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1 | /* Fallback frame-state unwinder for Darwin. |
2 | Copyright (C) 2004 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GCC. | |
5 | ||
6 | GCC is free software; you can redistribute it and/or modify it | |
7 | 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 | In addition to the permissions in the GNU General Public License, the | |
12 | Free Software Foundation gives you unlimited permission to link the | |
13 | compiled version of this file into combinations with other programs, | |
14 | and to distribute those combinations without any restriction coming | |
15 | from the use of this file. (The General Public License restrictions | |
16 | do apply in other respects; for example, they cover modification of | |
17 | the file, and distribution when not linked into a combined | |
18 | executable.) | |
19 | ||
20 | GCC is distributed in the hope that it will be useful, but WITHOUT | |
21 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY | |
22 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public | |
23 | License for more details. | |
24 | ||
25 | You should have received a copy of the GNU General Public License | |
26 | along with GCC; see the file COPYING. If not, write to the Free | |
27 | Software Foundation, 59 Temple Place - Suite 330, Boston, MA | |
28 | 02111-1307, USA. */ | |
29 | ||
30 | #include "tconfig.h" | |
31 | #include "tsystem.h" | |
32 | #include "coretypes.h" | |
33 | #include "tm.h" | |
34 | #include "dwarf2.h" | |
35 | #include "unwind.h" | |
36 | #include "unwind-dw2.h" | |
37 | #include <stdint.h> | |
38 | #include <stdbool.h> | |
39 | #include <signal.h> | |
40 | #include <ucontext.h> | |
41 | ||
42 | typedef unsigned long reg_unit; | |
43 | ||
44 | /* Place in GPRS the parameters to the first 'sc' instruction that would | |
45 | have been executed if we were returning from this CONTEXT, or | |
46 | return false if an unexpected instruction is encountered. */ | |
47 | ||
48 | static bool | |
49 | interpret_libc (reg_unit gprs[32], struct _Unwind_Context *context) | |
50 | { | |
51 | uint32_t *pc = (uint32_t *)_Unwind_GetIP (context); | |
52 | uint32_t cr; | |
53 | reg_unit lr = (reg_unit) pc; | |
54 | reg_unit ctr = 0; | |
55 | uint32_t *invalid_address = NULL; | |
56 | ||
57 | int i; | |
58 | ||
59 | for (i = 0; i < 13; i++) | |
60 | gprs[i] = 1; | |
61 | gprs[1] = _Unwind_GetCFA (context); | |
62 | for (; i < 32; i++) | |
63 | gprs[i] = _Unwind_GetGR (context, i); | |
64 | cr = _Unwind_GetGR (context, CR2_REGNO); | |
65 | ||
66 | /* For each supported Libc, we have to track the code flow | |
67 | all the way back into the kernel. | |
68 | ||
69 | This code is believed to support all released Libc/Libsystem builds since | |
70 | Jaguar 6C115, including all the security updates. To be precise, | |
71 | ||
72 | Libc Libsystem Build(s) | |
73 | 262~1 60~37 6C115 | |
74 | 262~1 60.2~4 6D52 | |
75 | 262~1 61~3 6F21-6F22 | |
76 | 262~1 63~24 6G30-6G37 | |
77 | 262~1 63~32 6I34-6I35 | |
78 | 262~1 63~64 6L29-6L60 | |
79 | 262.4.1~1 63~84 6L123-6R172 | |
80 | ||
81 | 320~1 71~101 7B85-7D28 | |
82 | 320~1 71~266 7F54-7F56 | |
83 | 320~1 71~288 7F112 | |
