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Fix memory leaks in tree-vect-data-refs.c
[official-gcc.git] / gcc / ada / init.c
blob2f01c8dce7cc5e293bea951f950d02d9255abd4a
1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * I N I T *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2015, Free Software Foundation, Inc. *
10 * *
11 * GNAT is free software; you can redistribute it and/or modify it under *
12 * terms of the GNU General Public License as published by the Free Soft- *
13 * ware Foundation; either version 3, or (at your option) any later ver- *
14 * sion. GNAT is distributed in the hope that it will be useful, but WITH- *
15 * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY *
16 * or FITNESS FOR A PARTICULAR PURPOSE. *
17 * *
18 * As a special exception under Section 7 of GPL version 3, you are granted *
19 * additional permissions described in the GCC Runtime Library Exception, *
20 * version 3.1, as published by the Free Software Foundation. *
21 * *
22 * You should have received a copy of the GNU General Public License and *
23 * a copy of the GCC Runtime Library Exception along with this program; *
24 * see the files COPYING3 and COPYING.RUNTIME respectively. If not, see *
25 * <http://www.gnu.org/licenses/>. *
26 * *
27 * GNAT was originally developed by the GNAT team at New York University. *
28 * Extensive contributions were provided by Ada Core Technologies Inc. *
29 * *
30 ****************************************************************************/
31
32 /* This unit contains initialization circuits that are system dependent.
33 A major part of the functionality involves stack overflow checking.
34 The GCC backend generates probe instructions to test for stack overflow.
35 For details on the exact approach used to generate these probes, see the
36 "Using and Porting GCC" manual, in particular the "Stack Checking" section
37 and the subsection "Specifying How Stack Checking is Done". The handlers
38 installed by this file are used to catch the resulting signals that come
39 from these probes failing (i.e. touching protected pages). */
40
41 /* This file should be kept synchronized with s-init.ads, s-init.adb and the
42 s-init-*.adb variants. All these files implement the required functionality
43 for different targets. */
44
45 /* The following include is here to meet the published VxWorks requirement
46 that the __vxworks header appear before any other include. */
47 #ifdef __vxworks
48 #include "vxWorks.h"
49 #include "version.h" /* for _WRS_VXWORKS_MAJOR */
50 #endif
51
52 #ifdef __ANDROID__
53 #undef __linux__
54 #endif
55
56 #ifdef IN_RTS
57 #include "tconfig.h"
58 #include "tsystem.h"
59 #include <sys/stat.h>
60
61 /* We don't have libiberty, so use malloc. */
62 #define xmalloc(S) malloc (S)
63 #else
64 #include "config.h"
65 #include "system.h"
66 #endif
67
68 #include "adaint.h"
69 #include "raise.h"
70
71 #ifdef __cplusplus
72 extern "C" {
73 #endif
74
75 extern void __gnat_raise_program_error (const char *, int);
76
77 /* Addresses of exception data blocks for predefined exceptions. Tasking_Error
78 is not used in this unit, and the abort signal is only used on IRIX.
