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root/cebix/BasiliskII/src/Unix/sigsegv.cpp
Revision: 1.24
Committed: 2003-09-29T07:02:58Z (20 years, 11 months ago) by gbeauche
Branch: MAIN
Changes since 1.23: +13 -74 lines
Log Message: 
New SIGSEGV API so that skip-instruction requests are more explicit. Yes,
that's api change, but that's cooler now for SheepShaver. ;-)

File Contents

# Content
1 /*
2 * sigsegv.cpp - SIGSEGV signals support
3 *
4 * Derived from Bruno Haible's work on his SIGSEGV library for clisp
5 * <http://clisp.sourceforge.net/>
6 *
7 * Basilisk II (C) 1997-2002 Christian Bauer
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 */
23
24 #ifdef HAVE_UNISTD_H
25 #include <unistd.h>
26 #endif
27
28 #ifdef HAVE_CONFIG_H
29 #include "config.h"
30 #endif
31
32 #include <list>
33 #include <signal.h>
34 #include "sigsegv.h"
35
36 #ifndef NO_STD_NAMESPACE
37 using std::list;
38 #endif
39
40 // Return value type of a signal handler (standard type if not defined)
41 #ifndef RETSIGTYPE
42 #define RETSIGTYPE void
43 #endif
44
45 // Type of the system signal handler
46 typedef RETSIGTYPE (*signal_handler)(int);
47
48 // User's SIGSEGV handler
49 static sigsegv_fault_handler_t sigsegv_fault_handler = 0;
50
51 // Function called to dump state if we can't handle the fault
52 static sigsegv_state_dumper_t sigsegv_state_dumper = 0;
53
54 // Actual SIGSEGV handler installer
55 static bool sigsegv_do_install_handler(int sig);
56
57
58 /*
59 * Instruction decoding aids
60 */
61
62 // Transfer size
63 enum transfer_size_t {
64 SIZE_UNKNOWN,
65 SIZE_BYTE,
66 SIZE_WORD,
67 SIZE_LONG
68 };
69
70 // Transfer type
71 typedef sigsegv_transfer_type_t transfer_type_t;
72
73 #if (defined(powerpc) || defined(__powerpc__) || defined(__ppc__))
74 // Addressing mode
75 enum addressing_mode_t {
76 MODE_UNKNOWN,
77 MODE_NORM,
78 MODE_U,
79 MODE_X,
80 MODE_UX
81 };
82
83 // Decoded instruction
84 struct instruction_t {
85 transfer_type_t transfer_type;
86 transfer_size_t transfer_size;
87 addressing_mode_t addr_mode;
88 unsigned int addr;
89 char ra, rd;
90 };
91
92 static void powerpc_decode_instruction(instruction_t *instruction, unsigned int nip, unsigned int * gpr)
93 {
94 // Get opcode and divide into fields
95 unsigned int opcode = *((unsigned int *)nip);
96 unsigned int primop = opcode >> 26;
97 unsigned int exop = (opcode >> 1) & 0x3ff;
98 unsigned int ra = (opcode >> 16) & 0x1f;
99 unsigned int rb = (opcode >> 11) & 0x1f;
100 unsigned int rd = (opcode >> 21) & 0x1f;
101 signed int imm = (signed short)(opcode & 0xffff);
102
103 // Analyze opcode
104 transfer_type_t transfer_type = SIGSEGV_TRANSFER_UNKNOWN;
105 transfer_size_t transfer_size = SIZE_UNKNOWN;
106 addressing_mode_t addr_mode = MODE_UNKNOWN;
107 switch (primop) {
108 case 31:
109 switch (exop) {
110 case 23: // lwzx
111 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_X; break;
112 case 55: // lwzux
113 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_UX; break;
114 case 87: // lbzx
115 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_X; break;
116 case 119: // lbzux
117 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_UX; break;
118 case 151: // stwx
119 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_X; break;