84 | 320~1 71~289 7F113 | |
85 | 320.1.3~1 71.1.1~29 7H60-7H105 | |
86 | 320.1.3~1 71.1.1~30 7H110-7H113 | |
87 | 320.1.3~1 71.1.1~31 7H114 | |
88 | ||
89 | That's a big table! It would be insane to try to keep track of | |
90 | every little detail, so we just read the code itself and do what | |
91 | it would do. | |
92 | */ | |
93 | ||
94 | for (;;) | |
95 | { | |
96 | uint32_t ins = *pc++; | |
97 | ||
98 | if ((ins & 0xFC000003) == 0x48000000) /* b instruction */ | |
99 | { | |
100 | pc += ((((int32_t) ins & 0x3FFFFFC) ^ 0x2000000) - 0x2000004) / 4; | |
101 | continue; | |
102 | } | |
103 | if ((ins & 0xFC600000) == 0x2C000000) /* cmpwi */ | |
104 | { | |
105 | int32_t val1 = (int16_t) ins; | |
106 | int32_t val2 = gprs[ins >> 16 & 0x1F]; | |
107 | /* Only beq and bne instructions are supported, so we only | |
108 | need to set the EQ bit. */ | |
109 | uint32_t mask = 0xF << ((ins >> 21 & 0x1C) ^ 0x1C); | |
110 | if (val1 == val2) | |
111 | cr |= mask; | |
112 | else | |
113 | cr &= ~mask; | |
114 | continue; | |
115 | } | |
116 | if ((ins & 0xFEC38003) == 0x40820000) /* forwards beq/bne */ | |
117 | { | |
118 | if ((cr >> ((ins >> 16 & 0x1F) ^ 0x1F) & 1) == (ins >> 24 & 1)) | |
119 | pc += (ins & 0x7FFC) / 4 - 1; | |
120 | continue; | |
121 | } | |
122 | if ((ins & 0xFC0007FF) == 0x7C000378) /* or, including mr */ | |
123 | { | |
124 | gprs [ins >> 16 & 0x1F] = (gprs [ins >> 11 & 0x1F] | |
125 | | gprs [ins >> 21 & 0x1F]); | |
126 | continue; | |
127 | } | |
128 | if (ins >> 26 == 0x0E) /* addi, including li */ | |
129 | { | |
130 | reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F]; | |
131 | gprs [ins >> 21 & 0x1F] = src + (int16_t) ins; | |
132 | continue; | |
133 | } | |
134 | if (ins >> 26 == 0x0F) /* addis, including lis */ | |
135 | { | |
136 | reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F]; | |
137 | gprs [ins >> 21 & 0x1F] = src + ((int16_t) ins << 16); | |
138 | continue; | |
139 | } | |
140 | if (ins >> 26 == 0x20) /* lwz */ | |
141 | { | |
142 | reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F]; | |
143 | uint32_t *p = (uint32_t *)(src + (int16_t) ins); | |
144 | if (p == invalid_address) | |
145 | return false; | |
146 | gprs [ins >> 21 & 0x1F] = *p; | |
147 | continue; | |
148 | } | |
149 | if (ins >> 26 == 0x21) /* lwzu */ | |
150 | { | |
151 | uint32_t *p = (uint32_t *)(gprs [ins >> 16 & 0x1F] += (int16_t) ins); | |
152 | if (p == invalid_address) | |
153 | return false; | |
154 | gprs [ins >> 21 & 0x1F] = *p; | |
155 | continue; | |
156 | } | |
157 | if (ins >> 26 == 0x24) /* stw */ | |
158 | /* What we hope this is doing is '--in_sigtramp'. We don't want | |
159 | to actually store to memory, so just make a note of the | |
160 | address and refuse to load from it. */ | |
161 | { | |
162 | reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F]; | |
163 | uint32_t *p = (uint32_t *)(src + (int16_t) ins); | |
164 | if (p == NULL || invalid_address != NULL) | |
165 | return false; | |
166 | invalid_address = p; | |
167 | continue; | |
168 | } | |
169 | if (ins >> 26 == 0x2E) /* lmw */ | |
170 | { | |
171 | reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F]; | |
172 | uint32_t *p = (uint32_t *)(src + (int16_t) ins); | |
