Changeset 12807


Ignore:
Timestamp:
Sep 10, 2009, 5:06:33 PM (10 years ago)
Author:
rme
Message:

Lisp kernel support for watching objects. Objects in this
context means "uvectors." This works only on x8664 for now.

There's a new UUO, UUO_WATCH_TRAP, which is used to add and remove
watched objects. Watching an object involves creating a new GC
area of type AREA_WATCHED, copying the object to be watched to the
new area, and then scanning all pointer-bearing areas to update
references to the watched object. Unwatching objects is basically
the inverse of this: space is allocated in the heap for the object,
it's copied there from the watched area, the area is condemned, and
pointers to the formerly watched object are updated.

The new functions watch_object() and unwatch_object() in
x86-exception.c handle this UUO. New functions
in x86-gc.c, which in large part duplicate the functionality of
the forward_xxx family of functions, handle updating references
to the watched object. The heap-checking code now also checks
AREA_WATCHED areas.

The function handle_fault() in x86-exceptions.c has been updated to
recognize when a write has been attempted to a watched area.
It passes the watched object and code to the lisp error callback.

MapMemory?() in memory.c was updated not to pass MAP_FIXED to mmap()
if NULL was passed in as the address.

Finally, unrelated to watchpoints, the function imm_word_count()
was added to x86-gc.c, and used in a few places to try to start
cleaning up places in the code marked by /* XXX bootstrapping */
(this is related to the dealing with large functions on x8632).

Location:
trunk/source/lisp-kernel
Files:
4 edited

Legend:

Unmodified
Added
Removed

  • trunk/source/lisp-kernel/memory.c

    r12806 r12807  
    290290  return VirtualAlloc(addr, nbytes, MEM_RESERVE|MEM_COMMIT, MEMPROTECT_RWX);
    291291#else
    292   return mmap(addr, nbytes, protection, MAP_PRIVATE|MAP_ANON|MAP_FIXED, -1, 0);
     292  {
     293    int flags = MAP_PRIVATE|MAP_ANON;
     294
     295    if (addr > 0) flags |= MAP_FIXED;
     296    return mmap(addr, nbytes, protection, flags, -1, 0);
     297  }
    293298#endif
    294299}

