l4/pkg/plr/server/src/app_thread.cc

   1 /*
   2  * app_thread.cc --
   3  *
   4  *     App_thread functions for creating and preparing a new VCPU
   5  *
   6  * (c) 2011-2013 Björn Döbel <doebel@os.inf.tu-dresden.de>,
   7  *     economic rights: Technische Universität Dresden (Germany)
   8  * This file is part of TUD:OS and distributed under the terms of the
   9  * GNU General Public License 2.
  10  * Please see the COPYING-GPL-2 file for details.
  11  */
  12
  13 #include "app"
  14 #include "app_loading"
  15 #include "thread_group.h"
  16
  17 #include <l4/libloader/remote_app_model>
  18 #include <pthread-l4.h>
  19
  20 void Romain::App_thread::alloc_vcpu_mem()
  21 {
  22         /* Alloc vUTCB */
  23         l4_addr_t kumem;
  24         L4Re::Util::kumem_alloc(&kumem, 0);
  25         _check(kumem == 0, "out of memory in kumem_alloc");
  26
  27         _vcpu_utcb = (l4_utcb_t *)kumem;
  28         _vcpu = L4vcpu::Vcpu::cast(kumem + L4_UTCB_OFFSET);
  29
  30         /* store segment registers - stolen from the example */
  31         //_vcpu->r()->gs = _master_ds;
  32         _vcpu->r()->fs = _master_ds;
  33         _vcpu->r()->es = _master_ds;
  34         _vcpu->r()->ds = _master_ds;
  35         _vcpu->r()->ss = _master_ds;
  36
  37         /* We want to catch ALL exceptions for this vCPU. */
  38         _vcpu->saved_state()->set(
  39                                   L4_VCPU_F_IRQ
  40                                   | L4_VCPU_F_PAGE_FAULTS
  41                                   | L4_VCPU_F_EXCEPTIONS
  42                                   | L4_VCPU_F_DEBUG_EXC
  43                                   | L4_VCPU_F_USER_MODE
  44                                   | L4_VCPU_F_FPU_ENABLED
  45         );
  46
  47         DEBUG() << "VCPU: utcb = " << (void*)vcpu_utcb()
  48                 << " vcpu @ " << (void*)vcpu();
  49 }
  50
  51
  52 void Romain::App_thread::touch_stacks()
  53 {
  54         /* We need to touch at least the handler stack, because upon entry, the vCPU
  55          * still has interrupts enabled and we must not raise one by causing a page
  56          * fault on the stack area.
  57          */
  58         DEBUG() << "Stack info:";
  59         DEBUG() << "   handler stack @ " << (void*)_handler_stack
  60                 << " - " << (void*)(_handler_stack + sizeof(_handler_stack));
  61
  62         l4_touch_rw(_handler_stack, sizeof(_handler_stack));
  63 }
  64
  65
  66 void Romain::App_thread::alloc_vcpu_cap()
  67 {
  68 #if 0
  69         _vcpu_cap = chkcap(L4Re::Util::cap_alloc.alloc<L4::Thread>(),
  70                            "vCPU cap alloc");
  71         chksys(L4Re::Env::env()->factory()->create_thread(_vcpu_cap),
  72                "create thread");
  73         l4_debugger_set_object_name(_vcpu_cap.cap(), "vcpu thread");
  74 #endif
  75 }
  76
  77
  78 extern "C" void* pthread_fn(void *);
  79
  80 /*
  81  * Create a replica thread
  82  */
  83 void Romain::App_thread::start()
  84 {
  85         /*
  86          * We only set handler IP and SP here, because beforehand our creator
  87          * may have modified them.
  88          */
  89         _vcpu->entry_sp(handler_sp());
  90         _vcpu->entry_ip((l4_umword_t)_handler_fn);
  91
  92         int err = pthread_create(&_pthread, NULL, pthread_fn, this);
  93         _check(err != 0, "pthread_create");
  94
  95         //_vcpu_cap = L4::Cap<L4::Thread>(pthread_getl4cap(_pthread));
  96 }
  97
  98
  99 /*
 100  * Calculate checksum of the replica's state
 101  *
 102  * This checksum is used to compare replica states.
 103  */
 104 unsigned long
 105 Romain::App_thread::csum_state()
 106 {
 107         // XXX: this should also include the UTCB, which
 108         //      means the _used_ part of the UTCB
 109         return _vcpu->r()->ip
 110              + _vcpu->r()->sp
 111              + _vcpu->r()->ax
 112              + _vcpu->r()->bx
 113              + _vcpu->r()->cx
 114              + _vcpu->r()->dx
 115              + _vcpu->r()->bp
 116              /*+ _vcpu->r()->fs
 117              + _vcpu->r()->gs*/
 118              ;
 119 }
 120
 121
 122 void
 123 Romain::Thread_group::ex_regs(Romain::App_thread *caller)
 124 {
 125         /*
 126          * Thoughts on ex_regs
 127          *
 128          * One use case of ex_regs is for an external thread to halt execution
 129          * of a thread, store the halted thread's state and later continue from
 130          * this point. As replicated threads execute independently, we will not
 131          * stop all replicas in the same state. However, we require the replicas
 132          * to be in the same state on resumption.