173 | int i; | |
174 | ||
175 | for (i = (ins >> 21 & 0x1F); i < 32; i++) | |
176 | { | |
177 | if (p == invalid_address) | |
178 | return false; | |
179 | gprs[i] = *p++; | |
180 | } | |
181 | continue; | |
182 | } | |
183 | if ((ins & 0xFC1FFFFF) == 0x7c0803a6) /* mtlr */ | |
184 | { | |
185 | lr = gprs [ins >> 21 & 0x1F]; | |
186 | continue; | |
187 | } | |
188 | if ((ins & 0xFC1FFFFF) == 0x7c0802a6) /* mflr */ | |
189 | { | |
190 | gprs [ins >> 21 & 0x1F] = lr; | |
191 | continue; | |
192 | } | |
193 | if ((ins & 0xFC1FFFFF) == 0x7c0903a6) /* mtctr */ | |
194 | { | |
195 | ctr = gprs [ins >> 21 & 0x1F]; | |
196 | continue; | |
197 | } | |
198 | /* The PowerPC User's Manual says that bit 11 of the mtcrf | |
199 | instruction is reserved and should be set to zero, but it | |
200 | looks like the Darwin assembler doesn't do that... */ | |
201 | if ((ins & 0xFC000FFF) == 0x7c000120) /* mtcrf */ | |
202 | { | |
203 | int i; | |
204 | uint32_t mask = 0; | |
205 | for (i = 0; i < 8; i++) | |
206 | mask |= ((-(ins >> (12 + i) & 1)) & 0xF) << 4 * i; | |
207 | cr = (cr & ~mask) | (gprs [ins >> 21 & 0x1F] & mask); | |
208 | continue; | |
209 | } | |
210 | if (ins == 0x429f0005) /* bcl- 20,4*cr7+so,.+4, loads pc into LR */ | |
211 | { | |
212 | lr = (reg_unit) pc; | |
213 | continue; | |
214 | } | |
215 | if (ins == 0x4e800420) /* bctr */ | |
216 | { | |
217 | pc = (uint32_t *) ctr; | |
218 | continue; | |
219 | } | |
220 | if (ins == 0x44000002) /* sc */ | |
221 | return true; | |
222 | ||
223 | return false; | |
224 | } | |
225 | } | |
226 | ||
227 | /* These defines are from the kernel's bsd/dev/ppc/unix_signal.c. */ | |
228 | #define UC_TRAD 1 | |
229 | #define UC_TRAD_VEC 6 | |
230 | #define UC_TRAD64 20 | |
231 | #define UC_TRAD64_VEC 25 | |
232 | #define UC_FLAVOR 30 | |
233 | #define UC_FLAVOR_VEC 35 | |
234 | #define UC_FLAVOR64 40 | |
235 | #define UC_FLAVOR64_VEC 45 | |
236 | #define UC_DUAL 50 | |
237 | #define UC_DUAL_VEC 55 | |
238 | ||
239 | /* These are based on /usr/include/ppc/ucontext.h and | |
240 | /usr/include/mach/ppc/thread_status.h, but rewritten to be more | |
241 | convenient, to compile on Jaguar, and to work around Radar 3712064 | |
242 | on Panther, which is that the 'es' field of 'struct mcontext64' has | |
243 | the wrong type (doh!). */ | |
244 | ||
245 | struct gcc_mcontext64 { | |
246 | uint64_t dar; | |
247 | uint32_t dsisr; | |
248 | uint32_t exception; | |
249 | uint32_t padding1[4]; | |
250 | uint64_t srr0; | |
251 | uint64_t srr1; | |
252 | uint32_t gpr[32][2]; | |
253 | uint32_t cr; | |
254 | uint32_t xer[2]; /* These are arrays because the original structure has them misaligned. */ | |
255 | uint32_t lr[2]; | |
256 | uint32_t ctr[2]; | |
257 | uint32_t vrsave; | |
258 | ppc_float_state_t fs; | |
259 | ppc_vector_state_t vs; | |
260 | }; | |
261 | ||
262 | #define UC_FLAVOR_SIZE \ | |
263 | (sizeof (struct mcontext) - sizeof (ppc_vector_state_t)) | |
264 | ||
265 | #define UC_FLAVOR_VEC_SIZE (sizeof (struct mcontext)) | |
266 | ||
267 | #define UC_FLAVOR64_SIZE \ | |
268 | (sizeof (struct gcc_mcontext64) - sizeof (ppc_vector_state_t)) | |
269 | ||
270 | #define UC_FLAVOR64_VEC_SIZE (sizeof (struct gcc_mcontext64)) | |
