mono/mini/tramp-arm.c

   1 /*
   2  * tramp-arm.c: JIT trampoline code for ARM
   3  *
   4  * Authors:
   5  *   Paolo Molaro (lupus@ximian.com)
   6  *
   7  * (C) 2001 Ximian, Inc.
   8  */
   9
  10 #include <config.h>
  11 #include <glib.h>
  12
  13 #include <mono/metadata/appdomain.h>
  14 #include <mono/metadata/marshal.h>
  15 #include <mono/metadata/tabledefs.h>
  16 #include <mono/arch/arm/arm-codegen.h>
  17
  18 #include "mini.h"
  19 #include "mini-arm.h"
  20
  21 static guint8* nullified_class_init_trampoline;
  22
  23 void
  24 mono_arch_patch_callsite (guint8 *method_start, guint8 *code_ptr, guint8 *addr)
  25 {
  26         guint32 *code = (guint32*)code_ptr;
  27
  28         /* This is the 'bl' or the 'mov pc' instruction */
  29         --code;
  30
  31         /*
  32          * Note that methods are called also with the bl opcode.
  33          */
  34         if ((((*code) >> 25)  & 7) == 5) {
  35                 /*g_print ("direct patching\n");*/
  36                 arm_patch ((guint8*)code, addr);
  37                 mono_arch_flush_icache ((guint8*)code, 4);
  38                 return;
  39         }
  40
  41         if ((((*code) >> 20) & 0xFF) == 0x12) {
  42                 /*g_print ("patching bx\n");*/
  43                 arm_patch ((guint8*)code, addr);
  44                 mono_arch_flush_icache ((guint8*)(code - 2), 4);
  45                 return;
  46         }
  47
  48         g_assert_not_reached ();
  49 }
  50
  51 void
  52 mono_arch_patch_plt_entry (guint8 *code, gpointer *got, mgreg_t *regs, guint8 *addr)
  53 {
  54         guint8 *jump_entry;
  55
  56         /* Patch the jump table entry used by the plt entry */
  57         if (*(guint32*)code == 0xe59fc000) {
  58                 /* ARM_LDR_IMM (code, ARMREG_IP, ARMREG_PC, 0); */
  59                 guint32 offset = ((guint32*)code)[2];
  60
  61                 jump_entry = code + offset + 12;
  62         } else {
  63                 g_assert_not_reached ();
  64         }
  65
  66         *(guint8**)jump_entry = addr;
  67 }
  68
  69 void
  70 mono_arch_nullify_class_init_trampoline (guint8 *code, mgreg_t *regs)
  71 {
  72         mono_arch_patch_callsite (NULL, code, nullified_class_init_trampoline);
  73 }
  74
  75 void
  76 mono_arch_nullify_plt_entry (guint8 *code, mgreg_t *regs)
  77 {
  78         if (mono_aot_only && !nullified_class_init_trampoline)
  79                 nullified_class_init_trampoline = mono_aot_get_trampoline ("nullified_class_init_trampoline");
  80
  81         mono_arch_patch_plt_entry (code, NULL, regs, nullified_class_init_trampoline);
  82 }
  83
  84 #ifndef DISABLE_JIT
  85
  86 #define arm_is_imm12(v) ((int)(v) > -4096 && (int)(v) < 4096)
  87
  88 /*
  89  * Return the instruction to jump from code to target, 0 if not
  90  * reachable with a single instruction
  91  */
  92 static guint32
  93 branch_for_target_reachable (guint8 *branch, guint8 *target)
  94 {
  95         gint diff = target - branch - 8;
  96         g_assert ((diff & 3) == 0);
  97         if (diff >= 0) {
  98                 if (diff <= 33554431)
  99                         return (ARMCOND_AL << ARMCOND_SHIFT) | (ARM_BR_TAG) | (diff >> 2);
 100         } else {
 101                 /* diff between 0 and -33554432 */
 102                 if (diff >= -33554432)
 103                         return (ARMCOND_AL << ARMCOND_SHIFT) | (ARM_BR_TAG) | ((diff >> 2) & ~0xff000000);
 104         }
 105         return 0;
 106 }
 107
 108 static inline guint8*
 109 emit_bx (guint8* code, int reg)
 110 {
 111         if (mono_arm_thumb_supported ())
 112                 ARM_BX (code, reg);
 113         else
 114                 ARM_MOV_REG_REG (code, ARMREG_PC, reg);
