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 #ifdef PLATFORM_WIN32
  31 static void (*restore_stack) (void *);
  32
  33 static MonoW32ExceptionHandler fpe_handler;
  34 static MonoW32ExceptionHandler ill_handler;
  35 static MonoW32ExceptionHandler segv_handler;
  36
  37 static LPTOP_LEVEL_EXCEPTION_FILTER old_handler;
  38
  39 #define W32_SEH_HANDLE_EX(_ex) \
  40         if (_ex##_handler) _ex##_handler((int)sctx)
  41
  42 /*
  43  * mono_win32_get_handle_stackoverflow (void):
  44  *
  45  * Returns a pointer to a method which restores the current context stack
  46  * and calls handle_exceptions, when done restores the original stack.
  47  */
  48 static gpointer
  49 mono_win32_get_handle_stackoverflow (void)
  50 {
  51         static guint8 *start = NULL;
  52         guint8 *code;
  53
  54         if (start)
  55                 return start;
  56
  57         /* restore_contect (void *sigctx) */
  58         start = code = mono_global_codeman_reserve (128);
  59
  60         /* load context into ebx */
  61         x86_mov_reg_membase (code, X86_EBX, X86_ESP, 4, 4);
  62
  63         /* move current stack into edi for later restore */
  64         x86_mov_reg_reg (code, X86_EDI, X86_ESP, 4);
  65
  66         /* use the new freed stack from sigcontext */
  67         x86_mov_reg_membase (code, X86_ESP, X86_EBX,  G_STRUCT_OFFSET (struct sigcontext, esp), 4);
  68
  69         /* get the current domain */
  70         x86_call_code (code, mono_domain_get);
  71
  72         /* get stack overflow exception from domain object */
  73         x86_mov_reg_membase (code, X86_EAX, X86_EAX, G_STRUCT_OFFSET (MonoDomain, stack_overflow_ex), 4);
  74
  75         /* call mono_arch_handle_exception (sctx, stack_overflow_exception_obj, FALSE) */
  76         x86_push_imm (code, 0);
  77         x86_push_reg (code, X86_EAX);
  78         x86_push_reg (code, X86_EBX);
  79         x86_call_code (code, mono_arch_handle_exception);
  80
  81         /* restore the SEH handler stack */
  82         x86_mov_reg_reg (code, X86_ESP, X86_EDI, 4);
  83
  84         /* return */
  85         x86_ret (code);
  86
  87         return start;
  88 }
  89
  90 /* Special hack to workaround the fact that the
  91  * when the SEH handler is called the stack is
  92  * to small to recover.
  93  *
  94  * Stack walking part of this method is from mono_handle_exception
  95  *
  96  * The idea is simple;
  97  *  - walk the stack to free some space (64k)
  98  *  - set esp to new stack location
  99  *  - call mono_arch_handle_exception with stack overflow exception
 100  *  - set esp to SEH handlers stack
 101  *  - done
 102  */
 103 static void
 104 win32_handle_stack_overflow (EXCEPTION_POINTERS* ep, struct sigcontext *sctx)
 105 {
 106     SYSTEM_INFO si;
 107     DWORD page_size;
 108         MonoDomain *domain = mono_domain_get ();
 109         MonoJitInfo *ji, rji;
 110         MonoJitTlsData *jit_tls = TlsGetValue (mono_jit_tls_id);
 111         MonoLMF *lmf = jit_tls->lmf;
 112         MonoContext initial_ctx;
 113         MonoContext ctx;
 114         guint32 free_stack = 0;
 115
 116         /* convert sigcontext to MonoContext (due to reuse of stack walking helpers */
 117         mono_arch_sigctx_to_monoctx (sctx, &ctx);
 118
 119         /* get our os page size */
 120     GetSystemInfo(&si);
 121         page_size = si.dwPageSize;
 122
 123         /* Let's walk the stack to recover
 124          * the needed stack space (if possible)
 125          */
 126         memset (&rji, 0, sizeof (rji));
 127
 128         initial_ctx = ctx;
 129         free_stack = (guint8*)(MONO_CONTEXT_GET_BP (&ctx)) - (guint8*)(MONO_CONTEXT_GET_BP (&initial_ctx));
 130
 131         /* try to free 64kb from our stack */
 132         do {
 133                 MonoContext new_ctx;
 134
 135                 ji = mono_arch_find_jit_info (domain, jit_tls, &rji, &rji, &ctx, &new_ctx, &lmf, NULL);
 136                 if (!ji) {
 137                         g_warning ("Exception inside function without unwind info");
 138                         g_assert_not_reached ();
 139                 }
 140
 141                 if (ji != (gpointer)-1) {
 142                         free_stack = (guint8*)(MONO_CONTEXT_GET_BP (&ctx)) - (guint8*)(MONO_CONTEXT_GET_BP (&initial_ctx));
 143                 }
 144
 145                 /* todo: we should call abort if ji is -1 */
 146                 ctx = new_ctx;
 147         } while (free_stack < 64 * 1024 && ji != (gpointer) -1);
 148
 149         /* convert into sigcontext to be used in mono_arch_handle_exception */
 150         mono_arch_monoctx_to_sigctx (&ctx, sctx);
 151
 152         /* todo: install new stack-guard page */
 153
 154         /* use the new stack and call mono_arch_handle_exception () */
 155         restore_stack (sctx);
 156 }
 157
 158 /*
 159  * Unhandled Exception Filter
 160  * Top-level per-process exception handler.
