mono/mini/exceptions-arm64.c

   1 /**
   2  * \file
   3  * exception support for ARM64
   4  *
   5  * Copyright 2013 Xamarin Inc
   6  *
   7  * Based on exceptions-arm.c:
   8  *
   9  * Authors:
  10  *   Dietmar Maurer (dietmar@ximian.com)
  11  *   Paolo Molaro (lupus@ximian.com)
  12  *
  13  * (C) 2001 Ximian, Inc.
  14  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
  15  */
  16
  17 #include "mini.h"
  18 #include "mini-runtime.h"
  19 #include "aot-runtime.h"
  20
  21 #include <mono/arch/arm64/arm64-codegen.h>
  22 #include <mono/metadata/abi-details.h>
  23
  24 #ifndef DISABLE_JIT
  25
  26 gpointer
  27 mono_arch_get_restore_context (MonoTrampInfo **info, gboolean aot)
  28 {
  29         guint8 *start, *code;
  30         MonoJumpInfo *ji = NULL;
  31         GSList *unwind_ops = NULL;
  32         int i, ctx_reg, size;
  33         guint8 *labels [16];
  34
  35         size = 256;
  36         code = start = mono_global_codeman_reserve (size);
  37
  38         arm_movx (code, ARMREG_IP0, ARMREG_R0);
  39         ctx_reg = ARMREG_IP0;
  40
  41         /* Restore fregs */
  42         arm_ldrx (code, ARMREG_IP1, ctx_reg, MONO_STRUCT_OFFSET (MonoContext, has_fregs));
  43         labels [0] = code;
  44         arm_cbzx (code, ARMREG_IP1, 0);
  45         for (i = 0; i < 32; ++i)
  46                 arm_ldrfpx (code, i, ctx_reg, MONO_STRUCT_OFFSET (MonoContext, fregs) + (i * sizeof (MonoContextSimdReg)));
  47         mono_arm_patch (labels [0], code, MONO_R_ARM64_CBZ);
  48         /* Restore gregs */
  49         // FIXME: Restore less registers
  50         // FIXME: fp should be restored later
  51         code = mono_arm_emit_load_regarray (code, 0xffffffff & ~(1 << ctx_reg) & ~(1 << ARMREG_SP), ctx_reg, MONO_STRUCT_OFFSET (MonoContext, regs));
  52         /* ip0/ip1 doesn't need to be restored */
  53         /* ip1 = pc */
  54         arm_ldrx (code, ARMREG_IP1, ctx_reg, MONO_STRUCT_OFFSET (MonoContext, pc));
  55         /* ip0 = sp */
  56         arm_ldrx (code, ARMREG_IP0, ctx_reg, MONO_STRUCT_OFFSET (MonoContext, regs) + (ARMREG_SP * 8));
  57         /* Restore sp, ctx is no longer valid */
  58         arm_movspx (code, ARMREG_SP, ARMREG_IP0);
  59         /* Branch to pc */
  60         arm_brx (code, ARMREG_IP1);
  61         /* Not reached */
  62         arm_brk (code, 0);
  63
  64         g_assert ((code - start) < size);
  65         mono_arch_flush_icache (start, code - start);
  66         MONO_PROFILER_RAISE (jit_code_buffer, (start, code - start, MONO_PROFILER_CODE_BUFFER_EXCEPTION_HANDLING, NULL));
  67
  68         if (info)
  69                 *info = mono_tramp_info_create ("restore_context", start, code - start, ji, unwind_ops);
  70
  71         return start;
  72 }
  73
  74 gpointer
  75 mono_arch_get_call_filter (MonoTrampInfo **info, gboolean aot)
  76 {
  77         guint8 *code;
  78         guint8* start;
  79         int i, size, offset, gregs_offset, fregs_offset, ctx_offset, num_fregs, frame_size;
  80         MonoJumpInfo *ji = NULL;
  81         GSList *unwind_ops = NULL;
  82         guint8 *labels [16];
  83
  84         size = 512;
  85         start = code = mono_global_codeman_reserve (size);
  86
  87         /* Compute stack frame size and offsets */
  88         offset = 0;
  89         /* frame block */
  90         offset += 2 * 8;
  91         /* gregs */
  92         gregs_offset = offset;
  93         offset += 32 * 8;
  94         /* fregs */
  95         num_fregs = 8;
  96         fregs_offset = offset;
  97         offset += num_fregs * 8;
  98         ctx_offset = offset;
  99         offset += 8;
 100         frame_size = ALIGN_TO (offset, MONO_ARCH_FRAME_ALIGNMENT);
 101
 102         /*
 103          * We are being called from C code, ctx is in r0, the address to call is in r1.
