mono/mini/exceptions-x86.c

   1 /*
   2  * exceptions-x86.c: exception support for x86
   3  *
   4  * Authors:
   5  *   Dietmar Maurer (dietmar@ximian.com)
   6  *
   7  * (C) 2001 Ximian, Inc.
   8  */
   9
  10 #include <config.h>
  11 #include <glib.h>
  12 #include <signal.h>
  13 #include <string.h>
  14
  15 #include <mono/arch/x86/x86-codegen.h>
  16 #include <mono/metadata/appdomain.h>
  17 #include <mono/metadata/tabledefs.h>
  18 #include <mono/metadata/threads.h>
  19 #include <mono/metadata/debug-helpers.h>
  20 #include <mono/metadata/exception.h>
  21 #include <mono/metadata/gc-internal.h>
  22 #include <mono/metadata/mono-debug.h>
  23 #include <mono/utils/mono-mmap.h>
  24
  25 #include "mini.h"
  26 #include "mini-x86.h"
  27 #include "tasklets.h"
  28 #include "debug-mini.h"
  29
  30 static gpointer signal_exception_trampoline;
  31
  32 gpointer
  33 mono_x86_get_signal_exception_trampoline (MonoTrampInfo **info, gboolean aot) MONO_INTERNAL;
  34
  35 #ifdef TARGET_WIN32
  36 static void (*restore_stack) (void *);
  37
  38 static MonoW32ExceptionHandler fpe_handler;
  39 static MonoW32ExceptionHandler ill_handler;
  40 static MonoW32ExceptionHandler segv_handler;
  41
  42 LPTOP_LEVEL_EXCEPTION_FILTER mono_old_win_toplevel_exception_filter;
  43 guint64 mono_win_chained_exception_filter_result;
  44 gboolean mono_win_chained_exception_filter_didrun;
  45
  46 #ifndef PROCESS_CALLBACK_FILTER_ENABLED
  47 #       define PROCESS_CALLBACK_FILTER_ENABLED 1
  48 #endif
  49
  50 #define W32_SEH_HANDLE_EX(_ex) \
  51         if (_ex##_handler) _ex##_handler(0, ep, sctx)
  52
  53 /*
  54  * mono_win32_get_handle_stackoverflow (void):
  55  *
  56  * Returns a pointer to a method which restores the current context stack
  57  * and calls handle_exceptions, when done restores the original stack.
  58  */
  59 static gpointer
  60 mono_win32_get_handle_stackoverflow (void)
  61 {
  62         static guint8 *start = NULL;
  63         guint8 *code;
  64
  65         if (start)
  66                 return start;
  67
  68         /* restore_contect (void *sigctx) */
  69         start = code = mono_global_codeman_reserve (128);
  70
  71         /* load context into ebx */
  72         x86_mov_reg_membase (code, X86_EBX, X86_ESP, 4, 4);
  73
  74         /* move current stack into edi for later restore */
  75         x86_mov_reg_reg (code, X86_EDI, X86_ESP, 4);
  76
  77         /* use the new freed stack from sigcontext */
  78         x86_mov_reg_membase (code, X86_ESP, X86_EBX,  G_STRUCT_OFFSET (struct sigcontext, esp), 4);
  79
  80         /* get the current domain */
  81         x86_call_code (code, mono_domain_get);
  82
  83         /* get stack overflow exception from domain object */
  84         x86_mov_reg_membase (code, X86_EAX, X86_EAX, G_STRUCT_OFFSET (MonoDomain, stack_overflow_ex), 4);
  85
  86         /* call mono_arch_handle_exception (sctx, stack_overflow_exception_obj) */
  87         x86_push_reg (code, X86_EAX);
  88         x86_push_reg (code, X86_EBX);
  89         x86_call_code (code, mono_arch_handle_exception);
  90
  91         /* restore the SEH handler stack */
  92         x86_mov_reg_reg (code, X86_ESP, X86_EDI, 4);
  93
  94         /* return */
  95         x86_ret (code);
  96
  97         return start;
  98 }
  99
 100 /* Special hack to workaround the fact that the
 101  * when the SEH handler is called the stack is
 102  * to small to recover.
 103  *
 104  * Stack walking part of this method is from mono_handle_exception
 105  *
 106  * The idea is simple;
 107  *  - walk the stack to free some space (64k)
 108  *  - set esp to new stack location
 109  *  - call mono_arch_handle_exception with stack overflow exception
 110  *  - set esp to SEH handlers stack
 111  *  - done
 112  */
 113 static void
 114 win32_handle_stack_overflow (EXCEPTION_POINTERS* ep, struct sigcontext *sctx)
 115 {
 116         SYSTEM_INFO si;
 117         DWORD page_size;
 118         MonoDomain *domain = mono_domain_get ();
 119         MonoJitInfo rji;
 120         MonoJitTlsData *jit_tls = mono_native_tls_get_value (mono_jit_tls_id);
 121         MonoLMF *lmf = jit_tls->lmf;
 122         MonoContext initial_ctx;
 123         MonoContext ctx;
 124         guint32 free_stack = 0;
 125         StackFrameInfo frame;
 126
 127         /* convert sigcontext to MonoContext (due to reuse of stack walking helpers */
 128         mono_arch_sigctx_to_monoctx (sctx, &ctx);
 129
 130         /* get our os page size */
 131         GetSystemInfo(&si);
 132         page_size = si.dwPageSize;
 133
 134         /* Let's walk the stack to recover
 135          * the needed stack space (if possible)
 136          */
 137         memset (&rji, 0, sizeof (rji));
 138
 139         initial_ctx = ctx;
 140         free_stack = (guint8*)(MONO_CONTEXT_GET_BP (&ctx)) - (guint8*)(MONO_CONTEXT_GET_BP (&initial_ctx));
 141
 142         /* try to free 64kb from our stack */
 143         do {
 144                 MonoContext new_ctx;
 145
 146                 mono_arch_find_jit_info (domain, jit_tls, &rji, &ctx, &new_ctx, &lmf, NULL, &frame);
 147                 if (!frame.ji) {
 148                         g_warning ("Exception inside function without unwind info");
 149                         g_assert_not_reached ();
 150                 }
 151
 152                 if (frame.ji != (gpointer)-1) {
 153                         free_stack = (guint8*)(MONO_CONTEXT_GET_BP (&ctx)) - (guint8*)(MONO_CONTEXT_GET_BP (&initial_ctx));
 154                 }
 155
 156                 /* todo: we should call abort if ji is -1 */
 157                 ctx = new_ctx;
 158         } while (free_stack < 64 * 1024 && frame.ji != (gpointer) -1);
 159
 160         /* convert into sigcontext to be used in mono_arch_handle_exception */
 161         mono_arch_monoctx_to_sigctx (&ctx, sctx);
 162
 163         /* todo: install new stack-guard page */
 164
 165         /* use the new stack and call mono_arch_handle_exception () */
 166         restore_stack (sctx);
 167 }
 168
 169 /*
 170  * Unhandled Exception Filter
 171  * Top-level per-process exception handler.