 161  */
 162 LONG CALLBACK seh_handler(EXCEPTION_POINTERS* ep)
 163 {
 164         EXCEPTION_RECORD* er;
 165         CONTEXT* ctx;
 166         struct sigcontext* sctx;
 167         LONG res;
 168
 169         res = EXCEPTION_CONTINUE_EXECUTION;
 170
 171         er = ep->ExceptionRecord;
 172         ctx = ep->ContextRecord;
 173         sctx = g_malloc(sizeof(struct sigcontext));
 174
 175         /* Copy Win32 context to UNIX style context */
 176         sctx->eax = ctx->Eax;
 177         sctx->ebx = ctx->Ebx;
 178         sctx->ecx = ctx->Ecx;
 179         sctx->edx = ctx->Edx;
 180         sctx->ebp = ctx->Ebp;
 181         sctx->esp = ctx->Esp;
 182         sctx->esi = ctx->Esi;
 183         sctx->edi = ctx->Edi;
 184         sctx->eip = ctx->Eip;
 185
 186         switch (er->ExceptionCode) {
 187         case EXCEPTION_STACK_OVERFLOW:
 188                 win32_handle_stack_overflow (ep, sctx);
 189                 break;
 190         case EXCEPTION_ACCESS_VIOLATION:
 191                 W32_SEH_HANDLE_EX(segv);
 192                 break;
 193         case EXCEPTION_ILLEGAL_INSTRUCTION:
 194                 W32_SEH_HANDLE_EX(ill);
 195                 break;
 196         case EXCEPTION_INT_DIVIDE_BY_ZERO:
 197         case EXCEPTION_INT_OVERFLOW:
 198         case EXCEPTION_FLT_DIVIDE_BY_ZERO:
 199         case EXCEPTION_FLT_OVERFLOW:
 200         case EXCEPTION_FLT_UNDERFLOW:
 201         case EXCEPTION_FLT_INEXACT_RESULT:
 202                 W32_SEH_HANDLE_EX(fpe);
 203                 break;
 204         default:
 205                 break;
 206         }
 207
 208         /* Copy context back */
 209         ctx->Eax = sctx->eax;
 210         ctx->Ebx = sctx->ebx;
 211         ctx->Ecx = sctx->ecx;
 212         ctx->Edx = sctx->edx;
 213         ctx->Ebp = sctx->ebp;
 214         ctx->Esp = sctx->esp;
 215         ctx->Esi = sctx->esi;
 216         ctx->Edi = sctx->edi;
 217         ctx->Eip = sctx->eip;
 218
 219         g_free (sctx);
 220
 221         return res;
 222 }
 223
 224 void win32_seh_init()
 225 {
 226         /* install restore stack helper */
 227         if (!restore_stack)
 228                 restore_stack = mono_win32_get_handle_stackoverflow ();
 229
 230         old_handler = SetUnhandledExceptionFilter(seh_handler);
 231 }
 232
 233 void win32_seh_cleanup()
 234 {
 235         if (old_handler) SetUnhandledExceptionFilter(old_handler);
 236 }
 237
 238 void win32_seh_set_handler(int type, MonoW32ExceptionHandler handler)
 239 {
 240         switch (type) {
 241         case SIGFPE:
 242                 fpe_handler = handler;
 243                 break;
 244         case SIGILL:
 245                 ill_handler = handler;
 246                 break;
 247         case SIGSEGV:
 248                 segv_handler = handler;
 249                 break;
 250         default:
 251                 break;
 252         }
 253 }
 254
 255 #endif /* PLATFORM_WIN32 */
 256
 257 /*
 258  * mono_arch_get_restore_context:
 259  *
 260  * Returns a pointer to a method which restores a previously saved sigcontext.
 261  */
 262 gpointer
 263 mono_arch_get_restore_context (void)
 264 {
 265         static guint8 *start = NULL;
 266         guint8 *code;
 267
 268         if (start)
 269                 return start;
 270
 271         /* restore_contect (MonoContext *ctx) */
 272         /* we do not restore X86_EAX, X86_EDX */
 273
 274         start = code = mono_global_codeman_reserve (128);
 275
 276         /* load ctx */
 277         x86_mov_reg_membase (code, X86_EAX, X86_ESP, 4, 4);
 278
 279         /* get return address, stored in EDX */
 280         x86_mov_reg_membase (code, X86_EDX, X86_EAX,  G_STRUCT_OFFSET (MonoContext, eip), 4);
 281         /* restore EBX */
 282         x86_mov_reg_membase (code, X86_EBX, X86_EAX,  G_STRUCT_OFFSET (MonoContext, ebx), 4);
 283         /* restore EDI */
 284         x86_mov_reg_membase (code, X86_EDI, X86_EAX,  G_STRUCT_OFFSET (MonoContext, edi), 4);
 285         /* restore ESI */
 286         x86_mov_reg_membase (code, X86_ESI, X86_EAX,  G_STRUCT_OFFSET (MonoContext, esi), 4);
 287         /* restore ESP */
 288         x86_mov_reg_membase (code, X86_ESP, X86_EAX,  G_STRUCT_OFFSET (MonoContext, esp), 4);
 289         /* restore EBP */
 290         x86_mov_reg_membase (code, X86_EBP, X86_EAX,  G_STRUCT_OFFSET (MonoContext, ebp), 4);
 291
 292         /* jump to the saved IP */
 293         x86_jump_reg (code, X86_EDX);
 294
 295         return start;
 296 }
 297
 298 /*
 299  * mono_arch_get_call_filter:
 300  *
 301  * Returns a pointer to a method which calls an exception filter. We
 302  * also use this function to call finally handlers (we pass NULL as
 303  * @exc object in this case).