 104          * We need to save state, restore ctx, make the call, then restore the previous state,
 105          * returning the value returned by the call.
 106          */
 107
 108         /* Setup a frame */
 109         arm_stpx_pre (code, ARMREG_FP, ARMREG_LR, ARMREG_SP, -frame_size);
 110         arm_movspx (code, ARMREG_FP, ARMREG_SP);
 111
 112         /* Save ctx */
 113         arm_strx (code, ARMREG_R0, ARMREG_FP, ctx_offset);
 114         /* Save gregs */
 115         code = mono_arm_emit_store_regarray (code, MONO_ARCH_CALLEE_SAVED_REGS | (1 << ARMREG_FP), ARMREG_FP, gregs_offset);
 116         /* Save fregs */
 117         for (i = 0; i < num_fregs; ++i)
 118                 arm_strfpx (code, ARMREG_D8 + i, ARMREG_FP, fregs_offset + (i * 8));
 119
 120         /* Load regs from ctx */
 121         code = mono_arm_emit_load_regarray (code, MONO_ARCH_CALLEE_SAVED_REGS, ARMREG_R0, MONO_STRUCT_OFFSET (MonoContext, regs));
 122         /* Load fregs */
 123         arm_ldrx (code, ARMREG_IP0, ARMREG_R0, MONO_STRUCT_OFFSET (MonoContext, has_fregs));
 124         labels [0] = code;
 125         arm_cbzx (code, ARMREG_IP0, 0);
 126         for (i = 0; i < num_fregs; ++i)
 127                 arm_ldrfpx (code, ARMREG_D8 + i, ARMREG_R0, MONO_STRUCT_OFFSET (MonoContext, fregs) + ((i + 8) * sizeof (MonoContextSimdReg)));
 128         mono_arm_patch (labels [0], code, MONO_R_ARM64_CBZ);
 129         /* Load fp */
 130         arm_ldrx (code, ARMREG_FP, ARMREG_R0, MONO_STRUCT_OFFSET (MonoContext, regs) + (ARMREG_FP * 8));
 131
 132         /* Make the call */
 133         arm_blrx (code, ARMREG_R1);
 134         /* For filters, the result is in R0 */
 135
 136         /* Restore fp */
 137         arm_ldrx (code, ARMREG_FP, ARMREG_SP, gregs_offset + (ARMREG_FP * 8));
 138         /* Load ctx */
 139         arm_ldrx (code, ARMREG_IP0, ARMREG_FP, ctx_offset);
 140         /* Save registers back to ctx */
 141         /* This isn't strictly neccessary since we don't allocate variables used in eh clauses to registers */
 142         code = mono_arm_emit_store_regarray (code, MONO_ARCH_CALLEE_SAVED_REGS, ARMREG_IP0, MONO_STRUCT_OFFSET (MonoContext, regs));
 143
 144         /* Restore regs */
 145         code = mono_arm_emit_load_regarray (code, MONO_ARCH_CALLEE_SAVED_REGS, ARMREG_FP, gregs_offset);
 146         /* Restore fregs */
 147         for (i = 0; i < num_fregs; ++i)
 148                 arm_ldrfpx (code, ARMREG_D8 + i, ARMREG_FP, fregs_offset + (i * 8));
 149         /* Destroy frame */
 150         code = mono_arm_emit_destroy_frame (code, frame_size, (1 << ARMREG_IP0));
 151         arm_retx (code, ARMREG_LR);
 152
 153         g_assert ((code - start) < size);
 154         mono_arch_flush_icache (start, code - start);
 155         MONO_PROFILER_RAISE (jit_code_buffer, (start, code - start, MONO_PROFILER_CODE_BUFFER_EXCEPTION_HANDLING, NULL));
 156
 157         if (info)
 158                 *info = mono_tramp_info_create ("call_filter", start, code - start, ji, unwind_ops);
 159
 160         return start;
 161 }
 162
 163 static gpointer
 164 get_throw_trampoline (int size, gboolean corlib, gboolean rethrow, gboolean llvm, gboolean resume_unwind, const char *tramp_name, MonoTrampInfo **info, gboolean aot, gboolean preserve_ips)
 165 {
 166         guint8 *start, *code;
 167         MonoJumpInfo *ji = NULL;