 172  */
 173 LONG CALLBACK seh_handler(EXCEPTION_POINTERS* ep)
 174 {
 175         EXCEPTION_RECORD* er;
 176         CONTEXT* ctx;
 177         struct sigcontext* sctx;
 178         LONG res;
 179
 180         mono_win_chained_exception_filter_didrun = FALSE;
 181         res = EXCEPTION_CONTINUE_EXECUTION;
 182
 183         er = ep->ExceptionRecord;
 184         ctx = ep->ContextRecord;
 185         sctx = g_malloc(sizeof(struct sigcontext));
 186
 187         /* Copy Win32 context to UNIX style context */
 188         sctx->eax = ctx->Eax;
 189         sctx->ebx = ctx->Ebx;
 190         sctx->ecx = ctx->Ecx;
 191         sctx->edx = ctx->Edx;
 192         sctx->ebp = ctx->Ebp;
 193         sctx->esp = ctx->Esp;
 194         sctx->esi = ctx->Esi;
 195         sctx->edi = ctx->Edi;
 196         sctx->eip = ctx->Eip;
 197
 198         switch (er->ExceptionCode) {
 199         case EXCEPTION_STACK_OVERFLOW:
 200                 win32_handle_stack_overflow (ep, sctx);
 201                 break;
 202         case EXCEPTION_ACCESS_VIOLATION:
 203                 W32_SEH_HANDLE_EX(segv);
 204                 break;
 205         case EXCEPTION_ILLEGAL_INSTRUCTION:
 206                 W32_SEH_HANDLE_EX(ill);
 207                 break;
 208         case EXCEPTION_INT_DIVIDE_BY_ZERO:
 209         case EXCEPTION_INT_OVERFLOW:
 210         case EXCEPTION_FLT_DIVIDE_BY_ZERO:
 211         case EXCEPTION_FLT_OVERFLOW:
 212         case EXCEPTION_FLT_UNDERFLOW:
 213         case EXCEPTION_FLT_INEXACT_RESULT:
 214                 W32_SEH_HANDLE_EX(fpe);
 215                 break;
 216         default:
 217                 break;
 218         }
 219
 220         /* Copy context back */
 221         ctx->Eax = sctx->eax;
 222         ctx->Ebx = sctx->ebx;
 223         ctx->Ecx = sctx->ecx;
 224         ctx->Edx = sctx->edx;
 225         ctx->Ebp = sctx->ebp;
 226         ctx->Esp = sctx->esp;
 227         ctx->Esi = sctx->esi;
 228         ctx->Edi = sctx->edi;
 229         ctx->Eip = sctx->eip;
 230
 231         g_free (sctx);
 232
 233         if (mono_win_chained_exception_filter_didrun)
 234                 res = mono_win_chained_exception_filter_result;
 235
 236         return res;
 237 }
 238
 239 void win32_seh_init()
 240 {
 241         /* install restore stack helper */
 242         if (!restore_stack)
 243                 restore_stack = mono_win32_get_handle_stackoverflow ();
 244
 245         mono_old_win_toplevel_exception_filter = SetUnhandledExceptionFilter(seh_handler);
 246 }
 247
 248 void win32_seh_cleanup()
 249 {
 250         if (mono_old_win_toplevel_exception_filter) SetUnhandledExceptionFilter(mono_old_win_toplevel_exception_filter);
 251 }
 252
 253 void win32_seh_set_handler(int type, MonoW32ExceptionHandler handler)
 254 {
 255         switch (type) {
 256         case SIGFPE:
 257                 fpe_handler = handler;
 258                 break;
 259         case SIGILL:
 260                 ill_handler = handler;
 261                 break;
 262         case SIGSEGV:
 263                 segv_handler = handler;
 264                 break;
 265         default:
 266                 break;
 267         }
 268 }
 269
 270 #endif /* TARGET_WIN32 */
 271
 272 /*
 273  * mono_arch_get_restore_context:
 274  *
 275  * Returns a pointer to a method which restores a previously saved sigcontext.
 276  */
 277 gpointer
 278 mono_arch_get_restore_context (MonoTrampInfo **info, gboolean aot)
 279 {
 280         guint8 *start = NULL;
 281         guint8 *code;
 282         MonoJumpInfo *ji = NULL;
 283         GSList *unwind_ops = NULL;
 284
 285         /* restore_contect (MonoContext *ctx) */
 286
 287         start = code = mono_global_codeman_reserve (128);
 288
 289         /* load ctx */
 290         x86_mov_reg_membase (code, X86_EAX, X86_ESP, 4, 4);
 291
 292         /* get return address, stored in ECX */
 293         x86_mov_reg_membase (code, X86_ECX, X86_EAX,  G_STRUCT_OFFSET (MonoContext, eip), 4);
 294         /* restore EBX */
 295         x86_mov_reg_membase (code, X86_EBX, X86_EAX,  G_STRUCT_OFFSET (MonoContext, ebx), 4);
 296         /* restore EDI */
 297         x86_mov_reg_membase (code, X86_EDI, X86_EAX,  G_STRUCT_OFFSET (MonoContext, edi), 4);
 298         /* restore ESI */
 299         x86_mov_reg_membase (code, X86_ESI, X86_EAX,  G_STRUCT_OFFSET (MonoContext, esi), 4);
 300         /* restore ESP */
 301         x86_mov_reg_membase (code, X86_ESP, X86_EAX,  G_STRUCT_OFFSET (MonoContext, esp), 4);
 302         /* save the return addr to the restored stack */
 303         x86_push_reg (code, X86_ECX);
 304         /* restore EBP */
 305         x86_mov_reg_membase (code, X86_EBP, X86_EAX,  G_STRUCT_OFFSET (MonoContext, ebp), 4);
 306         /* restore ECX */
 307         x86_mov_reg_membase (code, X86_ECX, X86_EAX,  G_STRUCT_OFFSET (MonoContext, ecx), 4);
 308         /* restore EDX */
 309         x86_mov_reg_membase (code, X86_EDX, X86_EAX,  G_STRUCT_OFFSET (MonoContext, edx), 4);
 310         /* restore EAX */
 311         x86_mov_reg_membase (code, X86_EAX, X86_EAX,  G_STRUCT_OFFSET (MonoContext, eax), 4);
 312
 313         /* jump to the saved IP */
 314         x86_ret (code);
 315
 316         nacl_global_codeman_validate(&start, 128, &code);
 317
 318         if (info)
 319                 *info = mono_tramp_info_create (g_strdup_printf ("restore_context"), start, code - start, ji, unwind_ops);
 320         else {
 321                 GSList *l;
 322
 323                 for (l = unwind_ops; l; l = l->next)
 324                         g_free (l->data);
 325                 g_slist_free (unwind_ops);
 326         }
 327
 328         return start;
 329 }
 330
 331 /*
 332  * mono_arch_get_call_filter:
 333  *
 334  * Returns a pointer to a method which calls an exception filter. We
 335  * also use this function to call finally handlers (we pass NULL as
 336  * @exc object in this case).