 304  */
 305 gpointer
 306 mono_arch_get_call_filter (void)
 307 {
 308         static guint8* start;
 309         static int inited = 0;
 310         guint8 *code;
 311
 312         if (inited)
 313                 return start;
 314
 315         inited = 1;
 316         /* call_filter (MonoContext *ctx, unsigned long eip) */
 317         start = code = mono_global_codeman_reserve (64);
 318
 319         x86_push_reg (code, X86_EBP);
 320         x86_mov_reg_reg (code, X86_EBP, X86_ESP, 4);
 321         x86_push_reg (code, X86_EBX);
 322         x86_push_reg (code, X86_EDI);
 323         x86_push_reg (code, X86_ESI);
 324
 325         /* load ctx */
 326         x86_mov_reg_membase (code, X86_EAX, X86_EBP, 8, 4);
 327         /* load eip */
 328         x86_mov_reg_membase (code, X86_ECX, X86_EBP, 12, 4);
 329         /* save EBP */
 330         x86_push_reg (code, X86_EBP);
 331
 332         /* set new EBP */
 333         x86_mov_reg_membase (code, X86_EBP, X86_EAX,  G_STRUCT_OFFSET (MonoContext, ebp), 4);
 334         /* restore registers used by global register allocation (EBX & ESI) */
 335         x86_mov_reg_membase (code, X86_EBX, X86_EAX,  G_STRUCT_OFFSET (MonoContext, ebx), 4);
 336         x86_mov_reg_membase (code, X86_ESI, X86_EAX,  G_STRUCT_OFFSET (MonoContext, esi), 4);
 337         x86_mov_reg_membase (code, X86_EDI, X86_EAX,  G_STRUCT_OFFSET (MonoContext, edi), 4);
 338
 339         /* align stack and save ESP */
 340         x86_mov_reg_reg (code, X86_EDX, X86_ESP, 4);
 341         x86_alu_reg_imm (code, X86_AND, X86_ESP, -MONO_ARCH_FRAME_ALIGNMENT);
 342         g_assert (MONO_ARCH_FRAME_ALIGNMENT >= 8);
 343         x86_alu_reg_imm (code, X86_SUB, X86_ESP, MONO_ARCH_FRAME_ALIGNMENT - 8);
 344         x86_push_reg (code, X86_EDX);
 345
 346         /* call the handler */
 347         x86_call_reg (code, X86_ECX);
 348
 349         /* restore ESP */
 350         x86_pop_reg (code, X86_ESP);
 351
 352         /* restore EBP */
 353         x86_pop_reg (code, X86_EBP);
 354
 355         /* restore saved regs */
 356         x86_pop_reg (code, X86_ESI);
 357         x86_pop_reg (code, X86_EDI);
 358         x86_pop_reg (code, X86_EBX);
 359         x86_leave (code);
 360         x86_ret (code);
 361
 362         g_assert ((code - start) < 64);
 363         return start;
 364 }
 365
 366 static void
 367 throw_exception (unsigned long eax, unsigned long ecx, unsigned long edx, unsigned long ebx,
 368                  unsigned long esi, unsigned long edi, unsigned long ebp, MonoObject *exc,
 369                  unsigned long eip,  unsigned long esp, gboolean rethrow)
 370 {
 371         static void (*restore_context) (MonoContext *);
 372         MonoContext ctx;
 373
 374         if (!restore_context)
 375                 restore_context = mono_arch_get_restore_context ();
 376
 377         /* Pop alignment added in get_throw_exception (), the return address, plus the argument and the alignment added at the call site */
 378         ctx.esp = esp + 8 + MONO_ARCH_FRAME_ALIGNMENT;
 379         ctx.eip = eip;
 380         ctx.ebp = ebp;
 381         ctx.edi = edi;
 382         ctx.esi = esi;
 383         ctx.ebx = ebx;
 384         ctx.edx = edx;
 385         ctx.ecx = ecx;
 386         ctx.eax = eax;
 387
 388 #ifdef __APPLE__
 389         /* The OSX ABI specifies 16 byte alignment at call sites */
 390         g_assert ((ctx.esp % MONO_ARCH_FRAME_ALIGNMENT) == 0);
 391 #endif
 392
 393         if (mono_object_isinst (exc, mono_defaults.exception_class)) {
 394                 MonoException *mono_ex = (MonoException*)exc;
 395                 if (!rethrow)
 396                         mono_ex->stack_trace = NULL;
 397         }
 398
 399         if (mono_debug_using_mono_debugger ()) {
 400                 guint8 buf [16], *code;
 401
 402                 mono_breakpoint_clean_code (NULL, (gpointer)eip, 8, buf, sizeof (buf));
 403                 code = buf + 8;
 404
 405                 if (buf [3] == 0xe8) {
 406                         MonoContext ctx_cp = ctx;
 407                         ctx_cp.eip = eip - 5;
 408
 409                         if (mono_debugger_handle_exception (&ctx_cp, exc)) {
 410                                 restore_context (&ctx_cp);
 411                                 g_assert_not_reached ();
 412                         }
 413                 }
 414         }
 415
 416         /* adjust eip so that it point into the call instruction */
 417         ctx.eip -= 1;
 418
 419         mono_handle_exception (&ctx, exc, (gpointer)eip, FALSE);
 420
 421         restore_context (&ctx);
 422
 423         g_assert_not_reached ();
 424 }
 425
 426 static guint8*
 427 get_throw_exception (gboolean rethrow)
 428 {
 429         guint8 *start, *code;
 430
 431         start = code = mono_global_codeman_reserve (64);
 432
 433         /*
 434          * Align the stack on apple, since we push 10 args, and the call pushed 4 bytes.
