else {
 121                 err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
 122                 if(err)
 123                         panic("Failed to continue stub, pid = %d, errno = %d\n",
 124                               pid, errno);
 125                 wait_stub_done(pid);
 126
 127                 /* faultinfo is prepared by the stub-segv-handler at start of
 128                  * the stub stack page. We just have to copy it.
 129                  */
 130                 memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
 131         }
 132 }
 133
 134 static void handle_segv(int pid, union uml_pt_regs * regs)
 135 {
 136         get_skas_faultinfo(pid, &regs->skas.faultinfo);
 137         segv(regs->skas.faultinfo, 0, 1, NULL);
 138 }
 139
 140 /*To use the same value of using_sysemu as the caller, ask it that value (in local_using_sysemu)*/
 141 static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu)
 142 {
 143         int err, status;
 144
 145         /* Mark this as a syscall */
 146         UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->skas.regs);
 147
 148         if (!local_using_sysemu)
 149         {
 150                 err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
 151                              __NR_getpid);
 152                 if(err < 0)
 153                         panic("handle_trap - nullifying syscall failed errno = %d\n",
 154                               errno);
 155
 156                 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
 157                 if(err < 0)
 158                         panic("handle_trap - continuing to end of syscall failed, "
 159                               "errno = %d\n", errno);
 160
 161                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
 162                 if((err < 0) || !WIFSTOPPED(status) ||
 163                    (WSTOPSIG(status) != SIGTRAP + 0x80)){
 164                         err = ptrace_dump_regs(pid);
 165                         if(err)
 166                                 printk("Failed to get registers from process, "
 167                                        "errno = %d\n", -err);
 168                         panic("handle_trap - failed to wait at end of syscall, "
 169                               "errno = %d, status = %d\n", errno, status);
 170                 }
 171         }
 172
 173         handle_syscall(regs);
 174 }
 175
 176 extern int __syscall_stub_start;
 177
 178 static int userspace_tramp(void *stack)
 179 {
 180         void *addr;
 181         int err;
 182
 183         ptrace(PTRACE_TRACEME, 0, 0, 0);
 184
 185         init_new_thread_signals();
 186         err = set_interval(1);
 187         if(err)
 188                 panic("userspace_tramp - setting timer failed, errno = %d\n",
 189                       err);
 190
 191         if(!proc_mm){
 192                 /* This has a pte, but it can't be mapped in with the usual
 193                  * tlb_flush mechanism because this is part of that mechanism
 194                  */
 195                 int fd;
 196                 __u64 offset;
 197                 fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
 198                 addr = mmap64((void *) UML_CONFIG_STUB_CODE, UM_KERN_PAGE_SIZE,
 199                               PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
 200                 if(addr == MAP_FAILED){
 201                         printk("mapping mmap stub failed, errno = %d\n",
 202                                errno);
 203                         exit(1);
 204                 }
 205
 206                 if(stack != NULL){
 207                         fd = phys_mapping(to_phys(stack), &offset);
 208                         addr = mmap((void *) UML_CONFIG_STUB_DATA,
 209                                     UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
 210                                     MAP_FIXED | MAP_SHARED, fd, offset);
 211                         if(addr == MAP_FAILED){
 212                                 printk("mapping segfault stack failed, "
 213                                        "errno = %d\n", errno);
 214                                 exit(1);
 215                         }
 216                 }
 217         }
 218         if(!ptrace_faultinfo && (stack != NULL)){
 219                 struct sigaction sa;
 220
 221                 unsigned long v = UML_CONFIG_STUB_CODE +
 222                                   (unsigned long) stub_segv_handler -
 223                                   (unsigned long) &__syscall_stub_start;
 224
 225                 set_sigstack((void *) UML_CONFIG_STUB_DATA, UM_KERN_PAGE_SIZE);
 226                 sigemptyset(&sa.sa_mask);
 227                 sigaddset(&sa.sa_mask, SIGIO);
 228                 sigaddset(&sa.sa_mask, SIGWINCH);
 229                 sigaddset(&sa.sa_mask, SIGALRM);
 230                 sigaddset(&sa.sa_mask, SIGVTALRM);
 231                 sigaddset(&sa.sa_mask, SIGUSR1);
 232                 sa.sa_flags = SA_ONSTACK;
 233                 sa.sa_handler = (void *) v;
 234                 sa.sa_restorer = NULL;
