src/runtime/ppc-arch.c

   1 /*
   2  * This software is part of the SBCL system. See the README file for
   3  * more information.
   4  *
   5  * This software is derived from the CMU CL system, which was
   6  * written at Carnegie Mellon University and released into the
   7  * public domain. The software is in the public domain and is
   8  * provided with absolutely no warranty. See the COPYING and CREDITS
   9  * files for more information.
  10  */
  11
  12 #include <stdio.h>
  13
  14 #include "sbcl.h"
  15 #include "arch.h"
  16 #include "globals.h"
  17 #include "validate.h"
  18 #include "os.h"
  19 #include "interrupt.h"
  20 #include "lispregs.h"
  21 #include "signal.h"
  22 #include "interrupt.h"
  23 #include "interr.h"
  24 #include "breakpoint.h"
  25 #include "alloc.h"
  26
  27 #if defined(LISP_FEATURE_GENCGC)
  28 #include "gencgc-alloc-region.h"
  29 #endif
  30
  31 #ifdef LISP_FEATURE_SB_THREAD
  32 #include "pseudo-atomic.h"
  33 #endif
  34
  35   /* The header files may not define PT_DAR/PT_DSISR.  This definition
  36      is correct for all versions of ppc linux >= 2.0.30
  37
  38      As of DR2.1u4, MkLinux doesn't pass these registers to signal
  39      handlers correctly; a patch is necessary in order to (partially)
  40      correct this.
  41
  42      Even with the patch, the DSISR may not have its 'write' bit set
  43      correctly (it tends not to be set if the fault was caused by
  44      something other than a protection violation.)
  45
  46      Caveat callers.  */
  47
  48 #if defined (LISP_FEATURE_DARWIN) || defined(LISP_FEATURE_LINUX)
  49 #ifndef PT_DAR
  50 #define PT_DAR          41
  51 #endif
  52
  53 #ifndef PT_DSISR
  54 #define PT_DSISR        42
  55 #endif
  56 #endif
  57
  58 /* Magic encoding for the instruction used for traps. */
  59 #define TRAP_INSTRUCTION(trap) ((3<<26) | (6 << 21) | (trap))
  60
  61 void arch_init() {
  62 }
  63
  64 os_vm_address_t
  65 arch_get_bad_addr(int sig, siginfo_t *code, os_context_t *context)
  66 {
  67     os_vm_address_t addr;
  68
  69 #if defined(LISP_FEATURE_NETBSD) || defined(LISP_FEATURE_OPENBSD)
  70     addr = (os_vm_address_t) (code->si_addr);
  71 #else
  72     addr = (os_vm_address_t) (*os_context_register_addr(context,PT_DAR));
  73 #endif
  74     return addr;
  75 }
  76
  77
  78 void
  79 arch_skip_instruction(os_context_t *context)
  80 {
  81     char** pcptr;
  82     pcptr = (char**) os_context_pc_addr(context);
  83     *pcptr += 4;
  84 }
  85
  86 unsigned char *
  87 arch_internal_error_arguments(os_context_t *context)
  88 {
  89     return (unsigned char *)(*os_context_pc_addr(context)+4);
  90 }
  91
  92
  93 boolean
  94 arch_pseudo_atomic_atomic(os_context_t *context)
  95 {
  96 #ifdef LISP_FEATURE_SB_THREAD
  97     struct thread *thread = arch_os_get_current_thread();
  98
  99     if (foreign_function_call_active_p(thread)) {
 100         return get_pseudo_atomic_atomic(thread);
 101     } else return
 102 #else
 103     /* FIXME: this foreign_function_call_active test is dubious at
 104      * best. If a foreign call is made in a pseudo atomic section
 105      * (?) or more likely a pseudo atomic section is in a foreign
 106      * call then an interrupt is executed immediately. Maybe it
 107      * has to do with C code not maintaining pseudo atomic
 108      * properly. MG - 2005-08-10
 109      *
 110      * The foreign_function_call_active used to live at each call-site
 111      * to arch_pseudo_atomic_atomic, but this seems clearer.
