1 /* Copyright (C) 2001-2021 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
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
live_image_destructor(struct live_images * image)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 *
examine_objects(void * pc,struct dwarf_eh_bases * bases,int dont_alloc)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 *
_Unwind_Find_FDE(void * pc,struct dwarf_eh_bases * bases)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 }
276