 337  */
 338 gpointer
 339 mono_arch_get_call_filter (MonoTrampInfo **info, gboolean aot)
 340 {
 341         guint8* start;
 342         guint8 *code;
 343         MonoJumpInfo *ji = NULL;
 344         GSList *unwind_ops = NULL;
 345         guint kMaxCodeSize = NACL_SIZE (64, 128);
 346
 347         /* call_filter (MonoContext *ctx, unsigned long eip) */
 348         start = code = mono_global_codeman_reserve (kMaxCodeSize);
 349
 350         x86_push_reg (code, X86_EBP);
 351         x86_mov_reg_reg (code, X86_EBP, X86_ESP, 4);
 352         x86_push_reg (code, X86_EBX);
 353         x86_push_reg (code, X86_EDI);
 354         x86_push_reg (code, X86_ESI);
 355
 356         /* load ctx */
 357         x86_mov_reg_membase (code, X86_EAX, X86_EBP, 8, 4);
 358         /* load eip */
 359         x86_mov_reg_membase (code, X86_ECX, X86_EBP, 12, 4);
 360         /* save EBP */
 361         x86_push_reg (code, X86_EBP);
 362
 363         /* set new EBP */
 364         x86_mov_reg_membase (code, X86_EBP, X86_EAX,  G_STRUCT_OFFSET (MonoContext, ebp), 4);
 365         /* restore registers used by global register allocation (EBX & ESI) */
 366         x86_mov_reg_membase (code, X86_EBX, X86_EAX,  G_STRUCT_OFFSET (MonoContext, ebx), 4);
 367         x86_mov_reg_membase (code, X86_ESI, X86_EAX,  G_STRUCT_OFFSET (MonoContext, esi), 4);
 368         x86_mov_reg_membase (code, X86_EDI, X86_EAX,  G_STRUCT_OFFSET (MonoContext, edi), 4);
 369
 370         /* align stack and save ESP */
 371         x86_mov_reg_reg (code, X86_EDX, X86_ESP, 4);
 372         x86_alu_reg_imm (code, X86_AND, X86_ESP, -MONO_ARCH_FRAME_ALIGNMENT);
 373         g_assert (MONO_ARCH_FRAME_ALIGNMENT >= 8);
 374         x86_alu_reg_imm (code, X86_SUB, X86_ESP, MONO_ARCH_FRAME_ALIGNMENT - 8);
 375         x86_push_reg (code, X86_EDX);
 376
 377         /* call the handler */
 378         x86_call_reg (code, X86_ECX);
 379
 380         /* restore ESP */
 381         x86_pop_reg (code, X86_ESP);
 382
 383         /* restore EBP */
 384         x86_pop_reg (code, X86_EBP);
 385
 386         /* restore saved regs */
 387         x86_pop_reg (code, X86_ESI);
 388         x86_pop_reg (code, X86_EDI);
 389         x86_pop_reg (code, X86_EBX);
 390         x86_leave (code);
 391         x86_ret (code);
 392
 393         nacl_global_codeman_validate(&start, kMaxCodeSize, &code);
 394
 395         if (info)
 396                 *info = mono_tramp_info_create (g_strdup_printf ("call_filter"), start, code - start, ji, unwind_ops);
 397         else {
 398                 GSList *l;
 399
 400                 for (l = unwind_ops; l; l = l->next)
 401                         g_free (l->data);
 402                 g_slist_free (unwind_ops);
 403         }
 404
 405         g_assert ((code - start) < kMaxCodeSize);
 406         return start;
 407 }
 408
 409 /*
 410  * mono_x86_throw_exception:
 411  *
 412  *   C function called from the throw trampolines.
 413  */
 414 void
 415 mono_x86_throw_exception (mgreg_t *regs, MonoObject *exc,
 416                                                   mgreg_t eip, gboolean rethrow)
 417 {
 418         static void (*restore_context) (MonoContext *);
 419         MonoContext ctx;
 420
 421         if (!restore_context)
 422                 restore_context = mono_get_restore_context ();
 423
 424         ctx.esp = regs [X86_ESP];
 425         ctx.eip = eip;
 426         ctx.ebp = regs [X86_EBP];
 427         ctx.edi = regs [X86_EDI];
 428         ctx.esi = regs [X86_ESI];
 429         ctx.ebx = regs [X86_EBX];
 430         ctx.edx = regs [X86_EDX];
 431         ctx.ecx = regs [X86_ECX];
 432         ctx.eax = regs [X86_EAX];
 433
 434 #ifdef __APPLE__
 435         /* The OSX ABI specifies 16 byte alignment at call sites */
 436         g_assert ((ctx.esp % MONO_ARCH_FRAME_ALIGNMENT) == 0);
 437 #endif
 438
 439         if (mono_object_isinst (exc, mono_defaults.exception_class)) {
 440                 MonoException *mono_ex = (MonoException*)exc;
 441                 if (!rethrow)
 442                         mono_ex->stack_trace = NULL;
 443         }
 444
 445         if (mono_debug_using_mono_debugger ()) {
 446                 guint8 buf [16], *code;
 447
 448                 mono_breakpoint_clean_code (NULL, (gpointer)eip, 8, buf, sizeof (buf));
 449                 code = buf + 8;
 450
 451                 if (buf [3] == 0xe8) {
 452                         MonoContext ctx_cp = ctx;
 453                         ctx_cp.eip = eip - 5;
 454
 455                         if (mono_debugger_handle_exception (&ctx_cp, exc)) {
 456                                 restore_context (&ctx_cp);
 457                                 g_assert_not_reached ();
 458                         }
 459                 }
 460         }
 461
 462         /* adjust eip so that it point into the call instruction */
 463         ctx.eip -= 1;
 464
 465         mono_handle_exception (&ctx, exc);
 466
 467         restore_context (&ctx);
 468
 469         g_assert_not_reached ();
 470 }
 471
 472 void
 473 mono_x86_throw_corlib_exception (mgreg_t *regs, guint32 ex_token_index,
 474                                                                  mgreg_t eip, gint32 pc_offset)
 475 {
 476         guint32 ex_token = MONO_TOKEN_TYPE_DEF | ex_token_index;
 477         MonoException *ex;
 478
 479         ex = mono_exception_from_token (mono_defaults.exception_class->image, ex_token);
 480
 481         eip -= pc_offset;
 482
 483         /* Negate the ip adjustment done in mono_x86_throw_exception () */
 484         eip += 1;
 485
 486         mono_x86_throw_exception (regs, (MonoObject*)ex, eip, FALSE);
 487 }
 488
 489 static void
 490 mono_x86_resume_unwind (mgreg_t *regs, MonoObject *exc,
 491                                                 mgreg_t eip, gboolean rethrow)
 492 {
 493         MonoContext ctx;
 494
 495         ctx.esp = regs [X86_ESP];
 496         ctx.eip = eip;
 497         ctx.ebp = regs [X86_EBP];
 498         ctx.edi = regs [X86_EDI];
 499         ctx.esi = regs [X86_ESI];
 500         ctx.ebx = regs [X86_EBX];
 501         ctx.edx = regs [X86_EDX];
 502         ctx.ecx = regs [X86_ECX];
 503         ctx.eax = regs [X86_EAX];
 504
 505         mono_resume_unwind (&ctx);
 506 }
 507
 508 /*
 509  * get_throw_trampoline:
 510  *
 511  *  Generate a call to mono_x86_throw_exception/
 512  * mono_x86_throw_corlib_exception.