 112      * --NS 2007-05-15 */
 113     return (!foreign_function_call_active_p(arch_os_get_current_thread())) &&
 114 #endif
 115         ((*os_context_register_addr(context,reg_ALLOC)) & flag_PseudoAtomic);
 116 }
 117
 118 void
 119 arch_set_pseudo_atomic_interrupted(os_context_t *context)
 120 {
 121 #ifdef LISP_FEATURE_SB_THREAD
 122     struct thread *thread = arch_os_get_current_thread();
 123
 124     if (foreign_function_call_active_p(thread)) {
 125         set_pseudo_atomic_interrupted(thread);
 126     } else
 127 #endif
 128         *os_context_register_addr(context,reg_ALLOC)
 129             |= flag_PseudoAtomicInterrupted;
 130 }
 131
 132 void
 133 arch_clear_pseudo_atomic_interrupted(os_context_t *context)
 134 {
 135 #ifdef LISP_FEATURE_SB_THREAD
 136     struct thread *thread = arch_os_get_current_thread();
 137
 138     if (foreign_function_call_active_p(thread)) {
 139         clear_pseudo_atomic_interrupted(thread);
 140     } else
 141 #endif
 142         *os_context_register_addr(context,reg_ALLOC)
 143             &= ~flag_PseudoAtomicInterrupted;
 144 }
 145
 146 unsigned int
 147 arch_install_breakpoint(void *pc)
 148 {
 149     unsigned int *ptr = (unsigned int *)pc;
 150     unsigned int result = *ptr;
 151     *ptr = TRAP_INSTRUCTION(trap_Breakpoint);
 152     os_flush_icache((os_vm_address_t) pc, sizeof(unsigned int));
 153     return result;
 154 }
 155
 156 void
 157 arch_remove_breakpoint(void *pc, unsigned int orig_inst)
 158 {
 159     *(unsigned int *)pc = orig_inst;
 160     os_flush_icache((os_vm_address_t) pc, sizeof(unsigned int));
 161 }
 162
 163 /*
 164  * Perform the instruction that we overwrote with a breakpoint.  As we
 165  * don't have a single-step facility, this means we have to:
 166  * - put the instruction back
 167  * - put a second breakpoint at the following instruction,
 168  *   set after_breakpoint and continue execution.
 169  *
 170  * When the second breakpoint is hit (very shortly thereafter, we hope)
 171  * sigtrap_handler gets called again, but follows the AfterBreakpoint
 172  * arm, which
 173  * - puts a bpt back in the first breakpoint place (running across a
 174  *   breakpoint shouldn't cause it to be uninstalled)
 175  * - replaces the second bpt with the instruction it was meant to be
 176  * - carries on
 177  *
 178  * Clear?
 179  */
 180 static unsigned int *skipped_break_addr, displaced_after_inst;
 181 static sigset_t orig_sigmask;
 182
 183 static boolean
 184 should_branch(os_context_t *context, unsigned int orig_inst)
 185 {
 186     /* orig_inst is a conditional branch instruction.  We need to
 187      * know if the branch will be taken if executed in context. */
 188     int ctr = *os_context_ctr_addr(context);
 189     int cr = *os_context_cr_addr(context);
 190     int bo_field = (orig_inst >> 21) & 0x1f;
 191     int bi_field = (orig_inst >> 16) & 0x1f;
 192     int ctr_ok;
 193
 194     if (!(bo_field & 4)) ctr--; /* Decrement CTR if necessary. */
 195
 196     ctr_ok = (bo_field & 4) || ((ctr == 0) == ((bo_field & 2) == 2));
 197     return ctr_ok && ((bo_field & 0x10) ||
 198                       !(((cr >> (31-bi_field)) ^ (bo_field >> 3)) & 1));
 199 }
 200
 201 void
 202 arch_do_displaced_inst(os_context_t *context, unsigned int orig_inst)
 203 {
 204     /* not sure how we ensure that we get the breakpoint reinstalled
 205      * after doing this -dan */
 206     unsigned int *pc = (unsigned int *)(*os_context_pc_addr(context));
 207     unsigned int *next_pc;
 208     int op = orig_inst >> 26;
 209     int sub_op = (orig_inst & 0x7fe) >> 1;  /* XL-form sub-opcode */
 210
 211     orig_sigmask = *os_context_sigmask_addr(context);
 212     sigaddset_blockable(os_context_sigmask_addr(context));
 213
 214     *pc = orig_inst;
 215     os_flush_icache((os_vm_address_t) pc, sizeof(unsigned int));
 216     skipped_break_addr = pc;
 217
 218     /* Figure out where we will end up after running the displaced
 219      * instruction by defaulting to the next instruction in the stream
 220      * and then checking for branch instructions.  FIXME: This will
 221      * probably screw up if it attempts to step a trap instruction. */
 222     next_pc = pc + 1;
 223
 224     if (op == 18) {
 225         /* Branch  I-form */
 226         unsigned int displacement = orig_inst & 0x03fffffc;
 227         /* Sign extend */
 228         if (displacement & 0x02000000) {
 229             displacement |= 0xc0000000;
 230         }
 231         if (orig_inst & 2) { /* Absolute Address */