120 case 183: // stwux
121 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_UX; break;
122 case 215: // stbx
123 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_X; break;
124 case 247: // stbux
125 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_UX; break;
126 case 279: // lhzx
127 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_X; break;
128 case 311: // lhzux
129 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_UX; break;
130 case 343: // lhax
131 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_X; break;
132 case 375: // lhaux
133 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_UX; break;
134 case 407: // sthx
135 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_X; break;
136 case 439: // sthux
137 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_UX; break;
138 }
139 break;
140
141 case 32: // lwz
142 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_NORM; break;
143 case 33: // lwzu
144 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_U; break;
145 case 34: // lbz
146 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_NORM; break;
147 case 35: // lbzu
148 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_U; break;
149 case 36: // stw
150 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_NORM; break;
151 case 37: // stwu
152 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_U; break;
153 case 38: // stb
154 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_NORM; break;
155 case 39: // stbu
156 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_U; break;
157 case 40: // lhz
158 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_NORM; break;
159 case 41: // lhzu
160 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_U; break;
161 case 42: // lha
162 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_NORM; break;
163 case 43: // lhau
164 transfer_type = SIGSEGV_TRANSFER_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_U; break;
165 case 44: // sth
166 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_NORM; break;
167 case 45: // sthu
168 transfer_type = SIGSEGV_TRANSFER_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_U; break;
169 }
170
171 // Calculate effective address
172 unsigned int addr = 0;
173 switch (addr_mode) {
174 case MODE_X:
175 case MODE_UX:
176 if (ra == 0)
177 addr = gpr[rb];
178 else
179 addr = gpr[ra] + gpr[rb];
180 break;
181 case MODE_NORM:
182 case MODE_U:
183 if (ra == 0)
184 addr = (signed int)(signed short)imm;
185 else
186 addr = gpr[ra] + (signed int)(signed short)imm;
187 break;
188 default:
189 break;
190 }
191
192 // Commit decoded instruction
193 instruction->addr = addr;
194 instruction->addr_mode = addr_mode;
195 instruction->transfer_type = transfer_type;
196 instruction->transfer_size = transfer_size;
197 instruction->ra = ra;
198 instruction->rd = rd;
199 }
200 #endif
201
202
203 /*
204 * OS-dependant SIGSEGV signals support section
205 */
206
207 #if HAVE_SIGINFO_T
208 // Generic extended signal handler
209 #if defined(__NetBSD__) || defined(__FreeBSD__)
210 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGBUS)
211 #else
212 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
213 #endif