 513  * If LLVM is true, generate code which assumes the caller is LLVM generated code,
 514  * which doesn't push the arguments.
 515  */
 516 static guint8*
 517 get_throw_trampoline (const char *name, gboolean rethrow, gboolean llvm, gboolean corlib, gboolean llvm_abs, gboolean resume_unwind, MonoTrampInfo **info, gboolean aot)
 518 {
 519         guint8 *start, *code;
 520         int i, stack_size, stack_offset, arg_offsets [5], regs_offset;
 521         MonoJumpInfo *ji = NULL;
 522         GSList *unwind_ops = NULL;
 523         guint kMaxCodeSize = NACL_SIZE (128, 256);
 524
 525         start = code = mono_global_codeman_reserve (kMaxCodeSize);
 526
 527         stack_size = 128;
 528
 529         /*
 530          * On apple, the stack is misaligned by the pushing of the return address.
 531          */
 532         if (!llvm && corlib)
 533                 /* On OSX, we don't generate alignment code to save space */
 534                 stack_size += 4;
 535         else
 536                 stack_size += MONO_ARCH_FRAME_ALIGNMENT - 4;
 537
 538         /*
 539          * The stack looks like this:
 540          * <pc offset> (only if corlib is TRUE)
 541          * <exception object>/<type token>
 542          * <return addr> <- esp (unaligned on apple)
 543          */
 544
 545         mono_add_unwind_op_def_cfa (unwind_ops, (guint8*)NULL, (guint8*)NULL, X86_ESP, 4);
 546         mono_add_unwind_op_offset (unwind_ops, (guint8*)NULL, (guint8*)NULL, X86_NREG, -4);
 547
 548         /* Alloc frame */
 549         x86_alu_reg_imm (code, X86_SUB, X86_ESP, stack_size);
 550         mono_add_unwind_op_def_cfa_offset (unwind_ops, code, start, stack_size + 4);
 551
 552         arg_offsets [0] = 0;
 553         arg_offsets [1] = 4;
 554         arg_offsets [2] = 8;
 555         arg_offsets [3] = 12;
 556         regs_offset = 16;
 557
 558         /* Save registers */
 559         for (i = 0; i < X86_NREG; ++i)
 560                 if (i != X86_ESP)
 561                         x86_mov_membase_reg (code, X86_ESP, regs_offset + (i * 4), i, 4);
 562         /* Calculate the offset between the current sp and the sp of the caller */
 563         if (llvm) {
 564                 /* LLVM doesn't push the arguments */
 565                 stack_offset = stack_size + 4;
 566         } else {
 567                 if (corlib) {
 568                         /* Two arguments */
 569                         stack_offset = stack_size + 4 + 8;
 570 #ifdef __APPLE__
 571                         /* We don't generate stack alignment code on osx to save space */
 572 #endif
 573                 } else {
 574                         /* One argument + stack alignment */
 575                         stack_offset = stack_size + 4 + 4;
 576 #ifdef __APPLE__
 577                         /* Pop the alignment added by OP_THROW too */
 578                         stack_offset += MONO_ARCH_FRAME_ALIGNMENT - 4;
 579 #else
 580                         if (mono_do_x86_stack_align)
 581                                 stack_offset += MONO_ARCH_FRAME_ALIGNMENT - 4;
 582 #endif
 583                 }
 584         }
 585         /* Save ESP */
 586         x86_lea_membase (code, X86_EAX, X86_ESP, stack_offset);
 587         x86_mov_membase_reg (code, X86_ESP, regs_offset + (X86_ESP * 4), X86_EAX, 4);
 588
 589         /* Set arg1 == regs */
 590         x86_lea_membase (code, X86_EAX, X86_ESP, regs_offset);
 591         x86_mov_membase_reg (code, X86_ESP, arg_offsets [0], X86_EAX, 4);
 592         /* Set arg2 == exc/ex_token_index */
 593         if (resume_unwind)
 594                 x86_mov_reg_imm (code, X86_EAX, 0);
 595         else
 596                 x86_mov_reg_membase (code, X86_EAX, X86_ESP, stack_size + 4, 4);
 597         x86_mov_membase_reg (code, X86_ESP, arg_offsets [1], X86_EAX, 4);
 598         /* Set arg3 == eip */
 599         if (llvm_abs)
 600                 x86_alu_reg_reg (code, X86_XOR, X86_EAX, X86_EAX);
 601         else
 602                 x86_mov_reg_membase (code, X86_EAX, X86_ESP, stack_size, 4);
 603         x86_mov_membase_reg (code, X86_ESP, arg_offsets [2], X86_EAX, 4);
 604         /* Set arg4 == rethrow/pc_offset */
 605         if (resume_unwind) {
 606                 x86_mov_membase_imm (code, X86_ESP, arg_offsets [3], 0, 4);
 607         } else if (corlib) {
 608                 x86_mov_reg_membase (code, X86_EAX, X86_ESP, stack_size + 8, 4);
 609                 if (llvm_abs) {
 610                         /*
 611                          * The caller is LLVM code which passes the absolute address not a pc offset,
 612                          * so compensate by passing 0 as 'ip' and passing the negated abs address as
 613                          * the pc offset.
 614                          */
 615                         x86_neg_reg (code, X86_EAX);
 616                 }
 617                 x86_mov_membase_reg (code, X86_ESP, arg_offsets [3], X86_EAX, 4);
 618         } else {
 619                 x86_mov_membase_imm (code, X86_ESP, arg_offsets [3], rethrow, 4);
 620         }
 621         /* Make the call */
 622         if (aot) {
 623                 // This can be called from runtime code, which can't guarantee that
 624                 // ebx contains the got address.