 115         return code;
 116 }
 117
 118 /* Stack size for trampoline function
 119  */
 120 #define STACK (sizeof (MonoLMF))
 121
 122 /* Method-specific trampoline code fragment size */
 123 #define METHOD_TRAMPOLINE_SIZE 64
 124
 125 /* Jump-specific trampoline code fragment size */
 126 #define JUMP_TRAMPOLINE_SIZE   64
 127
 128 #define GEN_TRAMP_SIZE 196
 129
 130 guchar*
 131 mono_arch_create_generic_trampoline (MonoTrampolineType tramp_type, MonoTrampInfo **info, gboolean aot)
 132 {
 133         guint8 *buf, *code = NULL;
 134         guint8 *load_get_lmf_addr, *load_trampoline;
 135         gpointer *constants;
 136         int cfa_offset;
 137         GSList *unwind_ops = NULL;
 138         MonoJumpInfo *ji = NULL;
 139
 140         /* Now we'll create in 'buf' the ARM trampoline code. This
 141          is the trampoline code common to all methods  */
 142
 143         code = buf = mono_global_codeman_reserve (GEN_TRAMP_SIZE);
 144
 145         /*
 146          * At this point lr points to the specific arg and sp points to the saved
 147          * regs on the stack (all but PC and SP). The original LR value has been
 148          * saved as sp + LR_OFFSET by the push in the specific trampoline
 149          */
 150 #define LR_OFFSET (sizeof (gpointer) * 13)
 151
 152         // FIXME: Finish the unwind info, the current info allows us to unwind
 153         // when the trampoline is not in the epilog
 154
 155         // CFA = SP + (num registers pushed) * 4
 156         cfa_offset = 14 * sizeof (gpointer);
 157         mono_add_unwind_op_def_cfa (unwind_ops, code, buf, ARMREG_SP, cfa_offset);
 158         // PC saved at sp+LR_OFFSET
 159         mono_add_unwind_op_offset (unwind_ops, code, buf, ARMREG_LR, -4);
 160
 161         ARM_MOV_REG_REG (code, ARMREG_V1, ARMREG_SP);
 162         if (aot && tramp_type != MONO_TRAMPOLINE_GENERIC_CLASS_INIT) {
 163                 /*
 164                  * The trampoline contains a pc-relative offset to the got slot
 165                  * preceeding the got slot where the value is stored. The offset can be
 166                  * found at [lr + 0].
 167                  */
 168                 ARM_LDR_IMM (code, ARMREG_V2, ARMREG_LR, 0);
 169                 ARM_ADD_REG_IMM (code, ARMREG_V2, ARMREG_V2, 4, 0);
 170                 ARM_LDR_REG_REG (code, ARMREG_V2, ARMREG_V2, ARMREG_LR);
 171         } else {
 172                 if (tramp_type != MONO_TRAMPOLINE_GENERIC_CLASS_INIT)
 173                         ARM_LDR_IMM (code, ARMREG_V2, ARMREG_LR, 0);
 174                 else
 175                         ARM_MOV_REG_REG (code, ARMREG_V2, MONO_ARCH_VTABLE_REG);
 176         }
 177         ARM_LDR_IMM (code, ARMREG_V3, ARMREG_SP, LR_OFFSET);
 178
 179         /* ok, now we can continue with the MonoLMF setup, mostly untouched
 180          * from emit_prolog in mini-arm.c
 181          * This is a synthetized call to mono_get_lmf_addr ()
 182          */
 183         if (aot) {
 184                 ji = mono_patch_info_list_prepend (ji, code - buf, MONO_PATCH_INFO_JIT_ICALL_ADDR, "mono_get_lmf_addr");
 185                 ARM_LDR_IMM (code, ARMREG_R0, ARMREG_PC, 0);
 186                 ARM_B (code, 0);
 187                 *(gpointer*)code = NULL;
 188                 code += 4;
 189                 ARM_LDR_REG_REG (code, ARMREG_R0, ARMREG_PC, ARMREG_R0);
 190         } else {
 191                 load_get_lmf_addr = code;
 192                 code += 4;
 193         }
 194         ARM_MOV_REG_REG (code, ARMREG_LR, ARMREG_PC);
 195         code = emit_bx (code, ARMREG_R0);
 196
 197         /* we build the MonoLMF structure on the stack - see mini-arm.h
 198          * The pointer to the struct is put in r1.