 168         GSList *unwind_ops = NULL;
 169         int i, offset, gregs_offset, fregs_offset, frame_size, num_fregs;
 170
 171         code = start = mono_global_codeman_reserve (size);
 172
 173         /* We are being called by JITted code, the exception object/type token is in R0 */
 174
 175         /* Compute stack frame size and offsets */
 176         offset = 0;
 177         /* frame block */
 178         offset += 2 * 8;
 179         /* gregs */
 180         gregs_offset = offset;
 181         offset += 32 * 8;
 182         /* fregs */
 183         num_fregs = 8;
 184         fregs_offset = offset;
 185         offset += num_fregs * 8;
 186         frame_size = ALIGN_TO (offset, MONO_ARCH_FRAME_ALIGNMENT);
 187
 188         /* Setup a frame */
 189         arm_stpx_pre (code, ARMREG_FP, ARMREG_LR, ARMREG_SP, -frame_size);
 190         arm_movspx (code, ARMREG_FP, ARMREG_SP);
 191
 192         /* Save gregs */
 193         code = mono_arm_emit_store_regarray (code, 0xffffffff, ARMREG_FP, gregs_offset);
 194         if (corlib && !llvm)
 195                 /* The real LR is in R1 */
 196                 arm_strx (code, ARMREG_R1, ARMREG_FP, gregs_offset + (ARMREG_LR * 8));
 197         /* Save fp/sp */
 198         arm_ldrx (code, ARMREG_IP0, ARMREG_FP, 0);
 199         arm_strx (code, ARMREG_IP0, ARMREG_FP, gregs_offset + (ARMREG_FP * 8));
 200         arm_addx_imm (code, ARMREG_IP0, ARMREG_FP, frame_size);
 201         arm_strx (code, ARMREG_IP0, ARMREG_FP, gregs_offset + (ARMREG_SP * 8));
 202         /* Save fregs */
 203         for (i = 0; i < num_fregs; ++i)
 204                 arm_strfpx (code, ARMREG_D8 + i, ARMREG_FP, fregs_offset + (i * 8));
 205
 206         /* Call the C trampoline function */
 207         /* Arg1 =  exception object/type token */
 208         arm_movx (code, ARMREG_R0, ARMREG_R0);
 209         /* Arg2 = caller ip */
 210         if (corlib) {
 211                 if (llvm)
 212                         arm_ldrx (code, ARMREG_R1, ARMREG_FP, gregs_offset + (ARMREG_LR * 8));
 213                 else
 214                         arm_movx (code, ARMREG_R1, ARMREG_R1);
 215         } else {
 216                 arm_ldrx (code, ARMREG_R1, ARMREG_FP, 8);
 217         }
 218         /* Arg 3 = gregs */
 219         arm_addx_imm (code, ARMREG_R2, ARMREG_FP, gregs_offset);
 220         /* Arg 4 = fregs */
 221         arm_addx_imm (code, ARMREG_R3, ARMREG_FP, fregs_offset);
 222         /* Arg 5 = corlib */
 223         arm_movzx (code, ARMREG_R4, corlib ? 1 : 0, 0);
 224         /* Arg 6 = rethrow */
 225         arm_movzx (code, ARMREG_R5, rethrow ? 1 : 0, 0);
 226         if (!resume_unwind) {
 227                 /* Arg 7 = preserve_ips */
 228                 arm_movzx (code, ARMREG_R6, preserve_ips ? 1 : 0, 0);
 229         }
 230
 231         /* Call the function */
 232         if (aot) {
 233                 MonoJitICallId icall_id;
 234
 235                 if (resume_unwind)
 236                         icall_id = MONO_JIT_ICALL_mono_arm_resume_unwind;
 237                 else
 238                         icall_id = MONO_JIT_ICALL_mono_arm_throw_exception;
 239
 240                 code = mono_arm_emit_aotconst (&ji, code, start, ARMREG_LR, MONO_PATCH_INFO_JIT_ICALL_ADDR, GUINT_TO_POINTER (icall_id));
 241         } else {
 242                 gpointer icall_func;