 435          */
 436         x86_alu_reg_imm (code, X86_SUB, X86_ESP, 4);
 437         x86_push_reg (code, X86_ESP);
 438         x86_push_membase (code, X86_ESP, 8); /* IP */
 439         x86_push_membase (code, X86_ESP, 16); /* exception */
 440         x86_push_reg (code, X86_EBP);
 441         x86_push_reg (code, X86_EDI);
 442         x86_push_reg (code, X86_ESI);
 443         x86_push_reg (code, X86_EBX);
 444         x86_push_reg (code, X86_EDX);
 445         x86_push_reg (code, X86_ECX);
 446         x86_push_reg (code, X86_EAX);
 447         x86_call_code (code, throw_exception);
 448         /* we should never reach this breakpoint */
 449         x86_breakpoint (code);
 450
 451         g_assert ((code - start) < 64);
 452
 453         return start;
 454 }
 455
 456 /**
 457  * mono_arch_get_throw_exception:
 458  *
 459  * Returns a function pointer which can be used to raise
 460  * exceptions. The returned function has the following
 461  * signature: void (*func) (MonoException *exc);
 462  * For example to raise an arithmetic exception you can use:
 463  *
 464  * x86_push_imm (code, mono_get_exception_arithmetic ());
 465  * x86_call_code (code, arch_get_throw_exception ());
 466  *
 467  */
 468 gpointer
 469 mono_arch_get_throw_exception (void)
 470 {
 471         static guint8 *start;
 472         static int inited = 0;
 473
 474         if (inited)
 475                 return start;
 476
 477         start = get_throw_exception (FALSE);
 478
 479         inited = 1;
 480
 481         return start;
 482 }
 483
 484 gpointer
 485 mono_arch_get_rethrow_exception (void)
 486 {
 487         static guint8 *start;
 488         static int inited = 0;
 489
 490         if (inited)
 491                 return start;
 492
 493         start = get_throw_exception (TRUE);
 494
 495         inited = 1;
 496
 497         return start;
 498 }
 499
 500 /**
 501  * mono_arch_get_throw_exception_by_name:
 502  *
 503  * Returns a function pointer which can be used to raise
 504  * corlib exceptions. The returned function has the following
 505  * signature: void (*func) (gpointer ip, char *exc_name);
 506  * For example to raise an arithmetic exception you can use:
 507  *
 508  * x86_push_imm (code, "ArithmeticException");
 509  * x86_push_imm (code, <IP>)
 510  * x86_jump_code (code, arch_get_throw_exception_by_name ());
 511  *
 512  */
 513 gpointer
 514 mono_arch_get_throw_exception_by_name (void)
 515 {
 516         guint8* start;
 517         guint8 *code;
 518
 519         start = code = mono_global_codeman_reserve (32);
 520
 521         /* Not used */
 522         x86_breakpoint (code);
 523
 524         mono_arch_flush_icache (start, code - start);
 525
 526         return start;
 527 }
 528
 529 /**
 530  * mono_arch_get_throw_corlib_exception:
 531  *
 532  * Returns a function pointer which can be used to raise
 533  * corlib exceptions. The returned function has the following
 534  * signature: void (*func) (guint32 ex_token, guint32 offset);
 535  * Here, offset is the offset which needs to be substracted from the caller IP
 536  * to get the IP of the throw. Passing the offset has the advantage that it
 537  * needs no relocations in the caller.
 538  */
 539 gpointer
 540 mono_arch_get_throw_corlib_exception (void)
 541 {
 542         static guint8* start;
 543         static int inited = 0;
 544         guint8 *code;
 545
 546         if (inited)
 547                 return start;
 548
 549         inited = 1;
 550         code = start = mono_global_codeman_reserve (64);
 551
 552         /*
 553          * Align the stack on apple, the caller doesn't do this to save space,
 554          * two arguments + the return addr are already on the stack.