  • trunk/source/lisp-kernel/x86-exceptions.c

    r12770 r12807  
    499499    return true;
    500500  }
    501   update_bytes_allocated(tcr, (void *)(void *) tcr->save_allocptr);
     501  update_bytes_allocated(tcr, (void *)tcr->save_allocptr);
    502502  if (allocate_object(xp,bytes_needed,bytes_needed-fulltag_cons,tcr)) {
    503503    tcr->save_allocptr -= fulltag_cons;
    … …  
    803803      xpPC(xp) = xpGPR(xp,Ira0);
    804804      return true;
    805     } else {
     805    }
     806   
     807    {
    806808      protected_area *a = find_protected_area(addr);
    807809      protection_handler *handler;
    … …  
    810812        handler = protection_handlers[a->why];
    811813        return handler(xp, a, addr);
    812       } else {
    813         if ((addr >= readonly_area->low) &&
    814             (addr < readonly_area->active)) {
    815           UnProtectMemory((LogicalAddress)(truncate_to_power_of_2(addr,log2_page_size)),
    816                           page_size);
    817           return true;
    818         }
    819814      }
    820815    }
    821   }
     816
     817    if ((addr >= readonly_area->low) &&
     818        (addr < readonly_area->active)) {
     819      UnProtectMemory((LogicalAddress)(truncate_to_power_of_2(addr,log2_page_size)),
     820                      page_size);
     821      return true;
     822    }
     823
     824    {
     825      area *a = area_containing(addr);
     826
     827      if (a && a->code == AREA_WATCHED && addr < a->high) {
     828        /* caught a write to a watched object */
     829        LispObj cmain = nrs_CMAIN.vcell;
     830        LispObj object = (LispObj)a->low + fulltag_misc; /* always uvectors */
     831
     832        if ((fulltag_of(cmain) == fulltag_misc) &&
     833            (header_subtag(header_of(cmain)) == subtag_macptr)) {
     834          LispObj xcf = create_exception_callback_frame(xp, tcr);
     835          int skip;
     836          LispObj addr = (LispObj)a->low;
     837
     838          /* The magic 2 means this was a write to a watchd object */
     839          skip = callback_to_lisp(tcr, cmain, xp, xcf, SIGSEGV, 2, object, 0);
     840          xpPC(xp) += skip;
     841          return true;
     842        }
     843      }
     844    }
     845  }
     846
    822847  if (old_valence == TCR_STATE_LISP) {
    823848    LispObj cmain = nrs_CMAIN.vcell,
    … …  
    9931018          }
    9941019          break;
    995            
     1020        case UUO_WATCH_TRAP:
     1021          /* add or remove watched object */
     1022          if (handle_watch_trap(context, tcr)) {
     1023            xpPC(context) += 2;
     1024            return true;
     1025          }
     1026          break;
    9961027        case UUO_DEBUG_TRAP:
    9971028          xpPC(context) = (natural) (program_counter+1);
    … …  
    35853616
    35863617#endif
     3618
     3619/* watchpoint stuff */
     3620
     3621area *
     3622new_watched_area(natural size)
     3623{
     3624  void *p;
     3625
     3626  p = MapMemory(NULL, size, MEMPROTECT_RWX);
     3627  if ((signed_natural)p == -1) {
     3628    allocation_failure(true, size);
     3629  }
     3630  return new_area(p, p + size, AREA_WATCHED);
     3631}
     3632
     3633void
     3634delete_watched_area(area *a, TCR *tcr)
     3635{
     3636  natural nbytes = a->high - a->low;
     3637  char *base = a->low;
     3638
     3639  condemn_area_holding_area_lock(a);
     3640
     3641  if (nbytes) {
     3642    int err = munmap(base, nbytes);
     3643    if (err < 0)
     3644      Fatal("munmap in delete_watched_area: ", strerror(errno));
     3645  }
     3646}
     3647
     3648natural
     3649uvector_total_size_in_bytes(LispObj *u)
     3650{
     3651  LispObj header = header_of(u);
     3652  natural header_tag = fulltag_of(header);
     3653  natural subtag = header_subtag(header);
     3654  natural element_count = header_element_count(header);
     3655  natural nbytes = 0;
     3656
     3657#ifdef X8632
     3658  if ((nodeheader_tag_p(header_tag)) ||
     3659      (subtag <= max_32_bit_ivector_subtag)) {
