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root/cebix/BasiliskII/src/Unix/sigsegv.cpp
Revision: 1.17
Committed: 2002-05-20T17:49:04Z (22 years, 5 months ago) by gbeauche
Branch: MAIN
Changes since 1.16: +38 -1 lines
Log Message:
Implement "ignoresegv" feature on FreeBSD/x86 (tested on FreeBSD 4.5)
- sigsegv.cpp (ix86_skip_instruction): Add decoder for movzwl instructions.
  (main): oddly, FreeBSD doesn't seem to let a write to a page if it is
  write-only. Aka. make the page readable too.

File Contents

# User Rev Content
1 gbeauche 1.1 /*
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 cebix 1.7 * Basilisk II (C) 1997-2002 Christian Bauer
8 gbeauche 1.1 *
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 <signal.h>
33     #include "sigsegv.h"
34    
35     // Return value type of a signal handler (standard type if not defined)
36     #ifndef RETSIGTYPE
37     #define RETSIGTYPE void
38     #endif
39    
40     // Type of the system signal handler
41     typedef RETSIGTYPE (*signal_handler)(int);
42    
43 gbeauche 1.10 // Is the fault to be ignored?
44     static bool sigsegv_ignore_fault = false;
45    
46 gbeauche 1.1 // User's SIGSEGV handler
47 gbeauche 1.12 static sigsegv_fault_handler_t sigsegv_fault_handler = 0;
48 gbeauche 1.1
49 gbeauche 1.10 // Function called to dump state if we can't handle the fault
50 gbeauche 1.12 static sigsegv_state_dumper_t sigsegv_state_dumper = 0;
51 gbeauche 1.10
52 gbeauche 1.1 // Actual SIGSEGV handler installer
53     static bool sigsegv_do_install_handler(int sig);
54    
55    
56     /*
57 gbeauche 1.14 * Instruction decoding aids
58     */
59    
60     // Transfer type
61     enum transfer_type_t {
62     TYPE_UNKNOWN,
63     TYPE_LOAD,
64     TYPE_STORE
65     };
66    
67     // Transfer size
68     enum transfer_size_t {
69     SIZE_UNKNOWN,
70     SIZE_BYTE,
71     SIZE_WORD,
72     SIZE_LONG
73     };
74    
75     #if (defined(powerpc) || defined(__powerpc__) || defined(__ppc__))
76     // Addressing mode
77     enum addressing_mode_t {
78     MODE_UNKNOWN,
79     MODE_NORM,
80     MODE_U,
81     MODE_X,
82     MODE_UX
83     };
84    
85     // Decoded instruction
86     struct instruction_t {
87     transfer_type_t transfer_type;
88     transfer_size_t transfer_size;
89     addressing_mode_t addr_mode;
90     unsigned int addr;
91     char ra, rd;
92     };
93    
94     static void powerpc_decode_instruction(instruction_t *instruction, unsigned int nip, unsigned int * gpr)
95     {
96     // Get opcode and divide into fields
97     unsigned int opcode = *((unsigned int *)nip);
98     unsigned int primop = opcode >> 26;
99     unsigned int exop = (opcode >> 1) & 0x3ff;
100     unsigned int ra = (opcode >> 16) & 0x1f;
101     unsigned int rb = (opcode >> 11) & 0x1f;
102     unsigned int rd = (opcode >> 21) & 0x1f;
103     signed int imm = (signed short)(opcode & 0xffff);
104    
105     // Analyze opcode
106     transfer_type_t transfer_type = TYPE_UNKNOWN;
107     transfer_size_t transfer_size = SIZE_UNKNOWN;
108     addressing_mode_t addr_mode = MODE_UNKNOWN;
109     switch (primop) {
110     case 31:
111     switch (exop) {
112     case 23: // lwzx
113     transfer_type = TYPE_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_X; break;
114     case 55: // lwzux
115     transfer_type = TYPE_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_UX; break;
116     case 87: // lbzx
117     transfer_type = TYPE_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_X; break;
118     case 119: // lbzux
119     transfer_type = TYPE_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_UX; break;
120     case 151: // stwx