 555          */
 556         x86_alu_reg_imm (code, X86_SUB, X86_ESP, 4);
 557         x86_mov_reg_membase (code, X86_EAX, X86_ESP, 4 + 4, 4); /* token */
 558         x86_alu_reg_imm (code, X86_ADD, X86_EAX, MONO_TOKEN_TYPE_DEF);
 559         /* Align the stack on apple */
 560         x86_alu_reg_imm (code, X86_SUB, X86_ESP, 8);
 561         x86_push_reg (code, X86_EAX);
 562         x86_push_imm (code, mono_defaults.exception_class->image);
 563         x86_call_code (code, mono_exception_from_token);
 564         x86_alu_reg_imm (code, X86_ADD, X86_ESP, 16);
 565         /* Compute caller ip */
 566         x86_mov_reg_membase (code, X86_ECX, X86_ESP, 4, 4);
 567         /* Compute offset */
 568         x86_mov_reg_membase (code, X86_EDX, X86_ESP, 4 + 4 + 4, 4);
 569         /* Pop everything */
 570         x86_alu_reg_imm (code, X86_ADD, X86_ESP, 4 + 4 + 4 + 4);
 571         x86_alu_reg_reg (code, X86_SUB, X86_ECX, X86_EDX);
 572         /* Align the stack on apple, mirrors the sub in OP_THROW. */
 573         x86_alu_reg_imm (code, X86_SUB, X86_ESP, MONO_ARCH_FRAME_ALIGNMENT - 4);
 574         /* Push exception object */
 575         x86_push_reg (code, X86_EAX);
 576         /* Push throw IP */
 577         x86_push_reg (code, X86_ECX);
 578         x86_jump_code (code, mono_arch_get_throw_exception ());
 579
 580         g_assert ((code - start) < 64);
 581
 582         return start;
 583 }
 584
 585 /* mono_arch_find_jit_info:
 586  *
 587  * This function is used to gather information from @ctx. It return the
 588  * MonoJitInfo of the corresponding function, unwinds one stack frame and
 589  * stores the resulting context into @new_ctx. It also stores a string
 590  * describing the stack location into @trace (if not NULL), and modifies
 591  * the @lmf if necessary. @native_offset return the IP offset from the
 592  * start of the function or -1 if that info is not available.
 593  */
 594 MonoJitInfo *
 595 mono_arch_find_jit_info (MonoDomain *domain, MonoJitTlsData *jit_tls, MonoJitInfo *res, MonoJitInfo *prev_ji, MonoContext *ctx,
 596                          MonoContext *new_ctx, MonoLMF **lmf, gboolean *managed)
 597 {
 598         MonoJitInfo *ji;
 599         gpointer ip = MONO_CONTEXT_GET_IP (ctx);
 600
 601         /* Avoid costly table lookup during stack overflow */
 602         if (prev_ji && (ip > prev_ji->code_start && ((guint8*)ip < ((guint8*)prev_ji->code_start) + prev_ji->code_size)))
 603                 ji = prev_ji;
 604         else
 605                 ji = mini_jit_info_table_find (domain, ip, NULL);
 606
 607         if (managed)
 608                 *managed = FALSE;
 609
 610         *new_ctx = *ctx;
 611
 612         if (ji != NULL) {
 613                 gssize regs [MONO_MAX_IREGS + 1];
 614                 guint8 *cfa;
 615                 guint32 unwind_info_len;
 616                 guint8 *unwind_info;
 617
 618                 if (managed)
 619                         if (!ji->method->wrapper_type)
 620                                 *managed = TRUE;
 621
 622                 if (ji->from_aot)
 623                         unwind_info = mono_aot_get_unwind_info (ji, &unwind_info_len);
 624                 else
 625                         unwind_info = mono_get_cached_unwind_info (ji->used_regs, &unwind_info_len);
 626
 627                 regs [X86_EAX] = new_ctx->eax;
 628                 regs [X86_EBX] = new_ctx->ebx;
 629                 regs [X86_ECX] = new_ctx->ecx;
 630                 regs [X86_EDX] = new_ctx->edx;
 631                 regs [X86_ESP] = new_ctx->esp;
 632                 regs [X86_EBP] = new_ctx->ebp;
 633                 regs [X86_ESI] = new_ctx->esi;
 634                 regs [X86_EDI] = new_ctx->edi;
 635                 regs [X86_NREG] = new_ctx->eip;
 636
 637                 mono_unwind_frame (unwind_info, unwind_info_len, ji->code_start,
 638                                                    (guint8*)ji->code_start + ji->code_size,
 639                                                    ip, regs, MONO_MAX_IREGS + 1, &cfa);
 640
 641                 new_ctx->eax = regs [X86_EAX];
 642                 new_ctx->ebx = regs [X86_EBX];
 643                 new_ctx->ecx = regs [X86_ECX];
 644                 new_ctx->edx = regs [X86_EDX];
 645                 new_ctx->esp = regs [X86_ESP];
 646                 new_ctx->ebp = regs [X86_EBP];
 647                 new_ctx->esi = regs [X86_ESI];
 648                 new_ctx->edi = regs [X86_EDI];
 649                 new_ctx->eip = regs [X86_NREG];
 650
 651                 /* The CFA becomes the new SP value */
 652                 new_ctx->esp = (gssize)cfa;
 653
 654                 /* Adjust IP */
 655                 new_ctx->eip --;
 656