 199          * the iregs array is already allocated on the stack by push.
 200          */
 201         ARM_SUB_REG_IMM8 (code, ARMREG_SP, ARMREG_SP, sizeof (MonoLMF) - sizeof (guint) * 14);
 202         cfa_offset += sizeof (MonoLMF) - sizeof (guint) * 14;
 203         mono_add_unwind_op_def_cfa_offset (unwind_ops, code, buf, cfa_offset);
 204         ARM_ADD_REG_IMM8 (code, ARMREG_R1, ARMREG_SP, STACK - sizeof (MonoLMF));
 205         /* r0 is the result from mono_get_lmf_addr () */
 206         ARM_STR_IMM (code, ARMREG_R0, ARMREG_R1, G_STRUCT_OFFSET (MonoLMF, lmf_addr));
 207         /* new_lmf->previous_lmf = *lmf_addr */
 208         ARM_LDR_IMM (code, ARMREG_R2, ARMREG_R0, G_STRUCT_OFFSET (MonoLMF, previous_lmf));
 209         ARM_STR_IMM (code, ARMREG_R2, ARMREG_R1, G_STRUCT_OFFSET (MonoLMF, previous_lmf));
 210         /* *(lmf_addr) = r1 */
 211         ARM_STR_IMM (code, ARMREG_R1, ARMREG_R0, G_STRUCT_OFFSET (MonoLMF, previous_lmf));
 212         /* save method info (it's in v2) */
 213         if ((tramp_type == MONO_TRAMPOLINE_JIT) || (tramp_type == MONO_TRAMPOLINE_JUMP))
 214                 ARM_STR_IMM (code, ARMREG_V2, ARMREG_R1, G_STRUCT_OFFSET (MonoLMF, method));
 215         else {
 216                 ARM_MOV_REG_IMM8 (code, ARMREG_R2, 0);
 217                 ARM_STR_IMM (code, ARMREG_R2, ARMREG_R1, G_STRUCT_OFFSET (MonoLMF, method));
 218         }
 219         ARM_STR_IMM (code, ARMREG_SP, ARMREG_R1, G_STRUCT_OFFSET (MonoLMF, ebp));
 220         /* save the IP (caller ip) */
 221         if (tramp_type == MONO_TRAMPOLINE_JUMP) {
 222                 ARM_MOV_REG_IMM8 (code, ARMREG_R2, 0);
 223         } else {
 224                 /* assumes STACK == sizeof (MonoLMF) */
 225                 ARM_LDR_IMM (code, ARMREG_R2, ARMREG_SP, (G_STRUCT_OFFSET (MonoLMF, iregs) + 13*4));
 226         }
 227         ARM_STR_IMM (code, ARMREG_R2, ARMREG_R1, G_STRUCT_OFFSET (MonoLMF, eip));
 228
 229         /*
 230          * Now we're ready to call xxx_trampoline ().
 231          */
 232         /* Arg 1: the saved registers. It was put in v1 */
 233         ARM_MOV_REG_REG (code, ARMREG_R0, ARMREG_V1);
 234
 235         /* Arg 2: code (next address to the instruction that called us) */
 236         if (tramp_type == MONO_TRAMPOLINE_JUMP) {
 237                 ARM_MOV_REG_IMM8 (code, ARMREG_R1, 0);
 238         } else {
 239                 ARM_MOV_REG_REG (code, ARMREG_R1, ARMREG_V3);
 240         }
 241
 242         /* Arg 3: the specific argument, stored in v2
 243          */
 244         ARM_MOV_REG_REG (code, ARMREG_R2, ARMREG_V2);
 245
 246         if (aot) {
 247                 char *icall_name = g_strdup_printf ("trampoline_func_%d", tramp_type);
 248                 ji = mono_patch_info_list_prepend (ji, code - buf, MONO_PATCH_INFO_JIT_ICALL_ADDR, icall_name);
 249                 ARM_LDR_IMM (code, ARMREG_IP, ARMREG_PC, 0);
 250                 ARM_B (code, 0);
 251                 *(gpointer*)code = NULL;
 252                 code += 4;
 253                 ARM_LDR_REG_REG (code, ARMREG_IP, ARMREG_PC, ARMREG_IP);
 254         } else {
 255                 load_trampoline = code;
 256                 code += 4;
 257         }
 258
 259         ARM_MOV_REG_REG (code, ARMREG_LR, ARMREG_PC);
 260         code = emit_bx (code, ARMREG_IP);
 261
 262         /* OK, code address is now on r0. Move it to the place on the stack
 263          * where IP was saved (it is now no more useful to us and it can be
 264          * clobbered). This way we can just restore all the regs in one inst
 265          * and branch to IP.