79 ??? Revisit this part since IRIX is no longer supported. */
80 extern struct Exception_Data constraint_error;
81 extern struct Exception_Data numeric_error;
82 extern struct Exception_Data program_error;
83 extern struct Exception_Data storage_error;
84
85 /* For the Cert run time we use the regular raise exception routine because
86 Raise_From_Signal_Handler is not available. */
87 #ifdef CERT
88 #define Raise_From_Signal_Handler \
89 __gnat_raise_exception
90 extern void Raise_From_Signal_Handler (struct Exception_Data *, const char *);
91 #else
92 #define Raise_From_Signal_Handler \
93 ada__exceptions__raise_from_signal_handler
94 extern void Raise_From_Signal_Handler (struct Exception_Data *, const char *);
95 #endif
96
97 /* Global values computed by the binder. Note that these variables are
98 declared here, not in the binder file, to avoid having unresolved
99 references in the shared libgnat. */
100 int __gl_main_priority = -1;
101 int __gl_main_cpu = -1;
102 int __gl_time_slice_val = -1;
103 char __gl_wc_encoding = 'n';
104 char __gl_locking_policy = ' ';
105 char __gl_queuing_policy = ' ';
106 char __gl_task_dispatching_policy = ' ';
107 char *__gl_priority_specific_dispatching = 0;
108 int __gl_num_specific_dispatching = 0;
109 char *__gl_interrupt_states = 0;
110 int __gl_num_interrupt_states = 0;
111 int __gl_unreserve_all_interrupts = 0;
112 int __gl_exception_tracebacks = 0;
113 int __gl_exception_tracebacks_symbolic = 0;
114 int __gl_detect_blocking = 0;
115 int __gl_default_stack_size = -1;
116 int __gl_leap_seconds_support = 0;
117 int __gl_canonical_streams = 0;
118 char *__gl_bind_env_addr = NULL;
119
120 /* This value is not used anymore, but kept for bootstrapping purpose. */
121 int __gl_zero_cost_exceptions = 0;
122
123 /* Indication of whether synchronous signal handler has already been
124 installed by a previous call to adainit. */
125 int __gnat_handler_installed = 0;
126
127 #ifndef IN_RTS
128 int __gnat_inside_elab_final_code = 0;
129 /* ??? This variable is obsolete since 2001-08-29 but is kept to allow
130 bootstrap from old GNAT versions (< 3.15). */
131 #endif
132
133 /* HAVE_GNAT_INIT_FLOAT must be set on every targets where a __gnat_init_float
134 is defined. If this is not set then a void implementation will be defined
135 at the end of this unit. */
136 #undef HAVE_GNAT_INIT_FLOAT
137
138 /******************************/
139 /* __gnat_get_interrupt_state */
140 /******************************/
141
142 char __gnat_get_interrupt_state (int);
143
144 /* This routine is called from the runtime as needed to determine the state
145 of an interrupt, as set by an Interrupt_State pragma appearing anywhere
146 in the current partition. The input argument is the interrupt number,
147 and the result is one of the following:
148
149 'n' this interrupt not set by any Interrupt_State pragma
150 'u' Interrupt_State pragma set state to User
151 'r' Interrupt_State pragma set state to Runtime
152 's' Interrupt_State pragma set state to System */
153
154 char
155 __gnat_get_interrupt_state (int intrup)
156 {
157 if (intrup >= __gl_num_interrupt_states)
158 return 'n';
159 else
160 return __gl_interrupt_states [intrup];
161 }
162
163 /***********************************/
164 /* __gnat_get_specific_dispatching */
165 /***********************************/
166
167 char __gnat_get_specific_dispatching (int);
168
169 /* This routine is called from the runtime as needed to determine the
170 priority specific dispatching policy, as set by a
171 Priority_Specific_Dispatching pragma appearing anywhere in the current
172 partition. The input argument is the priority number, and the result
