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1 | /* Copyright (C) 2001 Free Software Foundation, Inc. |
2 | Contributed by Jakub Jelinek <jakub@redhat.com>. | |
3 | ||
4 | This file is part of GNU CC. | |
5 | ||
6 | GNU CC is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GNU CC is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with GNU CC; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | /* As a special exception, if you link this library with other files, | |
22 | some of which are compiled with GCC, to produce an executable, | |
23 | this library does not by itself cause the resulting executable | |
24 | to be covered by the GNU General Public License. | |
25 | This exception does not however invalidate any other reasons why | |
26 | the executable file might be covered by the GNU General Public License. */ | |
27 | ||
28 | /* Locate the FDE entry for a given address, using PT_GNU_EH_FRAME ELF | |
29 | segment and dl_iterate_phdr to avoid register/deregister calls at | |
30 | DSO load/unload. */ | |
31 | ||
32 | #include "auto-host.h" /* For HAVE_LD_EH_FRAME_HDR. */ | |
33 | #include "tconfig.h" | |
34 | #include <stddef.h> | |
35 | #include <stdlib.h> | |
36 | #include <link.h> | |
37 | #include "tsystem.h" | |
38 | #include "dwarf2.h" | |
39 | #include "unwind.h" | |
40 | #define NO_BASE_OF_ENCODED_VALUE | |
41 | #include "unwind-pe.h" | |
42 | #include "unwind-dw2-fde.h" | |
43 | #include "gthr.h" | |
44 | ||
45 | #if defined(HAVE_LD_EH_FRAME_HDR) \ | |
46 | && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \ | |
47 | || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG))) | |
48 | ||
49 | static fde * _Unwind_Find_registered_FDE (void *pc, struct dwarf_eh_bases *bases); | |
50 | ||
51 | #define _Unwind_Find_FDE _Unwind_Find_registered_FDE | |
52 | #include "unwind-dw2-fde.c" | |
53 | #undef _Unwind_Find_FDE | |
54 | ||
55 | #ifndef PT_GNU_EH_FRAME | |
56 | #define PT_GNU_EH_FRAME (PT_LOOS + 0x474e550) | |
57 | #endif | |
58 | ||
59 | struct unw_eh_callback_data | |
60 | { | |
61 | _Unwind_Ptr pc; | |
62 | void *tbase; | |
63 | void *dbase; | |
64 | void *func; | |
65 | fde *ret; | |
66 | }; | |
67 | ||
68 | struct unw_eh_frame_hdr | |
69 | { | |
70 | unsigned char version; | |
71 | unsigned char eh_frame_ptr_enc; | |
72 | unsigned char fde_count_enc; | |
73 | unsigned char table_enc; | |
74 | }; | |
75 | ||
76 | /* Like base_of_encoded_value, but take the base from a struct object | |
77 | instead of an _Unwind_Context. */ | |
78 | ||
79 | static _Unwind_Ptr | |
80 | base_from_cb_data (unsigned char encoding, struct unw_eh_callback_data *data) | |
81 | { | |
82 | if (encoding == DW_EH_PE_omit) | |
83 | return 0; | |
84 | ||
85 | switch (encoding & 0x70) | |
86 | { | |
87 | case DW_EH_PE_absptr: | |
88 | case DW_EH_PE_pcrel: | |
89 | case DW_EH_PE_aligned: | |
90 | return 0; | |
91 | ||
92 | case DW_EH_PE_textrel: | |
93 | return (_Unwind_Ptr) data->tbase; | |
94 | case DW_EH_PE_datarel: | |
95 | return (_Unwind_Ptr) data->dbase; | |
96 | } | |
97 | abort (); | |
98 | } | |
99 | ||
100 | static int | |
101 | _Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr) | |
102 | { | |
103 | struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr; | |