 266          */
 267         ARM_STR_IMM (code, ARMREG_R0, ARMREG_V1, (ARMREG_R12 * 4));
 268
 269         /* Check for thread interruption */
 270         /* This is not perf critical code so no need to check the interrupt flag */
 271         /*
 272          * Have to call the _force_ variant, since there could be a protected wrapper on the top of the stack.
 273          */
 274         if (aot) {
 275                 ji = mono_patch_info_list_prepend (ji, code - buf, MONO_PATCH_INFO_JIT_ICALL_ADDR, "mono_thread_force_interruption_checkpoint");
 276                 ARM_LDR_IMM (code, ARMREG_IP, ARMREG_PC, 0);
 277                 ARM_B (code, 0);
 278                 *(gpointer*)code = NULL;
 279                 code += 4;
 280                 ARM_LDR_REG_REG (code, ARMREG_IP, ARMREG_PC, ARMREG_IP);
 281         } else {
 282                 ARM_LDR_IMM (code, ARMREG_IP, ARMREG_PC, 0);
 283                 ARM_B (code, 0);
 284                 *(gpointer*)code = mono_thread_force_interruption_checkpoint;
 285                 code += 4;
 286         }
 287         ARM_MOV_REG_REG (code, ARMREG_LR, ARMREG_PC);
 288         code = emit_bx (code, ARMREG_IP);
 289
 290         /*
 291          * Now we restore the MonoLMF (see emit_epilogue in mini-arm.c)
 292          * and the rest of the registers, so the method called will see
 293          * the same state as before we executed.
 294          * The pointer to MonoLMF is in r2.
 295          */
 296         ARM_MOV_REG_REG (code, ARMREG_R2, ARMREG_SP);
 297         /* ip = previous_lmf */
 298         ARM_LDR_IMM (code, ARMREG_IP, ARMREG_R2, G_STRUCT_OFFSET (MonoLMF, previous_lmf));
 299         /* lr = lmf_addr */
 300         ARM_LDR_IMM (code, ARMREG_LR, ARMREG_R2, G_STRUCT_OFFSET (MonoLMF, lmf_addr));
 301         /* *(lmf_addr) = previous_lmf */
 302         ARM_STR_IMM (code, ARMREG_IP, ARMREG_LR, G_STRUCT_OFFSET (MonoLMF, previous_lmf));
 303
 304         /* Non-standard function epilogue. Instead of doing a proper
 305          * return, we just jump to the compiled code.
 306          */
 307         /* Restore the registers and jump to the code:
 308          * Note that IP has been conveniently set to the method addr.
 309          */
 310         ARM_ADD_REG_IMM8 (code, ARMREG_SP, ARMREG_SP, sizeof (MonoLMF) - sizeof (guint) * 14);
 311         ARM_POP_NWB (code, 0x5fff);
 312         if (tramp_type == MONO_TRAMPOLINE_RGCTX_LAZY_FETCH)
 313                 ARM_MOV_REG_REG (code, ARMREG_R0, ARMREG_IP);
 314         /* do we need to set sp? */
 315         ARM_ADD_REG_IMM8 (code, ARMREG_SP, ARMREG_SP, (14 * 4));
 316         if ((tramp_type == MONO_TRAMPOLINE_CLASS_INIT) || (tramp_type == MONO_TRAMPOLINE_GENERIC_CLASS_INIT) || (tramp_type == MONO_TRAMPOLINE_RGCTX_LAZY_FETCH))
 317                 code = emit_bx (code, ARMREG_LR);
 318         else
 319                 code = emit_bx (code, ARMREG_IP);
 320
 321         constants = (gpointer*)code;
 322         constants [0] = mono_get_lmf_addr;
 323         constants [1] = (gpointer)mono_get_trampoline_func (tramp_type);
 324
 325         if (!aot) {
 326                 /* backpatch by emitting the missing instructions skipped above */
 327                 ARM_LDR_IMM (load_get_lmf_addr, ARMREG_R0, ARMREG_PC, (code - load_get_lmf_addr - 8));
 328                 ARM_LDR_IMM (load_trampoline, ARMREG_IP, ARMREG_PC, (code + 4 - load_trampoline - 8));
 329         }
 330
 331         code += 8;
 332
 333         /* Flush instruction cache, since we've generated code */
 334         mono_arch_flush_icache (buf, code - buf);
 335
 336         /* Sanity check */
 337         g_assert ((code - buf) <= GEN_TRAMP_SIZE);
 338
 339         if (tramp_type == MONO_TRAMPOLINE_CLASS_INIT)