121     transfer_type = TYPE_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_X; break;
122     case 183: // stwux
123     transfer_type = TYPE_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_UX; break;
124     case 215: // stbx
125     transfer_type = TYPE_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_X; break;
126     case 247: // stbux
127     transfer_type = TYPE_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_UX; break;
128     case 279: // lhzx
129     transfer_type = TYPE_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_X; break;
130     case 311: // lhzux
131     transfer_type = TYPE_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_UX; break;
132     case 343: // lhax
133     transfer_type = TYPE_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_X; break;
134     case 375: // lhaux
135     transfer_type = TYPE_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_UX; break;
136     case 407: // sthx
137     transfer_type = TYPE_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_X; break;
138     case 439: // sthux
139     transfer_type = TYPE_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_UX; break;
140     }
141     break;
142    
143     case 32: // lwz
144     transfer_type = TYPE_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_NORM; break;
145     case 33: // lwzu
146     transfer_type = TYPE_LOAD; transfer_size = SIZE_LONG; addr_mode = MODE_U; break;
147     case 34: // lbz
148     transfer_type = TYPE_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_NORM; break;
149     case 35: // lbzu
150     transfer_type = TYPE_LOAD; transfer_size = SIZE_BYTE; addr_mode = MODE_U; break;
151     case 36: // stw
152     transfer_type = TYPE_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_NORM; break;
153     case 37: // stwu
154     transfer_type = TYPE_STORE; transfer_size = SIZE_LONG; addr_mode = MODE_U; break;
155     case 38: // stb
156     transfer_type = TYPE_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_NORM; break;
157     case 39: // stbu
158     transfer_type = TYPE_STORE; transfer_size = SIZE_BYTE; addr_mode = MODE_U; break;
159     case 40: // lhz
160     transfer_type = TYPE_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_NORM; break;
161     case 41: // lhzu
162     transfer_type = TYPE_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_U; break;
163     case 42: // lha
164     transfer_type = TYPE_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_NORM; break;
165     case 43: // lhau
166     transfer_type = TYPE_LOAD; transfer_size = SIZE_WORD; addr_mode = MODE_U; break;
167     case 44: // sth
168     transfer_type = TYPE_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_NORM; break;
169     case 45: // sthu
170     transfer_type = TYPE_STORE; transfer_size = SIZE_WORD; addr_mode = MODE_U; break;
171     }
172    
173     // Calculate effective address
174     unsigned int addr = 0;
175     switch (addr_mode) {
176     case MODE_X:
177     case MODE_UX:
178     if (ra == 0)
179     addr = gpr[rb];
180     else
181     addr = gpr[ra] + gpr[rb];
182     break;
183     case MODE_NORM:
184     case MODE_U:
185     if (ra == 0)
186     addr = (signed int)(signed short)imm;
187     else
188     addr = gpr[ra] + (signed int)(signed short)imm;
189     break;
190     default:
191     break;
192     }
193    
194     // Commit decoded instruction
195     instruction->addr = addr;
196     instruction->addr_mode = addr_mode;
197     instruction->transfer_type = transfer_type;
198     instruction->transfer_size = transfer_size;
199     instruction->ra = ra;
200     instruction->rd = rd;
201     }
202     #endif
203    
204    
205     /*
