libgcc/config/unwind-dw2-fde-darwin.c

   1 /* Copyright (C) 2001-2020 Free Software Foundation, Inc.
   2
   3    This file is part of GCC.
   4
   5    GCC is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3, or (at your option)
   8    any later version.
   9
  10    GCC is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    Under Section 7 of GPL version 3, you are granted additional
  16    permissions described in the GCC Runtime Library Exception, version
  17    3.1, as published by the Free Software Foundation.
  18
  19    You should have received a copy of the GNU General Public License and
  20    a copy of the GCC Runtime Library Exception along with this program;
  21    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  22    <http://www.gnu.org/licenses/>.  */
  23
  24 /* Locate the FDE entry for a given address, using Darwin's keymgr support.  */
  25
  26 #include "tconfig.h"
  27 #include "tsystem.h"
  28 #include <string.h>
  29 #include <stdlib.h>
  30 #include "dwarf2.h"
  31 #include "unwind.h"
  32 #define NO_BASE_OF_ENCODED_VALUE
  33 #define DWARF2_OBJECT_END_PTR_EXTENSION
  34 #include "unwind-pe.h"
  35 #include "unwind-dw2-fde.h"
  36 /* Carefully don't include gthr.h.  */
  37
  38 typedef int __gthread_mutex_t;
  39 #define __gthread_mutex_lock(x)  (void)(x)
  40 #define __gthread_mutex_unlock(x) (void)(x)
  41
  42 static const fde * _Unwind_Find_registered_FDE (void *pc,
  43                                                 struct dwarf_eh_bases *bases);
  44
  45 #define _Unwind_Find_FDE _Unwind_Find_registered_FDE
  46 #include "unwind-dw2-fde.c"
  47 #undef _Unwind_Find_FDE
  48
  49 /* KeyMgr stuff.  */
  50 #define KEYMGR_GCC3_LIVE_IMAGE_LIST     301     /* loaded images  */
  51 #define KEYMGR_GCC3_DW2_OBJ_LIST        302     /* Dwarf2 object list  */
  52
  53 extern void *_keymgr_get_and_lock_processwide_ptr (int);
  54 extern void _keymgr_set_and_unlock_processwide_ptr (int, void *);
  55 extern void _keymgr_unlock_processwide_ptr (int);
  56
  57 struct mach_header;
  58 struct mach_header_64;
  59 extern char *getsectdatafromheader (struct mach_header*, const char*,
  60                                     const char *, unsigned long *);
  61 extern char *getsectdatafromheader_64 (struct mach_header_64*, const char*,
  62                                        const char *, unsigned long *);
  63
  64 /* This is referenced from KEYMGR_GCC3_DW2_OBJ_LIST.  */
  65 struct km_object_info {
  66   struct object *seen_objects;
  67   struct object *unseen_objects;
  68   unsigned spare[2];
  69 };
  70
  71 /* Node of KEYMGR_GCC3_LIVE_IMAGE_LIST.  Info about each resident image.  */
  72 struct live_images {
  73   unsigned long this_size;                      /* sizeof (live_images)  */
  74   struct mach_header *mh;                       /* the image info  */
  75   unsigned long vm_slide;
  76   void (*destructor)(struct live_images *);     /* destructor for this  */
  77   struct live_images *next;
  78   unsigned int examined_p;
  79   void *fde;
  80   void *object_info;
  81   unsigned long info[2];                        /* Future use.  */
  82 };
  83
  84 /* Bits in the examined_p field of struct live_images.  */
  85 enum {
  86   EXAMINED_IMAGE_MASK = 1,      /* We've seen this one.  */
  87   ALLOCED_IMAGE_MASK = 2,       /* The FDE entries were allocated by
  88                                    malloc, and must be freed.  This isn't
  89                                    used by newer libgcc versions.  */
  90   IMAGE_IS_TEXT_MASK = 4,       /* This image is in the TEXT segment.  */
  91   DESTRUCTOR_MAY_BE_CALLED_LIVE = 8  /* The destructor may be called on an
  92                                         object that's part of the live
  93                                         image list.  */
  94 };
  95 \f
  96 /* Delete any data we allocated on a live_images structure.  Either
  97    IMAGE has already been removed from the
  98    KEYMGR_GCC3_LIVE_IMAGE_LIST and the struct will be deleted
  99    after we return, or that list is locked and we're being called
 100    because this object might be about to be unloaded.  Called by
 101    KeyMgr.  */
 102
 103 static void
 104 live_image_destructor (struct live_images *image)
 105 {
 106   if (image->object_info)
 107     {
 108       struct km_object_info *the_obj_info;
 109
 110       the_obj_info =
 111         _keymgr_get_and_lock_processwide_ptr (KEYMGR_GCC3_DW2_OBJ_LIST);
 112       if (the_obj_info)
 113         {
 114           seen_objects = the_obj_info->seen_objects;
 115           unseen_objects = the_obj_info->unseen_objects;
 116
 117           /* Free any sorted arrays.  */
 118           __deregister_frame_info_bases (image->fde);
 119
 120           the_obj_info->seen_objects = seen_objects;
 121           the_obj_info->unseen_objects = unseen_objects;
 122         }
 123       _keymgr_set_and_unlock_processwide_ptr (KEYMGR_GCC3_DW2_OBJ_LIST,
 124                                               the_obj_info);
 125
 126       free (image->object_info);
 127       image->object_info = NULL;
 128       if (image->examined_p & ALLOCED_IMAGE_MASK)
 129         free (image->fde);
 130       image->fde = NULL;
 131     }
 132   image->examined_p = 0;
 133   image->destructor = NULL;
 134 }
 135
 136 /* Run through the list of live images.  If we can allocate memory,
 137    give each unseen image a new `struct object'.  Even if we can't,
 138    check whether the PC is inside the FDE of each unseen image.