 243
 244                 if (resume_unwind)
 245                         icall_func = (gpointer)mono_arm_resume_unwind;
 246                 else
 247                         icall_func = (gpointer)mono_arm_throw_exception;
 248
 249                 code = mono_arm_emit_imm64 (code, ARMREG_LR, (guint64)icall_func);
 250         }
 251         arm_blrx (code, ARMREG_LR);
 252         /* This shouldn't return */
 253         arm_brk (code, 0x0);
 254
 255         g_assert ((code - start) < size);
 256         mono_arch_flush_icache (start, code - start);
 257         MONO_PROFILER_RAISE (jit_code_buffer, (start, code - start, MONO_PROFILER_CODE_BUFFER_EXCEPTION_HANDLING, NULL));
 258
 259         if (info)
 260                 *info = mono_tramp_info_create (tramp_name, start, code - start, ji, unwind_ops);
 261
 262         return start;
 263 }
 264
 265 gpointer
 266 mono_arch_get_throw_exception (MonoTrampInfo **info, gboolean aot)
 267 {
 268         return get_throw_trampoline (256, FALSE, FALSE, FALSE, FALSE, "throw_exception", info, aot, FALSE);
 269 }
 270
 271 gpointer
 272 mono_arch_get_rethrow_exception (MonoTrampInfo **info, gboolean aot)
 273 {
 274         return get_throw_trampoline (256, FALSE, TRUE, FALSE, FALSE, "rethrow_exception", info, aot, FALSE);
 275 }
 276
 277 gpointer
 278 mono_arch_get_rethrow_preserve_exception (MonoTrampInfo **info, gboolean aot)
 279 {
 280         return get_throw_trampoline (256, FALSE, TRUE, FALSE, FALSE, "rethrow_preserve_exception", info, aot, TRUE);
 281 }
 282
 283 gpointer
 284 mono_arch_get_throw_corlib_exception (MonoTrampInfo **info, gboolean aot)
 285 {
 286         return get_throw_trampoline (256, TRUE, FALSE, FALSE, FALSE, "throw_corlib_exception", info, aot, FALSE);
 287 }
 288
 289 GSList*
 290 mono_arm_get_exception_trampolines (gboolean aot)
 291 {
 292         MonoTrampInfo *info;
 293         GSList *tramps = NULL;
 294
 295         // FIXME Macroize.
 296
 297         /* LLVM uses the normal trampolines, but with a different name */
 298         get_throw_trampoline (256, TRUE, FALSE, FALSE, FALSE, "llvm_throw_corlib_exception_trampoline", &info, aot, FALSE);
 299         info->jit_icall_info = &mono_get_jit_icall_info ()->mono_llvm_throw_corlib_exception_trampoline;
 300         tramps = g_slist_prepend (tramps, info);
 301
 302         get_throw_trampoline (256, TRUE, FALSE, TRUE, FALSE, "llvm_throw_corlib_exception_abs_trampoline", &info, aot, FALSE);
 303         info->jit_icall_info = &mono_get_jit_icall_info ()->mono_llvm_throw_corlib_exception_abs_trampoline;
 304         tramps = g_slist_prepend (tramps, info);
 305
 306         get_throw_trampoline (256, FALSE, FALSE, FALSE, TRUE, "llvm_resume_unwind_trampoline", &info, aot, FALSE);
 307         info->jit_icall_info = &mono_get_jit_icall_info ()->mono_llvm_resume_unwind_trampoline;
 308         tramps = g_slist_prepend (tramps, info);
 309
 310         return tramps;
 311 }
 312
 313 #else
 314
 315 GSList*
 316 mono_arm_get_exception_trampolines (gboolean aot)
 317 {
 318         g_assert_not_reached ();
 319         return NULL;
 320 }
 321
 322 #endif /* DISABLE_JIT */
 323
 324 void
 325 mono_arch_exceptions_init (void)
 326 {
 327         gpointer tramp;
 328         GSList *tramps, *l;
 329
 330         if (mono_aot_only) {
 331
 332                 // FIXME Macroize.
