mono/mini/exceptions-mips.c

   1 /*
   2  * exceptions-mips.c: exception support for MIPS
   3  *
   4  * Authors:
   5  *   Mark Mason (mason@broadcom.com)
   6  *
   7  * Based on exceptions-ppc.c by:
   8  *   Dietmar Maurer (dietmar@ximian.com)
   9  *   Paolo Molaro (lupus@ximian.com)
  10  *
  11  * (C) 2006 Broadcom
  12  * (C) 2001 Ximian, Inc.
  13  */
  14
  15 #include <config.h>
  16 #include <glib.h>
  17 #include <signal.h>
  18 #include <string.h>
  19
  20 #include <mono/arch/mips/mips-codegen.h>
  21 #include <mono/metadata/appdomain.h>
  22 #include <mono/metadata/tabledefs.h>
  23 #include <mono/metadata/threads.h>
  24 #include <mono/metadata/debug-helpers.h>
  25 #include <mono/metadata/exception.h>
  26 #include <mono/metadata/mono-debug.h>
  27
  28 #include "mini.h"
  29 #include "mini-mips.h"
  30
  31 #define GENERIC_EXCEPTION_SIZE 256
  32
  33 /*
  34  * mono_arch_get_restore_context:
  35  *
  36  * Returns a pointer to a method which restores a previously saved MonoContext.
  37  * The first argument in a0 is the pointer to the MonoContext.
  38  */
  39 gpointer
  40 mono_arch_get_restore_context (MonoTrampInfo **info, gboolean aot)
  41 {
  42         int i;
  43         guint8 *code;
  44         static guint8 start [512];
  45         static int inited = 0;
  46         guint32 iregs_to_restore;
  47
  48         g_assert (!aot);
  49         if (info)
  50                 *info = NULL;
  51
  52         if (inited)
  53                 return start;
  54         inited = 1;
  55         code = start;
  56
  57         mips_move (code, mips_at, mips_a0);
  58
  59         iregs_to_restore = (MONO_ARCH_CALLEE_SAVED_REGS \
  60                             | (1 << mips_sp) | (1 << mips_ra));
  61         for (i = 0; i < MONO_SAVED_GREGS; ++i) {
  62                 //if (iregs_to_restore & (1 << i)) {
  63                 if (i != mips_zero && i != mips_at) {
  64                         MIPS_LW (code, i, mips_at, G_STRUCT_OFFSET (MonoContext, sc_regs[i]));
  65                 }
  66         }
  67
  68         /* Get the address to return to */
  69         mips_lw (code, mips_t9, mips_at, G_STRUCT_OFFSET (MonoContext, sc_pc));
  70
  71         /* jump to the saved IP */
  72         mips_jr (code, mips_t9);
  73         mips_nop (code);
  74
  75         /* never reached */
  76         mips_break (code, 0xff);
  77
  78         g_assert ((code - start) < sizeof(start));
  79         mono_arch_flush_icache (start, code - start);
  80         return start;
  81 }
  82
  83 /*
  84  * mono_arch_get_call_filter:
  85  *
  86  * Returns a pointer to a method which calls an exception filter. We
  87  * also use this function to call finally handlers (we pass NULL as
  88  * @exc object in this case).