104 | const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic; | |
105 | long n, match; | |
106 | _Unwind_Ptr load_base; | |
107 | const unsigned char *p; | |
108 | const struct unw_eh_frame_hdr *hdr; | |
109 | _Unwind_Ptr eh_frame; | |
110 | struct object ob; | |
111 | ||
112 | /* Make sure struct dl_phdr_info is at least as big as we need. */ | |
113 | if (size < offsetof (struct dl_phdr_info, dlpi_phnum) | |
114 | + sizeof (info->dlpi_phnum)) | |
115 | return -1; | |
116 | ||
117 | match = 0; | |
118 | phdr = info->dlpi_phdr; | |
119 | load_base = info->dlpi_addr; | |
120 | p_eh_frame_hdr = NULL; | |
121 | p_dynamic = NULL; | |
122 | ||
123 | /* See if PC falls into one of the loaded segments. Find the eh_frame | |
124 | segment at the same time. */ | |
125 | for (n = info->dlpi_phnum; --n >= 0; phdr++) | |
126 | { | |
127 | if (phdr->p_type == PT_LOAD) | |
128 | { | |
129 | _Unwind_Ptr vaddr = phdr->p_vaddr + load_base; | |
130 | if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz) | |
131 | match = 1; | |
132 | } | |
133 | else if (phdr->p_type == PT_GNU_EH_FRAME) | |
134 | p_eh_frame_hdr = phdr; | |
135 | else if (phdr->p_type == PT_DYNAMIC) | |
136 | p_dynamic = phdr; | |
137 | } | |
138 | if (!match || !p_eh_frame_hdr) | |
139 | return 0; | |
140 | ||
141 | /* Read .eh_frame_hdr header. */ | |
142 | hdr = (const struct unw_eh_frame_hdr *) | |
143 | (p_eh_frame_hdr->p_vaddr + load_base); | |
144 | if (hdr->version != 1) | |
145 | return 1; | |
146 | ||
147 | #ifdef CRT_GET_RFIB_DATA | |
148 | # ifdef __i386__ | |
149 | data->dbase = NULL; | |
150 | if (p_dynamic) | |
151 | { | |
152 | /* For dynamicly linked executables and shared libraries, | |
153 | DT_PLTGOT is the gp value for that object. */ | |
154 | ElfW(Dyn) *dyn = (ElfW(Dyn) *)(p_dynamic->p_vaddr + load_base); | |
155 | for (; dyn->d_tag != DT_NULL ; dyn++) | |
156 | if (dyn->d_tag == DT_PLTGOT) | |
157 | { | |
158 | /* On IA-32, _DYNAMIC is writable and GLIBC has relocated it. */ | |
159 | data->dbase = (void *) dyn->d_un.d_ptr; | |
160 | break; | |
161 | } | |
162 | } | |
163 | # else | |
164 | # error What is DW_EH_PE_datarel base on this platform? | |
165 | # endif | |
166 | #endif | |
167 | #ifdef CRT_GET_RFIB_TEXT | |
168 | # error What is DW_EH_PE_textrel base on this platform? | |
169 | #endif | |
170 | ||
171 | p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc, | |
172 | base_from_cb_data (hdr->eh_frame_ptr_enc, | |
173 | data), | |
174 | (const unsigned char *) (hdr + 1), | |
175 | &eh_frame); | |
176 | ||
177 | /* We require here specific table encoding to speed things up. | |
178 | Also, DW_EH_PE_datarel here means using PT_GNU_EH_FRAME start | |
179 | as base, not the processor specific DW_EH_PE_datarel. */ | |
180 | if (hdr->fde_count_enc != DW_EH_PE_omit | |
181 | && hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata4)) | |
182 | { | |
183 | _Unwind_Ptr fde_count; | |
184 | ||
185 | p = read_encoded_value_with_base (hdr->fde_count_enc, | |
186 | base_from_cb_data (hdr->fde_count_enc, | |
187 | data), | |
188 | p, &fde_count); | |
189 | /* Shouldn't happen. */ | |
190 | if (fde_count == 0) | |
191 | return 1; | |