214 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, siginfo_t *sip, void *scp
215 #define SIGSEGV_FAULT_ADDRESS sip->si_addr
216 #if defined(__NetBSD__) || defined(__FreeBSD__)
217 #if (defined(i386) || defined(__i386__))
218 #define SIGSEGV_FAULT_INSTRUCTION (((struct sigcontext *)scp)->sc_eip)
219 #define SIGSEGV_REGISTER_FILE ((unsigned int *)&(((struct sigcontext *)scp)->sc_edi)) /* EDI is the first GPR (even below EIP) in sigcontext */
220 #define SIGSEGV_SKIP_INSTRUCTION ix86_skip_instruction
221 #endif
222 #endif
223 #if defined(__linux__)
224 #if (defined(i386) || defined(__i386__))
225 #include <sys/ucontext.h>
226 #define SIGSEGV_CONTEXT_REGS (((ucontext_t *)scp)->uc_mcontext.gregs)
227 #define SIGSEGV_FAULT_INSTRUCTION SIGSEGV_CONTEXT_REGS[14] /* should use REG_EIP instead */
228 #define SIGSEGV_REGISTER_FILE (unsigned int *)SIGSEGV_CONTEXT_REGS
229 #define SIGSEGV_SKIP_INSTRUCTION ix86_skip_instruction
230 #endif
231 #if (defined(x86_64) || defined(__x86_64__))
232 #include <sys/ucontext.h>
233 #define SIGSEGV_CONTEXT_REGS (((ucontext_t *)scp)->uc_mcontext.gregs)
234 #define SIGSEGV_FAULT_INSTRUCTION SIGSEGV_CONTEXT_REGS[16] /* should use REG_RIP instead */
235 #define SIGSEGV_REGISTER_FILE (unsigned long *)SIGSEGV_CONTEXT_REGS
236 #endif
237 #if (defined(ia64) || defined(__ia64__))
238 #define SIGSEGV_FAULT_INSTRUCTION (((struct sigcontext *)scp)->sc_ip & ~0x3ULL) /* slot number is in bits 0 and 1 */
239 #endif
240 #if (defined(powerpc) || defined(__powerpc__))
241 #include <sys/ucontext.h>
242 #define SIGSEGV_CONTEXT_REGS (((ucontext_t *)scp)->uc_mcontext.regs)
243 #define SIGSEGV_FAULT_INSTRUCTION (SIGSEGV_CONTEXT_REGS->nip)
244 #define SIGSEGV_REGISTER_FILE (unsigned int *)&SIGSEGV_CONTEXT_REGS->nip, (unsigned int *)(SIGSEGV_CONTEXT_REGS->gpr)
245 #define SIGSEGV_SKIP_INSTRUCTION powerpc_skip_instruction
246 #endif
247 #endif
248 #endif
249
250 #if HAVE_SIGCONTEXT_SUBTERFUGE
251 // Linux kernels prior to 2.4 ?
252 #if defined(__linux__)
253 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
254 #if (defined(i386) || defined(__i386__))
255 #include <asm/sigcontext.h>
256 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, struct sigcontext scs
257 #define SIGSEGV_FAULT_ADDRESS scs.cr2
258 #define SIGSEGV_FAULT_INSTRUCTION scs.eip
259 #define SIGSEGV_REGISTER_FILE (unsigned int *)(&scs)
260 #define SIGSEGV_SKIP_INSTRUCTION ix86_skip_instruction
261 #endif
262 #if (defined(sparc) || defined(__sparc__))
263 #include <asm/sigcontext.h>
264 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp, char *addr
265 #define SIGSEGV_FAULT_ADDRESS addr
266 #endif
267 #if (defined(powerpc) || defined(__powerpc__))
268 #include <asm/sigcontext.h>
269 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, struct sigcontext *scp
270 #define SIGSEGV_FAULT_ADDRESS scp->regs->dar
271 #define SIGSEGV_FAULT_INSTRUCTION scp->regs->nip
272 #define SIGSEGV_REGISTER_FILE (unsigned int *)&scp->regs->nip, (unsigned int *)(scp->regs->gpr)
273 #define SIGSEGV_SKIP_INSTRUCTION powerpc_skip_instruction
274 #endif
275 #if (defined(alpha) || defined(__alpha__))
276 #include <asm/sigcontext.h>
277 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
278 #define SIGSEGV_FAULT_ADDRESS get_fault_address(scp)