 333
 334                 tramp = mono_aot_get_trampoline ("llvm_throw_corlib_exception_trampoline");
 335                 mono_register_jit_icall_info (&mono_get_jit_icall_info ()->mono_llvm_throw_corlib_exception_trampoline, tramp, "llvm_throw_corlib_exception_trampoline", NULL, TRUE, NULL);
 336
 337                 tramp = mono_aot_get_trampoline ("llvm_throw_corlib_exception_abs_trampoline");
 338                 mono_register_jit_icall_info (&mono_get_jit_icall_info ()->mono_llvm_throw_corlib_exception_abs_trampoline, tramp, "llvm_throw_corlib_exception_abs_trampoline", NULL, TRUE, NULL);
 339
 340                 tramp = mono_aot_get_trampoline ("llvm_resume_unwind_trampoline");
 341                 mono_register_jit_icall_info (&mono_get_jit_icall_info ()->mono_llvm_resume_unwind_trampoline, tramp, "llvm_resume_unwind_trampoline", NULL, TRUE, NULL);
 342
 343         } else {
 344                 tramps = mono_arm_get_exception_trampolines (FALSE);
 345                 for (l = tramps; l; l = l->next) {
 346                         MonoTrampInfo *info = (MonoTrampInfo*)l->data;
 347                         mono_register_jit_icall_info (info->jit_icall_info, info->code, g_strdup (info->name), NULL, TRUE, NULL);
 348                         mono_tramp_info_register (info, NULL);
 349                 }
 350                 g_slist_free (tramps);
 351         }
 352 }
 353
 354 /*
 355  * mono_arm_throw_exception:
 356  *
 357  *   This function is called by the exception trampolines.
 358  * FP_REGS points to the 8 callee saved fp regs.
 359  */
 360 void
 361 mono_arm_throw_exception (gpointer arg, host_mgreg_t pc, host_mgreg_t *int_regs, gdouble *fp_regs, gboolean corlib, gboolean rethrow, gboolean preserve_ips)
 362 {
 363         ERROR_DECL (error);
 364         MonoContext ctx;
 365         MonoObject *exc = NULL;
 366         guint32 ex_token_index, ex_token;
 367
 368         if (!corlib)
 369                 exc = (MonoObject*)arg;
 370         else {
 371                 ex_token_index = (guint64)arg;
 372                 ex_token = MONO_TOKEN_TYPE_DEF | ex_token_index;
 373                 exc = (MonoObject*)mono_exception_from_token (mono_defaults.corlib, ex_token);
 374         }
 375
 376         /* Adjust pc so it points into the call instruction */
 377         pc -= 4;
 378
 379         /* Initialize a ctx based on the arguments */
 380         memset (&ctx, 0, sizeof (MonoContext));
 381         memcpy (&(ctx.regs [0]), int_regs, sizeof (host_mgreg_t) * 32);
 382         for (int i = 0; i < 8; i++)
 383                 *((gdouble*)&ctx.fregs [ARMREG_D8 + i]) = fp_regs [i];
 384         ctx.has_fregs = 1;
 385         ctx.pc = pc;
 386
 387         if (mono_object_isinst_checked (exc, mono_defaults.exception_class, error)) {
 388                 MonoException *mono_ex = (MonoException*)exc;
 389                 if (!rethrow) {
 390                         mono_ex->stack_trace = NULL;
 391                         mono_ex->trace_ips = NULL;
 392                 } else if (preserve_ips) {
 393                         mono_ex->caught_in_unmanaged = TRUE;
 394                 }
 395         }
 396         mono_error_assert_ok (error);
 397
 398         mono_handle_exception (&ctx, exc);
 399
 400         mono_restore_context (&ctx);
 401 }
 402
 403 void
 404 mono_arm_resume_unwind (gpointer arg, host_mgreg_t pc, host_mgreg_t *int_regs, gdouble *fp_regs, gboolean corlib, gboolean rethrow)
 405 {
 406         MonoContext ctx;
 407
 408         /* Adjust pc so it points into the call instruction */
 409         pc -= 4;
 410
 411         /* Initialize a ctx based on the arguments */
 412         memset (&ctx, 0, sizeof (MonoContext));
 413         memcpy (&(ctx.regs [0]), int_regs, sizeof (host_mgreg_t) * 32);
 414         for (int i = 0; i < 8; i++)
 415                 *((gdouble*)&ctx.fregs [ARMREG_D8 + i]) = fp_regs [i];
 416         ctx.has_fregs = 1;
 417         ctx.pc = pc;
 418
 419         mono_resume_unwind (&ctx);
 420 }
 421
 422 /*
 423  * mono_arch_unwind_frame:
 424  *