206 gbeauche 1.1 * OS-dependant SIGSEGV signals support section
207     */
208    
209     #if HAVE_SIGINFO_T
210     // Generic extended signal handler
211 cebix 1.8 #if defined(__NetBSD__) || defined(__FreeBSD__)
212     #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGBUS)
213     #else
214 gbeauche 1.1 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
215 cebix 1.8 #endif
216 gbeauche 1.5 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, siginfo_t *sip, void *scp
217 gbeauche 1.1 #define SIGSEGV_FAULT_ADDRESS sip->si_addr
218 gbeauche 1.17 #if (defined(i386) || defined(__i386__))
219     #define SIGSEGV_FAULT_INSTRUCTION (((struct sigcontext *)scp)->sc_eip)
220     #define SIGSEGV_REGISTER_FILE ((unsigned int *)&(((struct sigcontext *)scp)->sc_edi))
221     #define SIGSEGV_SKIP_INSTRUCTION ix86_skip_instruction
222     #endif
223 gbeauche 1.5 #if defined(__linux__)
224 gbeauche 1.6 #if (defined(i386) || defined(__i386__))
225     #include <sys/ucontext.h>
226 gbeauche 1.14 #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 gbeauche 1.10 #define SIGSEGV_SKIP_INSTRUCTION ix86_skip_instruction
230 gbeauche 1.6 #endif
231 gbeauche 1.5 #if (defined(ia64) || defined(__ia64__))
232     #define SIGSEGV_FAULT_INSTRUCTION (((struct sigcontext *)scp)->sc_ip & ~0x3ULL) /* slot number is in bits 0 and 1 */
233     #endif
234 gbeauche 1.9 #if (defined(powerpc) || defined(__powerpc__))
235     #include <sys/ucontext.h>
236 gbeauche 1.14 #define SIGSEGV_CONTEXT_REGS (((ucontext_t *)scp)->uc_mcontext.regs)
237     #define SIGSEGV_FAULT_INSTRUCTION (SIGSEGV_CONTEXT_REGS->nip)
238     #define SIGSEGV_REGISTER_FILE (unsigned int *)&SIGSEGV_CONTEXT_REGS->nip, (unsigned int *)(SIGSEGV_CONTEXT_REGS->gpr)
239 gbeauche 1.13 #define SIGSEGV_SKIP_INSTRUCTION powerpc_skip_instruction
240 gbeauche 1.9 #endif
241 gbeauche 1.5 #endif
242 gbeauche 1.1 #endif
243    
244     #if HAVE_SIGCONTEXT_SUBTERFUGE
245     // Linux kernels prior to 2.4 ?
246     #if defined(__linux__)
247     #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
248     #if (defined(i386) || defined(__i386__))
249     #include <asm/sigcontext.h>
250     #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, struct sigcontext scs
251     #define SIGSEGV_FAULT_ADDRESS scs.cr2
252     #define SIGSEGV_FAULT_INSTRUCTION scs.eip
253 gbeauche 1.16 #define SIGSEGV_REGISTER_FILE (unsigned int *)(&scs)
254 gbeauche 1.10 #define SIGSEGV_SKIP_INSTRUCTION ix86_skip_instruction
255 gbeauche 1.1 #endif
256     #if (defined(sparc) || defined(__sparc__))
257     #include <asm/sigcontext.h>
258 gbeauche 1.5 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp, char *addr
259 gbeauche 1.1 #define SIGSEGV_FAULT_ADDRESS addr
260     #endif
261     #if (defined(powerpc) || defined(__powerpc__))
262     #include <asm/sigcontext.h>
263 gbeauche 1.4 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, struct sigcontext *scp
264 gbeauche 1.1 #define SIGSEGV_FAULT_ADDRESS scp->regs->dar
265     #define SIGSEGV_FAULT_INSTRUCTION scp->regs->nip
266 gbeauche 1.14 #define SIGSEGV_REGISTER_FILE (unsigned int *)&scp->regs->nip, (unsigned int *)(scp->regs->gpr)
267 gbeauche 1.13 #define SIGSEGV_SKIP_INSTRUCTION powerpc_skip_instruction
268 gbeauche 1.1 #endif
269 gbeauche 1.4 #if (defined(alpha) || defined(__alpha__))
270     #include <asm/sigcontext.h>
271     #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
272     #define SIGSEGV_FAULT_ADDRESS get_fault_address(scp)
273     #define SIGSEGV_FAULT_INSTRUCTION scp->sc_pc
274    
275     // From Boehm's GC 6.0alpha8
276     static sigsegv_address_t get_fault_address(struct sigcontext *scp)
277     {