 657                 if (*lmf && (MONO_CONTEXT_GET_BP (ctx) >= (gpointer)(*lmf)->ebp)) {
 658                         /* remove any unused lmf */
 659                         *lmf = (gpointer)(((guint32)(*lmf)->previous_lmf) & ~1);
 660                 }
 661
 662                 /* Pop arguments off the stack */
 663                 {
 664                         MonoJitArgumentInfo *arg_info = g_newa (MonoJitArgumentInfo, mono_method_signature (ji->method)->param_count + 1);
 665
 666                         guint32 stack_to_pop = mono_arch_get_argument_info (mono_method_signature (ji->method), mono_method_signature (ji->method)->param_count, arg_info);
 667                         new_ctx->esp += stack_to_pop;
 668                 }
 669
 670                 return ji;
 671         } else if (*lmf) {
 672
 673                 *new_ctx = *ctx;
 674
 675                 if ((ji = mini_jit_info_table_find (domain, (gpointer)(*lmf)->eip, NULL))) {
 676                 } else {
 677                         if (!((guint32)((*lmf)->previous_lmf) & 1))
 678                                 /* Top LMF entry */
 679                                 return (gpointer)-1;
 680                         /* Trampoline lmf frame */
 681                         memset (res, 0, MONO_SIZEOF_JIT_INFO);
 682                         res->method = (*lmf)->method;
 683                 }
 684
 685                 new_ctx->esi = (*lmf)->esi;
 686                 new_ctx->edi = (*lmf)->edi;
 687                 new_ctx->ebx = (*lmf)->ebx;
 688                 new_ctx->ebp = (*lmf)->ebp;
 689                 new_ctx->eip = (*lmf)->eip;
 690
 691                 /* Check if we are in a trampoline LMF frame */
 692                 if ((guint32)((*lmf)->previous_lmf) & 1) {
 693                         /* lmf->esp is set by the trampoline code */
 694                         new_ctx->esp = (*lmf)->esp;
 695
 696                         /* Pop arguments off the stack */
 697                         /* FIXME: Handle the delegate case too ((*lmf)->method == NULL) */
 698                         /* FIXME: Handle the IMT/vtable case too */
 699                         if ((*lmf)->method && (*lmf)->method != MONO_FAKE_IMT_METHOD && (*lmf)->method != MONO_FAKE_VTABLE_METHOD) {
 700                                 MonoMethod *method = (*lmf)->method;
 701                                 MonoJitArgumentInfo *arg_info = g_newa (MonoJitArgumentInfo, mono_method_signature (method)->param_count + 1);
 702
 703                                 guint32 stack_to_pop = mono_arch_get_argument_info (mono_method_signature (method), mono_method_signature (method)->param_count, arg_info);
 704                                 new_ctx->esp += stack_to_pop;
 705                         }
 706                 }
 707                 else
 708                         /* the lmf is always stored on the stack, so the following
 709                          * expression points to a stack location which can be used as ESP */
 710                         new_ctx->esp = (unsigned long)&((*lmf)->eip);
 711
 712                 *lmf = (gpointer)(((guint32)(*lmf)->previous_lmf) & ~1);
 713
 714                 return ji ? ji : res;
 715         }
 716
 717         return NULL;
 718 }
 719
 720 #ifdef __sun
 721 #define REG_EAX EAX
 722 #define REG_EBX EBX
 723 #define REG_ECX ECX
 724 #define REG_EDX EDX
 725 #define REG_EBP EBP
 726 #define REG_ESP ESP
 727 #define REG_ESI ESI
 728 #define REG_EDI EDI
 729 #define REG_EIP EIP
 730 #endif
 731
 732 void
 733 mono_arch_sigctx_to_monoctx (void *sigctx, MonoContext *mctx)
 734 {
 735 #ifdef MONO_ARCH_USE_SIGACTION
 736         ucontext_t *ctx = (ucontext_t*)sigctx;
 737
 738         mctx->eax = UCONTEXT_REG_EAX (ctx);
 739         mctx->ebx = UCONTEXT_REG_EBX (ctx);
 740         mctx->ecx = UCONTEXT_REG_ECX (ctx);
 741         mctx->edx = UCONTEXT_REG_EDX (ctx);
 742         mctx->ebp = UCONTEXT_REG_EBP (ctx);
 743         mctx->esp = UCONTEXT_REG_ESP (ctx);
 744         mctx->esi = UCONTEXT_REG_ESI (ctx);
 745         mctx->edi = UCONTEXT_REG_EDI (ctx);
 746         mctx->eip = UCONTEXT_REG_EIP (ctx);
 747 #else
 748         struct sigcontext *ctx = (struct sigcontext *)sigctx;
 749
 750         mctx->eax = ctx->SC_EAX;
 751         mctx->ebx = ctx->SC_EBX;
 752         mctx->ecx = ctx->SC_ECX;
 753         mctx->edx = ctx->SC_EDX;
 754         mctx->ebp = ctx->SC_EBP;
 755         mctx->esp = ctx->SC_ESP;
 756         mctx->esi = ctx->SC_ESI;
 757         mctx->edi = ctx->SC_EDI;
 758         mctx->eip = ctx->SC_EIP;
 759 #endif
 760 }
 761
 762 void
 763 mono_arch_monoctx_to_sigctx (MonoContext *mctx, void *sigctx)
 764 {
 765 #ifdef MONO_ARCH_USE_SIGACTION
 766         ucontext_t *ctx = (ucontext_t*)sigctx;
 767
 768         UCONTEXT_REG_EAX (ctx) = mctx->eax;