271 | ||
272 | /* Given GPRS as input to a 'sc' instruction, and OLD_CFA, update FS | |
273 | to represent the execution of a signal return; or, if not a signal | |
274 | return, return false. */ | |
275 | ||
276 | static bool | |
277 | handle_syscall (_Unwind_FrameState *fs, const reg_unit gprs[32], | |
278 | _Unwind_Ptr old_cfa) | |
279 | { | |
280 | struct ucontext *uctx; | |
281 | bool is_64, is_vector; | |
282 | ppc_float_state_t *float_state; | |
283 | ppc_vector_state_t *vector_state; | |
284 | _Unwind_Ptr new_cfa; | |
285 | int i; | |
286 | static _Unwind_Ptr return_addr; | |
287 | ||
288 | /* Yay! We're in a Libc that we understand, and it's made a | |
289 | system call. It'll be one of two kinds: either a Jaguar-style | |
290 | SYS_sigreturn, or a Panther-style 'syscall' call with 184, which | |
291 | is also SYS_sigreturn. */ | |
292 | ||
293 | if (gprs[0] == 0x67 /* SYS_SIGRETURN */) | |
294 | { | |
295 | uctx = (struct ucontext *) gprs[3]; | |
296 | is_vector = (uctx->uc_mcsize == UC_FLAVOR64_VEC_SIZE | |
297 | || uctx->uc_mcsize == UC_FLAVOR_VEC_SIZE); | |
298 | is_64 = (uctx->uc_mcsize == UC_FLAVOR64_VEC_SIZE | |
299 | || uctx->uc_mcsize == UC_FLAVOR64_SIZE); | |
300 | } | |
301 | else if (gprs[0] == 0 && gprs[3] == 184) | |
302 | { | |
303 | int ctxstyle = gprs[5]; | |
304 | uctx = (struct ucontext *) gprs[4]; | |
305 | is_vector = (ctxstyle == UC_FLAVOR_VEC || ctxstyle == UC_FLAVOR64_VEC | |
306 | || ctxstyle == UC_TRAD_VEC || ctxstyle == UC_TRAD64_VEC); | |
307 | is_64 = (ctxstyle == UC_FLAVOR64_VEC || ctxstyle == UC_TRAD64_VEC | |
308 | || ctxstyle == UC_FLAVOR64 || ctxstyle == UC_TRAD64); | |
309 | } | |
310 | else | |
311 | return false; | |
312 | ||
313 | #define set_offset(r, addr) \ | |
314 | (fs->regs.reg[r].how = REG_SAVED_OFFSET, \ | |
315 | fs->regs.reg[r].loc.offset = (_Unwind_Ptr)(addr) - new_cfa) | |
316 | ||
317 | /* Restore even the registers that are not call-saved, since they | |
318 | might be being used in the prologue to save other registers, | |
319 | for instance GPR0 is sometimes used to save LR. */ | |
320 | ||
321 | /* Handle the GPRs, and produce the information needed to do the rest. */ | |
322 | if (is_64) | |
323 | { | |
324 | /* The context is 64-bit, but it doesn't carry any extra information | |
325 | for us because only the low 32 bits of the registers are | |
326 | call-saved. */ | |
327 | struct gcc_mcontext64 *m64 = (struct gcc_mcontext64 *)uctx->uc_mcontext; | |
328 | int i; | |
329 | ||
330 | float_state = &m64->fs; | |
331 | vector_state = &m64->vs; | |
332 | ||
333 | new_cfa = m64->gpr[1][1]; | |
334 | ||
335 | set_offset (CR2_REGNO, &m64->cr); | |
336 | for (i = 0; i < 32; i++) | |
337 | set_offset (i, m64->gpr[i] + 1); | |
338 | set_offset (XER_REGNO, m64->xer + 1); | |
339 | set_offset (LINK_REGISTER_REGNUM, m64->lr + 1); | |
340 | set_offset (COUNT_REGISTER_REGNUM, m64->ctr + 1); | |
341 | if (is_vector) | |
342 | set_offset (VRSAVE_REGNO, &m64->vrsave); | |
343 | ||
344 | /* Sometimes, srr0 points to the instruction that caused the exception, | |
345 | and sometimes to the next instruction to be executed; we want | |
346 | the latter. */ | |
347 | if (m64->exception == 3 || m64->exception == 4 | |