278     unsigned int instruction = *((unsigned int *)(scp->sc_pc));
279     unsigned long fault_address = scp->sc_regs[(instruction >> 16) & 0x1f];
280     fault_address += (signed long)(signed short)(instruction & 0xffff);
281     return (sigsegv_address_t)fault_address;
282     }
283     #endif
284 gbeauche 1.1 #endif
285    
286     // Irix 5 or 6 on MIPS
287     #if (defined(sgi) || defined(__sgi)) && (defined(SYSTYPE_SVR4) || defined(__SYSTYPE_SVR4))
288 gbeauche 1.11 #include <ucontext.h>
289 gbeauche 1.1 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
290     #define SIGSEGV_FAULT_ADDRESS scp->sc_badvaddr
291     #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
292     #endif
293    
294 gbeauche 1.11 // HP-UX
295     #if (defined(hpux) || defined(__hpux__))
296     #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
297     #define SIGSEGV_FAULT_ADDRESS scp->sc_sl.sl_ss.ss_narrow.ss_cr21
298     #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV) FAULT_HANDLER(SIGBUS)
299     #endif
300    
301 gbeauche 1.1 // OSF/1 on Alpha
302     #if defined(__osf__)
303 gbeauche 1.11 #include <ucontext.h>
304 gbeauche 1.1 #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
305     #define SIGSEGV_FAULT_ADDRESS scp->sc_traparg_a0
306     #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
307     #endif
308    
309     // AIX
310     #if defined(_AIX)
311     #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
312     #define SIGSEGV_FAULT_ADDRESS scp->sc_jmpbuf.jmp_context.o_vaddr
313     #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
314     #endif
315    
316     // NetBSD or FreeBSD
317     #if defined(__NetBSD__) || defined(__FreeBSD__)
318     #if (defined(m68k) || defined(__m68k__))
319     #include <m68k/frame.h>
320     #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
321 gbeauche 1.14 #define SIGSEGV_FAULT_ADDRESS get_fault_address(scp)
322 gbeauche 1.1 #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGSEGV)
323 gbeauche 1.14
324     // Use decoding scheme from BasiliskII/m68k native
325     static sigsegv_address_t get_fault_address(struct sigcontext *scp)
326     {
327     struct sigstate {
328     int ss_flags;
329     struct frame ss_frame;
330     };
331     struct sigstate *state = (struct sigstate *)scp->sc_ap;
332     char *fault_addr;
333     switch (state->ss_frame.f_format) {
334     case 7: /* 68040 access error */
335     /* "code" is sometimes unreliable (i.e. contains NULL or a bogus address), reason unknown */
336     fault_addr = state->ss_frame.f_fmt7.f_fa;
337     break;
338     default:
339     fault_addr = (char *)code;
340     break;
341     }
342     return (sigsegv_address_t)fault_addr;
343     }
344 gbeauche 1.1 #else
345     #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, void *scp, char *addr
346     #define SIGSEGV_FAULT_ADDRESS addr
347     #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGBUS)
348     #endif
349     #endif
350 gbeauche 1.4
351     // MacOS X
352     #if defined(__APPLE__) && defined(__MACH__)
353     #if (defined(ppc) || defined(__ppc__))
354     #define SIGSEGV_FAULT_HANDLER_ARGLIST int sig, int code, struct sigcontext *scp
355     #define SIGSEGV_FAULT_ADDRESS get_fault_address(scp)
356     #define SIGSEGV_FAULT_INSTRUCTION scp->sc_ir
357     #define SIGSEGV_ALL_SIGNALS FAULT_HANDLER(SIGBUS)
358 gbeauche 1.14 #define SIGSEGV_REGISTER_FILE (unsigned int *)&scp->sc_ir, &((unsigned int *) scp->sc_regs)[2]
359     #define SIGSEGV_SKIP_INSTRUCTION powerpc_skip_instruction
360 gbeauche 1.4
361 gbeauche 1.14 // Use decoding scheme from SheepShaver
362 gbeauche 1.4 static sigsegv_address_t get_fault_address(struct sigcontext *scp)