279 #define SIGSEGV_FAULT_INSTRUCTION scp->sc_pc
280
281 // From Boehm's GC 6.0alpha8
282 static sigsegv_address_t get_fault_address(struct sigcontext *scp)
283 {
284 unsigned int instruction = *((unsigned int *)(scp->sc_pc));
285 unsigned long fault_address = scp->sc_regs[(instruction >> 16) & 0x1f];
286 fault_address += (signed long)(signed short)(instruction & 0xffff);
287 return (sigsegv_address_t)fault_address;
288 }
289 #endif
290 #endif
291
292 // Irix 5 or 6 on MIPS
293 #if (defined(sgi) || defined(__sgi)) && (defined(SYSTYPE_SVR4) || defined(__SYSTYPE_SVR4))
294 #include <ucontext.h>
295 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
296 #define SIGSEGV_FAULT_ADDRESS scp->sc_badvaddr
297 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
298 #endif
299
300 // HP-UX
301 #if (defined(hpux) || defined(__hpux__))
302 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
303 #define SIGSEGV_FAULT_ADDRESS scp->sc_sl.sl_ss.ss_narrow.ss_cr21
304 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV) FAULT_HANDLER(SIGBUS)
305 #endif
306
307 // OSF/1 on Alpha
308 #if defined(__osf__)
309 #include <ucontext.h>
310 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
311 #define SIGSEGV_FAULT_ADDRESS scp->sc_traparg_a0
312 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
313 #endif
314
315 // AIX
316 #if defined(_AIX)
317 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
318 #define SIGSEGV_FAULT_ADDRESS scp->sc_jmpbuf.jmp_context.o_vaddr
319 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
320 #endif
321
322 // NetBSD or FreeBSD
323 #if defined(__NetBSD__) || defined(__FreeBSD__)
324 #if (defined(m68k) || defined(__m68k__))
325 #include <m68k/frame.h>
326 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
327 #define SIGSEGV_FAULT_ADDRESS get_fault_address(scp)
328 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
329
330 // Use decoding scheme from BasiliskII/m68k native
331 static sigsegv_address_t get_fault_address(struct sigcontext *scp)
332 {
333 struct sigstate {
334 int ss_flags;
335 struct frame ss_frame;
336 };
337 struct sigstate *state = (struct sigstate *)scp->sc_ap;
338 char *fault_addr;
339 switch (state->ss_frame.f_format) {
340 case 7: /* 68040 access error */
341 /* "code" is sometimes unreliable (i.e. contains NULL or a bogus address), reason unknown */
342 fault_addr = state->ss_frame.f_fmt7.f_fa;
343 break;
344 default:
345 fault_addr = (char *)code;
346 break;
347 }
348 return (sigsegv_address_t)fault_addr;
349 }
350 #else
351 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, void *scp, char *addr
352 #define SIGSEGV_FAULT_ADDRESS addr
353 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGBUS)
354 #endif
355 #endif
356
357 // MacOS X
358 #if defined(__APPLE__) && defined(__MACH__)
359 #if (defined(ppc) || defined(__ppc__))
360 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
361 #define SIGSEGV_FAULT_ADDRESS get_fault_address(scp)
362 #define SIGSEGV_FAULT_INSTRUCTION scp->sc_ir
363 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGBUS)
364 #define SIGSEGV_REGISTER_FILE (unsigned int *)&scp->sc_ir, &((unsigned int *) scp->sc_regs)[2]
365 #define SIGSEGV_SKIP_INSTRUCTION powerpc_skip_instruction