 139  */
 140
 141 static inline const fde *
 142 examine_objects (void *pc, struct dwarf_eh_bases *bases, int dont_alloc)
 143 {
 144   const fde *result = NULL;
 145   struct live_images *image;
 146
 147   image = _keymgr_get_and_lock_processwide_ptr (KEYMGR_GCC3_LIVE_IMAGE_LIST);
 148
 149   for (; image != NULL; image = image->next)
 150     if ((image->examined_p & EXAMINED_IMAGE_MASK) == 0)
 151       {
 152         char *fde = NULL;
 153         unsigned long sz;
 154
 155         /* For ppc only check whether or not we have __DATA eh frames.  */
 156 #ifdef __ppc__
 157         fde = getsectdatafromheader (image->mh, "__DATA", "__eh_frame", &sz);
 158 #endif
 159
 160         if (fde == NULL)
 161           {
 162 #if __LP64__
 163             fde = getsectdatafromheader_64 ((struct mach_header_64 *) image->mh,
 164                                             "__TEXT", "__eh_frame", &sz);
 165 #else
 166             fde = getsectdatafromheader (image->mh, "__TEXT",
 167                                          "__eh_frame", &sz);
 168 #endif
 169             if (fde != NULL)
 170               image->examined_p |= IMAGE_IS_TEXT_MASK;
 171           }
 172
 173         /* If .eh_frame is empty, don't register at all.  */
 174         if (fde != NULL && sz > 0)
 175           {
 176             char *real_fde = (fde + image->vm_slide);
 177             struct object *ob = NULL;
 178             struct object panicob;
 179
 180             if (! dont_alloc)
 181               ob = calloc (1, sizeof (struct object));
 182             dont_alloc |= ob == NULL;
 183             if (dont_alloc)
 184               ob = &panicob;
 185
 186             ob->pc_begin = (void *)-1;
 187             ob->tbase = 0;
 188             ob->dbase = 0;
 189             ob->u.single = (struct dwarf_fde *)real_fde;
 190             ob->s.i = 0;
 191             ob->s.b.encoding = DW_EH_PE_omit;
 192             ob->fde_end = real_fde + sz;
 193
 194             image->fde = real_fde;
 195
 196             result = search_object (ob, pc);
 197
 198             if (! dont_alloc)
 199               {
 200                 struct object **p;
 201
 202                 image->destructor = live_image_destructor;
 203                 image->object_info = ob;
 204
 205                 image->examined_p |= (EXAMINED_IMAGE_MASK
 206                                       | DESTRUCTOR_MAY_BE_CALLED_LIVE);
 207
 208                 /* Insert the object into the classified list.  */
 209                 for (p = &seen_objects; *p ; p = &(*p)->next)
 210                   if ((*p)->pc_begin < ob->pc_begin)
 211                     break;
 212                 ob->next = *p;
 213                 *p = ob;
 214               }
 215
 216             if (result)
 217               {
 218                 int encoding;
 219                 _Unwind_Ptr func;
 220
 221                 bases->tbase = ob->tbase;
 222                 bases->dbase = ob->dbase;
 223
 224                 encoding = ob->s.b.encoding;
 225                 if (ob->s.b.mixed_encoding)
 226                   encoding = get_fde_encoding (result);
 227                 read_encoded_value_with_base (encoding,
 228                                               base_from_object (encoding, ob),
 229                                               result->pc_begin, &func);
 230                 bases->func = (void *) func;
 231                 break;
 232               }
 233           }
 234         else
 235           image->examined_p |= EXAMINED_IMAGE_MASK;
 236       }
 237
 238   _keymgr_unlock_processwide_ptr (KEYMGR_GCC3_LIVE_IMAGE_LIST);
 239
 240   return result;
 241 }
 242
 243 const fde *
 244 _Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases)
 245 {
 246   struct km_object_info *the_obj_info;
 247   const fde *ret = NULL;
 248
 249   the_obj_info =
 250     _keymgr_get_and_lock_processwide_ptr (KEYMGR_GCC3_DW2_OBJ_LIST);
 251   if (! the_obj_info)
 252     the_obj_info = calloc (1, sizeof (*the_obj_info));
 253
 254   if (the_obj_info != NULL)
 255     {
 256       seen_objects = the_obj_info->seen_objects;
 257       unseen_objects = the_obj_info->unseen_objects;
 258
 259       ret = _Unwind_Find_registered_FDE (pc, bases);
 260     }
 261
 262   /* OK, didn't find it in the list of FDEs we've seen before,
 263      so go through and look at the new ones.  */
 264   if (ret == NULL)
 265     ret = examine_objects (pc, bases, the_obj_info == NULL);
 266
 267   if (the_obj_info != NULL)
 268     {
 269       the_obj_info->seen_objects = seen_objects;
 270       the_obj_info->unseen_objects = unseen_objects;
 271     }
 272   _keymgr_set_and_unlock_processwide_ptr (KEYMGR_GCC3_DW2_OBJ_LIST,
 273                                           the_obj_info);
 274   return ret;
 275 }