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 #if 0
 114              + _vcpu->r()->cx
 115              + _vcpu->r()->dx
 116              + _vcpu->r()->bp
 117              + _vcpu->r()->fs
 118              + _vcpu->r()->gs
 119 #endif
 120              ;
 121 }
 122
 123
 124 void
 125 Romain::Thread_group::ex_regs(Romain::App_thread *caller)
 126 {
 127         /*
 128          * Thoughts on ex_regs
 129          *
 130          * One use case of ex_regs is for an external thread to halt execution
 131          * of a thread, store the halted thread's state and later continue from
 132          * this point. As replicated threads execute independently, we will not
 133          * stop all replicas in the same state. However, we require the replicas
 134          * to be in the same state on resumption.
 135          *
 136          * To make things deterministic, we stop all replicas. As a heuristic, we
 137          * then assume that the replicas are all correct (as all state
 138          * difference can be attributed to diverging execution). We select the last
 139          * stopped replica (potentially being the most advanced) as good copy and
 140          * copy its state over to all other replicas, thereby forcing them to the
 141          * same state.
 142          *
 143          * 1) This may shadow certain errors that occurred prior to the ex_regs.
 144          *    -> we need to evaluate how often that happens
 145          *
 146          * 2) HP NonStop instead executes replicas in lock-step until it can
 147          *    figure out which is the most advanced. THen they execute everyone
 148          *    else up to this point.
 149          *    -> higher overhead
 150          *    -> no lack in error detection
 151          *
 152          * 3) Can we detect situations where this happens as hard overwrite of
 153          *    the replicated thread's state -> hence we would not need to first
 154          *    enforce identical states? -> heuristics only, cannot determine
 155          *    upfront if the caller will later reuse the state.
 156          *
 157          */
 158         bool need_to_stop = !this->stopped;
 159
 160         if (need_to_stop) {
 161                 enter_kdebug("stop thread magic goes here");
 162         }
 163
 164         l4_msg_regs_t *buf = l4_utcb_mr_u(reinterpret_cast<l4_utcb_t*>(caller->remote_utcb()));
 165         DEBUG() << std::hex << buf->mr[0];
 166         DEBUG() << std::hex << buf->mr[1];
 167         DEBUG() << std::hex << buf->mr[2];
 168
 169         Romain::App_thread* thread = threads[0];
 170         l4_umword_t eip = thread->vcpu()->r()->ip;
 171         l4_umword_t esp = thread->vcpu()->r()->sp;
 172
 173         DEBUG() << (void*)thread->vcpu();
 174         for (unsigned i = 0; i < threads.size(); ++i) {
 175                 threads[i]->vcpu()->r()->ip = buf->mr[1];
 176                 threads[i]->vcpu()->r()->sp = buf->mr[2];
 177         }
 178
 179         buf->mr[1] = eip;
 180         buf->mr[2] = esp;
 181
 182         caller->vcpu()->r()->ax = l4_msgtag(0,3,0,0).raw;
 183
 184         if (need_to_stop) {
 185                 /*
 186                  * If we stopped the threads before,
 187                  * we need to reactivate them now.
 188                  */
 189                 enter_kdebug("reactivation magic goes here");
 190         }
 191         //enter_kdebug("Thread_group::ex_regs");
 192 }
 193
 194
 195 void
 196 Romain::Thread_group::scheduler_run(Romain::App_thread *caller)
 197 {
 198         l4_msg_regs_t *buf = l4_utcb_mr_u(reinterpret_cast<l4_utcb_t*>(caller->remote_utcb()));
 199
 200         DEBUG() << "Thread_group::scheduler_run("
 201                 << (void*)threads[0]->vcpu()
 202                 << ")";
 203         DEBUG() << "granularity | affinity.offs : " << std::hex << buf->mr[1];
 204         DEBUG() << "affinity.map                : " << std::hex << buf->mr[2];
 205         DEBUG() << "prio                        : " << std::hex << buf->mr[3];
 206         DEBUG() << "quantum                     : " << std::hex << buf->mr[4];
 207         DEBUG() << "obj_control                 : " << std::hex << buf->mr[5];
 208         DEBUG() << "thread                      : " << std::hex << buf->mr[6];
 209
 210         activate();
 211
 212         //enter_kdebug("Thread_group::schedule()");
 213 }
 214
 215
 216 void
 217 Romain::Thread_group::sanity_check_control(unsigned flags, l4_utcb_t *utcb)
 218 {
 219         DEBUG() << "Control flags: " << std::hex << l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_FLAGS];
 220
 221         if ((flags & L4_THREAD_CONTROL_ALIEN) ||
 222                 (flags & L4_THREAD_CONTROL_UX_NATIVE)) {
 223                 ERROR() << "ux_native and alien not supported yet";
 224         }
 225
 226         if (flags & L4_THREAD_CONTROL_BIND_TASK) {
 227                 l4_fpage_t fp;
 228                 fp.raw = l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_BIND_TASK + 1];
 229                 DEBUG() << std::hex << "L4_THREAD_CONTROL_BIND_TASK := ("
 230                         << l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_BIND_UTCB] << ", "
 231                         << l4_fpage_page(fp) << ")";
 232                 if (l4_fpage_page(fp) != (L4Re::This_task >> L4_CAP_SHIFT)) {
 233                         ERROR() << "Binding to different task not supported yet.";
 234                         enter_kdebug("error");
 235                 }
 236                 /* Apart from these checks, don't do anything. The replica vCPUs
 237                  * are already bound.