     3660    nbytes = element_count << 2;
     3661  } else if (subtag <= max_8_bit_ivector_subtag) {
     3662    nbytes = element_count;
     3663  } else if (subtag <= max_16_bit_ivector_subtag) {
     3664    nbytes = element_count << 1;
     3665  } else if (subtag == subtag_double_float_vector) {
     3666    nbytes = element_count << 3;
     3667  } else {
     3668    nbytes = (element_count + 7) >> 3;
     3669  }
     3670  /* add 4 byte header and round up to multiple of 8 bytes */
     3671  return ~7 & (4 + nbytes + 7);
     3672#endif
     3673#ifdef X8664
     3674  if ((nodeheader_tag_p(header_tag)) || (header_tag == ivector_class_64_bit)) {
     3675    nbytes = element_count << 3;
     3676  } else if (header_tag == ivector_class_32_bit) {
     3677    nbytes = element_count << 2;
     3678  } else {
     3679    /* ivector_class_other_bit contains 8, 16-bit arrays & bit vector */
     3680    if (subtag == subtag_bit_vector) {
     3681      nbytes = (element_count + 7) >> 3;
     3682    } else if (subtag >= min_8_bit_ivector_subtag) {
     3683      nbytes = element_count;
     3684    } else {
     3685      nbytes = element_count << 1;
     3686    }
     3687  }
     3688  /* add 8 byte header and round up to multiple of 16 bytes */
     3689  return ~15 & (8 + nbytes + 15);
     3690#endif
     3691}
     3692
     3693extern void wp_update_references(TCR *, LispObj, LispObj);
     3694
     3695/*
     3696 * Other threads are suspended and pc-lusered.
     3697 *
     3698 * param contains a tagged pointer to a uvector.
     3699 */
     3700signed_natural
     3701watch_object(TCR *tcr, signed_natural param)
     3702{
     3703  TCR *other_tcr;
     3704  LispObj uvector = (LispObj)param;
     3705  LispObj *noderef = (LispObj *)untag(uvector);
     3706  natural size = uvector_total_size_in_bytes(noderef);
     3707  area *uvector_area = area_containing((BytePtr)noderef);
     3708
     3709  if (uvector_area && uvector_area->code != AREA_WATCHED) {
     3710    area *a = new_watched_area(size);
     3711    LispObj old = uvector;
     3712    LispObj new = (LispObj)((natural)a->low + fulltag_misc);
     3713
     3714    add_area_holding_area_lock(a);
     3715
     3716    /* move object to watched area */
     3717    bcopy(noderef, a->low, size);
     3718    ProtectMemory(a->low, size);
     3719    bzero(noderef, size);
     3720    wp_update_references(tcr, old, new);
     3721    check_all_areas(tcr);
     3722  }
     3723  return 0;
     3724}
     3725
     3726signed_natural
     3727unwatch_object(TCR *tcr, signed_natural param)
     3728{
     3729  TCR *other_tcr;
     3730  LispObj uvector = (LispObj)param;
     3731  LispObj *noderef = (LispObj *)untag(uvector);
     3732  LispObj old = uvector;
     3733  LispObj new;
     3734  natural size = uvector_total_size_in_bytes(noderef);
     3735  area *a = area_containing((BytePtr)noderef);
     3736  ExceptionInformation *xp = tcr->xframe->curr;
     3737
     3738  if (a && a->code == AREA_WATCHED) {
     3739    update_bytes_allocated(tcr, (void *)tcr->save_allocptr);
     3740    if (allocate_object(xp, size, size - fulltag_misc, tcr)) {
     3741      new = (LispObj)tcr->save_allocptr;
     3742      tcr->save_allocptr -= fulltag_misc;
     3743    } else {
     3744      lisp_allocation_failure(xp, tcr, size);
     3745    }
     3746
     3747    bcopy(noderef, tcr->save_allocptr, size);
     3748    delete_watched_area(a, tcr);
     3749    wp_update_references(tcr, old, new);
     3750    check_all_areas(tcr);
     3751  }
     3752  return 0;
     3753}
     3754
     3755Boolean
     3756handle_watch_trap(ExceptionInformation *xp, TCR *tcr)
     3757{
     3758  LispObj selector = xpGPR(xp,Iimm0);
     3759  LispObj uvector = xpGPR(xp, Iarg_z);
     3760 
     3761  switch (selector) {
     3762    case WATCH_TRAP_FUNCTION_WATCH:
     3763      gc_like_from_xp(xp, watch_object, uvector);
     3764      break;
     3765    case WATCH_TRAP_FUNCTION_UNWATCH:
     3766      gc_like_from_xp(xp, unwatch_object, uvector);
     3767      break;
     3768    default:
     3769      break;
     3770  }
     3771  return true;
     3772}
     3773