 625                 // So emit the got address loading code too
 626                 code = mono_arch_emit_load_got_addr (start, code, NULL, &ji);
 627                 code = mono_arch_emit_load_aotconst (start, code, &ji, MONO_PATCH_INFO_JIT_ICALL_ADDR, corlib ? "mono_x86_throw_corlib_exception" : "mono_x86_throw_exception");
 628                 x86_call_reg (code, X86_EAX);
 629         } else {
 630                 x86_call_code (code, resume_unwind ? (gpointer)(mono_x86_resume_unwind) : (corlib ? (gpointer)mono_x86_throw_corlib_exception : (gpointer)mono_x86_throw_exception));
 631         }
 632         x86_breakpoint (code);
 633
 634         nacl_global_codeman_validate(&start, kMaxCodeSize, &code);
 635
 636         g_assert ((code - start) < kMaxCodeSize);
 637
 638         if (info)
 639                 *info = mono_tramp_info_create (g_strdup (name), start, code - start, ji, unwind_ops);
 640         else {
 641                 GSList *l;
 642
 643                 for (l = unwind_ops; l; l = l->next)
 644                         g_free (l->data);
 645                 g_slist_free (unwind_ops);
 646         }
 647
 648         return start;
 649 }
 650
 651 /**
 652  * mono_arch_get_throw_exception:
 653  *
 654  * Returns a function pointer which can be used to raise
 655  * exceptions. The returned function has the following
 656  * signature: void (*func) (MonoException *exc);
 657  * For example to raise an arithmetic exception you can use:
 658  *
 659  * x86_push_imm (code, mono_get_exception_arithmetic ());
 660  * x86_call_code (code, arch_get_throw_exception ());
 661  *
 662  */
 663 gpointer
 664 mono_arch_get_throw_exception (MonoTrampInfo **info, gboolean aot)
 665 {
 666         return get_throw_trampoline ("throw_exception", FALSE, FALSE, FALSE, FALSE, FALSE, info, aot);
 667 }
 668
 669 gpointer
 670 mono_arch_get_rethrow_exception (MonoTrampInfo **info, gboolean aot)
 671 {
 672         return get_throw_trampoline ("rethrow_exception", TRUE, FALSE, FALSE, FALSE, FALSE, info, aot);
 673 }
 674
 675 /**
 676  * mono_arch_get_throw_corlib_exception:
 677  *
 678  * Returns a function pointer which can be used to raise
 679  * corlib exceptions. The returned function has the following
 680  * signature: void (*func) (guint32 ex_token, guint32 offset);
 681  * Here, offset is the offset which needs to be substracted from the caller IP
 682  * to get the IP of the throw. Passing the offset has the advantage that it
 683  * needs no relocations in the caller.
 684  */
 685 gpointer
 686 mono_arch_get_throw_corlib_exception (MonoTrampInfo **info, gboolean aot)
 687 {
 688         return get_throw_trampoline ("throw_corlib_exception", FALSE, FALSE, TRUE, FALSE, FALSE, info, aot);
 689 }
 690
 691 void
 692 mono_arch_exceptions_init (void)
 693 {
 694         guint8 *tramp;
 695
 696 /*
 697  * If we're running WoW64, we need to set the usermode exception policy
 698  * for SEHs to behave. This requires hotfix http://support.microsoft.com/kb/976038
 699  * or (eventually) Windows 7 SP1.
 700  */
 701 #ifdef HOST_WIN32
 702         DWORD flags;
 703         FARPROC getter;
 704         FARPROC setter;
 705         HMODULE kernel32 = LoadLibraryW (L"kernel32.dll");
 706
 707         if (kernel32) {
 708                 getter = GetProcAddress (kernel32, "GetProcessUserModeExceptionPolicy");
 709                 setter = GetProcAddress (kernel32, "SetProcessUserModeExceptionPolicy");
 710                 if (getter && setter) {
 711                         if (getter (&flags))
 712                                 setter (flags & ~PROCESS_CALLBACK_FILTER_ENABLED);
 713                 }
 714         }
 715 #endif
 716
 717         if (mono_aot_only) {
 718                 signal_exception_trampoline = mono_aot_get_trampoline ("x86_signal_exception_trampoline");
 719                 return;
 720         }
 721
 722         /* LLVM needs different throw trampolines */
 723         tramp = get_throw_trampoline ("llvm_throw_exception_trampoline", FALSE, TRUE, FALSE, FALSE, FALSE, NULL, FALSE);
 724         mono_register_jit_icall (tramp, "llvm_throw_exception_trampoline", NULL, TRUE);
 725
 726         tramp = get_throw_trampoline ("llvm_rethrow_exception_trampoline", FALSE, TRUE, FALSE, FALSE, FALSE, NULL, FALSE);
 727         mono_register_jit_icall (tramp, "llvm_rethrow_exception_trampoline", NULL, TRUE);
 728
 729         tramp = get_throw_trampoline ("llvm_throw_corlib_exception_trampoline", FALSE, TRUE, TRUE, FALSE, FALSE, NULL, FALSE);
 730         mono_register_jit_icall (tramp, "llvm_throw_corlib_exception_trampoline", NULL, TRUE);
 731
 732         tramp = get_throw_trampoline ("llvm_throw_corlib_exception_abs_trampoline", FALSE, TRUE, TRUE, TRUE, FALSE, NULL, FALSE);
 733         mono_register_jit_icall (tramp, "llvm_throw_corlib_exception_abs_trampoline", NULL, TRUE);
 734
 735         tramp = get_throw_trampoline ("llvm_resume_unwind_trampoline", FALSE, FALSE, FALSE, FALSE, TRUE, NULL, FALSE);
 736         mono_register_jit_icall (tramp, "llvm_resume_unwind_trampoline", NULL, TRUE);
 737
 738         signal_exception_trampoline = mono_x86_get_signal_exception_trampoline (NULL, FALSE);
 739 }
 740
 741 /*
 742  * mono_arch_find_jit_info:
 743  *
 744  * See exceptions-amd64.c for docs.