363     {
364 gbeauche 1.14 unsigned int nip = (unsigned int) scp->sc_ir;
365     unsigned int * gpr = &((unsigned int *) scp->sc_regs)[2];
366     instruction_t instr;
367    
368     powerpc_decode_instruction(&instr, nip, gpr);
369     return (sigsegv_address_t)instr.addr;
370 gbeauche 1.4 }
371     #endif
372     #endif
373 gbeauche 1.1 #endif
374    
375 gbeauche 1.14
376     /*
377     * Instruction skipping
378     */
379    
380 gbeauche 1.10 #ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
381     // Decode and skip X86 instruction
382     #if (defined(i386) || defined(__i386__))
383     #if defined(__linux__)
384     enum {
385     X86_REG_EIP = 14,
386     X86_REG_EAX = 11,
387     X86_REG_ECX = 10,
388     X86_REG_EDX = 9,
389     X86_REG_EBX = 8,
390     X86_REG_ESP = 7,
391     X86_REG_EBP = 6,
392     X86_REG_ESI = 5,
393     X86_REG_EDI = 4
394     };
395     #endif
396 gbeauche 1.17 #if defined(__NetBSD__) || defined(__FreeBSD__)
397     enum {
398     X86_REG_EIP = 10,
399     X86_REG_EAX = 7,
400     X86_REG_ECX = 6,
401     X86_REG_EDX = 5,
402     X86_REG_EBX = 4,
403     X86_REG_ESP = 13,
404     X86_REG_EBP = 2,
405     X86_REG_ESI = 1,
406     X86_REG_EDI = 0
407     };
408     #endif
409 gbeauche 1.10 // FIXME: this is partly redundant with the instruction decoding phase
410     // to discover transfer type and register number
411     static inline int ix86_step_over_modrm(unsigned char * p)
412     {
413     int mod = (p[0] >> 6) & 3;
414     int rm = p[0] & 7;
415     int offset = 0;
416    
417     // ModR/M Byte
418     switch (mod) {
419     case 0: // [reg]
420     if (rm == 5) return 4; // disp32
421     break;
422     case 1: // disp8[reg]
423     offset = 1;
424     break;
425     case 2: // disp32[reg]
426     offset = 4;
427     break;
428     case 3: // register
429     return 0;
430     }
431    
432     // SIB Byte
433     if (rm == 4) {
434     if (mod == 0 && (p[1] & 7) == 5)
435     offset = 5; // disp32[index]
436     else
437     offset++;
438     }
439    
440     return offset;
441     }
442    
443 gbeauche 1.14 static bool ix86_skip_instruction(unsigned int * regs)
444 gbeauche 1.10 {
445 gbeauche 1.14 unsigned char * eip = (unsigned char *)regs[X86_REG_EIP];
446 gbeauche 1.10
447     if (eip == 0)
448     return false;
449    
450 gbeauche 1.14 transfer_type_t transfer_type = TYPE_UNKNOWN;
451     transfer_size_t transfer_size = SIZE_LONG;
452 gbeauche 1.10
453     int reg = -1;
454     int len = 0;
455    
456     // Operand size prefix
457     if (*eip == 0x66) {
458     eip++;
459     len++;
460     transfer_size = SIZE_WORD;
461     }
462    
463     // Decode instruction
464     switch (eip[0]) {
465 gbeauche 1.17 case 0x0f:
466     if (eip[1] == 0xb7) { // MOVZX r32, r/m16
467     switch (eip[2] & 0xc0) {
468     case 0x80:
469     reg = (eip[2] >> 3) & 7;
470     transfer_type = TYPE_LOAD;
471     break;
472     case 0x40:
473     reg = (eip[2] >> 3) & 7;
474     transfer_type = TYPE_LOAD;
475     break;
476     case 0x00:
477     reg = (eip[2] >> 3) & 7;
478     transfer_type = TYPE_LOAD;
479     break;
480     }
481     len += 3 + ix86_step_over_modrm(eip + 2);
482     }
483     break;
484 gbeauche 1.10 case 0x8a: // MOV r8, r/m8
485     transfer_size = SIZE_BYTE;
486     case 0x8b: // MOV r32, r/m32 (or 16-bit operation)
487     switch (eip[1] & 0xc0) {
488     case 0x80:
489     reg = (eip[1] >> 3) & 7;
490     transfer_type = TYPE_LOAD;
491     break;
492     case 0x40:
493     reg = (eip[1] >> 3) & 7;
494     transfer_type = TYPE_LOAD;
495     break;
496     case 0x00:
497     reg = (eip[1] >> 3) & 7;
498     transfer_type = TYPE_LOAD;