 232             next_pc = (unsigned int *)displacement;
 233         } else {
 234             next_pc = (unsigned int *)(((unsigned int)pc) + displacement);
 235         }
 236     } else if ((op == 16)
 237                && should_branch(context, orig_inst)) {
 238         /* Branch Conditional  B-form */
 239         unsigned int displacement = orig_inst & 0x0000fffc;
 240         /* Sign extend */
 241         if (displacement & 0x00008000) {
 242             displacement |= 0xffff0000;
 243         }
 244         if (orig_inst & 2) { /* Absolute Address */
 245             next_pc = (unsigned int *)displacement;
 246         } else {
 247             next_pc = (unsigned int *)(((unsigned int)pc) + displacement);
 248         }
 249     } else if ((op == 19) && (sub_op == 16)
 250                && should_branch(context, orig_inst)) {
 251         /* Branch Conditional to Link Register  XL-form */
 252         next_pc = (unsigned int *)
 253             ((*os_context_lr_addr(context)) & ~3);
 254     } else if ((op == 19) && (sub_op == 528)
 255                && should_branch(context, orig_inst)) {
 256         /* Branch Conditional to Count Register  XL-form */
 257         next_pc = (unsigned int *)
 258             ((*os_context_ctr_addr(context)) & ~3);
 259     }
 260
 261     /* Set the "after" breakpoint. */
 262     displaced_after_inst = *next_pc;
 263     *next_pc = TRAP_INSTRUCTION(trap_AfterBreakpoint);
 264     os_flush_icache((os_vm_address_t)next_pc, sizeof(unsigned int));
 265 }
 266
 267 #ifdef LISP_FEATURE_GENCGC
 268 /*
 269  * Return non-zero if the current instruction is an allocation trap
 270  */
 271 static int
 272 allocation_trap_p(os_context_t * context)
 273 {
 274     int result;
 275     unsigned int *pc;
 276     unsigned inst;
 277     unsigned opcode;
 278     unsigned src;
 279     unsigned dst;
 280
 281     result = 0;
 282
 283     /*
 284      * First, the instruction has to be a TWLGE temp, NL3, which has the
 285      * format.
 286      * | 6| 5| 5 | 5 | 10|1|  width
 287      * |31|5 |dst|src|  4|0|  field
 288      */
 289     pc = (unsigned int *) (*os_context_pc_addr(context));
 290     inst = *pc;
 291
 292 #if 0
 293     fprintf(stderr, "allocation_trap_p at %p:  inst = 0x%08x\n", pc, inst);
 294 #endif
 295
 296     opcode = inst >> 26;
 297     src = (inst >> 11) & 0x1f;
 298     dst = (inst >> 16) & 0x1f;
 299     if ((opcode == 31) && (src == reg_NL3) && (5 == ((inst >> 21) & 0x1f))
 300         && (4 == ((inst >> 1) & 0x3ff))) {
 301         /*
 302          * We got the instruction.  Now, look back to make sure it was
 303          * proceeded by what we expected.  The previous instruction
 304          * should be an ADD or ADDI instruction.
 305          */
 306         unsigned int add_inst;
 307
 308         add_inst = pc[-1];
 309 #if 0
 310         fprintf(stderr, "   add inst at %p:  inst = 0x%08x\n",
 311                 pc - 1, add_inst);
 312 #endif
 313         opcode = add_inst >> 26;
 314         if ((opcode == 31) && (266 == ((add_inst >> 1) & 0x1ff))) {
 315             return 1;
 316         } else if ((opcode == 14)) {
 317             return 1;
 318         } else {
 319             fprintf(stderr,
 320                     "Whoa! Got allocation trap but could not find ADD or ADDI instruction: 0x%08x in the proper place\n",
 321                     add_inst);
 322         }
 323     }
 324     return 0;
 325 }
 326
 327 extern struct alloc_region boxed_region;
 328
 329 void
 330 handle_allocation_trap(os_context_t * context)
 331 {
 332     unsigned int *pc;
 333     unsigned int inst;
 334     unsigned int target, target_ptr, end_addr;
 335     unsigned int opcode;
 336     int size;
 337     boolean were_in_lisp;
 338     char *memory;
 339
 340     target = 0;
 341     size = 0;
 342
 343 #if 0
 344     fprintf(stderr, "In handle_allocation_trap\n");
 345 #endif
 346
 347     /* I don't think it's possible for us NOT to be in lisp when we get
 348      * here.  Remove this later? */
 349     were_in_lisp = !foreign_function_call_active_p(arch_os_get_current_thread());
 350
 351     if (were_in_lisp) {
 352         fake_foreign_function_call(context);
 353     } else {
 354         fprintf(stderr, "**** Whoa! allocation trap and we weren't in lisp!\n");
 355     }
 356
 357     /*
 358      * Look at current instruction: TWNE temp, NL3. We're here because
 359      * temp > NL3 and temp is the end of the allocation, and NL3 is
 360      * current-region-end-addr.