 235                 if(sigaction(SIGSEGV, &sa, NULL) < 0)
 236                         panic("userspace_tramp - setting SIGSEGV handler "
 237                               "failed - errno = %d\n", errno);
 238         }
 239
 240         os_stop_process(os_getpid());
 241         return(0);
 242 }
 243
 244 /* Each element set once, and only accessed by a single processor anyway */
 245 #undef NR_CPUS
 246 #define NR_CPUS 1
 247 int userspace_pid[NR_CPUS];
 248
 249 int start_userspace(unsigned long stub_stack)
 250 {
 251         void *stack;
 252         unsigned long sp;
 253         int pid, status, n, flags;
 254
 255         stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
 256                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 257         if(stack == MAP_FAILED)
 258                 panic("start_userspace : mmap failed, errno = %d", errno);
 259         sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
 260
 261         flags = CLONE_FILES | SIGCHLD;
 262         if(proc_mm) flags |= CLONE_VM;
 263         pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
 264         if(pid < 0)
 265                 panic("start_userspace : clone failed, errno = %d", errno);
 266
 267         do {
 268                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 269                 if(n < 0)
 270                         panic("start_userspace : wait failed, errno = %d",
 271                               errno);
 272         } while(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
 273
 274         if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
 275                 panic("start_userspace : expected SIGSTOP, got status = %d",
 276                       status);
 277
 278         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, (void *)PTRACE_O_TRACESYSGOOD) < 0)
 279                 panic("start_userspace : PTRACE_OLDSETOPTIONS failed, errno=%d\n",
 280                       errno);
 281
 282         if(munmap(stack, PAGE_SIZE) < 0)
 283                 panic("start_userspace : munmap failed, errno = %d\n", errno);
 284
 285         return(pid);
 286 }
 287
 288 void userspace(union uml_pt_regs *regs)
 289 {
 290         int err, status, op, pid = userspace_pid[0];
 291         int local_using_sysemu; /*To prevent races if using_sysemu changes under us.*/
 292
 293         while(1){
 294                 restore_registers(pid, regs);
 295
 296                 /* Now we set local_using_sysemu to be used for one loop */
 297                 local_using_sysemu = get_using_sysemu();
 298
 299                 op = SELECT_PTRACE_OPERATION(local_using_sysemu, singlestepping(NULL));
 300
 301                 err = ptrace(op, pid, 0, 0);
 302                 if(err)
 303                         panic("userspace - could not resume userspace process, "
 304                               "pid=%d, ptrace operation = %d, errno = %d\n",
 305                               pid, op, errno);
 306
 307                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
 308                 if(err < 0)
 309                         panic("userspace - waitpid failed, errno = %d\n",
 310                               errno);
 311
 312                 regs->skas.is_user = 1;
 313                 save_registers(pid, regs);
 314                 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
 315
 316                 if(WIFSTOPPED(status)){
 317                         int sig = WSTOPSIG(status);
 318                         switch(sig){
 319                         case SIGSEGV:
 320                                 if(PTRACE_FULL_FAULTINFO || !ptrace_faultinfo){
 321                                         get_skas_faultinfo(pid, &regs->skas.faultinfo);
 322                                         (*sig_info[SIGSEGV])(SIGSEGV, regs);
 323                                 }
 324                                 else handle_segv(pid, regs);
 325                                 break;
 326                         case SIGTRAP + 0x80:
 327                                 handle_trap(pid, regs, local_using_sysemu);
 328                                 break;
 329                         case SIGTRAP:
 330                                 relay_signal(SIGTRAP, regs);
 331                                 break;
 332                         case SIGIO:
 333                         case SIGVTALRM:
 334                         case SIGILL:
 335                         case SIGBUS:
 336                         case SIGFPE:
 337                         case SIGWINCH:
 338                                 block_signals();
 339                                 (*sig_info[sig])(sig, regs);
 340                                 unblock_signals();
 341                                 break;
 342                         default:
 343                                 printk("userspace - child stopped with signal "
 344                                        "%d\n", sig);
 345                         }
 346                         pid = userspace_pid[0];
 347                         interrupt_end();