  • trunk/source/lisp-kernel/x86-exceptions.h

    r11896 r12807  
    138138#define UUO_DEBUG_TRAP 0xca
    139139#define UUO_DEBUG_TRAP_WITH_STRING 0xcd
     140#define UUO_WATCH_TRAP 0xce
     141  #define WATCH_TRAP_FUNCTION_WATCH 0
     142  #define WATCH_TRAP_FUNCTION_UNWATCH 1
    140143
    141144#define XUUO_OPCODE_0 0x0f

  • trunk/source/lisp-kernel/x86-gc.c

    r12374 r12807  
    2626#include <sys/time.h>
    2727
     28#ifdef X8632
     29static inline natural
     30imm_word_count(LispObj fn)
     31{
     32  natural w = ((unsigned short *)fn)[-1];
     33
     34  if (w & 0x8000) {
     35    /*
     36     * The low 15 bits encode the number of contants.
     37     * Compute and return the immediate word count.
     38     */
     39    LispObj header = header_of(fn);
     40    natural element_count = header_element_count(header);
     41
     42    return element_count - (w & 0x7fff);
     43  } else {
     44    /* The immediate word count is encoded directly. */
     45    return w;
     46  }
     47}
     48#endif
    2849
    2950/* Heap sanity checking. */
    … …  
    318339    switch (code) {
    319340    case AREA_DYNAMIC:
     341    case AREA_WATCHED:
    320342    case AREA_STATIC:
    321343    case AREA_MANAGED_STATIC:
    … …  
    959981      header = *(natural *)base;
    960982      subtag = header_subtag(header);
    961       boundary = base + (unsigned short)base[1];
    962 
    963       /* XXX bootstrapping */
    964       {
    965         natural word_count = (unsigned short)base[1];
    966         natural element_count = header_element_count(header);
    967 
    968         if (word_count & 0x8000)
    969           boundary = base + element_count - (word_count & 0x7fff);
    970       }
     983      boundary = base + imm_word_count(fn);
    971984
    972985      /*
    … …  
    9911004      subtag = header_subtag(header);
    9921005      if (subtag == subtag_function) {
    993         boundary = base + (unsigned short)base[1];
    994         /* XXX bootstrapping */
    995         {
    996           natural word_count = (unsigned short)base[1];
    997           natural element_count = header_element_count(header);
    998 
    999           if (word_count & 0x8000)
    1000             boundary = base + element_count - (word_count & 0x7fff);
    1001         }
     1006        boundary = base + imm_word_count(this);
    10021007
    10031008        *((int *)boundary) &= 0xff;
    … …  
    19021907  LispObj fn = fulltag_misc + (LispObj)node;
    19031908  unsigned char *p = (unsigned char *)node;
    1904   natural i, offset;
    1905   LispObj header = *node;
    1906 
    1907   i = ((unsigned short *)node)[2];
     1909  natural i = imm_word_count(fn);
     1910
    19081911  if (i) {
    1909     /* XXX bootstrapping for new scheme */
    1910     if (i & 0x8000) {
    1911       i = header_element_count(header) - (i & 0x7fff);
    1912     }
    1913     offset = node[--i];
     1912    natural offset = node[--i];
    19141913
    19151914    while (offset) {
    … …  
    19831982          if (header_subtag(node) == subtag_function) {
    19841983#ifdef X8632
    1985             int skip = *((unsigned short *)src);
    19861984            LispObj *f = dest;
    1987 
    1988             /* XXX bootstrapping for new scheme */
    1989             if (skip & 0x8000)
    1990               skip = elements - (skip & 0x7fff);
     1985            int skip = imm_word_count(fulltag_misc + (LispObj)current);
    19911986#else
    19921987            int skip = *((int *)src);
    … …  
    28112806  return -1;
    28122807}
     2808
     2809/*
     2810 * This stuff is all adapted from the forward_xxx functions for use by
     2811 * the watchpoint code.  It's a lot of duplicated code, and it would
     2812 * be nice to generalize it somehow.
     2813 */
     2814
     2815static inline void
     2816wp_maybe_update(LispObj *p, LispObj old, LispObj new)
     2817{
     2818  if (*p == old) {
     2819    *p = new;
     2820  }
     2821}
     2822
     2823static void
     2824wp_update_headerless_range(LispObj *start, LispObj *end,
     2825                           LispObj old, LispObj new)
     2826{
     2827  LispObj *p = start;
     2828
     2829  while (p < end) {
     2830    wp_maybe_update(p, old, new);
     2831    p++;
     2832  }
     2833}
     2834
     2835static void
     2836wp_update_range(LispObj *start, LispObj *end, LispObj old, LispObj new)
     2837{
     2838  LispObj *p = start, node;
     2839  int tag_n;
     2840  natural nwords;
     2841
     2842  while (p < end) {
     2843    node = *p;
     2844    tag_n = fulltag_of(node);
     2845
     2846    if (immheader_tag_p(tag_n)) {
     2847      p = (LispObj *)skip_over_ivector(ptr_to_lispobj(p), node);
     2848    } else if (nodeheader_tag_p(tag_n)) {
     2849      nwords = header_element_count(node);
     2850     
     2851      nwords += 1 - (nwords & 1);
     2852
     2853      if ((header_subtag(node) == subtag_hash_vector) &&
     2854          ((((hash_table_vector_header *)p)->flags) & nhash_track_keys_mask)) {
     2855        natural skip = hash_table_vector_header_count - 1;
     2856        hash_table_vector_header *hashp = (hash_table_vector_header *)p;
     2857
     2858        p++;
     2859        nwords -= skip;
     2860        while(skip--) {
     2861          if (*p == old) *p = new;
     2862          p++;
     2863        }