 425  * See exceptions-amd64.c for docs;
 426  */
 427 gboolean
 428 mono_arch_unwind_frame (MonoDomain *domain, MonoJitTlsData *jit_tls,
 429                                                          MonoJitInfo *ji, MonoContext *ctx,
 430                                                          MonoContext *new_ctx, MonoLMF **lmf,
 431                                                          host_mgreg_t **save_locations,
 432                                                          StackFrameInfo *frame)
 433 {
 434         gpointer ip = MONO_CONTEXT_GET_IP (ctx);
 435
 436         memset (frame, 0, sizeof (StackFrameInfo));
 437         frame->ji = ji;
 438
 439         *new_ctx = *ctx;
 440
 441         if (ji != NULL) {
 442                 host_mgreg_t regs [MONO_MAX_IREGS + 8 + 1];
 443                 guint8 *cfa;
 444                 guint32 unwind_info_len;
 445                 guint8 *unwind_info;
 446
 447
 448                 if (ji->is_trampoline)
 449                         frame->type = FRAME_TYPE_TRAMPOLINE;
 450                 else
 451                         frame->type = FRAME_TYPE_MANAGED;
 452
 453                 unwind_info = mono_jinfo_get_unwind_info (ji, &unwind_info_len);
 454
 455                 memcpy (regs, &new_ctx->regs, sizeof (host_mgreg_t) * 32);
 456                 /* v8..v15 are callee saved */
 457                 for (int i = 0; i < 8; i++)
 458                         (regs + MONO_MAX_IREGS) [i] = *((host_mgreg_t*)&new_ctx->fregs [8 + i]);
 459
 460                 gboolean success = mono_unwind_frame (unwind_info, unwind_info_len, (guint8*)ji->code_start,
 461                                                    (guint8*)ji->code_start + ji->code_size,
 462                                                    (guint8*)ip, NULL, regs, MONO_MAX_IREGS + 8,
 463                                                    save_locations, MONO_MAX_IREGS, (guint8**)&cfa);
 464
 465                 if (!success)
 466                         return FALSE;
 467
 468                 memcpy (&new_ctx->regs, regs, sizeof (host_mgreg_t) * 32);
 469                 for (int i = 0; i < 8; i++)
 470                         *((host_mgreg_t*)&new_ctx->fregs [8 + i]) = (regs + MONO_MAX_IREGS) [i];
 471
 472                 new_ctx->pc = regs [ARMREG_LR];
 473                 new_ctx->regs [ARMREG_SP] = (host_mgreg_t)(gsize)cfa;
 474
 475                 if (*lmf && (*lmf)->gregs [MONO_ARCH_LMF_REG_SP] && (MONO_CONTEXT_GET_SP (ctx) >= (gpointer)(*lmf)->gregs [MONO_ARCH_LMF_REG_SP])) {
 476                         /* remove any unused lmf */
 477                         *lmf = (MonoLMF*)(((gsize)(*lmf)->previous_lmf) & ~3);
 478                 }
 479
 480                 /* we substract 1, so that the IP points into the call instruction */
 481                 new_ctx->pc--;
 482
 483                 return TRUE;
 484         } else if (*lmf) {
 485                 g_assert ((((guint64)(*lmf)->previous_lmf) & 2) == 0);
 486
 487                 frame->type = FRAME_TYPE_MANAGED_TO_NATIVE;
 488
 489                 ji = mini_jit_info_table_find (domain, (gpointer)(*lmf)->pc, NULL);
 490                 if (!ji)
 491                         return FALSE;
 492
 493                 g_assert (MONO_ARCH_LMF_REGS == ((0x3ff << 19) | (1 << ARMREG_FP) | (1 << ARMREG_SP)));
 494                 memcpy (&new_ctx->regs [ARMREG_R19], &(*lmf)->gregs [0], sizeof (host_mgreg_t) * 10);
 495                 new_ctx->regs [ARMREG_FP] = (*lmf)->gregs [MONO_ARCH_LMF_REG_FP];
 496                 new_ctx->regs [ARMREG_SP] = (*lmf)->gregs [MONO_ARCH_LMF_REG_SP];
 497                 new_ctx->pc = (*lmf)->pc;
 498
 499                 /* we substract 1, so that the IP points into the call instruction */
 500                 new_ctx->pc--;
 501
 502                 *lmf = (MonoLMF*)(((gsize)(*lmf)->previous_lmf) & ~3);
 503
 504                 return TRUE;
 505         }
 506
 507         return FALSE;
 508 }
 509
 510 /*
 511  * handle_exception:
 512  *
 513  *   Called by resuming from a signal handler.