 348
 349                         /* Avoid -ERESTARTSYS handling in host */
 350                         if(PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
 351                                 PT_SYSCALL_NR(regs->skas.regs) = -1;
 352                 }
 353         }
 354 }
 355
 356 static unsigned long thread_regs[MAX_REG_NR];
 357 static unsigned long thread_fp_regs[HOST_FP_SIZE];
 358
 359 static int __init init_thread_regs(void)
 360 {
 361         get_safe_registers(thread_regs, thread_fp_regs);
 362         /* Set parent's instruction pointer to start of clone-stub */
 363         thread_regs[REGS_IP_INDEX] = UML_CONFIG_STUB_CODE +
 364                                 (unsigned long) stub_clone_handler -
 365                                 (unsigned long) &__syscall_stub_start;
 366         thread_regs[REGS_SP_INDEX] = UML_CONFIG_STUB_DATA + PAGE_SIZE -
 367                 sizeof(void *);
 368 #ifdef __SIGNAL_FRAMESIZE
 369         thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
 370 #endif
 371         return 0;
 372 }
 373
 374 __initcall(init_thread_regs);
 375
 376 int copy_context_skas0(unsigned long new_stack, int pid)
 377 {
 378         int err;
 379         unsigned long current_stack = current_stub_stack();
 380         struct stub_data *data = (struct stub_data *) current_stack;
 381         struct stub_data *child_data = (struct stub_data *) new_stack;
 382         __u64 new_offset;
 383         int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
 384
 385         /* prepare offset and fd of child's stack as argument for parent's
 386          * and child's mmap2 calls
 387          */
 388         *data = ((struct stub_data) { .offset   = MMAP_OFFSET(new_offset),
 389                                       .fd       = new_fd,
 390                                       .timer    = ((struct itimerval)
 391                                                     { { 0, 1000000 / hz() },
 392                                                       { 0, 1000000 / hz() }})});
 393         err = ptrace_setregs(pid, thread_regs);
 394         if(err < 0)
 395                 panic("copy_context_skas0 : PTRACE_SETREGS failed, "
 396                       "pid = %d, errno = %d\n", pid, -err);
 397
 398         err = ptrace_setfpregs(pid, thread_fp_regs);
 399         if(err < 0)
 400                 panic("copy_context_skas0 : PTRACE_SETFPREGS failed, "
 401                       "pid = %d, errno = %d\n", pid, -err);
 402
 403         /* set a well known return code for detection of child write failure */
 404         child_data->err = 12345678;
 405
 406         /* Wait, until parent has finished its work: read child's pid from
 407          * parent's stack, and check, if bad result.
 408          */
 409         err = ptrace(PTRACE_CONT, pid, 0, 0);
 410         if(err)
 411                 panic("Failed to continue new process, pid = %d, "
 412                       "errno = %d\n", pid, errno);
 413         wait_stub_done(pid);
 414
 415         pid = data->err;
 416         if(pid < 0)
 417                 panic("copy_context_skas0 - stub-parent reports error %d\n",
 418                       -pid);
 419
 420         /* Wait, until child has finished too: read child's result from
 421          * child's stack and check it.
 422          */
 423         wait_stub_done(pid);
 424         if (child_data->err != UML_CONFIG_STUB_DATA)
 425                 panic("copy_context_skas0 - stub-child reports error %ld\n",
 426                       child_data->err);
 427
 428         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
 429                    (void *)PTRACE_O_TRACESYSGOOD) < 0)
 430                 panic("copy_context_skas0 : PTRACE_OLDSETOPTIONS failed, "
 431                       "errno = %d\n", errno);
 432
 433         return pid;
 434 }
 435
 436 /*
 437  * This is used only, if stub pages are needed, while proc_mm is
 438  * available. Opening /proc/mm creates a new mm_context, which lacks
 439  * the stub-pages. Thus, we map them using /proc/mm-fd
 440  */
 441 void map_stub_pages(int fd, unsigned long code,
 442                     unsigned long data, unsigned long stack)
 443 {
 444         struct proc_mm_op mmop;
 445         int n;
 446         __u64 code_offset;
 447         int code_fd = phys_mapping(to_phys((void *) &__syscall_stub_start),
 448                                    &code_offset);
 449
 450         mmop = ((struct proc_mm_op) { .op        = MM_MMAP,
 451                                       .u         =
 452                                       { .mmap    =
 453                                         { .addr    = code,
 454                                           .len     = PAGE_SIZE,
 455                                           .prot    = PROT_EXEC,
 456                                           .flags   = MAP_FIXED | MAP_PRIVATE,
 457                                           .fd      = code_fd,
 458                                           .offset  = code_offset
 459         } } });
 460         CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