 133          *
 134          * To make things deterministic, we stop all replicas. As a heuristic, we
 135          * then assume that the replicas are all correct (as all state
 136          * difference can be attributed to diverging execution). We select the last
 137          * stopped replica (potentially being the most advanced) as good copy and
 138          * copy its state over to all other replicas, thereby forcing them to the
 139          * same state.
 140          *
 141          * 1) This may shadow certain errors that occurred prior to the ex_regs.
 142          *    -> we need to evaluate how often that happens
 143          *
 144          * 2) HP NonStop instead executes replicas in lock-step until it can
 145          *    figure out which is the most advanced. THen they execute everyone
 146          *    else up to this point.
 147          *    -> higher overhead
 148          *    -> no lack in error detection
 149          *
 150          * 3) Can we detect situations where this happens as hard overwrite of
 151          *    the replicated thread's state -> hence we would not need to first
 152          *    enforce identical states? -> heuristics only, cannot determine
 153          *    upfront if the caller will later reuse the state.
 154          *
 155          */
 156         bool need_to_stop = !this->stopped;
 157
 158         if (need_to_stop) {
 159                 enter_kdebug("stop thread magic goes here");
 160         }
 161
 162         l4_msg_regs_t *buf = l4_utcb_mr_u(reinterpret_cast<l4_utcb_t*>(caller->remote_utcb()));
 163         DEBUG() << std::hex << buf->mr[0];
 164         DEBUG() << std::hex << buf->mr[1];
 165         DEBUG() << std::hex << buf->mr[2];
 166
 167         Romain::App_thread* thread = threads[0];
 168         l4_umword_t eip = thread->vcpu()->r()->ip;
 169         l4_umword_t esp = thread->vcpu()->r()->sp;
 170
 171         DEBUG() << (void*)thread->vcpu();
 172         for (unsigned i = 0; i < threads.size(); ++i) {
 173                 threads[i]->vcpu()->r()->ip = buf->mr[1];
 174                 threads[i]->vcpu()->r()->sp = buf->mr[2];
 175         }
 176
 177         buf->mr[1] = eip;
 178         buf->mr[2] = esp;
 179
 180         caller->vcpu()->r()->ax = l4_msgtag(0,3,0,0).raw;
 181
 182         if (need_to_stop) {
 183                 /*
 184                  * If we stopped the threads before,
 185                  * we need to reactivate them now.
 186                  */
 187                 enter_kdebug("reactivation magic goes here");
 188         }
 189         //enter_kdebug("Thread_group::ex_regs");
 190 }
 191
 192
 193 void
 194 Romain::Thread_group::scheduler_run(Romain::App_thread *caller)
 195 {
 196         l4_msg_regs_t *buf = l4_utcb_mr_u(reinterpret_cast<l4_utcb_t*>(caller->remote_utcb()));
 197
 198         DEBUG() << "Thread_group::scheduler_run("
 199                 << (void*)threads[0]->vcpu()
 200                 << ")";
 201         DEBUG() << "granularity | affinity.offs : " << std::hex << buf->mr[1];
 202         DEBUG() << "affinity.map                : " << std::hex << buf->mr[2];
 203         DEBUG() << "prio                        : " << std::hex << buf->mr[3];
 204         DEBUG() << "quantum                     : " << std::hex << buf->mr[4];
 205         DEBUG() << "obj_control                 : " << std::hex << buf->mr[5];
 206         DEBUG() << "thread                      : " << std::hex << buf->mr[6];
 207
 208         activate();
 209
 210         //enter_kdebug("Thread_group::schedule()");
 211 }
 212
 213
 214 void
 215 Romain::Thread_group::sanity_check_control(unsigned flags, l4_utcb_t *utcb)
 216 {
 217         DEBUG() << "Control flags: " << std::hex << l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_FLAGS];
 218
 219         if ((flags & L4_THREAD_CONTROL_ALIEN) ||
 220                 (flags & L4_THREAD_CONTROL_UX_NATIVE)) {
 221                 ERROR() << "ux_native and alien not supported yet";
 222         }
 223
 224         if (flags & L4_THREAD_CONTROL_BIND_TASK) {
 225                 l4_fpage_t fp;
 226                 fp.raw = l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_BIND_TASK + 1];
 227                 DEBUG() << std::hex << "L4_THREAD_CONTROL_BIND_TASK := ("
 228                         << l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_BIND_UTCB] << ", "
 229                         << l4_fpage_page(fp) << ")";
 230                 if (l4_fpage_page(fp) != (L4Re::This_task >> L4_CAP_SHIFT)) {
 231                         ERROR() << "Binding to different task not supported yet.";
 232                         enter_kdebug("error");
 233                 }
 234                 /* Apart from these checks, don't do anything. The replica vCPUs
 235                  * are already bound.