 340                 /* Initialize the nullified class init trampoline used in the AOT case */
 341                 nullified_class_init_trampoline = mono_arch_get_nullified_class_init_trampoline (NULL);
 342
 343         if (info)
 344                 *info = mono_tramp_info_create (g_strdup_printf ("generic_trampoline_%d", tramp_type), buf, code - buf, ji, unwind_ops);
 345
 346         return buf;
 347 }
 348
 349 gpointer
 350 mono_arch_get_nullified_class_init_trampoline (MonoTrampInfo **info)
 351 {
 352         guint8 *buf, *code;
 353
 354         code = buf = mono_global_codeman_reserve (16);
 355
 356         code = emit_bx (code, ARMREG_LR);
 357
 358         mono_arch_flush_icache (buf, code - buf);
 359
 360         if (info)
 361                 *info = mono_tramp_info_create (g_strdup_printf ("nullified_class_init_trampoline"), buf, code - buf, NULL, NULL);
 362
 363         return buf;
 364 }
 365
 366 #define SPEC_TRAMP_SIZE 24
 367
 368 gpointer
 369 mono_arch_create_specific_trampoline (gpointer arg1, MonoTrampolineType tramp_type, MonoDomain *domain, guint32 *code_len)
 370 {
 371         guint8 *code, *buf, *tramp;
 372         gpointer *constants;
 373         guint32 short_branch, size = SPEC_TRAMP_SIZE;
 374
 375         tramp = mono_get_trampoline_code (tramp_type);
 376
 377         mono_domain_lock (domain);
 378         code = buf = mono_domain_code_reserve_align (domain, size, 4);
 379         if ((short_branch = branch_for_target_reachable (code + 8, tramp))) {
 380                 size = 12;
 381                 mono_domain_code_commit (domain, code, SPEC_TRAMP_SIZE, size);
 382         }
 383         mono_domain_unlock (domain);
 384
 385         /* we could reduce this to 12 bytes if tramp is within reach:
 386          * ARM_PUSH ()
 387          * ARM_BL ()
 388          * method-literal
 389          * The called code can access method using the lr register
 390          * A 20 byte sequence could be:
 391          * ARM_PUSH ()
 392          * ARM_MOV_REG_REG (lr, pc)
 393          * ARM_LDR_IMM (pc, pc, 0)
 394          * method-literal
 395          * tramp-literal
 396          */
 397         /* We save all the registers, except PC and SP */
 398         ARM_PUSH (code, 0x5fff);
 399         if (short_branch) {
 400                 constants = (gpointer*)code;
 401                 constants [0] = GUINT_TO_POINTER (short_branch | (1 << 24));
 402                 constants [1] = arg1;
 403                 code += 8;
 404         } else {
 405                 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_PC, 8); /* temp reg */
 406                 ARM_MOV_REG_REG (code, ARMREG_LR, ARMREG_PC);
 407                 code = emit_bx (code, ARMREG_R1);
 408
 409                 constants = (gpointer*)code;
 410                 constants [0] = arg1;
 411                 constants [1] = tramp;
 412                 code += 8;
 413         }
 414
 415         /* Flush instruction cache, since we've generated code */
 416         mono_arch_flush_icache (buf, code - buf);
 417
 418         g_assert ((code - buf) <= size);
 419
 420         if (code_len)
 421                 *code_len = code - buf;
 422
 423         return buf;
 424 }
 425
 426 /*
 427  * mono_arch_get_unbox_trampoline:
 428  * @gsctx: the generic sharing context
 429  * @m: method pointer
 430  * @addr: pointer to native code for @m
 431  *
 432  * when value type methods are called through the vtable we need to unbox the
 433  * this argument. This method returns a pointer to a trampoline which does
 434  * unboxing before calling the method
 435  */
 436 gpointer
 437 mono_arch_get_unbox_trampoline (MonoGenericSharingContext *gsctx, MonoMethod *m, gpointer addr)
 438 {
 439         guint8 *code, *start;