173 is the upper case first character of the policy name, e.g. 'F' for
174 FIFO_Within_Priorities. A space ' ' is returned if no
175 Priority_Specific_Dispatching pragma is used in the partition. */
176
177 char
178 __gnat_get_specific_dispatching (int priority)
179 {
180 if (__gl_num_specific_dispatching == 0)
181 return ' ';
182 else if (priority >= __gl_num_specific_dispatching)
183 return 'F';
184 else
185 return __gl_priority_specific_dispatching [priority];
186 }
187
188 #ifndef IN_RTS
189
190 /**********************/
191 /* __gnat_set_globals */
192 /**********************/
193
194 /* This routine is kept for bootstrapping purposes, since the binder generated
195 file now sets the __gl_* variables directly. */
196
197 void
198 __gnat_set_globals (void)
199 {
200 }
201
202 #endif
203
204 /***************/
205 /* AIX Section */
206 /***************/
207
208 #if defined (_AIX)
209
210 #include <signal.h>
211 #include <sys/time.h>
212
213 /* Some versions of AIX don't define SA_NODEFER. */
214
215 #ifndef SA_NODEFER
216 #define SA_NODEFER 0
217 #endif /* SA_NODEFER */
218
219 /* Versions of AIX before 4.3 don't have nanosleep but provide
220 nsleep instead. */
221
222 #ifndef _AIXVERSION_430
223
224 extern int nanosleep (struct timestruc_t *, struct timestruc_t *);
225
226 int
227 nanosleep (struct timestruc_t *Rqtp, struct timestruc_t *Rmtp)
228 {
229 return nsleep (Rqtp, Rmtp);
230 }
231
232 #endif /* _AIXVERSION_430 */
233
234 static void
235 __gnat_error_handler (int sig,
236 siginfo_t *si ATTRIBUTE_UNUSED,
237 void *ucontext ATTRIBUTE_UNUSED)
238 {
239 struct Exception_Data *exception;
240 const char *msg;
241
242 switch (sig)
243 {
244 case SIGSEGV:
245 /* FIXME: we need to detect the case of a *real* SIGSEGV. */
246 exception = &storage_error;
247 msg = "stack overflow or erroneous memory access";
248 break;
249
250 case SIGBUS:
251 exception = &constraint_error;
252 msg = "SIGBUS";
253 break;
254
255 case SIGFPE:
256 exception = &constraint_error;
257 msg = "SIGFPE";
258 break;
259
260 default:
261 exception = &program_error;
262 msg = "unhandled signal";
263 }
264
265 Raise_From_Signal_Handler (exception, msg);
266 }
267
268 void
269 __gnat_install_handler (void)
270 {
271 struct sigaction act;
272
273 /* Set up signal handler to map synchronous signals to appropriate
274 exceptions. Make sure that the handler isn't interrupted by another
275 signal that might cause a scheduling event! */
276
277 act.sa_flags = SA_NODEFER | SA_RESTART | SA_SIGINFO;
278 act.sa_sigaction = __gnat_error_handler;
279 sigemptyset (&act.sa_mask);
280
281 /* Do not install handlers if interrupt state is "System". */
282 if (__gnat_get_interrupt_state (SIGABRT) != 's')
283 sigaction (SIGABRT, &act, NULL);
284 if (__gnat_get_interrupt_state (SIGFPE) != 's')
285 sigaction (SIGFPE, &act, NULL);
286 if (__gnat_get_interrupt_state (SIGILL) != 's')
287 sigaction (SIGILL, &act, NULL);
288 if (__gnat_get_interrupt_state (SIGSEGV) != 's')
289 sigaction (SIGSEGV, &act, NULL);
290 if (__gnat_get_interrupt_state (SIGBUS) != 's')
291 sigaction (SIGBUS, &act, NULL);
292
293 __gnat_handler_installed = 1;
294 }
295
296 /*****************/
297 /* HP-UX section */
298 /*****************/
299
300 #elif defined (__hpux__)
301
302 #include <signal.h>
303 #include <sys/ucontext.h>
304
305 #if defined (IN_RTS) && defined (__ia64__)
306
307 #include <sys/uc_access.h>
308
309 #define HAVE_GNAT_ADJUST_CONTEXT_FOR_RAISE
310
311 void
312 __gnat_adjust_context_for_raise (int signo ATTRIBUTE_UNUSED, void *ucontext)
313 {
314 ucontext_t *uc = (ucontext_t *) ucontext;
315 uint64_t ip;
316
317 /* Adjust on itanium, as GetIPInfo is not supported. */