     2864        /* "nwords" is odd at this point: there are (floor nwords 2)
     2865           key/value pairs to look at, and then an extra word for
     2866           alignment.  Process them two at a time, then bump "p"
     2867           past the alignment word. */
     2868        nwords >>= 1;
     2869        while(nwords--) {
     2870          if (*p == old && hashp) {
     2871            *p = new;
     2872            hashp->flags |= nhash_key_moved_mask;
     2873            hashp = NULL;
     2874          }
     2875          p++;
     2876          if (*p == old) *p = new;
     2877          p++;
     2878        }
     2879        *p++ = 0;
     2880      } else {
     2881        if (header_subtag(node) == subtag_function) {
     2882#ifdef X8632
     2883          int skip = (unsigned short)(p[1]);
     2884
     2885          /* XXX bootstrapping */
     2886          if (skip & 0x8000)
     2887            skip = header_element_count(node) - (skip & 0x7fff);
     2888
     2889#else
     2890          int skip = (int)(p[1]);
     2891#endif
     2892          p += skip;
     2893          nwords -= skip;
     2894        }
     2895        p++;
     2896        while(nwords--) {
     2897          wp_maybe_update(p, old, new);
     2898          p++;
     2899        }
     2900      }
     2901    } else {
     2902      /* a cons cell */
     2903      wp_maybe_update(p, old, new);
     2904      p++;
     2905      wp_maybe_update(p, old, new);
     2906      p++;
     2907    }
     2908  }
     2909}
     2910
     2911static void
     2912wp_update_xp(ExceptionInformation *xp, LispObj old, LispObj new)
     2913{
     2914  natural *regs = (natural *)xpGPRvector(xp);
     2915
     2916#ifdef X8664
     2917  wp_maybe_update(&regs[Iarg_z], old, new);
     2918  wp_maybe_update(&regs[Iarg_y], old, new);
     2919  wp_maybe_update(&regs[Iarg_x], old, new);
     2920  wp_maybe_update(&regs[Isave3], old, new);
     2921  wp_maybe_update(&regs[Isave2], old, new);
     2922  wp_maybe_update(&regs[Isave1], old, new);
     2923  wp_maybe_update(&regs[Isave0], old, new);
     2924  wp_maybe_update(&regs[Ifn], old, new);
     2925  wp_maybe_update(&regs[Itemp0], old, new);
     2926  wp_maybe_update(&regs[Itemp1], old, new);
     2927  wp_maybe_update(&regs[Itemp2], old, new);
     2928#endif
     2929
     2930#if 0
     2931  /*
     2932   * We don't allow watching functions, so this presumably doesn't
     2933   * matter.
     2934   */
     2935  update_locref(&(regs[Iip]));
     2936#endif
     2937
     2938}
     2939
     2940static void
     2941wp_update_tcr_xframes(TCR *tcr, LispObj old, LispObj new)
     2942{
     2943  xframe_list *xframes;
     2944  ExceptionInformation *xp;
     2945
     2946#ifdef X8664
     2947  xp = tcr->gc_context;
     2948  if (xp) {
     2949    wp_update_xp(xp, old, new);
     2950  }
     2951  for (xframes = tcr->xframe; xframes; xframes = xframes->prev) {
     2952    wp_update_xp(xframes->curr, old, new);
     2953  }
     2954#endif
     2955}
     2956
     2957/*
     2958 * Scan all pointer-bearing areas, updating all references to
     2959 * "old" to "new".
     2960 */
     2961static void
     2962wp_update_all_areas(LispObj old, LispObj new)
     2963{
     2964  area *a = active_dynamic_area;
     2965  natural code = a->code;
     2966
     2967  while (code != AREA_VOID) {
     2968    switch (code) {
     2969      case AREA_DYNAMIC:
     2970      case AREA_STATIC:
     2971      case AREA_MANAGED_STATIC:
     2972      case AREA_WATCHED:
     2973        wp_update_range((LispObj *)a->low, (LispObj *)a->active, old, new);
     2974        break;
     2975      case AREA_VSTACK:
     2976      {
     2977        LispObj *low = (LispObj *)a->active;
     2978        LispObj *high = (LispObj *)a->high;
     2979       
     2980        wp_update_headerless_range(low, high, old, new);
     2981      }
     2982      break;
     2983      case AREA_TSTACK:
     2984      {
     2985        LispObj *current, *next;
     2986        LispObj *start = (LispObj *)a->active, *end = start;
     2987        LispObj *limit = (LispObj *)a->high;
     2988       
     2989        for (current = start; end != limit; current = next) {
     2990          next = ptr_from_lispobj(*current);
     2991          end = ((next >= start) && (next < limit)) ? next : limit;
     2992          wp_update_range(current+2, end, old, new);
     2993        }
     2994      break;
     2995      }
     2996      default:
     2997        break;
     2998    }
     2999    a = a->succ;
     3000    code = a->code;
     3001  }
     3002}
     3003
     3004static void
     3005wp_update_tcr_tlb(TCR *tcr, LispObj old, LispObj new)
     3006{
     3007  natural n = tcr->tlb_limit;
     3008  LispObj *start = tcr->tlb_pointer;
     3009  LispObj *end = start + (n >> fixnumshift);
     3010
     3011  while (start < end) {
     3012    wp_maybe_update(start, old, new);
     3013    start++;
     3014  }
     3015}
     3016
     3017void
     3018wp_update_references(TCR *tcr, LispObj old, LispObj new)
     3019{
     3020  TCR *other_tcr = tcr;
     3021
     3022  do {
     3023    wp_update_tcr_xframes(other_tcr, old, new);
     3024    wp_update_tcr_tlb(other_tcr, old, new);
     3025    other_tcr = other_tcr->next;
     3026  } while (other_tcr != tcr);
     3027  wp_update_all_areas(old, new);
     3028}
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