 236                  */
 237         }
 238
 239         unsigned handler = 0;
 240         unsigned pager   = 0;
 241
 242         if (flags & L4_THREAD_CONTROL_SET_PAGER) {
 243                 pager = l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_PAGER];
 244                 DEBUG() << "pager <- " << std::hex << pager;
 245         }
 246
 247         if (flags & L4_THREAD_CONTROL_SET_EXC_HANDLER) {
 248                 handler = l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_EXC_HANDLER];
 249                 DEBUG() << "exc handler <- " << std::hex << handler;
 250         }
 251
 252         if (handler && pager) {
 253                 if ((handler != pager)  ||
 254                         (handler != Ldr::Remote_app_std_caps::Rm_thread_cap << L4_CAP_SHIFT) ||
 255                         (pager != Ldr::Remote_app_std_caps::Rm_thread_cap << L4_CAP_SHIFT)) {
 256                         ERROR() << "setting different pager or exc. handler not supported yet";
 257                         enter_kdebug("error");
 258                 }
 259         }
 260
 261         if (handler && (handler != Ldr::Remote_app_std_caps::Rm_thread_cap << L4_CAP_SHIFT)) {
 262                 ERROR() << "setting non-standard pager not supported yet";
 263         }
 264
 265         if (pager && (pager != Ldr::Remote_app_std_caps::Rm_thread_cap << L4_CAP_SHIFT)) {
 266                 ERROR() << "setting non-standard exc. handler not supported yet";
 267         }
 268 }
 269
 270
 271 void
 272 Romain::Thread_group::control(Romain::App_thread *t, l4_utcb_t *utcb, Romain::App_model *am)
 273 {
 274         unsigned flags = l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_FLAGS];
 275
 276         sanity_check_control(flags, utcb);
 277
 278         if (flags & L4_THREAD_CONTROL_BIND_TASK) {
 279                 l4_addr_t utcb_remote = l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_BIND_UTCB];
 280                 DEBUG() << "Setting remote UTCB to " << (void*)utcb_remote;
 281
 282                 Romain::App_model::Dataspace ds = am->alloc_ds(L4_PAGESIZE); // thread info page
 283                 l4_addr_t local_addr = am->local_attach_ds(ds, L4_PAGESIZE, 0);
 284                 DEBUG() << "Attached TIP to " << (void*)local_addr;
 285
 286                 *reinterpret_cast<l4_umword_t*>(local_addr) = utcb_remote;
 287                 void* tip_addr = am->prog_attach_ds(0, L4_PAGESIZE, ds, 0,
 288                                                                                         L4Re::Rm::Search_addr, "thread info page", local_addr);
 289                 DEBUG() << "Remote TIP address: " << tip_addr;
 290
 291                 for (unsigned i = 0; i < threads.size(); ++i) {
 292                         threads[i]->setup_utcb_segdesc(reinterpret_cast<l4_addr_t>(tip_addr), 4);
 293
 294                         l4_addr_t utcb_local = am->rm()->remote_to_local(utcb_remote, i);
 295                         threads[i]->remote_utcb(utcb_local);
 296                         //threads[i]->commit_client_gdt();
 297                 }
 298
 299                 //enter_kdebug("utcb");
 300         }
 301
 302         /*
 303          * Our current assumption is that the replicated app uses only default
 304          * threading features, e.g. does not change pager, exception handler or
 305          * any other thread features. Therefore, after sanity checking for these
 306          * assumptions, we simply pretend everything went alright.