318 __uc_get_ip (uc, &ip);
319 __uc_set_ip (uc, ip + 1);
320 }
321 #endif /* IN_RTS && __ia64__ */
322
323 /* Tasking and Non-tasking signal handler. Map SIGnal to Ada exception
324 propagation after the required low level adjustments. */
325
326 static void
327 __gnat_error_handler (int sig, siginfo_t *si ATTRIBUTE_UNUSED, void *ucontext)
328 {
329 struct Exception_Data *exception;
330 const char *msg;
331
332 __gnat_adjust_context_for_raise (sig, ucontext);
333
334 switch (sig)
335 {
336 case SIGSEGV:
337 /* FIXME: we need to detect the case of a *real* SIGSEGV. */
338 exception = &storage_error;
339 msg = "stack overflow or erroneous memory access";
340 break;
341
342 case SIGBUS:
343 exception = &constraint_error;
344 msg = "SIGBUS";
345 break;
346
347 case SIGFPE:
348 exception = &constraint_error;
349 msg = "SIGFPE";
350 break;
351
352 default:
353 exception = &program_error;
354 msg = "unhandled signal";
355 }
356
357 Raise_From_Signal_Handler (exception, msg);
358 }
359
360 /* This must be in keeping with System.OS_Interface.Alternate_Stack_Size. */
361 #if defined (__hppa__)
362 char __gnat_alternate_stack[16 * 1024]; /* 2 * SIGSTKSZ */
363 #else
364 char __gnat_alternate_stack[128 * 1024]; /* MINSIGSTKSZ */
365 #endif
366
367 void
368 __gnat_install_handler (void)
369 {
370 struct sigaction act;
371
372 /* Set up signal handler to map synchronous signals to appropriate
373 exceptions. Make sure that the handler isn't interrupted by another
374 signal that might cause a scheduling event! Also setup an alternate
375 stack region for the handler execution so that stack overflows can be
376 handled properly, avoiding a SEGV generation from stack usage by the
377 handler itself. */
378
379 stack_t stack;
380 stack.ss_sp = __gnat_alternate_stack;
381 stack.ss_size = sizeof (__gnat_alternate_stack);
382 stack.ss_flags = 0;
383 sigaltstack (&stack, NULL);
384
385 act.sa_sigaction = __gnat_error_handler;
386 act.sa_flags = SA_NODEFER | SA_RESTART | SA_SIGINFO;
387 sigemptyset (&act.sa_mask);
388
389 /* Do not install handlers if interrupt state is "System". */
390 if (__gnat_get_interrupt_state (SIGABRT) != 's')
391 sigaction (SIGABRT, &act, NULL);
392 if (__gnat_get_interrupt_state (SIGFPE) != 's')
393 sigaction (SIGFPE, &act, NULL);
394 if (__gnat_get_interrupt_state (SIGILL) != 's')
395 sigaction (SIGILL, &act, NULL);
396 if (__gnat_get_interrupt_state (SIGBUS) != 's')
397 sigaction (SIGBUS, &act, NULL);
398 act.sa_flags |= SA_ONSTACK;
399 if (__gnat_get_interrupt_state (SIGSEGV) != 's')
400 sigaction (SIGSEGV, &act, NULL);
401
402 __gnat_handler_installed = 1;
403 }
404
405 /*********************/
406 /* GNU/Linux Section */
407 /*********************/
408
409 #elif defined (__linux__)
410
411 #include <signal.h>
412
413 #define __USE_GNU 1 /* required to get REG_EIP/RIP from glibc's ucontext.h */
414 #include <sys/ucontext.h>
415
416 /* GNU/Linux, which uses glibc, does not define NULL in included
417 header files. */
418
419 #if !defined (NULL)
420 #define NULL ((void *) 0)
421 #endif
422
423 #if defined (MaRTE)
424
425 /* MaRTE OS provides its own version of sigaction, sigfillset, and
426 sigemptyset (overriding these symbol names). We want to make sure that
427 the versions provided by the underlying C library are used here (these
428 versions are renamed by MaRTE to linux_sigaction, fake_linux_sigfillset,
429 and fake_linux_sigemptyset, respectively). The MaRTE library will not
430 always be present (it will not be linked if no tasking constructs are
431 used), so we use the weak symbol mechanism to point always to the symbols
432 defined within the C library. */
433
434 #pragma weak linux_sigaction