  89  *
  90  * This function is invoked as
  91  *      call_handler (MonoContext *ctx, handler)
  92  *
  93  * Where 'handler' is a function to be invoked as:
  94  *      handler (void)
  95  */
  96 gpointer
  97 mono_arch_get_call_filter (MonoTrampInfo **info, gboolean aot)
  98 {
  99         static guint8 start [320];
 100         static int inited = 0;
 101         guint8 *code;
 102         int alloc_size;
 103         int offset;
 104
 105         g_assert (!aot);
 106         if (info)
 107                 *info = NULL;
 108
 109         if (inited)
 110                 return start;
 111
 112         inited = 1;
 113         code = start;
 114
 115         alloc_size = 64;
 116         g_assert ((alloc_size & (MIPS_STACK_ALIGNMENT-1)) == 0);
 117
 118         mips_addiu (code, mips_sp, mips_sp, -alloc_size);
 119         mips_sw (code, mips_ra, mips_sp, alloc_size + MIPS_RET_ADDR_OFFSET);
 120
 121         /* Save global registers on stack (s0 - s7) */
 122         offset = 16;
 123         MIPS_SW (code, mips_s0, mips_sp, offset); offset += IREG_SIZE;
 124         MIPS_SW (code, mips_s1, mips_sp, offset); offset += IREG_SIZE;
 125         MIPS_SW (code, mips_s2, mips_sp, offset); offset += IREG_SIZE;
 126         MIPS_SW (code, mips_s3, mips_sp, offset); offset += IREG_SIZE;
 127         MIPS_SW (code, mips_s4, mips_sp, offset); offset += IREG_SIZE;
 128         MIPS_SW (code, mips_s5, mips_sp, offset); offset += IREG_SIZE;
 129         MIPS_SW (code, mips_s6, mips_sp, offset); offset += IREG_SIZE;
 130         MIPS_SW (code, mips_s7, mips_sp, offset); offset += IREG_SIZE;
 131         MIPS_SW (code, mips_fp, mips_sp, offset); offset += IREG_SIZE;
 132
 133         /* Restore global registers from MonoContext, including the frame pointer */
 134         MIPS_LW (code, mips_s0, mips_a0, G_STRUCT_OFFSET (MonoContext, sc_regs[mips_s0]));
 135         MIPS_LW (code, mips_s1, mips_a0, G_STRUCT_OFFSET (MonoContext, sc_regs[mips_s1]));
 136         MIPS_LW (code, mips_s2, mips_a0, G_STRUCT_OFFSET (MonoContext, sc_regs[mips_s2]));
 137         MIPS_LW (code, mips_s3, mips_a0, G_STRUCT_OFFSET (MonoContext, sc_regs[mips_s3]));
 138         MIPS_LW (code, mips_s4, mips_a0, G_STRUCT_OFFSET (MonoContext, sc_regs[mips_s4]));
 139         MIPS_LW (code, mips_s5, mips_a0, G_STRUCT_OFFSET (MonoContext, sc_regs[mips_s5]));
 140         MIPS_LW (code, mips_s6, mips_a0, G_STRUCT_OFFSET (MonoContext, sc_regs[mips_s6]));
 141         MIPS_LW (code, mips_s7, mips_a0, G_STRUCT_OFFSET (MonoContext, sc_regs[mips_s7]));
 142         MIPS_LW (code, mips_fp, mips_a0, G_STRUCT_OFFSET (MonoContext, sc_regs[mips_fp]));
 143
 144         /* a1 is the handler to call */
 145         mips_move (code, mips_t9, mips_a1);
 146
 147         /* jump to the saved IP */
 148         mips_jalr (code, mips_t9, mips_ra);
 149         mips_nop (code);
 150
 151         /* restore all regs from the stack */
 152         offset = 16;
 153         MIPS_LW (code, mips_s0, mips_sp, offset); offset += IREG_SIZE;
 154         MIPS_LW (code, mips_s1, mips_sp, offset); offset += IREG_SIZE;
 155         MIPS_LW (code, mips_s2, mips_sp, offset); offset += IREG_SIZE;
 156         MIPS_LW (code, mips_s3, mips_sp, offset); offset += IREG_SIZE;
 157         MIPS_LW (code, mips_s4, mips_sp, offset); offset += IREG_SIZE;
 158         MIPS_LW (code, mips_s5, mips_sp, offset); offset += IREG_SIZE;
 159         MIPS_LW (code, mips_s6, mips_sp, offset); offset += IREG_SIZE;
 160         MIPS_LW (code, mips_s7, mips_sp, offset); offset += IREG_SIZE;
 161         MIPS_LW (code, mips_fp, mips_sp, offset); offset += IREG_SIZE;
 162
 163         /* epilog */
 164         mips_lw (code, mips_ra, mips_sp, alloc_size + MIPS_RET_ADDR_OFFSET);
 165         mips_addiu (code, mips_sp, mips_sp, alloc_size);
 166         mips_jr (code, mips_ra);
 167         mips_nop (code);
 168
 169         g_assert ((code - start) < sizeof(start));