 361      *
 362      * We need to adjust temp and alloc-tn.
 363      */
 364
 365     pc = (unsigned int *) (*os_context_pc_addr(context));
 366     inst = pc[0];
 367     end_addr = (inst >> 11) & 0x1f;
 368     target = (inst >> 16) & 0x1f;
 369
 370     target_ptr = *os_context_register_addr(context, target);
 371
 372 #if 0
 373     fprintf(stderr, "handle_allocation_trap at %p:\n", pc);
 374     fprintf(stderr, "boxed_region.free_pointer: %p\n", boxed_region.free_pointer);
 375     fprintf(stderr, "boxed_region.end_addr: %p\n", boxed_region.end_addr);
 376     fprintf(stderr, "target reg: %d, end_addr reg: %d\n", target, end_addr);
 377     fprintf(stderr, "target: %x\n", *os_context_register_addr(context, target));
 378     fprintf(stderr, "end_addr: %x\n", *os_context_register_addr(context, end_addr));
 379 #endif
 380
 381 #if 0
 382     fprintf(stderr, "handle_allocation_trap at %p:\n", pc);
 383     fprintf(stderr, "  trap inst = 0x%08x\n", inst);
 384     fprintf(stderr, "  target reg = %s\n", lisp_register_names[target]);
 385 #endif
 386
 387     /*
 388      * Go back and look at the add/addi instruction.  The second src arg
 389      * is the size of the allocation.  Get it and call alloc to allocate
 390      * new space.
 391      */
 392     inst = pc[-1];
 393     opcode = inst >> 26;
 394 #if 0
 395     fprintf(stderr, "  add inst  = 0x%08x, opcode = %d\n", inst, opcode);
 396 #endif
 397     if (opcode == 14) {
 398         /*
 399          * ADDI temp-tn, alloc-tn, size
 400          *
 401          * Extract the size
 402          */
 403         size = (inst & 0xffff);
 404     } else if (opcode == 31) {
 405         /*
 406          * ADD temp-tn, alloc-tn, size-tn
 407          *
 408          * Extract the size
 409          */
 410         int reg;
 411
 412         reg = (inst >> 11) & 0x1f;
 413 #if 0
 414         fprintf(stderr, "  add, reg = %s\n", lisp_register_names[reg]);
 415 #endif
 416         size = *os_context_register_addr(context, reg);
 417
 418     }
 419
 420 #if 0
 421     fprintf(stderr, "Alloc %d to %s\n", size, lisp_register_names[target]);
 422 #endif
 423
 424 #if INLINE_ALLOC_DEBUG
 425     if ((((unsigned long)boxed_region.end_addr + size) / PAGE_SIZE) ==
 426         (((unsigned long)boxed_region.end_addr) / PAGE_SIZE)) {
 427       fprintf(stderr,"*** possibly bogus trap allocation of %d bytes at %p\n",
 428               size, target_ptr);
 429       fprintf(stderr, "    dynamic_space_free_pointer: %p, boxed_region.end_addr %p\n",
 430               dynamic_space_free_pointer, boxed_region.end_addr);
 431     }
 432 #endif
 433
 434 #if 0
 435     fprintf(stderr, "Ready to alloc\n");
 436     fprintf(stderr, "free_pointer = 0x%08x\n",
 437             dynamic_space_free_pointer);
 438 #endif
 439
 440     /*
 441      * alloc-tn was incremented by size.  Need to decrement it by size
 442      * to restore its original value. This is not true on GENCGC
 443      * anymore. d_s_f_p and reg_alloc get out of sync, but the p_a
 444      * bits stay intact and we set it to the proper value when it
 445      * needs to be. Keep this comment here for the moment in case
 446      * somebody tries to figure out what happened here.