435 int linux_sigaction (int signum, const struct sigaction *act,
436 struct sigaction *oldact)
437 {
438 return sigaction (signum, act, oldact);
439 }
440 #define sigaction(signum, act, oldact) linux_sigaction (signum, act, oldact)
441
442 #pragma weak fake_linux_sigfillset
443 void fake_linux_sigfillset (sigset_t *set)
444 {
445 sigfillset (set);
446 }
447 #define sigfillset(set) fake_linux_sigfillset (set)
448
449 #pragma weak fake_linux_sigemptyset
450 void fake_linux_sigemptyset (sigset_t *set)
451 {
452 sigemptyset (set);
453 }
454 #define sigemptyset(set) fake_linux_sigemptyset (set)
455
456 #endif
457
458 #if defined (__i386__) || defined (__x86_64__) || defined (__ia64__) \
459 || defined (__ARMEL__)
460
461 #define HAVE_GNAT_ADJUST_CONTEXT_FOR_RAISE
462
463 void
464 __gnat_adjust_context_for_raise (int signo ATTRIBUTE_UNUSED, void *ucontext)
465 {
466 mcontext_t *mcontext = &((ucontext_t *) ucontext)->uc_mcontext;
467
468 /* On the i386 and x86-64 architectures, stack checking is performed by
469 means of probes with moving stack pointer, that is to say the probed
470 address is always the value of the stack pointer. Upon hitting the
471 guard page, the stack pointer therefore points to an inaccessible
472 address and an alternate signal stack is needed to run the handler.
473 But there is an additional twist: on these architectures, the EH
474 return code writes the address of the handler at the target CFA's
475 value on the stack before doing the jump. As a consequence, if
476 there is an active handler in the frame whose stack has overflowed,
477 the stack pointer must nevertheless point to an accessible address
478 by the time the EH return is executed.
479
480 We therefore adjust the saved value of the stack pointer by the size
481 of one page + a small dope of 4 words, in order to make sure that it
482 points to an accessible address in case it's used as the target CFA.
483 The stack checking code guarantees that this address is unused by the
484 time this happens. */
485
486 #if defined (__i386__)
487 unsigned long *pc = (unsigned long *)mcontext->gregs[REG_EIP];
488 /* The pattern is "orl $0x0,(%esp)" for a probe in 32-bit mode. */
489 if (signo == SIGSEGV && pc && *pc == 0x00240c83)
490 mcontext->gregs[REG_ESP] += 4096 + 4 * sizeof (unsigned long);
491 #elif defined (__x86_64__)
492 unsigned long long *pc = (unsigned long long *)mcontext->gregs[REG_RIP];
493 if (signo == SIGSEGV && pc
494 /* The pattern is "orq $0x0,(%rsp)" for a probe in 64-bit mode. */
495 && ((*pc & 0xffffffffffLL) == 0x00240c8348LL
496 /* The pattern may also be "orl $0x0,(%esp)" for a probe in
497 x32 mode. */
498 || (*pc & 0xffffffffLL) == 0x00240c83LL))
499 mcontext->gregs[REG_RSP] += 4096 + 4 * sizeof (unsigned long);
500 #elif defined (__ia64__)
501 /* ??? The IA-64 unwinder doesn't compensate for signals. */
502 mcontext->sc_ip++;
503 #elif defined (__ARMEL__)
504 /* ARM Bump has to be an even number because of odd/even architecture. */
505 mcontext->arm_pc+=2;
506 #endif
507 }
508
509 #endif
510
511 static void
512 __gnat_error_handler (int sig, siginfo_t *si ATTRIBUTE_UNUSED, void *ucontext)
513 {
514 struct Exception_Data *exception;
515 const char *msg;
516
517 /* Adjusting is required for every fault context, so adjust for this one
518 now, before we possibly trigger a recursive fault below. */
519 __gnat_adjust_context_for_raise (sig, ucontext);
520
521 switch (sig)
522 {
523 case SIGSEGV:
524 /* Here we would like a discrimination test to see whether the page
525 before the faulting address is accessible. Unfortunately, Linux
526 seems to have no way of giving us the faulting address.