 514  */
 515 static void
 516 handle_signal_exception (gpointer obj)
 517 {
 518         MonoJitTlsData *jit_tls = mono_tls_get_jit_tls ();
 519         MonoContext ctx;
 520
 521         memcpy (&ctx, &jit_tls->ex_ctx, sizeof (MonoContext));
 522
 523         mono_handle_exception (&ctx, (MonoObject*)obj);
 524
 525         mono_restore_context (&ctx);
 526 }
 527
 528 /*
 529  * This is the function called from the signal handler
 530  */
 531 gboolean
 532 mono_arch_handle_exception (void *ctx, gpointer obj)
 533 {
 534 #if defined(MONO_CROSS_COMPILE)
 535         g_assert_not_reached ();
 536 #else
 537         MonoJitTlsData *jit_tls;
 538         void *sigctx = ctx;
 539
 540         /*
 541          * Resume into the normal stack and handle the exception there.
 542          */
 543         jit_tls = mono_tls_get_jit_tls ();
 544
 545         /* Pass the ctx parameter in TLS */
 546         mono_sigctx_to_monoctx (sigctx, &jit_tls->ex_ctx);
 547         /* The others in registers */
 548         UCONTEXT_REG_R0 (sigctx) = (gsize)obj;
 549
 550         UCONTEXT_REG_PC (sigctx) = (gsize)handle_signal_exception;
 551         UCONTEXT_REG_SP (sigctx) = UCONTEXT_REG_SP (sigctx) - MONO_ARCH_REDZONE_SIZE;
 552 #endif
 553
 554         return TRUE;
 555 }
 556
 557 gpointer
 558 mono_arch_ip_from_context (void *sigctx)
 559 {
 560 #ifdef MONO_CROSS_COMPILE
 561         g_assert_not_reached ();
 562         return NULL;
 563 #else
 564         return (gpointer)UCONTEXT_REG_PC (sigctx);
 565 #endif
 566 }
 567
 568 void
 569 mono_arch_setup_async_callback (MonoContext *ctx, void (*async_cb)(void *fun), gpointer user_data)
 570 {
 571         host_mgreg_t sp = (host_mgreg_t)MONO_CONTEXT_GET_SP (ctx);
 572
 573         // FIXME:
 574         g_assert (!user_data);
 575
 576         /* Allocate a stack frame */
 577         sp -= 32;
 578         MONO_CONTEXT_SET_SP (ctx, sp);
 579
 580         mono_arch_setup_resume_sighandler_ctx (ctx, (gpointer)async_cb);
 581 }
 582
 583 /*
 584  * mono_arch_setup_resume_sighandler_ctx:
 585  *
 586  *   Setup CTX so execution continues at FUNC.
 587  */
 588 void
 589 mono_arch_setup_resume_sighandler_ctx (MonoContext *ctx, gpointer func)
 590 {
 591         MONO_CONTEXT_SET_IP (ctx,func);
 592 }
 593
 594 void
 595 mono_arch_undo_ip_adjustment (MonoContext *ctx)
 596 {
 597         ctx->pc++;
 598 }
 599
 600 void
 601 mono_arch_do_ip_adjustment (MonoContext *ctx)
 602 {
 603         ctx->pc--;
 604 }