366
367 // Use decoding scheme from SheepShaver
368 static sigsegv_address_t get_fault_address(struct sigcontext *scp)
369 {
370 unsigned int nip = (unsigned int) scp->sc_ir;
371 unsigned int * gpr = &((unsigned int *) scp->sc_regs)[2];
372 instruction_t instr;
373
374 powerpc_decode_instruction(&instr, nip, gpr);
375 return (sigsegv_address_t)instr.addr;
376 }
377 #endif
378 #endif
379 #endif
380
381
382 /*
383 * Instruction skipping
384 */
385
386 #ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
387 // Decode and skip X86 instruction
388 #if (defined(i386) || defined(__i386__))
389 #if defined(__linux__)
390 enum {
391 X86_REG_EIP = 14,
392 X86_REG_EAX = 11,
393 X86_REG_ECX = 10,
394 X86_REG_EDX = 9,
395 X86_REG_EBX = 8,
396 X86_REG_ESP = 7,
397 X86_REG_EBP = 6,
398 X86_REG_ESI = 5,
399 X86_REG_EDI = 4
400 };
401 #endif
402 #if defined(__NetBSD__) || defined(__FreeBSD__)
403 enum {
404 X86_REG_EIP = 10,
405 X86_REG_EAX = 7,
406 X86_REG_ECX = 6,
407 X86_REG_EDX = 5,
408 X86_REG_EBX = 4,
409 X86_REG_ESP = 13,
410 X86_REG_EBP = 2,
411 X86_REG_ESI = 1,
412 X86_REG_EDI = 0
413 };
414 #endif
415 // FIXME: this is partly redundant with the instruction decoding phase
416 // to discover transfer type and register number
417 static inline int ix86_step_over_modrm(unsigned char * p)
418 {
419 int mod = (p[0] >> 6) & 3;
420 int rm = p[0] & 7;
421 int offset = 0;
422
423 // ModR/M Byte
424 switch (mod) {
425 case 0: // [reg]
426 if (rm == 5) return 4; // disp32
427 break;
428 case 1: // disp8[reg]
429 offset = 1;
430 break;
431 case 2: // disp32[reg]
432 offset = 4;
433 break;
434 case 3: // register
435 return 0;
436 }
437
438 // SIB Byte
439 if (rm == 4) {
440 if (mod == 0 && (p[1] & 7) == 5)
441 offset = 5; // disp32[index]
442 else
443 offset++;
444 }
445
446 return offset;
447 }
448
449 static bool ix86_skip_instruction(unsigned int * regs)
450 {
451 unsigned char * eip = (unsigned char *)regs[X86_REG_EIP];
452
453 if (eip == 0)
454 return false;
455
456 transfer_type_t transfer_type = SIGSEGV_TRANSFER_UNKNOWN;
457 transfer_size_t transfer_size = SIZE_LONG;
458
459 int reg = -1;
460 int len = 0;
461
462 // Operand size prefix
463 if (*eip == 0x66) {
464 eip++;
465 len++;
466 transfer_size = SIZE_WORD;
467 }
468
469 // Decode instruction
470 switch (eip[0]) {
471 case 0x0f:
472 switch (eip[1]) {
473 case 0xb6: // MOVZX r32, r/m8
474 case 0xb7: // MOVZX r32, r/m16
475 switch (eip[2] & 0xc0) {
476 case 0x80:
477 reg = (eip[2] >> 3) & 7;
478 transfer_type = SIGSEGV_TRANSFER_LOAD;
479 break;
480 case 0x40:
481 reg = (eip[2] >> 3) & 7;
482 transfer_type = SIGSEGV_TRANSFER_LOAD;
483 break;
484 case 0x00:
485 reg = (eip[2] >> 3) & 7;
486 transfer_type = SIGSEGV_TRANSFER_LOAD;
487 break;
488 }
489 len += 3 + ix86_step_over_modrm(eip + 2);
490 break;
491 }
492 break;
493 case 0x8a: // MOV r8, r/m8
494 transfer_size = SIZE_BYTE;
495 case 0x8b: // MOV r32, r/m32 (or 16-bit operation)
496 switch (eip[1] & 0xc0) {
497 case 0x80:
498 reg = (eip[1] >> 3) & 7;
499 transfer_type = SIGSEGV_TRANSFER_LOAD;
500 break;
501 case 0x40:
502 reg = (eip[1] >> 3) & 7;
503 transfer_type = SIGSEGV_TRANSFER_LOAD;
504 break;
505 case 0x00:
506 reg = (eip[1] >> 3) & 7;