 447      */
 448     /*    dynamic_space_free_pointer =
 449         (lispobj *) ((long) dynamic_space_free_pointer - size);
 450     */
 451 #if 0
 452     fprintf(stderr, "free_pointer = 0x%08x new\n",
 453             dynamic_space_free_pointer);
 454 #endif
 455
 456     {
 457         struct interrupt_data *data =
 458             arch_os_get_current_thread()->interrupt_data;
 459         data->allocation_trap_context = context;
 460         memory = (char *) alloc(size);
 461         data->allocation_trap_context = 0;
 462     }
 463
 464 #if 0
 465     fprintf(stderr, "alloc returned %p\n", memory);
 466     fprintf(stderr, "free_pointer = 0x%08x\n",
 467             dynamic_space_free_pointer);
 468 #endif
 469
 470     /*
 471      * The allocation macro wants the result to point to the end of the
 472      * object!
 473      */
 474     memory += size;
 475
 476 #if 0
 477     fprintf(stderr, "object end at %p\n", memory);
 478 #endif
 479
 480     *os_context_register_addr(context, target) = (unsigned long) memory;
 481 #ifndef LISP_FEATURE_SB_THREAD
 482     /* This is handled by the fake_foreign_function_call machinery on
 483      * threaded targets. */
 484     *os_context_register_addr(context, reg_ALLOC) =
 485       (unsigned long) dynamic_space_free_pointer
 486       | (*os_context_register_addr(context, reg_ALLOC)
 487          & LOWTAG_MASK);
 488 #endif
 489
 490     if (were_in_lisp) {
 491         undo_fake_foreign_function_call(context);
 492     }
 493
 494     /* Skip the allocation trap and the write of the updated free
 495      * pointer back to the allocation region.  This is two
 496      * instructions when threading is enabled and four instructions
 497      * otherwise. */
 498 #ifdef LISP_FEATURE_SB_THREAD
 499     (*os_context_pc_addr(context)) = pc + 2;
 500 #else
 501     (*os_context_pc_addr(context)) = pc + 4;
 502 #endif
 503
 504 }
 505 #endif
 506
 507 void
 508 arch_handle_breakpoint(os_context_t *context)
 509 {
 510     handle_breakpoint(context);
 511 }
 512
 513 void
 514 arch_handle_fun_end_breakpoint(os_context_t *context)
 515 {
 516     *os_context_pc_addr(context)
 517         =(int)handle_fun_end_breakpoint(context);
 518 }
 519
 520 void
 521 arch_handle_after_breakpoint(os_context_t *context)
 522 {
 523     *skipped_break_addr = TRAP_INSTRUCTION(trap_Breakpoint);
 524     os_flush_icache((os_vm_address_t) skipped_break_addr,
 525                     sizeof(unsigned int));
 526     skipped_break_addr = NULL;
 527     *(unsigned int *)*os_context_pc_addr(context)
 528         = displaced_after_inst;
 529     *os_context_sigmask_addr(context)= orig_sigmask;
 530     os_flush_icache((os_vm_address_t) *os_context_pc_addr(context),
 531                     sizeof(unsigned int));
 532 }
 533
 534 void
 535 arch_handle_single_step_trap(os_context_t *context, int trap)
 536 {
 537     unsigned int code = *((u32 *)(*os_context_pc_addr(context)));
 538     int register_offset = code >> 5 & 0x1f;
 539     handle_single_step_trap(context, trap, register_offset);
 540     arch_skip_instruction(context);
 541 }
 542
 543 static void
 544 sigtrap_handler(int signal, siginfo_t *siginfo, os_context_t *context)
 545 {
 546     unsigned int code;
 547
 548     code=*((u32 *)(*os_context_pc_addr(context)));
 549     if (code == ((3 << 26) | (0x18 << 21) | (reg_NL3 << 16))) {
 550         arch_clear_pseudo_atomic_interrupted(context);
 551         arch_skip_instruction(context);
 552         /* interrupt or GC was requested in PA; now we're done with the
 553            PA section we may as well get around to it */
 554         interrupt_handle_pending(context);
 555         return;
 556     }
 557
 558 #ifdef LISP_FEATURE_GENCGC