 170         mono_arch_flush_icache (start, code - start);
 171         return start;
 172 }
 173
 174 static void
 175 throw_exception (MonoObject *exc, unsigned long eip, unsigned long esp, gboolean rethrow)
 176 {
 177         static void (*restore_context) (MonoContext *);
 178         MonoContext ctx;
 179
 180 #ifdef DEBUG_EXCEPTIONS
 181         g_print ("throw_exception: exc=%p eip=%p esp=%p rethrow=%d\n",
 182                  exc, (void *)eip, (void *) esp, rethrow);
 183 #endif
 184
 185         if (!restore_context)
 186                 restore_context = mono_get_restore_context ();
 187
 188         /* adjust eip so that it point into the call instruction */
 189         eip -= 8;
 190
 191         memset (&ctx, 0, sizeof (MonoContext));
 192
 193         /*g_print  ("stack in throw: %p\n", esp);*/
 194         memcpy (&ctx.sc_regs, (void *)(esp + MIPS_STACK_PARAM_OFFSET),
 195                 sizeof (gulong) * MONO_SAVED_GREGS);
 196         memset (&ctx.sc_fpregs, 0, sizeof (mips_freg) * MONO_SAVED_FREGS);
 197         MONO_CONTEXT_SET_IP (&ctx, eip);
 198
 199         if (mono_object_isinst (exc, mono_defaults.exception_class)) {
 200                 MonoException *mono_ex = (MonoException*)exc;
 201                 if (!rethrow)
 202                         mono_ex->stack_trace = NULL;
 203         }
 204         mono_handle_exception (&ctx, exc);
 205 #ifdef DEBUG_EXCEPTIONS
 206         g_print ("throw_exception: restore to pc=%p sp=%p fp=%p ctx=%p\n",
 207                  (void *) ctx.sc_pc, (void *) ctx.sc_regs[mips_sp],
 208                  (void *) ctx.sc_regs[mips_fp], &ctx);
 209 #endif
 210         restore_context (&ctx);
 211
 212         g_assert_not_reached ();
 213 }
 214
 215 /**
 216  * arch_get_throw_exception_generic:
 217  *
 218  * Returns a function pointer which can be used to raise
 219  * exceptions. The returned function has the following
 220  * signature: void (*func) (MonoException *exc); or
 221  * void (*func) (char *exc_name);
 222  *
 223  */
 224 static gpointer
 225 mono_arch_get_throw_exception_generic (guint8 *start, int size, int corlib, gboolean rethrow)
 226 {
 227         guint8 *code;
 228         int alloc_size, pos, i;
 229
 230         code = start;
 231
 232         //g_print ("mono_arch_get_throw_exception_generic: code=%p\n", code);
 233
 234         pos = 0;
 235         /* XXX - save all the FP regs on the stack ? */
 236
 237         pos += MONO_MAX_IREGS * sizeof(guint32);
 238
 239         alloc_size = MIPS_MINIMAL_STACK_SIZE + pos + 64;
 240         // align to MIPS_STACK_ALIGNMENT bytes
 241         alloc_size += MIPS_STACK_ALIGNMENT - 1;
 242         alloc_size &= ~(MIPS_STACK_ALIGNMENT - 1);
 243
 244         g_assert ((alloc_size & (MIPS_STACK_ALIGNMENT-1)) == 0);
 245         mips_addiu (code, mips_sp, mips_sp, -alloc_size);
 246         mips_sw (code, mips_ra, mips_sp, alloc_size + MIPS_RET_ADDR_OFFSET);
 247
 248         /* Save all the regs on the stack */
 249         for (i = 0; i < MONO_MAX_IREGS; i++) {
 250                 if (i != mips_sp)
 251                         MIPS_SW (code, i, mips_sp, i*IREG_SIZE + MIPS_STACK_PARAM_OFFSET);
 252                 else {
 253                         mips_addiu (code, mips_at, mips_sp, alloc_size);
 254                         MIPS_SW (code, mips_at, mips_sp, i*IREG_SIZE + MIPS_STACK_PARAM_OFFSET);
 255                 }
 256         }
 257
 258         if (corlib) {
 259                 mips_move (code, mips_a1, mips_a0);
 260                 mips_load (code, mips_a0, mono_defaults.corlib);
 261                 mips_load (code, mips_t9, mono_exception_from_token);
 262                 mips_jalr (code, mips_t9, mips_ra);
 263                 mips_nop (code);
 264                 mips_move (code, mips_a0, mips_v0);
 265         }
 266         /* call throw_exception (exc, ip, sp, rethrow) */
 267
 268         /* exc is already in place in a0 */
 269