 238                  */
 239         }
 240
 241         unsigned handler = 0;
 242         unsigned pager   = 0;
 243
 244         if (flags & L4_THREAD_CONTROL_SET_PAGER) {
 245                 pager = l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_PAGER];
 246                 DEBUG() << "pager <- " << std::hex << pager;
 247         }
 248
 249         if (flags & L4_THREAD_CONTROL_SET_EXC_HANDLER) {
 250                 handler = l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_EXC_HANDLER];
 251                 DEBUG() << "exc handler <- " << std::hex << handler;
 252         }
 253
 254         if (handler && pager) {
 255                 if ((handler != pager)  ||
 256                         (handler != Ldr::Remote_app_std_caps::Rm_thread_cap << L4_CAP_SHIFT) ||
 257                         (pager != Ldr::Remote_app_std_caps::Rm_thread_cap << L4_CAP_SHIFT)) {
 258                         ERROR() << "setting different pager or exc. handler not supported yet";
 259                         enter_kdebug("error");
 260                 }
 261         }
 262
 263         if (handler && (handler != Ldr::Remote_app_std_caps::Rm_thread_cap << L4_CAP_SHIFT)) {
 264                 ERROR() << "setting non-standard pager not supported yet";
 265         }
 266
 267         if (pager && (pager != Ldr::Remote_app_std_caps::Rm_thread_cap << L4_CAP_SHIFT)) {
 268                 ERROR() << "setting non-standard exc. handler not supported yet";
 269         }
 270 }
 271
 272
 273 void
 274 Romain::Thread_group::control(Romain::App_thread *t, l4_utcb_t *utcb, Romain::App_model *am)
 275 {
 276         unsigned flags = l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_FLAGS];
 277
 278         sanity_check_control(flags, utcb);
 279
 280         if (flags & L4_THREAD_CONTROL_BIND_TASK) {
 281                 l4_addr_t utcb_remote = l4_utcb_mr_u(utcb)->mr[L4_THREAD_CONTROL_MR_IDX_BIND_UTCB];
 282                 DEBUG() << "Setting remote UTCB to " << (void*)utcb_remote;
 283
 284                 Romain::App_model::Dataspace ds = am->alloc_ds(L4_PAGESIZE); // thread info page
 285                 l4_addr_t local_addr = am->local_attach_ds(ds, L4_PAGESIZE, 0);
 286                 DEBUG() << "Attached TIP to " << (void*)local_addr;
 287
 288                 *reinterpret_cast<l4_umword_t*>(local_addr) = utcb_remote;
 289                 void* tip_addr = am->prog_attach_ds(0, L4_PAGESIZE, ds, 0,
 290                                                                                         L4Re::Rm::Search_addr, "thread info page", local_addr);
 291
 292                 for (unsigned i = 0; i < threads.size(); ++i) {
 293                         threads[i]->setup_utcb_segdesc(reinterpret_cast<l4_addr_t>(tip_addr), 4);
 294
 295                         l4_addr_t utcb_local = am->rm()->remote_to_local(utcb_remote, i);
 296                         threads[i]->remote_utcb(utcb_local);
 297                         //threads[i]->commit_client_gdt();
 298                 }
 299
 300                 //enter_kdebug("utcb");
 301         }
 302
 303         /*
 304          * Our current assumption is that the replicated app uses only default
 305          * threading features, e.g. does not change pager, exception handler or
 306          * any other thread features. Therefore, after sanity checking for these
 307          * assumptions, we simply pretend everything went alright.