 440         int this_pos = 0;
 441         MonoDomain *domain = mono_domain_get ();
 442
 443         if (MONO_TYPE_ISSTRUCT (mono_method_signature (m)->ret))
 444                 this_pos = 1;
 445
 446         start = code = mono_domain_code_reserve (domain, 16);
 447
 448         ARM_LDR_IMM (code, ARMREG_IP, ARMREG_PC, 4);
 449         ARM_ADD_REG_IMM8 (code, this_pos, this_pos, sizeof (MonoObject));
 450         code = emit_bx (code, ARMREG_IP);
 451         *(guint32*)code = (guint32)addr;
 452         code += 4;
 453         mono_arch_flush_icache (start, code - start);
 454         g_assert ((code - start) <= 16);
 455         /*g_print ("unbox trampoline at %d for %s:%s\n", this_pos, m->klass->name, m->name);
 456         g_print ("unbox code is at %p for method at %p\n", start, addr);*/
 457
 458         return start;
 459 }
 460
 461 gpointer
 462 mono_arch_get_static_rgctx_trampoline (MonoMethod *m, MonoMethodRuntimeGenericContext *mrgctx, gpointer addr)
 463 {
 464         guint8 *code, *start;
 465         int buf_len;
 466
 467         MonoDomain *domain = mono_domain_get ();
 468
 469         buf_len = 16;
 470
 471         start = code = mono_domain_code_reserve (domain, buf_len);
 472
 473         ARM_LDR_IMM (code, MONO_ARCH_RGCTX_REG, ARMREG_PC, 0);
 474         ARM_LDR_IMM (code, ARMREG_PC, ARMREG_PC, 0);
 475         *(guint32*)code = (guint32)mrgctx;
 476         code += 4;
 477         *(guint32*)code = (guint32)addr;
 478         code += 4;
 479
 480         g_assert ((code - start) <= buf_len);
 481
 482         mono_arch_flush_icache (start, code - start);
 483
 484         return start;
 485 }
 486
 487 gpointer
 488 mono_arch_create_rgctx_lazy_fetch_trampoline (guint32 slot, MonoTrampInfo **info, gboolean aot)
 489 {
 490         guint8 *tramp;
 491         guint8 *code, *buf;
 492         int tramp_size;
 493         guint32 code_len;
 494         guint8 **rgctx_null_jumps;
 495         int depth, index;
 496         int i, njumps;
 497         gboolean mrgctx;
 498         MonoJumpInfo *ji = NULL;
 499         GSList *unwind_ops = NULL;
 500
 501         mrgctx = MONO_RGCTX_SLOT_IS_MRGCTX (slot);
 502         index = MONO_RGCTX_SLOT_INDEX (slot);
 503         if (mrgctx)
 504                 index += MONO_SIZEOF_METHOD_RUNTIME_GENERIC_CONTEXT / sizeof (gpointer);
 505         for (depth = 0; ; ++depth) {
 506                 int size = mono_class_rgctx_get_array_size (depth, mrgctx);
 507
 508                 if (index < size - 1)
 509                         break;
 510                 index -= size - 1;
 511         }
 512
 513         tramp_size = 64 + 16 * depth;
 514
 515         code = buf = mono_global_codeman_reserve (tramp_size);
 516
 517         rgctx_null_jumps = g_malloc (sizeof (guint8*) * (depth + 2));
 518         njumps = 0;
 519
 520         /* The vtable/mrgctx is in R0 */
 521         g_assert (MONO_ARCH_VTABLE_REG == ARMREG_R0);
 522
 523         if (mrgctx) {
 524                 /* get mrgctx ptr */
 525                 ARM_MOV_REG_REG (code, ARMREG_R1, ARMREG_R0);
 526         } else {
 527                 /* load rgctx ptr from vtable */
 528                 g_assert (arm_is_imm12 (G_STRUCT_OFFSET (MonoVTable, runtime_generic_context)));
 529                 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_R0, G_STRUCT_OFFSET (MonoVTable, runtime_generic_context));
 530                 /* is the rgctx ptr null? */
 531                 ARM_CMP_REG_IMM (code, ARMREG_R1, 0, 0);
 532                 /* if yes, jump to actual trampoline */
 533                 rgctx_null_jumps [njumps ++] = code;
 534                 ARM_B_COND (code, ARMCOND_EQ, 0);
 535         }
 536
 537         for (i = 0; i < depth; ++i) {
 538                 /* load ptr to next array */