507 transfer_type = SIGSEGV_TRANSFER_LOAD;
508 break;
509 }
510 len += 2 + ix86_step_over_modrm(eip + 1);
511 break;
512 case 0x88: // MOV r/m8, r8
513 transfer_size = SIZE_BYTE;
514 case 0x89: // MOV r/m32, r32 (or 16-bit operation)
515 switch (eip[1] & 0xc0) {
516 case 0x80:
517 reg = (eip[1] >> 3) & 7;
518 transfer_type = SIGSEGV_TRANSFER_STORE;
519 break;
520 case 0x40:
521 reg = (eip[1] >> 3) & 7;
522 transfer_type = SIGSEGV_TRANSFER_STORE;
523 break;
524 case 0x00:
525 reg = (eip[1] >> 3) & 7;
526 transfer_type = SIGSEGV_TRANSFER_STORE;
527 break;
528 }
529 len += 2 + ix86_step_over_modrm(eip + 1);
530 break;
531 }
532
533 if (transfer_type == SIGSEGV_TRANSFER_UNKNOWN) {
534 // Unknown machine code, let it crash. Then patch the decoder
535 return false;
536 }
537
538 if (transfer_type == SIGSEGV_TRANSFER_LOAD && reg != -1) {
539 static const int x86_reg_map[8] = {
540 X86_REG_EAX, X86_REG_ECX, X86_REG_EDX, X86_REG_EBX,
541 X86_REG_ESP, X86_REG_EBP, X86_REG_ESI, X86_REG_EDI
542 };
543
544 if (reg < 0 || reg >= 8)
545 return false;
546
547 int rloc = x86_reg_map[reg];
548 switch (transfer_size) {
549 case SIZE_BYTE:
550 regs[rloc] = (regs[rloc] & ~0xff);
551 break;
552 case SIZE_WORD:
553 regs[rloc] = (regs[rloc] & ~0xffff);
554 break;
555 case SIZE_LONG:
556 regs[rloc] = 0;
557 break;
558 }
559 }
560
561 #if DEBUG
562 printf("%08x: %s %s access", regs[X86_REG_EIP],
563 transfer_size == SIZE_BYTE ? "byte" : transfer_size == SIZE_WORD ? "word" : "long",
564 transfer_type == SIGSEGV_TRANSFER_LOAD ? "read" : "write");
565
566 if (reg != -1) {
567 static const char * x86_reg_str_map[8] = {
568 "eax", "ecx", "edx", "ebx",
569 "esp", "ebp", "esi", "edi"
570 };
571 printf(" %s register %%%s", transfer_type == SIGSEGV_TRANSFER_LOAD ? "to" : "from", x86_reg_str_map[reg]);
572 }
573 printf(", %d bytes instruction\n", len);
574 #endif
575
576 regs[X86_REG_EIP] += len;
577 return true;
578 }
579 #endif
580
581 // Decode and skip PPC instruction
582 #if (defined(powerpc) || defined(__powerpc__) || defined(__ppc__))
583 static bool powerpc_skip_instruction(unsigned int * nip_p, unsigned int * regs)
584 {
585 instruction_t instr;
586 powerpc_decode_instruction(&instr, *nip_p, regs);
587
588 if (instr.transfer_type == SIGSEGV_TRANSFER_UNKNOWN) {
589 // Unknown machine code, let it crash. Then patch the decoder
590 return false;
591 }
592
593 #if DEBUG
594 printf("%08x: %s %s access", *nip_p,
595 instr.transfer_size == SIZE_BYTE ? "byte" : instr.transfer_size == SIZE_WORD ? "word" : "long",
596 instr.transfer_type == SIGSEGV_TRANSFER_LOAD ? "read" : "write");
597
598 if (instr.addr_mode == MODE_U || instr.addr_mode == MODE_UX)
599 printf(" r%d (ra = %08x)\n", instr.ra, instr.addr);
600 if (instr.transfer_type == SIGSEGV_TRANSFER_LOAD)
601 printf(" r%d (rd = 0)\n", instr.rd);
602 #endif
603
604 if (instr.addr_mode == MODE_U || instr.addr_mode == MODE_UX)
605 regs[instr.ra] = instr.addr;
606 if (instr.transfer_type == SIGSEGV_TRANSFER_LOAD)
607 regs[instr.rd] = 0;
608
609 *nip_p += 4;
610 return true;
611 }
612 #endif
613 #endif
614
615 // Fallbacks
616 #ifndef SIGSEGV_FAULT_INSTRUCTION
617 #define SIGSEGV_FAULT_INSTRUCTION SIGSEGV_INVALID_PC
618 #endif
619
620 // SIGSEGV recovery supported ?