527
528 In old versions of init.c, we had a test of the page before the
529 stack pointer:
530
531 ((volatile char *)
532 ((long) si->esp_at_signal & - getpagesize ()))[getpagesize ()];
533
534 but that's wrong since it tests the stack pointer location and the
535 stack probing code may not move it until all probes succeed.
536
537 For now we simply do not attempt any discrimination at all. Note
538 that this is quite acceptable, since a "real" SIGSEGV can only
539 occur as the result of an erroneous program. */
540 exception = &storage_error;
541 msg = "stack overflow or erroneous memory access";
542 break;
543
544 case SIGBUS:
545 exception = &storage_error;
546 msg = "SIGBUS: possible stack overflow";
547 break;
548
549 case SIGFPE:
550 exception = &constraint_error;
551 msg = "SIGFPE";
552 break;
553
554 default:
555 exception = &program_error;
556 msg = "unhandled signal";
557 }
558
559 Raise_From_Signal_Handler (exception, msg);
560 }
561
562 #ifndef __ia64__
563 #define HAVE_GNAT_ALTERNATE_STACK 1
564 /* This must be in keeping with System.OS_Interface.Alternate_Stack_Size.
565 It must be larger than MINSIGSTKSZ and hopefully near 2 * SIGSTKSZ. */
566 # if 16 * 1024 < MINSIGSTKSZ
567 # error "__gnat_alternate_stack too small"
568 # endif
569 char __gnat_alternate_stack[16 * 1024];
570 #endif
571
572 #ifdef __XENO__
573 #include <sys/mman.h>
574 #include <native/task.h>
575
576 RT_TASK main_task;
577 #endif
578
579 void
580 __gnat_install_handler (void)
581 {
582 struct sigaction act;
583
584 #ifdef __XENO__
585 int prio;
586
587 if (__gl_main_priority == -1)
588 prio = 49;
589 else
590 prio = __gl_main_priority;
591
592 /* Avoid memory swapping for this program */
593
594 mlockall (MCL_CURRENT|MCL_FUTURE);
595
596 /* Turn the current Linux task into a native Xenomai task */
597
598 rt_task_shadow (&main_task, "environment_task", prio, T_FPU);
599 #endif
600
601 /* Set up signal handler to map synchronous signals to appropriate
602 exceptions. Make sure that the handler isn't interrupted by another
603 signal that might cause a scheduling event! Also setup an alternate
604 stack region for the handler execution so that stack overflows can be
605 handled properly, avoiding a SEGV generation from stack usage by the
606 handler itself. */
607
608 act.sa_sigaction = __gnat_error_handler;
609 act.sa_flags = SA_NODEFER | SA_RESTART | SA_SIGINFO;
610 sigemptyset (&act.sa_mask);
611
612 /* Do not install handlers if interrupt state is "System". */
613 if (__gnat_get_interrupt_state (SIGABRT) != 's')
614 sigaction (SIGABRT, &act, NULL);
615 if (__gnat_get_interrupt_state (SIGFPE) != 's')
616 sigaction (SIGFPE, &act, NULL);
617 if (__gnat_get_interrupt_state (SIGILL) != 's')
618 sigaction (SIGILL, &act, NULL);