 307          */
 308         t->vcpu()->r()->ax = l4_msgtag(0, 3, 0, 0).raw;
 309 }
 310
 311 void
 312 Romain::Thread_group::gdt(Romain::App_thread* t, l4_utcb_t *utcb)
 313 {
 314         enum { replica_gs_base = 0x58 };
 315
 316         l4_msgtag_t *tag = reinterpret_cast<l4_msgtag_t*>(&t->vcpu()->r()->ax);
 317         DEBUG() << BOLD_BLUE "GDT: words" << NOCOLOR << " = " << tag->words();
 318
 319         // 1 word -> query GDT start
 320         if (tag->words() == 1) {
 321                 l4_utcb_mr_u(utcb)->mr[0] = replica_gs_base >> 3;
 322                 t->vcpu()->r()->ax = l4_msgtag(0, 1, 0, 0).raw;
 323                 enter_kdebug("gdt query");
 324         } else { // setup new GDT entry
 325                 unsigned idx      = l4_utcb_mr_u(utcb)->mr[1];
 326                 unsigned numbytes = (tag->words() == 4) ? 8 : 16;
 327
 328                 for (unsigned i = 0; i < threads.size(); ++i) {
 329                         Romain::App_thread* thread = threads[i];
 330
 331                         if ((idx == 0) and (numbytes == 8)) { // actually, we only support a single entry here
 332                                 thread->write_gdt_entry(&l4_utcb_mr_u(utcb)->mr[2], numbytes);
 333                                 DEBUG() << "GS: " << std::hex << thread->vcpu()->r()->gs;
 334                         } else {
 335                                 enter_kdebug("GDT??");
 336                         }
 337                 }
 338
 339                 t->vcpu()->r()->ax = l4_msgtag((idx << 3) + replica_gs_base + 3, 0, 0, 0).raw;
 340         }
 341 }
 342
 343
 344 void* Romain::GateAgent::listener_function(void *gk)
 345 {
 346         GateAgent *agent = reinterpret_cast<GateAgent*>(gk);
 347         static char* utcb_copy[L4_UTCB_OFFSET];
 348
 349         char namebuf[16];
 350         snprintf(namebuf, 16, "GK::%s", agent->owner_group->name.c_str());
 351         l4_debugger_set_object_name(pthread_getl4cap(pthread_self()), namebuf);
 352
 353         sem_wait(&agent->init_sem);
 354         sem_destroy(&agent->init_sem);
 355         DEBUG() << "starting agent loop";
 356
 357         l4_utcb_t *my_utcb = l4_utcb();
 358         l4_msgtag_t tag;
 359
 360         while (1) {
 361 #if USE_SHMSYNC
 362                 while (agent->current_client == 0) {
 363                         l4_thread_yield();
 364                 }
 365 #endif
 366
 367 #if USE_IRQ
 368                 tag = agent->gate_irq->receive();
 369 #endif
 370
 371 #if 0
 372                 DEBUG() << "Keeper activated by replica.";
 373                 DEBUG() << "agent " << (void*)agent;
 374                 DEBUG() << "client " << (void*)agent->current_client;
 375                 DEBUG() << " CLNT: " << (void*)agent->current_client << " remote_utcb: "
 376                         << (void*)agent->current_client->remote_utcb();
 377                 if (agent->current_client == 0) {
 378                         DEBUG() << "!!!!!" << std::hex << " " << tag.raw;
 379                         DEBUG() << l4sys_errtostr(l4_error(tag));
 380                         enter_kdebug();
 381                         continue;
 382                 }
 383                 _check(agent->current_client == 0, "agent called with client NULL?");
 384 #endif
 385
 386                 memcpy(utcb_copy, my_utcb, L4_UTCB_OFFSET);
 387                 memcpy(my_utcb, (void*)agent->current_client->remote_utcb(), L4_UTCB_OFFSET);
 388
 389                 //outhex32((unsigned)agent->current_client->vcpu()); outstring(" enter kernel\n");
 390                 asm volatile( L4_ENTER_KERNEL
 391                           : "=a" (agent->current_client->vcpu()->r()->ax),
 392                         "=b" (agent->current_client->vcpu()->r()->bx),
 393                         /* ECX, EDX are overwritten anyway */
 394                         "=S" (agent->current_client->vcpu()->r()->si),
 395                         "=D" (agent->current_client->vcpu()->r()->di)
 396                           : "a" (agent->current_client->vcpu()->r()->ax),
 397                         /* EBX and EBP will be overwritten with local
 398                          * values in L4_ENTER_KERNEL */
 399                         "c" (agent->current_client->vcpu()->r()->cx),
 400                         "d" (agent->current_client->vcpu()->r()->dx),
 401                         "S" (agent->current_client->vcpu()->r()->si),
 402                         "D" (agent->current_client->vcpu()->r()->di)
 403                           : "memory", "cc"
 404                 );
 405 #if 0
 406                 outhex32((unsigned)agent->current_client->vcpu()); outstring(" ret from kernel ");
 407                 outhex32((unsigned)agent->current_client->vcpu()->r()->ax); outstring("\n");
 408 #endif
 409
 410                 memcpy((void*)agent->current_client->remote_utcb(), my_utcb, L4_UTCB_OFFSET);
 411                 memcpy(my_utcb, utcb_copy, L4_UTCB_OFFSET);
 412
 413                 l4_cap_idx_t cap = agent->current_client->vcpu_cap().cap();
 414                 agent->current_client = 0;
 415                 tag = l4_ipc_send(cap, l4_utcb(), l4_msgtag(0,0,0,0), L4_IPC_NEVER);
 416         }
 417
 418         enter_kdebug("gateagent exited");
 419
 420         return 0;
 421 }