621 #if defined(SIGSEGV_ALL_SIGNALS) && defined(SIGSEGV_FAULT_HANDLER_ARGLIST) && defined(SIGSEGV_FAULT_ADDRESS)
622 #define HAVE_SIGSEGV_RECOVERY
623 #endif
624
625
626 /*
627 * SIGSEGV global handler
628 */
629
630 #ifdef HAVE_SIGSEGV_RECOVERY
631 static void sigsegv_handler(SIGSEGV_FAULT_HANDLER_ARGLIST)
632 {
633 sigsegv_address_t fault_address = (sigsegv_address_t)SIGSEGV_FAULT_ADDRESS;
634 sigsegv_address_t fault_instruction = (sigsegv_address_t)SIGSEGV_FAULT_INSTRUCTION;
635 bool fault_recovered = false;
636
637 // Call user's handler and reinstall the global handler, if required
638 switch (sigsegv_fault_handler(fault_address, fault_instruction)) {
639 case SIGSEGV_RETURN_SUCCESS:
640 #if (defined(HAVE_SIGACTION) ? defined(SIGACTION_NEED_REINSTALL) : defined(SIGNAL_NEED_REINSTALL))
641 sigsegv_do_install_handler(sig);
642 #endif
643 fault_recovered = true;
644 break;
645 #if HAVE_SIGSEGV_SKIP_INSTRUCTION
646 case SIGSEGV_RETURN_SKIP_INSTRUCTION:
647 // Call the instruction skipper with the register file available
648 if (SIGSEGV_SKIP_INSTRUCTION(SIGSEGV_REGISTER_FILE))
649 fault_recovered = true;
650 break;
651 #endif
652 }
653
654 if (!fault_recovered) {
655 // Failure: reinstall default handler for "safe" crash
656 #define FAULT_HANDLER(sig) signal(sig, SIG_DFL);
657 SIGSEGV_ALL_SIGNALS
658 #undef FAULT_HANDLER
659
660 // We can't do anything with the fault_address, dump state?
661 if (sigsegv_state_dumper != 0)
662 sigsegv_state_dumper(fault_address, fault_instruction);
663 }
664 }
665 #endif
666
667
668 /*
669 * SIGSEGV handler initialization
670 */
671
672 #if defined(HAVE_SIGINFO_T)
673 static bool sigsegv_do_install_handler(int sig)
674 {
675 // Setup SIGSEGV handler to process writes to frame buffer
676 #ifdef HAVE_SIGACTION
677 struct sigaction sigsegv_sa;
678 sigemptyset(&sigsegv_sa.sa_mask);
679 sigsegv_sa.sa_sigaction = sigsegv_handler;
680 sigsegv_sa.sa_flags = SA_SIGINFO;
681 return (sigaction(sig, &sigsegv_sa, 0) == 0);
682 #else
683 return (signal(sig, (signal_handler)sigsegv_handler) != SIG_ERR);
684 #endif
685 }
686 #endif
687
688 #if defined(HAVE_SIGCONTEXT_SUBTERFUGE)
689 static bool sigsegv_do_install_handler(int sig)
690 {
691 // Setup SIGSEGV handler to process writes to frame buffer
692 #ifdef HAVE_SIGACTION
693 struct sigaction sigsegv_sa;
694 sigemptyset(&sigsegv_sa.sa_mask);
695 sigsegv_sa.sa_handler = (signal_handler)sigsegv_handler;
696 sigsegv_sa.sa_flags = 0;
697 #if !EMULATED_68K && defined(__NetBSD__)
698 sigaddset(&sigsegv_sa.sa_mask, SIGALRM);
699 sigsegv_sa.sa_flags |= SA_ONSTACK;
700 #endif
701 return (sigaction(sig, &sigsegv_sa, 0) == 0);
702 #else
703 return (signal(sig, (signal_handler)sigsegv_handler) != SIG_ERR);
704 #endif
705 }
706 #endif
707
708 bool sigsegv_install_handler(sigsegv_fault_handler_t handler)
709 {
710 #ifdef HAVE_SIGSEGV_RECOVERY
711 sigsegv_fault_handler = handler;
712 bool success = true;
713 #define FAULT_HANDLER(sig) success = success && sigsegv_do_install_handler(sig);