499     break;
500     }
501     len += 2 + ix86_step_over_modrm(eip + 1);
502     break;
503     case 0x88: // MOV r/m8, r8
504     transfer_size = SIZE_BYTE;
505     case 0x89: // MOV r/m32, r32 (or 16-bit operation)
506     switch (eip[1] & 0xc0) {
507     case 0x80:
508     reg = (eip[1] >> 3) & 7;
509     transfer_type = TYPE_STORE;
510     break;
511     case 0x40:
512     reg = (eip[1] >> 3) & 7;
513     transfer_type = TYPE_STORE;
514     break;
515     case 0x00:
516     reg = (eip[1] >> 3) & 7;
517     transfer_type = TYPE_STORE;
518     break;
519     }
520     len += 2 + ix86_step_over_modrm(eip + 1);
521     break;
522     }
523    
524     if (transfer_type == TYPE_UNKNOWN) {
525     // Unknown machine code, let it crash. Then patch the decoder
526     return false;
527     }
528    
529     if (transfer_type == TYPE_LOAD && reg != -1) {
530     static const int x86_reg_map[8] = {
531     X86_REG_EAX, X86_REG_ECX, X86_REG_EDX, X86_REG_EBX,
532     X86_REG_ESP, X86_REG_EBP, X86_REG_ESI, X86_REG_EDI
533     };
534    
535     if (reg < 0 || reg >= 8)
536     return false;
537    
538     int rloc = x86_reg_map[reg];
539     switch (transfer_size) {
540     case SIZE_BYTE:
541     regs[rloc] = (regs[rloc] & ~0xff);
542     break;
543     case SIZE_WORD:
544     regs[rloc] = (regs[rloc] & ~0xffff);
545     break;
546     case SIZE_LONG:
547     regs[rloc] = 0;
548     break;
549     }
550     }
551    
552     #if DEBUG
553 gbeauche 1.15 printf("%08x: %s %s access", regs[X86_REG_EIP],
554 gbeauche 1.10 transfer_size == SIZE_BYTE ? "byte" : transfer_size == SIZE_WORD ? "word" : "long",
555     transfer_type == TYPE_LOAD ? "read" : "write");
556    
557     if (reg != -1) {
558     static const char * x86_reg_str_map[8] = {
559     "eax", "ecx", "edx", "ebx",
560     "esp", "ebp", "esi", "edi"
561     };
562     printf(" %s register %%%s", transfer_type == TYPE_LOAD ? "to" : "from", x86_reg_str_map[reg]);
563     }
564     printf(", %d bytes instruction\n", len);
565     #endif
566    
567     regs[X86_REG_EIP] += len;
568 gbeauche 1.13 return true;
569     }
570     #endif
571 gbeauche 1.14
572 gbeauche 1.13 // Decode and skip PPC instruction
573 gbeauche 1.14 #if (defined(powerpc) || defined(__powerpc__) || defined(__ppc__))
574     static bool powerpc_skip_instruction(unsigned int * nip_p, unsigned int * regs)
575 gbeauche 1.13 {
576 gbeauche 1.14 instruction_t instr;
577     powerpc_decode_instruction(&instr, *nip_p, regs);
578 gbeauche 1.13
579 gbeauche 1.14 if (instr.transfer_type == TYPE_UNKNOWN) {
580 gbeauche 1.13 // Unknown machine code, let it crash. Then patch the decoder
581     return false;
582     }
583    
584     #if DEBUG
585 gbeauche 1.14 printf("%08x: %s %s access", *nip_p,
586     instr.transfer_size == SIZE_BYTE ? "byte" : instr.transfer_size == SIZE_WORD ? "word" : "long",
587     instr.transfer_type == TYPE_LOAD ? "read" : "write");
588    
589     if (instr.addr_mode == MODE_U || instr.addr_mode == MODE_UX)
590     printf(" r%d (ra = %08x)\n", instr.ra, instr.addr);
591     if (instr.transfer_type == TYPE_LOAD)
592     printf(" r%d (rd = 0)\n", instr.rd);
593     #endif
594    
595     if (instr.addr_mode == MODE_U || instr.addr_mode == MODE_UX)
596     regs[instr.ra] = instr.addr;
597     if (instr.transfer_type == TYPE_LOAD)
598     regs[instr.rd] = 0;
599 gbeauche 1.13
600 gbeauche 1.14 *nip_p += 4;
601 gbeauche 1.10 return true;
602     }
603     #endif
604     #endif
605    
606 gbeauche 1.1 // Fallbacks
607     #ifndef SIGSEGV_FAULT_INSTRUCTION
608     #define SIGSEGV_FAULT_INSTRUCTION SIGSEGV_INVALID_PC
609     #endif
610    
611 gbeauche 1.2 // SIGSEGV recovery supported ?