 559     /* Is this an allocation trap? */
 560     if (allocation_trap_p(context)) {
 561         handle_allocation_trap(context);
 562         return;
 563     }
 564 #endif
 565
 566     if ((code >> 16) == ((3 << 10) | (6 << 5))) {
 567         /* twllei reg_ZERO,N will always trap if reg_ZERO = 0 */
 568         int trap = code & 0x1f;
 569         handle_trap(context,trap);
 570         return;
 571     }
 572     if (((code >> 26) == 3) && (((code >> 21) & 31) == 24)) {
 573         interrupt_internal_error(context, 0);
 574         return;
 575     }
 576
 577     interrupt_handle_now(signal, (siginfo_t *)code, context);
 578 }
 579
 580
 581 void arch_install_interrupt_handlers()
 582 {
 583     undoably_install_low_level_interrupt_handler(SIGILL, sigtrap_handler);
 584     undoably_install_low_level_interrupt_handler(SIGTRAP, sigtrap_handler);
 585 }
 586
 587 void
 588 ppc_flush_icache(os_vm_address_t address, os_vm_size_t length)
 589 {
 590   os_vm_address_t end = (os_vm_address_t) ((int)(address+length+(32-1)) &~(32-1));
 591   extern void ppc_flush_cache_line(os_vm_address_t);
 592
 593   while (address < end) {
 594     ppc_flush_cache_line(address);
 595     address += 32;
 596   }
 597 }
 598
 599 #ifdef LISP_FEATURE_LINKAGE_TABLE
 600
 601 /* Linkage tables for PowerPC
 602  *
 603  * Linkage entry size is 16, because we need at least 4 instructions to
 604  * implement a jump.
 605  */
 606
 607 /*
 608  * Define the registers to use in the linkage jump table. Can be the
 609  * same. Some care must be exercised when choosing these. It has to be
 610  * a register that is not otherwise being used. reg_NFP is a good
 611  * choice. call_into_c trashes reg_NFP without preserving it, so we can
 612  * trash it in the linkage jump table.
 613  */
 614 #define LINKAGE_TEMP_REG        reg_NFP
 615 #define LINKAGE_ADDR_REG        reg_NFP
 616
 617 /*
 618  * Insert the necessary jump instructions at the given address.
 619  */
 620 void
 621 arch_write_linkage_table_jmp(void* reloc_addr, void *target_addr)
 622 {
 623   /*
 624    * Make JMP to function entry.
 625    *
 626    * The instruction sequence is:
 627    *
 628    *        addis 13, 0, (hi part of addr)
 629    *        ori   13, 13, (low part of addr)
 630    *        mtctr 13
 631    *        bctr
 632    *
 633    */
 634   int* inst_ptr;
 635   unsigned long hi;                   /* Top 16 bits of address */
 636   unsigned long lo;                   /* Low 16 bits of address */
 637   unsigned int inst;
 638
 639   inst_ptr = (int*) reloc_addr;
 640
 641   /*
 642    * Split the target address into hi and lo parts for the sethi
 643    * instruction.  hi is the top 22 bits.  lo is the low 10 bits.
 644    */
 645   hi = (unsigned long) target_addr;
 646   lo = hi & 0xffff;
 647   hi >>= 16;
 648
 649   /*
 650    * addis 13, 0, (hi part)
 651    */
 652
 653   inst = (15 << 26) | (LINKAGE_TEMP_REG << 21) | (0 << 16) | hi;
 654   *inst_ptr++ = inst;
 655
 656   /*
 657    * ori 13, 13, (lo part)
 658    */
 659
 660   inst = (24 << 26) | (LINKAGE_TEMP_REG << 21) | (LINKAGE_TEMP_REG << 16) | lo;
 661   *inst_ptr++ = inst;
 662
 663   /*
 664    * mtctr 13
 665    */
 666
 667   inst = (31 << 26) | (LINKAGE_TEMP_REG << 21) | (9 << 16) | (467 << 1);
 668   *inst_ptr++ = inst;
 669
 670   /*
 671    * bctr
 672    */
 673
 674   inst = (19 << 26) | (20 << 21) | (528 << 1);
 675   *inst_ptr++ = inst;
 676
 677   os_flush_icache((os_vm_address_t) reloc_addr, (char*) inst_ptr - (char*) reloc_addr);
 678 }
 679
 680 void
 681 arch_write_linkage_table_ref(void * reloc_addr, void *target_addr)
 682 {
 683     *(unsigned long *)reloc_addr = (unsigned long)target_addr;
 684 }
 685
 686 #endif