 769         UCONTEXT_REG_EBX (ctx) = mctx->ebx;
 770         UCONTEXT_REG_ECX (ctx) = mctx->ecx;
 771         UCONTEXT_REG_EDX (ctx) = mctx->edx;
 772         UCONTEXT_REG_EBP (ctx) = mctx->ebp;
 773         UCONTEXT_REG_ESP (ctx) = mctx->esp;
 774         UCONTEXT_REG_ESI (ctx) = mctx->esi;
 775         UCONTEXT_REG_EDI (ctx) = mctx->edi;
 776         UCONTEXT_REG_EIP (ctx) = mctx->eip;
 777 #else
 778         struct sigcontext *ctx = (struct sigcontext *)sigctx;
 779
 780         ctx->SC_EAX = mctx->eax;
 781         ctx->SC_EBX = mctx->ebx;
 782         ctx->SC_ECX = mctx->ecx;
 783         ctx->SC_EDX = mctx->edx;
 784         ctx->SC_EBP = mctx->ebp;
 785         ctx->SC_ESP = mctx->esp;
 786         ctx->SC_ESI = mctx->esi;
 787         ctx->SC_EDI = mctx->edi;
 788         ctx->SC_EIP = mctx->eip;
 789 #endif
 790 }
 791
 792 gpointer
 793 mono_arch_ip_from_context (void *sigctx)
 794 {
 795 #ifdef MONO_ARCH_USE_SIGACTION
 796         ucontext_t *ctx = (ucontext_t*)sigctx;
 797         return (gpointer)UCONTEXT_REG_EIP (ctx);
 798 #else
 799         struct sigcontext *ctx = sigctx;
 800         return (gpointer)ctx->SC_EIP;
 801 #endif
 802 }
 803
 804 gboolean
 805 mono_arch_handle_exception (void *sigctx, gpointer obj, gboolean test_only)
 806 {
 807         MonoContext mctx;
 808
 809         mono_arch_sigctx_to_monoctx (sigctx, &mctx);
 810
 811         if (mono_debugger_handle_exception (&mctx, (MonoObject *)obj))
 812                 return TRUE;
 813
 814         mono_handle_exception (&mctx, obj, (gpointer)mctx.eip, test_only);
 815
 816         mono_arch_monoctx_to_sigctx (&mctx, sigctx);
 817
 818         return TRUE;
 819 }
 820
 821 static void
 822 restore_soft_guard_pages (void)
 823 {
 824         MonoJitTlsData *jit_tls = TlsGetValue (mono_jit_tls_id);
 825         if (jit_tls->stack_ovf_guard_base)
 826                 mono_mprotect (jit_tls->stack_ovf_guard_base, jit_tls->stack_ovf_guard_size, MONO_MMAP_NONE);
 827 }
 828
 829 /*
 830  * this function modifies mctx so that when it is restored, it
 831  * won't execcute starting at mctx.eip, but in a function that
 832  * will restore the protection on the soft-guard pages and return back to
 833  * continue at mctx.eip.
 834  */
 835 static void
 836 prepare_for_guard_pages (MonoContext *mctx)
 837 {
 838         gpointer *sp;
 839         sp = (gpointer)(mctx->esp);
 840         sp -= 1;
 841         /* the resturn addr */
 842         sp [0] = (gpointer)(mctx->eip);
 843         mctx->eip = (unsigned long)restore_soft_guard_pages;
 844         mctx->esp = (unsigned long)sp;
 845 }
 846
 847 static void
 848 altstack_handle_and_restore (void *sigctx, gpointer obj, gboolean stack_ovf)
 849 {
 850         void (*restore_context) (MonoContext *);
 851         MonoContext mctx;
 852
 853         restore_context = mono_arch_get_restore_context ();
 854         mono_arch_sigctx_to_monoctx (sigctx, &mctx);
 855
 856         if (mono_debugger_handle_exception (&mctx, (MonoObject *)obj)) {
 857                 if (stack_ovf)
 858                         prepare_for_guard_pages (&mctx);
 859                 restore_context (&mctx);
 860         }
 861
 862         mono_handle_exception (&mctx, obj, (gpointer)mctx.eip, FALSE);
 863         if (stack_ovf)
 864                 prepare_for_guard_pages (&mctx);
 865         restore_context (&mctx);
 866 }
 867
 868 void
 869 mono_arch_handle_altstack_exception (void *sigctx, gpointer fault_addr, gboolean stack_ovf)
 870 {
 871 #ifdef MONO_ARCH_USE_SIGACTION
 872         MonoException *exc = NULL;
 873         ucontext_t *ctx = (ucontext_t*)sigctx;
 874         MonoJitInfo *ji = mini_jit_info_table_find (mono_domain_get (), (gpointer)UCONTEXT_REG_EIP (ctx), NULL);
 875         gpointer *sp;
 876         int frame_size;
 877
 878         /* if we didn't find a managed method for the ip address and it matches the fault
 879          * address, we assume we followed a broken pointer during an indirect call, so
 880          * we try the lookup again with the return address pushed on the stack
 881          */
 882         if (!ji && fault_addr == (gpointer)UCONTEXT_REG_EIP (ctx)) {
 883                 glong *sp = (gpointer)UCONTEXT_REG_ESP (ctx);
 884                 ji = mini_jit_info_table_find (mono_domain_get (), (gpointer)sp [0], NULL);
 885                 if (ji)
 886                         UCONTEXT_REG_EIP (ctx) = sp [0];
 887         }
 888         if (stack_ovf)
 889                 exc = mono_domain_get ()->stack_overflow_ex;
 890         if (!ji)
 891                 mono_handle_native_sigsegv (SIGSEGV, sigctx);
 892         /* setup a call frame on the real stack so that control is returned there
 893          * and exception handling can continue.