 539                 if (mrgctx && i == 0) {
 540                         g_assert (arm_is_imm12 (MONO_SIZEOF_METHOD_RUNTIME_GENERIC_CONTEXT));
 541                         ARM_LDR_IMM (code, ARMREG_R1, ARMREG_R1, MONO_SIZEOF_METHOD_RUNTIME_GENERIC_CONTEXT);
 542                 } else {
 543                         ARM_LDR_IMM (code, ARMREG_R1, ARMREG_R1, 0);
 544                 }
 545                 /* is the ptr null? */
 546                 ARM_CMP_REG_IMM (code, ARMREG_R1, 0, 0);
 547                 /* if yes, jump to actual trampoline */
 548                 rgctx_null_jumps [njumps ++] = code;
 549                 ARM_B_COND (code, ARMCOND_EQ, 0);
 550         }
 551
 552         /* fetch slot */
 553         code = mono_arm_emit_load_imm (code, ARMREG_R2, sizeof (gpointer) * (index + 1));
 554         ARM_LDR_REG_REG (code, ARMREG_R1, ARMREG_R1, ARMREG_R2);
 555         /* is the slot null? */
 556         ARM_CMP_REG_IMM (code, ARMREG_R1, 0, 0);
 557         /* if yes, jump to actual trampoline */
 558         rgctx_null_jumps [njumps ++] = code;
 559         ARM_B_COND (code, ARMCOND_EQ, 0);
 560         /* otherwise return, result is in R1 */
 561         ARM_MOV_REG_REG (code, ARMREG_R0, ARMREG_R1);
 562         code = emit_bx (code, ARMREG_LR);
 563
 564         g_assert (njumps <= depth + 2);
 565         for (i = 0; i < njumps; ++i)
 566                 arm_patch (rgctx_null_jumps [i], code);
 567
 568         g_free (rgctx_null_jumps);
 569
 570         /* Slowpath */
 571
 572         /* The vtable/mrgctx is still in R0 */
 573
 574         if (aot) {
 575                 ji = mono_patch_info_list_prepend (ji, code - buf, MONO_PATCH_INFO_JIT_ICALL_ADDR, g_strdup_printf ("specific_trampoline_lazy_fetch_%u", slot));
 576                 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_PC, 0);
 577                 ARM_B (code, 0);
 578                 *(gpointer*)code = NULL;
 579                 code += 4;
 580                 ARM_LDR_REG_REG (code, ARMREG_PC, ARMREG_PC, ARMREG_R1);
 581         } else {
 582                 tramp = mono_arch_create_specific_trampoline (GUINT_TO_POINTER (slot), MONO_TRAMPOLINE_RGCTX_LAZY_FETCH, mono_get_root_domain (), &code_len);
 583
 584                 /* Jump to the actual trampoline */
 585                 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_PC, 0); /* temp reg */
 586                 code = emit_bx (code, ARMREG_R1);
 587                 *(gpointer*)code = tramp;
 588                 code += 4;
 589         }
 590
 591         mono_arch_flush_icache (buf, code - buf);
 592
 593         g_assert (code - buf <= tramp_size);
 594
 595         if (info)
 596                 *info = mono_tramp_info_create (g_strdup_printf ("rgctx_fetch_trampoline_%u", slot), buf, code - buf, ji, unwind_ops);
 597
 598         return buf;
 599 }
 600
 601 #define arm_is_imm8(v) ((v) > -256 && (v) < 256)
 602
 603 gpointer
 604 mono_arch_create_generic_class_init_trampoline (MonoTrampInfo **info, gboolean aot)
 605 {
 606         guint8 *tramp;
 607         guint8 *code, *buf;
 608         static int byte_offset = -1;
 609         static guint8 bitmask;
 610         guint8 *jump;
 611         int tramp_size;
 612         guint32 code_len, imm8;
 613         gint rot_amount;
 614         GSList *unwind_ops = NULL;
 615         MonoJumpInfo *ji = NULL;
 616
 617         tramp_size = 64;
 618
 619         code = buf = mono_global_codeman_reserve (tramp_size);
 620
 621         if (byte_offset < 0)
 622                 mono_marshal_find_bitfield_offset (MonoVTable, initialized, &byte_offset, &bitmask);
 623
 624         g_assert (arm_is_imm8 (byte_offset));
 625         ARM_LDRSB_IMM (code, ARMREG_IP, MONO_ARCH_VTABLE_REG, byte_offset);