714 SIGSEGV_ALL_SIGNALS
715 #undef FAULT_HANDLER
716 return success;
717 #else
718 // FAIL: no siginfo_t nor sigcontext subterfuge is available
719 return false;
720 #endif
721 }
722
723
724 /*
725 * SIGSEGV handler deinitialization
726 */
727
728 void sigsegv_deinstall_handler(void)
729 {
730 #ifdef HAVE_SIGSEGV_RECOVERY
731 sigsegv_fault_handler = 0;
732 #define FAULT_HANDLER(sig) signal(sig, SIG_DFL);
733 SIGSEGV_ALL_SIGNALS
734 #undef FAULT_HANDLER
735 #endif
736 }
737
738
739 /*
740 * Set callback function when we cannot handle the fault
741 */
742
743 void sigsegv_set_dump_state(sigsegv_state_dumper_t handler)
744 {
745 sigsegv_state_dumper = handler;
746 }
747
748
749 /*
750 * Test program used for configure/test
751 */
752
753 #ifdef CONFIGURE_TEST_SIGSEGV_RECOVERY
754 #include <stdio.h>
755 #include <stdlib.h>
756 #include <fcntl.h>
757 #include <sys/mman.h>
758 #include "vm_alloc.h"
759
760 static int page_size;
761 static volatile char * page = 0;
762 static volatile int handler_called = 0;
763
764 static sigsegv_return_t sigsegv_test_handler(sigsegv_address_t fault_address, sigsegv_address_t instruction_address)
765 {
766 handler_called++;
767 if ((fault_address - 123) != page)
768 exit(1);
769 if (vm_protect((char *)((unsigned long)fault_address & -page_size), page_size, VM_PAGE_READ | VM_PAGE_WRITE) != 0)
770 exit(1);
771 return SIGSEGV_RETURN_SUCCESS;
772 }
773
774 #ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
775 static sigsegv_return_t sigsegv_insn_handler(sigsegv_address_t fault_address, sigsegv_address_t instruction_address)
776 {
777 if (((unsigned long)fault_address - (unsigned long)page) < page_size)
778 return SIGSEGV_SRETURN_KIP_INSTRUCTION;
779 return SIGSEGV_RETURN_FAILURE;
780 }
781 #endif
782
783 int main(void)
784 {
785 if (vm_init() < 0)
786 return 1;
787
788 page_size = getpagesize();
789 if ((page = (char *)vm_acquire(page_size)) == VM_MAP_FAILED)
790 return 1;
791
792 if (vm_protect((char *)page, page_size, VM_PAGE_READ) < 0)
793 return 1;
794
795 if (!sigsegv_install_handler(sigsegv_test_handler))
796 return 1;
797
798 page[123] = 45;
799 page[123] = 45;
800
801 if (handler_called != 1)
802 return 1;
803
804 #ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
805 if (!sigsegv_install_handler(sigsegv_insn_handler))
806 return 1;
807
808 if (vm_protect((char *)page, page_size, VM_PAGE_READ | VM_PAGE_WRITE) < 0)
809 return 1;
810
811 for (int i = 0; i < page_size; i++)
812 page[i] = (i + 1) % page_size;
813
814 if (vm_protect((char *)page, page_size, VM_PAGE_NOACCESS) < 0)
815 return 1;
816
817 #define TEST_SKIP_INSTRUCTION(TYPE) do { \
818 const unsigned int TAG = 0x12345678; \
819 TYPE data = *((TYPE *)(page + sizeof(TYPE))); \
820 volatile unsigned int effect = data + TAG; \
821 if (effect != TAG) \
822 return 1; \
823 } while (0)
824
825 TEST_SKIP_INSTRUCTION(unsigned char);
826 TEST_SKIP_INSTRUCTION(unsigned short);
827 TEST_SKIP_INSTRUCTION(unsigned int);
828 #endif
829
830 vm_exit();
831 return 0;
832 }
833 #endif