348 | || m64->exception == 6 | |
349 | || (m64->exception == 7 && !(m64->srr1 & 0x10000))) | |
350 | return_addr = m64->srr0 + 4; | |
351 | else | |
352 | return_addr = m64->srr0; | |
353 | } | |
354 | else | |
355 | { | |
356 | struct mcontext *m = uctx->uc_mcontext; | |
357 | int i; | |
358 | ||
359 | float_state = &m->fs; | |
360 | vector_state = &m->vs; | |
361 | ||
362 | new_cfa = m->ss.r1; | |
363 | ||
364 | set_offset (CR2_REGNO, &m->ss.cr); | |
365 | for (i = 0; i < 32; i++) | |
366 | set_offset (i, &m->ss.r0 + i); | |
367 | set_offset (XER_REGNO, &m->ss.xer); | |
368 | set_offset (LINK_REGISTER_REGNUM, &m->ss.lr); | |
369 | set_offset (COUNT_REGISTER_REGNUM, &m->ss.ctr); | |
370 | ||
371 | if (is_vector) | |
372 | set_offset (VRSAVE_REGNO, &m->ss.vrsave); | |
373 | ||
374 | /* Sometimes, srr0 points to the instruction that caused the exception, | |
375 | and sometimes to the next instruction to be executed; we want | |
376 | the latter. */ | |
377 | if (m->es.exception == 3 || m->es.exception == 4 | |
378 | || m->es.exception == 6 | |
379 | || (m->es.exception == 7 && !(m->ss.srr1 & 0x10000))) | |
380 | return_addr = m->ss.srr0 + 4; | |
381 | else | |
382 | return_addr = m->ss.srr0; | |
383 | } | |
384 | ||
385 | fs->cfa_how = CFA_REG_OFFSET; | |
386 | fs->cfa_reg = STACK_POINTER_REGNUM; | |
387 | fs->cfa_offset = new_cfa - old_cfa;; | |
388 | ||
389 | /* The choice of column for the return address is somewhat tricky. | |
390 | Fortunately, the actual choice is private to this file, and | |
391 | the space it's reserved from is the GCC register space, not the | |
392 | DWARF2 numbering. So any free element of the right size is an OK | |
393 | choice. Thus: */ | |
394 | fs->retaddr_column = ARG_POINTER_REGNUM; | |
395 | /* FIXME: this should really be done using a DWARF2 location expression, | |
396 | not using a static variable. In fact, this entire file should | |
397 | be implemented in DWARF2 expressions. */ | |
398 | set_offset (ARG_POINTER_REGNUM, &return_addr); | |
399 | ||
400 | for (i = 0; i < 32; i++) | |
401 | set_offset (32 + i, float_state->fpregs + i); | |
402 | set_offset (SPEFSCR_REGNO, &float_state->fpscr); | |
403 | ||
404 | if (is_vector) | |
405 | { | |
406 | for (i = 0; i < 32; i++) | |
407 | set_offset (FIRST_ALTIVEC_REGNO + i, vector_state->save_vr + i); | |
408 | set_offset (VSCR_REGNO, vector_state->save_vscr); | |
409 | } | |
410 | ||
411 | return true; | |
412 | } | |
413 | ||
414 | /* This is also prototyped in rs6000/darwin.h, inside the | |
415 | MD_FALLBACK_FRAME_STATE_FOR macro. */ | |
416 | extern bool _Unwind_fallback_frame_state_for (struct _Unwind_Context *context, | |
417 | _Unwind_FrameState *fs); | |
418 | ||
419 | /* Implement the MD_FALLBACK_FRAME_STATE_FOR macro, | |
420 | returning true iff the frame was a sigreturn() frame that we | |
421 | can understand. */ | |
422 | ||
423 | bool | |
424 | _Unwind_fallback_frame_state_for (struct _Unwind_Context *context, | |
425 | _Unwind_FrameState *fs) | |
426 | { | |
427 | reg_unit gprs[32]; | |
428 | ||
429 | if (!interpret_libc (gprs, context)) | |
430 | return false; | |
431 | return handle_syscall (fs, gprs, _Unwind_GetCFA (context)); | |
432 | } |