 626         imm8 = mono_arm_is_rotated_imm8 (bitmask, &rot_amount);
 627         g_assert (imm8 >= 0);
 628         ARM_AND_REG_IMM (code, ARMREG_IP, ARMREG_IP, imm8, rot_amount);
 629         ARM_CMP_REG_IMM (code, ARMREG_IP, 0, 0);
 630         jump = code;
 631         ARM_B_COND (code, ARMCOND_EQ, 0);
 632
 633         /* Initialized case */
 634         ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_LR);
 635
 636         /* Uninitialized case */
 637         arm_patch (jump, code);
 638
 639         if (aot) {
 640                 ji = mono_patch_info_list_prepend (ji, code - buf, MONO_PATCH_INFO_JIT_ICALL_ADDR, "specific_trampoline_generic_class_init");
 641                 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_PC, 0);
 642                 ARM_B (code, 0);
 643                 *(gpointer*)code = NULL;
 644                 code += 4;
 645                 ARM_LDR_REG_REG (code, ARMREG_PC, ARMREG_PC, ARMREG_R1);
 646         } else {
 647                 tramp = mono_arch_create_specific_trampoline (NULL, MONO_TRAMPOLINE_GENERIC_CLASS_INIT, mono_get_root_domain (), &code_len);
 648
 649                 /* Jump to the actual trampoline */
 650                 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_PC, 0); /* temp reg */
 651                 code = emit_bx (code, ARMREG_R1);
 652                 *(gpointer*)code = tramp;
 653                 code += 4;
 654         }
 655
 656         mono_arch_flush_icache (buf, code - buf);
 657
 658         g_assert (code - buf <= tramp_size);
 659
 660         if (info)
 661                 *info = mono_tramp_info_create (g_strdup_printf ("generic_class_init_trampoline"), buf, code - buf, ji, unwind_ops);
 662
 663         return buf;
 664 }
 665
 666 #else
 667
 668 guchar*
 669 mono_arch_create_generic_trampoline (MonoTrampolineType tramp_type, MonoTrampInfo **info, gboolean aot)
 670 {
 671         g_assert_not_reached ();
 672         return NULL;
 673 }
 674
 675 gpointer
 676 mono_arch_create_specific_trampoline (gpointer arg1, MonoTrampolineType tramp_type, MonoDomain *domain, guint32 *code_len)
 677 {
 678         g_assert_not_reached ();
 679         return NULL;
 680 }
 681
 682 gpointer
 683 mono_arch_get_unbox_trampoline (MonoGenericSharingContext *gsctx, MonoMethod *m, gpointer addr)
 684 {
 685         g_assert_not_reached ();
 686         return NULL;
 687 }
 688
 689 gpointer
 690 mono_arch_get_static_rgctx_trampoline (MonoMethod *m, MonoMethodRuntimeGenericContext *mrgctx, gpointer addr)
 691 {
 692         g_assert_not_reached ();
 693         return NULL;
 694 }
 695
 696 gpointer
 697 mono_arch_create_rgctx_lazy_fetch_trampoline (guint32 slot, MonoTrampInfo **info, gboolean aot)
 698 {
 699         g_assert_not_reached ();
 700         return NULL;
 701 }
 702
 703 gpointer
 704 mono_arch_create_generic_class_init_trampoline (MonoTrampInfo **info, gboolean aot)
 705 {
 706         g_assert_not_reached ();
 707         return NULL;
 708 }
 709
 710 #endif /* DISABLE_JIT */
 711
 712 guint8*
 713 mono_arch_get_call_target (guint8 *code)
 714 {
 715         guint32 ins = ((guint32*)(gpointer)code) [-1];
 716
 717         /* Should be a 'bl' */
 718         if ((((ins >> 25) & 0x7) == 0x5) && (((ins >> 24) & 0x1) == 0x1)) {
 719                 gint32 disp = ((gint32)ins) & 0xffffff;
 720                 guint8 *target = code - 4 + 8 + (disp * 4);
 721
 722                 return target;
 723         } else {
 724                 return NULL;
 725         }
 726 }
 727
 728 guint32
 729 mono_arch_get_plt_info_offset (guint8 *plt_entry, mgreg_t *regs, guint8 *code)
 730 {
 731         /* The offset is stored as the 4th word of the plt entry */
 732         return ((guint32*)plt_entry) [3];
 733 }