 745  */
 746 gboolean
 747 mono_arch_find_jit_info (MonoDomain *domain, MonoJitTlsData *jit_tls,
 748                                                          MonoJitInfo *ji, MonoContext *ctx,
 749                                                          MonoContext *new_ctx, MonoLMF **lmf,
 750                                                          mgreg_t **save_locations,
 751                                                          StackFrameInfo *frame)
 752 {
 753         gpointer ip = MONO_CONTEXT_GET_IP (ctx);
 754
 755         memset (frame, 0, sizeof (StackFrameInfo));
 756         frame->ji = ji;
 757
 758         *new_ctx = *ctx;
 759
 760         if (ji != NULL) {
 761                 gssize regs [MONO_MAX_IREGS + 1];
 762                 guint8 *cfa;
 763                 guint32 unwind_info_len;
 764                 guint8 *unwind_info;
 765
 766                 frame->type = FRAME_TYPE_MANAGED;
 767
 768                 if (ji->from_aot)
 769                         unwind_info = mono_aot_get_unwind_info (ji, &unwind_info_len);
 770                 else
 771                         unwind_info = mono_get_cached_unwind_info (ji->used_regs, &unwind_info_len);
 772
 773                 regs [X86_EAX] = new_ctx->eax;
 774                 regs [X86_EBX] = new_ctx->ebx;
 775                 regs [X86_ECX] = new_ctx->ecx;
 776                 regs [X86_EDX] = new_ctx->edx;
 777                 regs [X86_ESP] = new_ctx->esp;
 778                 regs [X86_EBP] = new_ctx->ebp;
 779                 regs [X86_ESI] = new_ctx->esi;
 780                 regs [X86_EDI] = new_ctx->edi;
 781                 regs [X86_NREG] = new_ctx->eip;
 782
 783                 mono_unwind_frame (unwind_info, unwind_info_len, ji->code_start,
 784                                                    (guint8*)ji->code_start + ji->code_size,
 785                                                    ip, regs, MONO_MAX_IREGS + 1,
 786                                                    save_locations, MONO_MAX_IREGS, &cfa);
 787
 788                 new_ctx->eax = regs [X86_EAX];
 789                 new_ctx->ebx = regs [X86_EBX];
 790                 new_ctx->ecx = regs [X86_ECX];
 791                 new_ctx->edx = regs [X86_EDX];
 792                 new_ctx->esp = regs [X86_ESP];
 793                 new_ctx->ebp = regs [X86_EBP];
 794                 new_ctx->esi = regs [X86_ESI];
 795                 new_ctx->edi = regs [X86_EDI];
 796                 new_ctx->eip = regs [X86_NREG];
 797
 798                 /* The CFA becomes the new SP value */
 799                 new_ctx->esp = (gssize)cfa;
 800
 801                 /* Adjust IP */
 802                 new_ctx->eip --;
 803
 804                 if (*lmf && (MONO_CONTEXT_GET_BP (ctx) >= (gpointer)(*lmf)->ebp)) {
 805                         /* remove any unused lmf */
 806                         *lmf = (gpointer)(((gsize)(*lmf)->previous_lmf) & ~3);
 807                 }
 808
 809                 /* Pop arguments off the stack */
 810                 /*
 811                  * FIXME: LLVM doesn't push these, we can't use ji->from_llvm as it describes
 812                  * the callee.
 813                  */
 814 #ifndef ENABLE_LLVM
 815                 if (ji->has_arch_eh_info)
 816                         new_ctx->esp += mono_jit_info_get_arch_eh_info (ji)->stack_size;
 817 #endif
 818
 819                 return TRUE;
 820         } else if (*lmf) {
 821
 822                 if (((guint64)(*lmf)->previous_lmf) & 2) {
 823                         /*
 824                          * This LMF entry is created by the soft debug code to mark transitions to
 825                          * managed code done during invokes.
 826                          */
 827                         MonoLMFExt *ext = (MonoLMFExt*)(*lmf);
 828
 829                         g_assert (ext->debugger_invoke);
 830
 831                         memcpy (new_ctx, &ext->ctx, sizeof (MonoContext));
 832
 833                         *lmf = (gpointer)(((gsize)(*lmf)->previous_lmf) & ~3);
 834
 835                         frame->type = FRAME_TYPE_DEBUGGER_INVOKE;
 836
 837                         return TRUE;
 838                 }
 839
 840                 if ((ji = mini_jit_info_table_find (domain, (gpointer)(*lmf)->eip, NULL))) {
 841                 } else {
 842                         if (!((guint32)((*lmf)->previous_lmf) & 1))
 843                                 /* Top LMF entry */
 844                                 return FALSE;
 845                         g_assert_not_reached ();
 846                         /* Trampoline lmf frame */
 847                         frame->method = (*lmf)->method;
 848                 }
 849
 850                 new_ctx->esi = (*lmf)->esi;
 851                 new_ctx->edi = (*lmf)->edi;
 852                 new_ctx->ebx = (*lmf)->ebx;
 853                 new_ctx->ebp = (*lmf)->ebp;
 854                 new_ctx->eip = (*lmf)->eip;
 855
 856                 /* Adjust IP */
 857                 new_ctx->eip --;
 858
 859                 frame->ji = ji;
 860                 frame->type = FRAME_TYPE_MANAGED_TO_NATIVE;
 861
 862                 /* Check if we are in a trampoline LMF frame */
 863                 if ((guint32)((*lmf)->previous_lmf) & 1) {
 864                         /* lmf->esp is set by the trampoline code */
 865                         new_ctx->esp = (*lmf)->esp;
 866
 867                         /* Pop arguments off the stack */
 868                         /* FIXME: Handle the delegate case too ((*lmf)->method == NULL) */
 869                         /* FIXME: Handle the IMT/vtable case too */
 870 #if 0
 871 #ifndef ENABLE_LLVM
 872                         if ((*lmf)->method) {
 873                                 MonoMethod *method = (*lmf)->method;
 874                                 MonoJitArgumentInfo *arg_info = g_newa (MonoJitArgumentInfo, mono_method_signature (method)->param_count + 1);
 875
 876                                 guint32 stack_to_pop = mono_arch_get_argument_info (NULL, mono_method_signature (method), mono_method_signature (method)->param_count, arg_info);
 877                                 new_ctx->esp += stack_to_pop;
 878                         }
 879 #endif
 880 #endif
 881                 }
 882                 else
 883                         /* the lmf is always stored on the stack, so the following
 884                          * expression points to a stack location which can be used as ESP */
 885                         new_ctx->esp = (unsigned long)&((*lmf)->eip);
 886
 887                 *lmf = (gpointer)(((gsize)(*lmf)->previous_lmf) & ~3);
 888
 889                 return TRUE;
 890         }
 891
 892         return FALSE;
 893 }
 894
 895 void
 896 mono_arch_sigctx_to_monoctx (void *sigctx, MonoContext *mctx)
 897 {
 898         mono_sigctx_to_monoctx (sigctx, mctx);
 899 }
 900
 901 void
 902 mono_arch_monoctx_to_sigctx (MonoContext *mctx, void *sigctx)
 903 {
 904         mono_monoctx_to_sigctx (mctx, sigctx);
 905 }
 906
 907 gpointer
 908 mono_arch_ip_from_context (void *sigctx)
 909 {
 910 #if defined(__native_client__)
 911         printf("WARNING: mono_arch_ip_from_context() called!\n");
 912         return (NULL);
 913 #else
 914 #ifdef MONO_ARCH_USE_SIGACTION
 915         ucontext_t *ctx = (ucontext_t*)sigctx;
 916         return (gpointer)UCONTEXT_REG_EIP (ctx);
 917 #else
 918         struct sigcontext *ctx = sigctx;
 919         return (gpointer)ctx->SC_EIP;
 920 #endif
 921 #endif  /* __native_client__ */
 922 }
 923
 924 /*
 925  * handle_exception:
 926  *
 927  *   Called by resuming from a signal handler.