 461         if(n != sizeof(mmop)){
 462                 n = errno;
 463                 printk("mmap args - addr = 0x%lx, fd = %d, offset = %llx\n",
 464                        code, code_fd, (unsigned long long) code_offset);
 465                 panic("map_stub_pages : /proc/mm map for code failed, "
 466                       "err = %d\n", n);
 467         }
 468
 469         if ( stack ) {
 470                 __u64 map_offset;
 471                 int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
 472                 mmop = ((struct proc_mm_op)
 473                                 { .op        = MM_MMAP,
 474                                   .u         =
 475                                   { .mmap    =
 476                                     { .addr    = data,
 477                                       .len     = PAGE_SIZE,
 478                                       .prot    = PROT_READ | PROT_WRITE,
 479                                       .flags   = MAP_FIXED | MAP_SHARED,
 480                                       .fd      = map_fd,
 481                                       .offset  = map_offset
 482                 } } });
 483                 CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
 484                 if(n != sizeof(mmop))
 485                         panic("map_stub_pages : /proc/mm map for data failed, "
 486                               "err = %d\n", errno);
 487         }
 488 }
 489
 490 void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
 491 {
 492         (*buf)[0].JB_IP = (unsigned long) handler;
 493         (*buf)[0].JB_SP = (unsigned long) stack +
 494                 (PAGE_SIZE << UML_CONFIG_KERNEL_STACK_ORDER) - sizeof(void *);
 495 }
 496
 497 #define INIT_JMP_NEW_THREAD 0
 498 #define INIT_JMP_CALLBACK 1
 499 #define INIT_JMP_HALT 2
 500 #define INIT_JMP_REBOOT 3
 501
 502 void switch_threads(jmp_buf *me, jmp_buf *you)
 503 {
 504         if(UML_SETJMP(me) == 0)
 505                 UML_LONGJMP(you, 1);
 506 }
 507
 508 static jmp_buf initial_jmpbuf;
 509
 510 /* XXX Make these percpu */
 511 static void (*cb_proc)(void *arg);
 512 static void *cb_arg;
 513 static jmp_buf *cb_back;
 514
 515 int start_idle_thread(void *stack, jmp_buf *switch_buf)
 516 {
 517         int n;
 518
 519         set_handler(SIGWINCH, (__sighandler_t) sig_handler,
 520                     SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGALRM,
 521                     SIGVTALRM, -1);
 522
 523         /*
 524          * Can't use UML_SETJMP or UML_LONGJMP here because they save
 525          * and restore signals, with the possible side-effect of
 526          * trying to handle any signals which came when they were
 527          * blocked, which can't be done on this stack.
 528          * Signals must be blocked when jumping back here and restored
 529          * after returning to the jumper.
 530          */
 531         n = setjmp(initial_jmpbuf);
 532         switch(n){
 533         case INIT_JMP_NEW_THREAD:
 534                 (*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
 535                 (*switch_buf)[0].JB_SP = (unsigned long) stack +
 536                         (PAGE_SIZE << UML_CONFIG_KERNEL_STACK_ORDER) -
 537                         sizeof(void *);
 538                 break;
 539         case INIT_JMP_CALLBACK:
 540                 (*cb_proc)(cb_arg);
 541                 longjmp(*cb_back, 1);
 542                 break;
 543         case INIT_JMP_HALT:
 544                 kmalloc_ok = 0;
 545                 return(0);
 546         case INIT_JMP_REBOOT:
 547                 kmalloc_ok = 0;
 548                 return(1);
 549         default:
 550                 panic("Bad sigsetjmp return in start_idle_thread - %d\n", n);
 551         }
 552         longjmp(*switch_buf, 1);
 553 }
 554
 555 void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 556 {
 557         jmp_buf here;
 558
 559         cb_proc = proc;
 560         cb_arg = arg;
 561         cb_back = &here;
 562
 563         block_signals();
 564         if(UML_SETJMP(&here) == 0)
 565                 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
 566         unblock_signals();
 567
 568         cb_proc = NULL;
 569         cb_arg = NULL;
 570         cb_back = NULL;
 571 }
 572
 573 void halt_skas(void)
 574 {
 575         block_signals();
 576         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
 577 }
 578
 579 void reboot_skas(void)
 580 {
 581         block_signals();
 582         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
 583 }
 584
 585 void switch_mm_skas(struct mm_id *mm_idp)
 586 {
 587         int err;
 588
 589         /* FIXME: need cpu pid in switch_mm_skas */
 590         if(proc_mm){
 591                 err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
 592                              mm_idp->u.mm_fd);
 593                 if(err)
 594                         panic("switch_mm_skas - PTRACE_SWITCH_MM failed, "
 595                               "errno = %d\n", errno);
 596         }
 597         else userspace_pid[0] = mm_idp->u.pid;
 598 }