612     #if defined(SIGSEGV_ALL_SIGNALS) && defined(SIGSEGV_FAULT_HANDLER_ARGLIST) && defined(SIGSEGV_FAULT_ADDRESS)
613     #define HAVE_SIGSEGV_RECOVERY
614     #endif
615    
616 gbeauche 1.1
617     /*
618     * SIGSEGV global handler
619     */
620    
621 gbeauche 1.2 #ifdef HAVE_SIGSEGV_RECOVERY
622 gbeauche 1.1 static void sigsegv_handler(SIGSEGV_FAULT_HANDLER_ARGLIST)
623     {
624 gbeauche 1.10 sigsegv_address_t fault_address = (sigsegv_address_t)SIGSEGV_FAULT_ADDRESS;
625     sigsegv_address_t fault_instruction = (sigsegv_address_t)SIGSEGV_FAULT_INSTRUCTION;
626     bool fault_recovered = false;
627    
628 gbeauche 1.1 // Call user's handler and reinstall the global handler, if required
629 gbeauche 1.12 if (sigsegv_fault_handler(fault_address, fault_instruction)) {
630 gbeauche 1.1 #if (defined(HAVE_SIGACTION) ? defined(SIGACTION_NEED_REINSTALL) : defined(SIGNAL_NEED_REINSTALL))
631     sigsegv_do_install_handler(sig);
632     #endif
633 gbeauche 1.10 fault_recovered = true;
634 gbeauche 1.1 }
635 gbeauche 1.10 #if HAVE_SIGSEGV_SKIP_INSTRUCTION
636     else if (sigsegv_ignore_fault) {
637     // Call the instruction skipper with the register file available
638 gbeauche 1.14 if (SIGSEGV_SKIP_INSTRUCTION(SIGSEGV_REGISTER_FILE))
639 gbeauche 1.10 fault_recovered = true;
640     }
641     #endif
642    
643     if (!fault_recovered) {
644 gbeauche 1.1 // FAIL: reinstall default handler for "safe" crash
645     #define FAULT_HANDLER(sig) signal(sig, SIG_DFL);
646     SIGSEGV_ALL_SIGNALS
647     #undef FAULT_HANDLER
648 gbeauche 1.10
649     // We can't do anything with the fault_address, dump state?
650 gbeauche 1.12 if (sigsegv_state_dumper != 0)
651     sigsegv_state_dumper(fault_address, fault_instruction);
652 gbeauche 1.1 }
653     }
654 gbeauche 1.2 #endif
655 gbeauche 1.1
656    
657     /*
658     * SIGSEGV handler initialization
659     */
660    
661     #if defined(HAVE_SIGINFO_T)
662     static bool sigsegv_do_install_handler(int sig)
663     {
664     // Setup SIGSEGV handler to process writes to frame buffer
665     #ifdef HAVE_SIGACTION
666     struct sigaction vosf_sa;
667     sigemptyset(&vosf_sa.sa_mask);
668     vosf_sa.sa_sigaction = sigsegv_handler;
669     vosf_sa.sa_flags = SA_SIGINFO;
670     return (sigaction(sig, &vosf_sa, 0) == 0);
671     #else
672     return (signal(sig, (signal_handler)sigsegv_handler) != SIG_ERR);
673     #endif
674     }
675 gbeauche 1.2 #endif
676    
677     #if defined(HAVE_SIGCONTEXT_SUBTERFUGE)
678 gbeauche 1.1 static bool sigsegv_do_install_handler(int sig)
679     {
680     // Setup SIGSEGV handler to process writes to frame buffer
681     #ifdef HAVE_SIGACTION
682     struct sigaction vosf_sa;
683     sigemptyset(&vosf_sa.sa_mask);
684     vosf_sa.sa_handler = (signal_handler)sigsegv_handler;
685     #if !EMULATED_68K && defined(__NetBSD__)
686     sigaddset(&vosf_sa.sa_mask, SIGALRM);
687     vosf_sa.sa_flags = SA_ONSTACK;
688     #else
689     vosf_sa.sa_flags = 0;
690     #endif
691     return (sigaction(sig, &vosf_sa, 0) == 0);
692     #else
693     return (signal(sig, (signal_handler)sigsegv_handler) != SIG_ERR);
694     #endif
695     }
696     #endif
697    
698 gbeauche 1.12 bool sigsegv_install_handler(sigsegv_fault_handler_t handler)
699 gbeauche 1.1 {
700 gbeauche 1.2 #ifdef HAVE_SIGSEGV_RECOVERY
701 gbeauche 1.12 sigsegv_fault_handler = handler;
702 gbeauche 1.1 bool success = true;