 928  */
 929 static void
 930 handle_signal_exception (gpointer obj)
 931 {
 932         MonoJitTlsData *jit_tls = mono_native_tls_get_value (mono_jit_tls_id);
 933         MonoContext ctx;
 934         static void (*restore_context) (MonoContext *);
 935
 936         if (!restore_context)
 937                 restore_context = mono_get_restore_context ();
 938
 939         memcpy (&ctx, &jit_tls->ex_ctx, sizeof (MonoContext));
 940
 941         if (mono_debugger_handle_exception (&ctx, (MonoObject *)obj))
 942                 return;
 943
 944         mono_handle_exception (&ctx, obj);
 945
 946         restore_context (&ctx);
 947 }
 948
 949 /*
 950  * mono_x86_get_signal_exception_trampoline:
 951  *
 952  *   This x86 specific trampoline is used to call handle_signal_exception.
 953  */
 954 gpointer
 955 mono_x86_get_signal_exception_trampoline (MonoTrampInfo **info, gboolean aot)
 956 {
 957         guint8 *start, *code;
 958         MonoJumpInfo *ji = NULL;
 959         GSList *unwind_ops = NULL;
 960         int stack_size;
 961
 962         start = code = mono_global_codeman_reserve (128);
 963
 964         /* Caller ip */
 965         x86_push_reg (code, X86_ECX);
 966
 967         mono_add_unwind_op_def_cfa (unwind_ops, (guint8*)NULL, (guint8*)NULL, X86_ESP, 4);
 968         mono_add_unwind_op_offset (unwind_ops, (guint8*)NULL, (guint8*)NULL, X86_NREG, -4);
 969
 970         /* Fix the alignment to be what apple expects */
 971         stack_size = 12;
 972
 973         x86_alu_reg_imm (code, X86_SUB, X86_ESP, stack_size);
 974         mono_add_unwind_op_def_cfa_offset (unwind_ops, code, start, stack_size + 4);
 975
 976         /* Arg1 */
 977         x86_mov_membase_reg (code, X86_ESP, 0, X86_EAX, 4);
 978         /* Branch to target */
 979         x86_call_reg (code, X86_EDX);
 980
 981         g_assert ((code - start) < 128);
 982
 983         if (info)
 984                 *info = mono_tramp_info_create (g_strdup ("x86_signal_exception_trampoline"), start, code - start, ji, unwind_ops);
 985         else {
 986                 GSList *l;
 987
 988                 for (l = unwind_ops; l; l = l->next)
 989                         g_free (l->data);
 990                 g_slist_free (unwind_ops);
 991         }
 992
 993         return start;
 994 }
 995
 996
 997 void
 998 mono_arch_setup_async_callback (MonoContext *ctx, void (*async_cb)(void *fun), gpointer user_data)
 999 {
1000         /*
1001          * Can't pass the obj on the stack, since we are executing on the
1002          * same stack. Can't save it into MonoJitTlsData, since it needs GC tracking.
1003          * So put it into a register, and branch to a trampoline which
1004          * pushes it.
1005          */
1006         ctx->eax = (mgreg_t)user_data;
1007         ctx->ecx = ctx->eip;
1008         ctx->edx = (mgreg_t)async_cb;
1009
1010         /*align the stack*/
1011         ctx->esp = (ctx->esp - 16) & ~15;
1012         ctx->eip = (mgreg_t)signal_exception_trampoline;
1013 }
1014
1015 gboolean
1016 mono_arch_handle_exception (void *sigctx, gpointer obj)
1017 {
1018 #if defined(MONO_ARCH_USE_SIGACTION)
1019         MonoContext mctx;
1020         ucontext_t *ctx = (ucontext_t*)sigctx;
1021
1022         /*
1023          * Handling the exception in the signal handler is problematic, since the original
1024          * signal is disabled, and we could run arbitrary code though the debugger. So
1025          * resume into the normal stack and do most work there if possible.
1026          */
1027         MonoJitTlsData *jit_tls = mono_native_tls_get_value (mono_jit_tls_id);
1028
1029         /* Pass the ctx parameter in TLS */
1030         mono_arch_sigctx_to_monoctx (ctx, &jit_tls->ex_ctx);
1031
1032         mctx = jit_tls->ex_ctx;
1033         mono_setup_async_callback (&mctx, handle_signal_exception, obj);
1034         mono_monoctx_to_sigctx (&mctx, sigctx);
1035
1036         return TRUE;
1037 #elif defined (TARGET_WIN32)
1038         MonoContext mctx;
1039         MonoJitTlsData *jit_tls = mono_native_tls_get_value (mono_jit_tls_id);
1040         struct sigcontext *ctx = (struct sigcontext *)sigctx;
1041
1042         mono_arch_sigctx_to_monoctx (sigctx, &jit_tls->ex_ctx);
1043
1044         mctx = jit_tls->ex_ctx;
1045         mono_setup_async_callback (&mctx, handle_signal_exception, obj);
1046         mono_monoctx_to_sigctx (&mctx, sigctx);
1047
1048         return TRUE;
1049 #else
1050         MonoContext mctx;
1051
1052         mono_arch_sigctx_to_monoctx (sigctx, &mctx);
1053
1054         if (mono_debugger_handle_exception (&mctx, (MonoObject *)obj))
1055                 return TRUE;
1056
1057         mono_handle_exception (&mctx, obj);
1058
1059         mono_arch_monoctx_to_sigctx (&mctx, sigctx);
1060
1061         return TRUE;
1062 #endif
1063 }
1064
1065 static void
1066 restore_soft_guard_pages (void)
1067 {
1068         MonoJitTlsData *jit_tls = mono_native_tls_get_value (mono_jit_tls_id);
1069         if (jit_tls->stack_ovf_guard_base)
1070                 mono_mprotect (jit_tls->stack_ovf_guard_base, jit_tls->stack_ovf_guard_size, MONO_MMAP_NONE);
1071 }
1072
1073 /*
1074  * this function modifies mctx so that when it is restored, it
1075  * won't execcute starting at mctx.eip, but in a function that
1076  * will restore the protection on the soft-guard pages and return back to
1077  * continue at mctx.eip.