 270         /* pointer to ip */
 271         if (corlib)
 272                 mips_lw (code, mips_a1, mips_sp, alloc_size + MIPS_RET_ADDR_OFFSET);
 273         else
 274                 mips_move (code, mips_a1, mips_ra);
 275
 276         /* current sp & rethrow */
 277         mips_move (code, mips_a2, mips_sp);
 278         mips_addiu (code, mips_a3, mips_zero, rethrow);
 279
 280         mips_load (code, mips_t9, throw_exception);
 281         mips_jr (code, mips_t9);
 282         mips_nop (code);
 283         /* we should never reach this breakpoint */
 284         mips_break (code, 0xfe);
 285
 286         g_assert ((code - start) < size);
 287         mono_arch_flush_icache (start, code - start);
 288         return start;
 289 }
 290
 291 /**
 292  * mono_arch_get_rethrow_exception:
 293  *
 294  * Returns a function pointer which can be used to rethrow
 295  * exceptions. The returned function has the following
 296  * signature: void (*func) (MonoException *exc);
 297  *
 298  */
 299 gpointer
 300 mono_arch_get_rethrow_exception (MonoTrampInfo **info, gboolean aot)
 301 {
 302         static guint8 start [GENERIC_EXCEPTION_SIZE];
 303         static int inited = 0;
 304
 305         g_assert (!aot);
 306         if (info)
 307                 *info = NULL;
 308
 309         if (inited)
 310                 return start;
 311         mono_arch_get_throw_exception_generic (start, sizeof (start), FALSE, TRUE);
 312         inited = 1;
 313         return start;
 314 }
 315
 316 /**
 317  * arch_get_throw_exception:
 318  *
 319  * Returns a function pointer which can be used to raise
 320  * exceptions. The returned function has the following
 321  * signature: void (*func) (MonoException *exc);
 322  * For example to raise an arithmetic exception you can use:
 323  *
 324  * x86_push_imm (code, mono_get_exception_arithmetic ());
 325  * x86_call_code (code, arch_get_throw_exception ());
 326  *
 327  */
 328 gpointer
 329 mono_arch_get_throw_exception (MonoTrampInfo **info, gboolean aot)
 330 {
 331         static guint8 start [GENERIC_EXCEPTION_SIZE];
 332         static int inited = 0;
 333
 334         g_assert (!aot);
 335         if (info)
 336                 *info = NULL;
 337
 338         if (inited)
 339                 return start;
 340         mono_arch_get_throw_exception_generic (start, sizeof (start), FALSE, FALSE);
 341         inited = 1;
 342         return start;
 343 }
 344
 345 gpointer
 346 mono_arch_get_throw_exception_by_name (void)
 347 {
 348         guint8 *start, *code;
 349         int size = 64;
 350
 351         /* Not used on MIPS */
 352         start = code = mono_global_codeman_reserve (size);
 353         mips_break (code, 0xfd);
 354         mono_arch_flush_icache (start, code - start);
 355         return start;
 356 }
 357
 358 /**
 359  * mono_arch_get_throw_corlib_exception:
 360  *
 361  * Returns a function pointer which can be used to raise
 362  * corlib exceptions. The returned function has the following
 363  * signature: void (*func) (guint32 ex_token, guint32 offset);
 364  * On MIPS, the offset argument is missing.
 365  */
 366 gpointer
 367 mono_arch_get_throw_corlib_exception (MonoTrampInfo **info, gboolean aot)
 368 {
 369         static guint8 start [GENERIC_EXCEPTION_SIZE];
 370         static int inited = 0;
 371
 372         g_assert (!aot);
 373         if (info)
 374                 *info = NULL;
 375
 376         if (inited)
 377                 return start;
 378         mono_arch_get_throw_exception_generic (start, sizeof (start), TRUE, FALSE);
 379         inited = 1;
 380         return start;
 381 }
 382
 383 /*
 384  * mono_arch_find_jit_info:
 385  *
 386  * This function is used to gather information from @ctx, and store it in @frame_info.
 387  * It unwinds one stack frame, and stores the resulting context into @new_ctx. @lmf
 388  * is modified if needed.
 389  * Returns TRUE on success, FALSE otherwise.