619 if (__gnat_get_interrupt_state (SIGBUS) != 's')
620 sigaction (SIGBUS, &act, NULL);
621 if (__gnat_get_interrupt_state (SIGSEGV) != 's')
622 {
623 #ifdef HAVE_GNAT_ALTERNATE_STACK
624 /* Setup an alternate stack region for the handler execution so that
625 stack overflows can be handled properly, avoiding a SEGV generation
626 from stack usage by the handler itself. */
627 stack_t stack;
628
629 stack.ss_sp = __gnat_alternate_stack;
630 stack.ss_size = sizeof (__gnat_alternate_stack);
631 stack.ss_flags = 0;
632 sigaltstack (&stack, NULL);
633
634 act.sa_flags |= SA_ONSTACK;
635 #endif
636 sigaction (SIGSEGV, &act, NULL);
637 }
638
639 __gnat_handler_installed = 1;
640 }
641
642 /*******************/
643 /* LynxOS Section */
644 /*******************/
645
646 #elif defined (__Lynx__)
647
648 #include <signal.h>
649 #include <unistd.h>
650
651 static void
652 __gnat_error_handler (int sig)
653 {
654 struct Exception_Data *exception;
655 const char *msg;
656
657 switch(sig)
658 {
659 case SIGFPE:
660 exception = &constraint_error;
661 msg = "SIGFPE";
662 break;
663 case SIGILL:
664 exception = &constraint_error;
665 msg = "SIGILL";
666 break;
667 case SIGSEGV:
668 exception = &storage_error;
669 msg = "stack overflow or erroneous memory access";
670 break;
671 case SIGBUS:
672 exception = &constraint_error;
673 msg = "SIGBUS";
674 break;
675 default:
676 exception = &program_error;
677 msg = "unhandled signal";
678 }
679
680 Raise_From_Signal_Handler (exception, msg);
681 }
682
683 void
684 __gnat_install_handler (void)
685 {
686 struct sigaction act;
687
688 act.sa_handler = __gnat_error_handler;
689 act.sa_flags = 0x0;
690 sigemptyset (&act.sa_mask);
691
692 /* Do not install handlers if interrupt state is "System". */
693 if (__gnat_get_interrupt_state (SIGFPE) != 's')
694 sigaction (SIGFPE, &act, NULL);
695 if (__gnat_get_interrupt_state (SIGILL) != 's')
696 sigaction (SIGILL, &act, NULL);
697 if (__gnat_get_interrupt_state (SIGSEGV) != 's')
698 sigaction (SIGSEGV, &act, NULL);
699 if (__gnat_get_interrupt_state (SIGBUS) != 's')
700 sigaction (SIGBUS, &act, NULL);
701
702 __gnat_handler_installed = 1;
703 }
704
705 /*******************/
706 /* Solaris Section */
707 /*******************/
708
709 #elif defined (__sun__) && !defined (__vxworks)
710
711 #include <signal.h>
712 #include <siginfo.h>
713 #include <sys/ucontext.h>
714 #include <sys/regset.h>
715
716 static void
717 __gnat_error_handler (int sig, siginfo_t *si, void *ucontext ATTRIBUTE_UNUSED)
718 {
719 struct Exception_Data *exception;
720 static int recurse = 0;
721 const char *msg;
722
723 switch (sig)
724 {
725 case SIGSEGV:
726 /* If the problem was permissions, this is a constraint error.
727 Likewise if the failing address isn't maximally aligned or if
728 we've recursed.