 894          * If this was a stack overflow the caller already ensured the stack pages
 895          * needed have been unprotected.
 896          * The frame looks like:
 897          *   ucontext struct
 898          *   test_only arg
 899          *   exception arg
 900          *   ctx arg
 901          *   return ip
 902          */
 903         frame_size = sizeof (ucontext_t) + sizeof (gpointer) * 4;
 904         frame_size += 15;
 905         frame_size &= ~15;
 906         sp = (gpointer)(UCONTEXT_REG_ESP (ctx) & ~15);
 907         sp = (gpointer)((char*)sp - frame_size);
 908         /* the incoming arguments are aligned to 16 bytes boundaries, so the return address IP
 909          * goes at sp [-1]
 910          */
 911         sp [-1] = (gpointer)UCONTEXT_REG_EIP (ctx);
 912         sp [0] = sp + 4;
 913         sp [1] = exc;
 914         sp [2] = (gpointer)stack_ovf;
 915         /* may need to adjust pointers in the new struct copy, depending on the OS */
 916         memcpy (sp + 4, ctx, sizeof (ucontext_t));
 917         /* at the return form the signal handler execution starts in altstack_handle_and_restore() */
 918         UCONTEXT_REG_EIP (ctx) = (unsigned long)altstack_handle_and_restore;
 919         UCONTEXT_REG_ESP (ctx) = (unsigned long)(sp - 1);
 920 #endif
 921 }
 922
 923 #if MONO_SUPPORT_TASKLETS
 924 MonoContinuationRestore
 925 mono_tasklets_arch_restore (void)
 926 {
 927         static guint8* saved = NULL;
 928         guint8 *code, *start;
 929
 930         if (saved)
 931                 return (MonoContinuationRestore)saved;
 932         code = start = mono_global_codeman_reserve (48);
 933         /* the signature is: restore (MonoContinuation *cont, int state, MonoLMF **lmf_addr) */
 934         /* put cont in edx */
 935         x86_mov_reg_membase (code, X86_EDX, X86_ESP, 4, 4);
 936         /* setup the copy of the stack */
 937         x86_mov_reg_membase (code, X86_ECX, X86_EDX, G_STRUCT_OFFSET (MonoContinuation, stack_used_size), 4);
 938         x86_shift_reg_imm (code, X86_SHR, X86_ECX, 2);
 939         x86_cld (code);
 940         x86_mov_reg_membase (code, X86_ESI, X86_EDX, G_STRUCT_OFFSET (MonoContinuation, saved_stack), 4);
 941         x86_mov_reg_membase (code, X86_EDI, X86_EDX, G_STRUCT_OFFSET (MonoContinuation, return_sp), 4);
 942         x86_prefix (code, X86_REP_PREFIX);
 943         x86_movsl (code);
 944
 945         /* now restore the registers from the LMF */
 946         x86_mov_reg_membase (code, X86_ECX, X86_EDX, G_STRUCT_OFFSET (MonoContinuation, lmf), 4);
 947         x86_mov_reg_membase (code, X86_EBX, X86_ECX, G_STRUCT_OFFSET (MonoLMF, ebx), 4);
 948         x86_mov_reg_membase (code, X86_EBP, X86_ECX, G_STRUCT_OFFSET (MonoLMF, ebp), 4);
 949         x86_mov_reg_membase (code, X86_ESI, X86_ECX, G_STRUCT_OFFSET (MonoLMF, esi), 4);
 950         x86_mov_reg_membase (code, X86_EDI, X86_ECX, G_STRUCT_OFFSET (MonoLMF, edi), 4);
 951
 952         /* restore the lmf chain */
 953         /*x86_mov_reg_membase (code, X86_ECX, X86_ESP, 12, 4);
 954         x86_mov_membase_reg (code, X86_ECX, 0, X86_EDX, 4);*/
 955
 956         /* state in eax, so it's setup as the return value */
 957         x86_mov_reg_membase (code, X86_EAX, X86_ESP, 8, 4);
 958         x86_jump_membase (code, X86_EDX, G_STRUCT_OFFSET (MonoContinuation, return_ip));
 959         g_assert ((code - start) <= 48);
 960         saved = start;
 961         return (MonoContinuationRestore)saved;
 962 }
 963 #endif
 964