 390  */
 391 gboolean
 392 mono_arch_find_jit_info (MonoDomain *domain, MonoJitTlsData *jit_tls,
 393                                                          MonoJitInfo *ji, MonoContext *ctx,
 394                                                          MonoContext *new_ctx, MonoLMF **lmf,
 395                                                          mgreg_t **save_locations,
 396                                                          StackFrameInfo *frame)
 397 {
 398         memset (frame, 0, sizeof (StackFrameInfo));
 399         frame->ji = ji;
 400
 401         *new_ctx = *ctx;
 402
 403         if (ji != NULL) {
 404                 int i;
 405                 gpointer ip = MONO_CONTEXT_GET_IP (ctx);
 406                 mgreg_t regs [MONO_MAX_IREGS + 1];
 407                 guint8 *cfa;
 408                 guint32 unwind_info_len;
 409                 guint8 *unwind_info;
 410
 411                 frame->type = FRAME_TYPE_MANAGED;
 412
 413                 if (ji->from_aot)
 414                         unwind_info = mono_aot_get_unwind_info (ji, &unwind_info_len);
 415                 else
 416                         unwind_info = mono_get_cached_unwind_info (ji->used_regs, &unwind_info_len);
 417
 418                 for (i = 0; i < MONO_MAX_IREGS; ++i)
 419                         regs [i] = new_ctx->sc_regs [i];
 420
 421                 mono_unwind_frame (unwind_info, unwind_info_len, ji->code_start,
 422                                                    (guint8*)ji->code_start + ji->code_size,
 423                                                    ip, regs, MONO_MAX_IREGS,
 424                                                    save_locations, MONO_MAX_IREGS, &cfa);
 425
 426                 for (i = 0; i < MONO_MAX_IREGS; ++i)
 427                         new_ctx->sc_regs [i] = regs [i];
 428                 new_ctx->sc_pc = regs [mips_ra];
 429                 new_ctx->sc_regs [mips_sp] = (mgreg_t)cfa;
 430
 431                 if (*lmf && (MONO_CONTEXT_GET_SP (ctx) >= (gpointer)(*lmf)->iregs [mips_sp])) {
 432                         /* remove any unused lmf */
 433                         *lmf = (gpointer)(((gsize)(*lmf)->previous_lmf) & ~3);
 434                 }
 435
 436                 /* we substract 8, so that the IP points into the call instruction */
 437                 MONO_CONTEXT_SET_IP (new_ctx, new_ctx->sc_pc - 8);
 438
 439                 /* Sanity check -- we should have made progress here */
 440                 g_assert (MONO_CONTEXT_GET_SP (new_ctx) != MONO_CONTEXT_GET_SP (ctx));
 441                 return TRUE;
 442         } else if (*lmf) {
 443
 444                 if (((mgreg_t)(*lmf)->previous_lmf) & 2) {
 445                         /*
 446                          * This LMF entry is created by the soft debug code to mark transitions to
 447                          * managed code done during invokes.
 448                          */
 449                         MonoLMFExt *ext = (MonoLMFExt*)(*lmf);
 450
 451                         g_assert (ext->debugger_invoke);
 452
 453                         memcpy (new_ctx, &ext->ctx, sizeof (MonoContext));
 454
 455                         *lmf = (gpointer)(((gsize)(*lmf)->previous_lmf) & ~3);
 456
 457                         frame->type = FRAME_TYPE_DEBUGGER_INVOKE;
 458
 459                         return TRUE;
 460                 }
 461
 462                 if (!(*lmf)->method) {
 463 #ifdef DEBUG_EXCEPTIONS
 464                         g_print ("mono_arch_find_jit_info: bad lmf @ %p\n", (void *) *lmf);
 465 #endif
 466                         return FALSE;
 467                 }
 468                 g_assert (((*lmf)->magic == MIPS_LMF_MAGIC1) || ((*lmf)->magic == MIPS_LMF_MAGIC2));
 469
 470                 ji = mini_jit_info_table_find (domain, (gpointer)(*lmf)->eip, NULL);