192 | if ((((_Unwind_Ptr) p) & 3) == 0) | |
193 | { | |
194 | struct fde_table { | |
195 | signed initial_loc __attribute__ ((mode (SI))); | |
196 | signed fde __attribute__ ((mode (SI))); | |
197 | }; | |
198 | const struct fde_table *table = (const struct fde_table *) p; | |
199 | size_t lo, hi, mid; | |
200 | _Unwind_Ptr data_base = (_Unwind_Ptr) hdr; | |
201 | fde *f; | |
202 | unsigned int f_enc, f_enc_size; | |
203 | _Unwind_Ptr range; | |
204 | ||
205 | mid = fde_count - 1; | |
206 | if (data->pc < table[0].initial_loc + data_base) | |
207 | return 1; | |
208 | else if (data->pc < table[mid].initial_loc + data_base) | |
209 | { | |
210 | lo = 0; | |
211 | hi = mid; | |
212 | ||
213 | while (lo < hi) | |
214 | { | |
215 | mid = (lo + hi) / 2; | |
216 | if (data->pc < table[mid].initial_loc + data_base) | |
217 | hi = mid; | |
218 | else if (data->pc >= table[mid + 1].initial_loc + data_base) | |
219 | lo = mid + 1; | |
220 | else | |
221 | break; | |
222 | } | |
223 | ||
224 | if (lo >= hi) | |
225 | __gxx_abort (); | |
226 | } | |
227 | ||
228 | f = (fde *) (table[mid].fde + data_base); | |
229 | f_enc = get_fde_encoding (f); | |
230 | f_enc_size = size_of_encoded_value (f_enc); | |
231 | read_encoded_value_with_base (f_enc & 0x0f, 0, | |
232 | &f->pc_begin[f_enc_size], &range); | |
233 | if (data->pc < table[mid].initial_loc + data_base + range) | |
234 | data->ret = f; | |
235 | data->func = (void *) (table[mid].initial_loc + data_base); | |
236 | return 1; | |
237 | } | |
238 | } | |
239 | ||
240 | /* We have no sorted search table, so need to go the slow way. | |
241 | As soon as GLIBC will provide API so to notify that a library has been | |
242 | removed, we could cache this (and thus use search_object). */ | |
243 | ob.pc_begin = NULL; | |
244 | ob.tbase = data->tbase; | |
245 | ob.dbase = data->dbase; | |
246 | ob.u.single = (fde *) eh_frame; | |
247 | ob.s.i = 0; | |
248 | ob.s.b.mixed_encoding = 1; /* Need to assume worst case. */ | |
249 | data->ret = linear_search_fdes (&ob, (fde *) eh_frame, (void *) data->pc); | |
250 | if (data->ret != NULL) | |
251 | { | |
252 | unsigned int encoding = get_fde_encoding (data->ret); | |
253 | read_encoded_value_with_base (encoding, | |
254 | base_from_cb_data (encoding, data), | |
255 | data->ret->pc_begin, | |
256 | (_Unwind_Ptr *)&data->func); | |
257 | } | |
258 | return 1; | |
259 | } | |
260 | ||
261 | fde * | |
262 | _Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases) | |
263 | { | |
264 | struct unw_eh_callback_data data; | |
265 | fde *ret; | |
266 | ||
267 | ret = _Unwind_Find_registered_FDE (pc, bases); | |
268 | if (ret != NULL) | |
269 | return ret; | |
270 | ||
271 | data.pc = (_Unwind_Ptr) pc; | |
272 | data.tbase = NULL; | |
273 | data.dbase = NULL; | |
274 | data.func = NULL; | |
275 | data.ret = NULL; | |
276 | ||
277 | if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0) | |
278 | return NULL; | |
279 | ||
280 | if (data.ret) | |
281 | { | |
282 | bases->tbase = data.tbase; | |
283 | bases->dbase = data.dbase; | |
284 | bases->func = data.func; | |
285 | } | |
286 | return data.ret; | |
287 | } | |
288 | ||
289 | #else | |
290 | #include "unwind-dw2-fde.c" | |
291 | #endif |