 308          */
 309         t->vcpu()->r()->ax = l4_msgtag(0, 3, 0, 0).raw;
 310 }
 311
 312 void
 313 Romain::Thread_group::gdt(Romain::App_thread* t, l4_utcb_t *utcb)
 314 {
 315         enum { replica_gs_base = 0x58 };
 316
 317         l4_msgtag_t *tag = reinterpret_cast<l4_msgtag_t*>(&t->vcpu()->r()->ax);
 318         DEBUG() << "\033[34;1mGDT: words\033[0m = " << tag->words();
 319
 320         // 1 word -> query GDT start
 321         if (tag->words() == 1) {
 322                 l4_utcb_mr_u(utcb)->mr[0] = replica_gs_base >> 3;
 323                 t->vcpu()->r()->ax = l4_msgtag(0, 1, 0, 0).raw;
 324                 enter_kdebug("gdt query");
 325         } else { // setup new GDT entry
 326                 unsigned idx      = l4_utcb_mr_u(utcb)->mr[1];
 327                 unsigned numbytes = (tag->words() == 4) ? 8 : 16;
 328
 329                 for (unsigned i = 0; i < threads.size(); ++i) {
 330                         Romain::App_thread* thread = threads[i];
 331
 332                         if ((idx == 0) and (numbytes == 8)) { // actually, we only support a single entry here
 333                                 thread->write_gdt_entry(&l4_utcb_mr_u(utcb)->mr[2], numbytes);
 334                                 DEBUG() << "GS: " << std::hex << thread->vcpu()->r()->gs;
 335                         } else {
 336                                 enter_kdebug("GDT??");
 337                         }
 338                 }
 339
 340                 t->vcpu()->r()->ax = l4_msgtag((idx << 3) + replica_gs_base + 3, 0, 0, 0).raw;
 341         }
 342 }
 343
 344
 345 void* Romain::GateAgent::listener_function(void *gk)
 346 {
 347         GateAgent *agent = reinterpret_cast<GateAgent*>(gk);
 348         static char* utcb_copy[L4_UTCB_OFFSET];
 349
 350         char namebuf[16];
 351         snprintf(namebuf, 16, "GK::%s", agent->owner_group->name.c_str());
 352         l4_debugger_set_object_name(pthread_getl4cap(pthread_self()), namebuf);
 353
 354         sem_wait(&agent->init_sem);
 355         sem_destroy(&agent->init_sem);
 356         DEBUG() << "starting agent loop";
 357
 358         l4_utcb_t *my_utcb = l4_utcb();
 359         l4_msgtag_t tag;
 360
 361         while (1) {
 362 #if USE_SHMSYNC
 363                 while (agent->current_client == 0) {
 364                         l4_thread_yield();
 365                 }
 366 #endif
 367
 368 #if USE_IRQ
 369                 tag = agent->gate_irq->receive();
 370 #endif
 371
 372 #if 0
 373                 DEBUG() << "Keeper activated by replica.";
 374                 DEBUG() << "agent " << (void*)agent;
 375                 DEBUG() << "client " << (void*)agent->current_client;
 376                 DEBUG() << " CLNT: " << (void*)agent->current_client << " remote_utcb: "
 377                         << (void*)agent->current_client->remote_utcb();
 378                 if (agent->current_client == 0) {
 379                         DEBUG() << "!!!!!" << std::hex << " " << tag.raw;
 380                         DEBUG() << l4sys_errtostr(l4_error(tag));
 381                         enter_kdebug();
 382                         continue;
 383                 }
 384                 _check(agent->current_client == 0, "agent called with client NULL?");
 385 #endif
 386
 387                 memcpy(utcb_copy, my_utcb, L4_UTCB_OFFSET);
 388                 memcpy(my_utcb, (void*)agent->current_client->remote_utcb(), L4_UTCB_OFFSET);
 389
 390                 //outhex32((unsigned)agent->current_client->vcpu()); outstring(" enter kernel\n");
 391                 asm volatile( L4_ENTER_KERNEL
 392                           : "=a" (agent->current_client->vcpu()->r()->ax),
 393                         "=b" (agent->current_client->vcpu()->r()->bx),
 394                         /* ECX, EDX are overwritten anyway */
 395                         "=S" (agent->current_client->vcpu()->r()->si),
 396                         "=D" (agent->current_client->vcpu()->r()->di)
 397                           : "a" (agent->current_client->vcpu()->r()->ax),
 398                         /* EBX and EBP will be overwritten with local
 399                          * values in L4_ENTER_KERNEL */
 400                         "c" (agent->current_client->vcpu()->r()->cx),
 401                         "d" (agent->current_client->vcpu()->r()->dx),
 402                         "S" (agent->current_client->vcpu()->r()->si),
 403                         "D" (agent->current_client->vcpu()->r()->di)
 404                           : "memory", "cc"
 405                 );
 406 #if 0
 407                 outhex32((unsigned)agent->current_client->vcpu()); outstring(" ret from kernel ");
 408                 outhex32((unsigned)agent->current_client->vcpu()->r()->ax); outstring("\n");
 409 #endif
 410
 411                 memcpy((void*)agent->current_client->remote_utcb(), my_utcb, L4_UTCB_OFFSET);
 412                 memcpy(my_utcb, utcb_copy, L4_UTCB_OFFSET);
 413
 414                 l4_cap_idx_t cap = agent->current_client->vcpu_cap().cap();
 415                 agent->current_client = 0;
 416                 tag = l4_ipc_send(cap, l4_utcb(), l4_msgtag(0,0,0,0), L4_IPC_NEVER);
 417         }
 418
 419         enter_kdebug("gateagent exited");
 420
 421         return 0;
 422 }