 471                 if (!ji) {
 472                         // FIXME: This can happen with multiple appdomains (bug #444383)
 473                         return FALSE;
 474                 }
 475
 476                 frame->ji = ji;
 477                 frame->type = FRAME_TYPE_MANAGED_TO_NATIVE;
 478
 479                 memcpy (&new_ctx->sc_regs, (*lmf)->iregs, sizeof (gulong) * MONO_SAVED_GREGS);
 480                 memcpy (&new_ctx->sc_fpregs, (*lmf)->fregs, sizeof (float) * MONO_SAVED_FREGS);
 481                 MONO_CONTEXT_SET_IP (new_ctx, (*lmf)->eip);
 482                 /* ensure that we've made progress */
 483                 g_assert (new_ctx->sc_pc != ctx->sc_pc);
 484
 485                 *lmf = (gpointer)(((gsize)(*lmf)->previous_lmf) & ~3);
 486
 487                 return TRUE;
 488         }
 489
 490         return FALSE;
 491 }
 492
 493 void
 494 mono_arch_sigctx_to_monoctx (void *sigctx, MonoContext *mctx)
 495 {
 496         mono_sigctx_to_monoctx (sigctx, mctx);
 497 }
 498
 499 void
 500 mono_arch_monoctx_to_sigctx (MonoContext *mctx, void *sigctx)
 501 {
 502         mono_monoctx_to_sigctx (mctx, sigctx);
 503 }
 504
 505 gpointer
 506 mono_arch_ip_from_context (void *sigctx)
 507 {
 508         return (gpointer)UCONTEXT_REG_PC (sigctx);
 509 }
 510
 511 /*
 512  * handle_exception:
 513  *
 514  *   Called by resuming from a signal handler.
 515  */
 516 static void
 517 handle_signal_exception (gpointer obj)
 518 {
 519         MonoJitTlsData *jit_tls = mono_native_tls_get_value (mono_jit_tls_id);
 520         MonoContext ctx;
 521         static void (*restore_context) (MonoContext *);
 522
 523         if (!restore_context)
 524                 restore_context = mono_get_restore_context ();
 525
 526         memcpy (&ctx, &jit_tls->ex_ctx, sizeof (MonoContext));
 527
 528         mono_handle_exception (&ctx, obj);
 529
 530         restore_context (&ctx);
 531 }
 532
 533 /*
 534  * This is the function called from the signal handler
 535  */
 536 gboolean
 537 mono_arch_handle_exception (void *ctx, gpointer obj)
 538 {
 539 #if defined(MONO_CROSS_COMPILE)
 540         g_assert_not_reached ();
 541 #elif defined(MONO_ARCH_USE_SIGACTION)
 542         void *sigctx = ctx;
 543
 544         /*
 545          * Handling the exception in the signal handler is problematic, since the original
 546          * signal is disabled, and we could run arbitrary code though the debugger. So
 547          * resume into the normal stack and do most work there if possible.
 548          */
 549         MonoJitTlsData *jit_tls = mono_native_tls_get_value (mono_jit_tls_id);
 550         guint64 sp = UCONTEXT_GREGS (sigctx) [mips_sp];
 551
 552         /* Pass the ctx parameter in TLS */
 553         mono_arch_sigctx_to_monoctx (sigctx, &jit_tls->ex_ctx);
 554         /* The others in registers */
 555         UCONTEXT_GREGS (sigctx)[mips_a0] = (gsize)obj;
 556
 557         /* Allocate a stack frame */
 558         sp -= 256;
 559         UCONTEXT_GREGS (sigctx)[mips_sp] = sp;
 560
 561         UCONTEXT_REG_PC (sigctx) = (gsize)handle_signal_exception;
 562
 563         return TRUE;
 564 #else
 565         MonoContext mctx;
 566         gboolean result;
 567
 568         mono_arch_sigctx_to_monoctx (ctx, &mctx);
 569
 570         result = mono_handle_exception (&mctx, obj);
 571         /* restore the context so that returning from the signal handler will invoke
 572          * the catch clause
 573          */
 574         mono_arch_monoctx_to_sigctx (&mctx, ctx);
 575         return result;
 576 #endif
 577 }
 578
 579 /*
 580  * mono_arch_setup_resume_sighandler_ctx:
 581  *
 582  *   Setup CTX so execution continues at FUNC.
 583  */
 584 void
 585 mono_arch_setup_resume_sighandler_ctx (MonoContext *ctx, gpointer func)
 586 {
 587         MONO_CONTEXT_SET_IP (ctx,func);
 588 }