1078  */
1079 static void
1080 prepare_for_guard_pages (MonoContext *mctx)
1081 {
1082         gpointer *sp;
1083         sp = (gpointer)(mctx->esp);
1084         sp -= 1;
1085         /* the resturn addr */
1086         sp [0] = (gpointer)(mctx->eip);
1087         mctx->eip = (unsigned long)restore_soft_guard_pages;
1088         mctx->esp = (unsigned long)sp;
1089 }
1090
1091 static void
1092 altstack_handle_and_restore (MonoContext *ctx, gpointer obj, gboolean stack_ovf)
1093 {
1094         void (*restore_context) (MonoContext *);
1095         MonoContext mctx;
1096
1097         restore_context = mono_get_restore_context ();
1098         mctx = *ctx;
1099
1100         if (mono_debugger_handle_exception (&mctx, (MonoObject *)obj)) {
1101                 if (stack_ovf)
1102                         prepare_for_guard_pages (&mctx);
1103                 restore_context (&mctx);
1104         }
1105
1106         mono_handle_exception (&mctx, obj);
1107         if (stack_ovf)
1108                 prepare_for_guard_pages (&mctx);
1109         restore_context (&mctx);
1110 }
1111
1112 void
1113 mono_arch_handle_altstack_exception (void *sigctx, gpointer fault_addr, gboolean stack_ovf)
1114 {
1115 #ifdef MONO_ARCH_USE_SIGACTION
1116         MonoException *exc = NULL;
1117         ucontext_t *ctx = (ucontext_t*)sigctx;
1118         MonoJitInfo *ji = mini_jit_info_table_find (mono_domain_get (), (gpointer)UCONTEXT_REG_EIP (ctx), NULL);
1119         gpointer *sp;
1120         int frame_size;
1121
1122         /* if we didn't find a managed method for the ip address and it matches the fault
1123          * address, we assume we followed a broken pointer during an indirect call, so
1124          * we try the lookup again with the return address pushed on the stack
1125          */
1126         if (!ji && fault_addr == (gpointer)UCONTEXT_REG_EIP (ctx)) {
1127                 glong *sp = (gpointer)UCONTEXT_REG_ESP (ctx);
1128                 ji = mini_jit_info_table_find (mono_domain_get (), (gpointer)sp [0], NULL);
1129                 if (ji)
1130                         UCONTEXT_REG_EIP (ctx) = sp [0];
1131         }
1132         if (stack_ovf)
1133                 exc = mono_domain_get ()->stack_overflow_ex;
1134         if (!ji)
1135                 mono_handle_native_sigsegv (SIGSEGV, sigctx);
1136         /* setup a call frame on the real stack so that control is returned there
1137          * and exception handling can continue.
1138          * If this was a stack overflow the caller already ensured the stack pages
1139          * needed have been unprotected.
1140          * The frame looks like:
1141          *   ucontext struct
1142          *   test_only arg
1143          *   exception arg
1144          *   ctx arg
1145          *   return ip
1146          */
1147         // FIXME: test_only is no more.
1148         frame_size = sizeof (MonoContext) + sizeof (gpointer) * 4;
1149         frame_size += 15;
1150         frame_size &= ~15;
1151         sp = (gpointer)(UCONTEXT_REG_ESP (ctx) & ~15);
1152         sp = (gpointer)((char*)sp - frame_size);
1153         /* the incoming arguments are aligned to 16 bytes boundaries, so the return address IP
1154          * goes at sp [-1]
1155          */
1156         sp [-1] = (gpointer)UCONTEXT_REG_EIP (ctx);
1157         sp [0] = sp + 4;
1158         sp [1] = exc;
1159         sp [2] = (gpointer)stack_ovf;
1160         mono_sigctx_to_monoctx (sigctx, (MonoContext*)(sp + 4));
1161         /* at the return form the signal handler execution starts in altstack_handle_and_restore() */
1162         UCONTEXT_REG_EIP (ctx) = (unsigned long)altstack_handle_and_restore;
1163         UCONTEXT_REG_ESP (ctx) = (unsigned long)(sp - 1);
1164 #endif
1165 }
1166
1167 #if MONO_SUPPORT_TASKLETS
1168 MonoContinuationRestore
1169 mono_tasklets_arch_restore (void)
1170 {
1171         static guint8* saved = NULL;
1172         guint8 *code, *start;
1173
1174 #ifdef __native_client_codegen__
1175         g_print("mono_tasklets_arch_restore needs to be aligned for Native Client\n");
1176 #endif
1177         if (saved)
1178                 return (MonoContinuationRestore)saved;
1179         code = start = mono_global_codeman_reserve (48);
1180         /* the signature is: restore (MonoContinuation *cont, int state, MonoLMF **lmf_addr) */
1181         /* put cont in edx */
1182         x86_mov_reg_membase (code, X86_EDX, X86_ESP, 4, 4);
1183         /* state in eax, so it's setup as the return value */
1184         x86_mov_reg_membase (code, X86_EAX, X86_ESP, 8, 4);
1185
1186         /* setup the copy of the stack */
1187         x86_mov_reg_membase (code, X86_ECX, X86_EDX, G_STRUCT_OFFSET (MonoContinuation, stack_used_size), 4);
1188         x86_shift_reg_imm (code, X86_SHR, X86_ECX, 2);
1189         x86_cld (code);
1190         x86_mov_reg_membase (code, X86_ESI, X86_EDX, G_STRUCT_OFFSET (MonoContinuation, saved_stack), 4);
1191         x86_mov_reg_membase (code, X86_EDI, X86_EDX, G_STRUCT_OFFSET (MonoContinuation, return_sp), 4);
1192         x86_prefix (code, X86_REP_PREFIX);
1193         x86_movsl (code);
1194
1195         /* now restore the registers from the LMF */
1196         x86_mov_reg_membase (code, X86_ECX, X86_EDX, G_STRUCT_OFFSET (MonoContinuation, lmf), 4);
1197         x86_mov_reg_membase (code, X86_EBX, X86_ECX, G_STRUCT_OFFSET (MonoLMF, ebx), 4);
1198         x86_mov_reg_membase (code, X86_EBP, X86_ECX, G_STRUCT_OFFSET (MonoLMF, ebp), 4);
1199         x86_mov_reg_membase (code, X86_ESI, X86_ECX, G_STRUCT_OFFSET (MonoLMF, esi), 4);
1200         x86_mov_reg_membase (code, X86_EDI, X86_ECX, G_STRUCT_OFFSET (MonoLMF, edi), 4);
1201
1202         /* restore the lmf chain */
1203         /*x86_mov_reg_membase (code, X86_ECX, X86_ESP, 12, 4);
1204         x86_mov_membase_reg (code, X86_ECX, 0, X86_EDX, 4);*/
1205
1206         x86_jump_membase (code, X86_EDX, G_STRUCT_OFFSET (MonoContinuation, return_ip));
1207         g_assert ((code - start) <= 48);
1208         saved = start;
1209         return (MonoContinuationRestore)saved;
1210 }
1211 #endif
1212
1213 /*
1214  * mono_arch_setup_resume_sighandler_ctx:
1215  *
1216  *   Setup CTX so execution continues at FUNC.
1217  */
1218 void
1219 mono_arch_setup_resume_sighandler_ctx (MonoContext *ctx, gpointer func)
1220 {
1221         int align = (((gint32)MONO_CONTEXT_GET_SP (ctx)) % MONO_ARCH_FRAME_ALIGNMENT + 4);
1222
1223         if (align != 0)
1224                 MONO_CONTEXT_SET_SP (ctx, (gsize)MONO_CONTEXT_GET_SP (ctx) - align);
1225
1226         MONO_CONTEXT_SET_IP (ctx, func);
1227 }