703     #define FAULT_HANDLER(sig) success = success && sigsegv_do_install_handler(sig);
704     SIGSEGV_ALL_SIGNALS
705     #undef FAULT_HANDLER
706     return success;
707     #else
708     // FAIL: no siginfo_t nor sigcontext subterfuge is available
709     return false;
710     #endif
711     }
712    
713    
714     /*
715     * SIGSEGV handler deinitialization
716     */
717    
718     void sigsegv_deinstall_handler(void)
719     {
720 gbeauche 1.2 #ifdef HAVE_SIGSEGV_RECOVERY
721 gbeauche 1.12 sigsegv_fault_handler = 0;
722 gbeauche 1.1 #define FAULT_HANDLER(sig) signal(sig, SIG_DFL);
723     SIGSEGV_ALL_SIGNALS
724     #undef FAULT_HANDLER
725 gbeauche 1.2 #endif
726 gbeauche 1.1 }
727    
728 gbeauche 1.10
729     /*
730     * SIGSEGV ignore state modifier
731     */
732    
733     void sigsegv_set_ignore_state(bool ignore_fault)
734     {
735     sigsegv_ignore_fault = ignore_fault;
736     }
737    
738    
739     /*
740     * Set callback function when we cannot handle the fault
741     */
742    
743 gbeauche 1.12 void sigsegv_set_dump_state(sigsegv_state_dumper_t handler)
744 gbeauche 1.10 {
745 gbeauche 1.12 sigsegv_state_dumper = handler;
746 gbeauche 1.10 }
747    
748    
749 gbeauche 1.1 /*
750     * Test program used for configure/test
751     */
752    
753 gbeauche 1.4 #ifdef CONFIGURE_TEST_SIGSEGV_RECOVERY
754 gbeauche 1.1 #include <stdio.h>
755     #include <stdlib.h>
756     #include <fcntl.h>
757     #include <sys/mman.h>
758 gbeauche 1.4 #include "vm_alloc.h"
759 gbeauche 1.1
760     static int page_size;
761 gbeauche 1.3 static volatile char * page = 0;
762     static volatile int handler_called = 0;
763 gbeauche 1.1
764     static bool 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 gbeauche 1.4 if (vm_protect((char *)((unsigned long)fault_address & -page_size), page_size, VM_PAGE_READ | VM_PAGE_WRITE) != 0)
770 gbeauche 1.1 exit(1);
771     return true;
772     }
773    
774 gbeauche 1.10 #ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
775     static bool sigsegv_insn_handler(sigsegv_address_t fault_address, sigsegv_address_t instruction_address)
776     {
777     return false;
778     }
779     #endif
780    
781 gbeauche 1.1 int main(void)
782     {
783 gbeauche 1.4 if (vm_init() < 0)
784 gbeauche 1.1 return 1;
785    
786     page_size = getpagesize();
787 gbeauche 1.4 if ((page = (char *)vm_acquire(page_size)) == VM_MAP_FAILED)
788     return 1;
789    
790     if (vm_protect((char *)page, page_size, VM_PAGE_READ) < 0)
791 gbeauche 1.1 return 1;
792    
793     if (!sigsegv_install_handler(sigsegv_test_handler))
794     return 1;
795    
796     page[123] = 45;
797     page[123] = 45;
798    
799     if (handler_called != 1)
800     return 1;
801 gbeauche 1.10
802     #ifdef HAVE_SIGSEGV_SKIP_INSTRUCTION
803     if (!sigsegv_install_handler(sigsegv_insn_handler))
804     return 1;
805    
806 gbeauche 1.17 if (vm_protect((char *)page, page_size, VM_PAGE_READ | VM_PAGE_WRITE) < 0)
807 gbeauche 1.10 return 1;
808    
809     for (int i = 0; i < page_size; i++)
810     page[i] = (i + 1) % page_size;
811    
812     if (vm_protect((char *)page, page_size, VM_PAGE_NOACCESS) < 0)
813     return 1;
814    
815     sigsegv_set_ignore_state(true);
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 gbeauche 1.1
830 gbeauche 1.4 vm_exit();
831 gbeauche 1.1 return 0;
832     }
833     #endif