729
730 ??? Using a static variable here isn't task-safe, but it's
731 much too hard to do anything else and we're just determining
732 which exception to raise. */
733 if (si->si_code == SEGV_ACCERR
734 || (long) si->si_addr == 0
735 || (((long) si->si_addr) & 3) != 0
736 || recurse)
737 {
738 exception = &constraint_error;
739 msg = "SIGSEGV";
740 }
741 else
742 {
743 /* See if the page before the faulting page is accessible. Do that
744 by trying to access it. We'd like to simply try to access
745 4096 + the faulting address, but it's not guaranteed to be
746 the actual address, just to be on the same page. */
747 recurse++;
748 ((volatile char *)
749 ((long) si->si_addr & - getpagesize ()))[getpagesize ()];
750 exception = &storage_error;
751 msg = "stack overflow or erroneous memory access";
752 }
753 break;
754
755 case SIGBUS:
756 exception = &program_error;
757 msg = "SIGBUS";
758 break;
759
760 case SIGFPE:
761 exception = &constraint_error;
762 msg = "SIGFPE";
763 break;
764
765 default:
766 exception = &program_error;
767 msg = "unhandled signal";
768 }
769
770 recurse = 0;
771 Raise_From_Signal_Handler (exception, msg);
772 }
773
774 void
775 __gnat_install_handler (void)
776 {
777 struct sigaction act;
778
779 /* Set up signal handler to map synchronous signals to appropriate
780 exceptions. Make sure that the handler isn't interrupted by another
781 signal that might cause a scheduling event! */
782
783 act.sa_sigaction = __gnat_error_handler;
784 act.sa_flags = SA_NODEFER | SA_RESTART | SA_SIGINFO;
785 sigemptyset (&act.sa_mask);
786
787 /* Do not install handlers if interrupt state is "System". */
788 if (__gnat_get_interrupt_state (SIGABRT) != 's')
789 sigaction (SIGABRT, &act, NULL);
790 if (__gnat_get_interrupt_state (SIGFPE) != 's')
791 sigaction (SIGFPE, &act, NULL);
792 if (__gnat_get_interrupt_state (SIGSEGV) != 's')
793 sigaction (SIGSEGV, &act, NULL);
794 if (__gnat_get_interrupt_state (SIGBUS) != 's')
795 sigaction (SIGBUS, &act, NULL);
796
797 __gnat_handler_installed = 1;
798 }
799
800 /***************/
801 /* VMS Section */
802 /***************/
803
804 #elif defined (VMS)
805
806 /* Routine called from binder to override default feature values. */
807 void __gnat_set_features (void);
808 int __gnat_features_set = 0;
809 void (*__gnat_ctrl_c_handler) (void) = 0;
810
811 #ifdef __IA64
812 #define lib_get_curr_invo_context LIB$I64_GET_CURR_INVO_CONTEXT
813 #define lib_get_prev_invo_context LIB$I64_GET_PREV_INVO_CONTEXT
814 #define lib_get_invo_handle LIB$I64_GET_INVO_HANDLE
815 #else
816 #define lib_get_curr_invo_context LIB$GET_CURR_INVO_CONTEXT
817 #define lib_get_prev_invo_context LIB$GET_PREV_INVO_CONTEXT
818 #define lib_get_invo_handle LIB$GET_INVO_HANDLE
819 #endif
820
821 /* Masks for facility identification. */
822 #define FAC_MASK 0x0fff0000
823 #define DECADA_M_FACILITY 0x00310000
824
825 /* Define macro symbols for the VMS conditions that become Ada exceptions.
826 It would be better to just include <ssdef.h> */
827
828 #define SS$_CONTINUE 1
829 #define SS$_ACCVIO 12
830 #define SS$_HPARITH 1284
831 #define SS$_INTDIV 1156
832 #define SS$_STKOVF 1364
833 #define SS$_CONTROLC 1617
834 #define SS$_RESIGNAL 2328
835
836 #define MTH$_FLOOVEMAT 1475268 /* Some ACVC_21 CXA tests */
837
838 /* The following codes must be resignalled, and not handled here. */
839
840 /* These codes are in standard message libraries. */
841 extern int C$_SIGKILL;
842 extern int C$_SIGINT;
843 extern int SS$_DEBUG;
844 extern int LIB$_KEYNOTFOU;
845 extern int LIB$_ACTIMAGE;
846
847 /* These codes are non standard, which is to say the author is
848 not sure if they are defined in the standard message libraries
849 so keep them as macros for now. */
850 #define RDB$_STREAM_EOF 20480426
851 #define FDL$_UNPRIKW 11829410
852 #define CMA$_EXIT_THREAD 4227492
853
854 struct cond_sigargs
855 {
856 unsigned int sigarg;
857 unsigned int sigargval;
858 };
859
860 struct cond_subtests
861 {
862 unsigned int num;
863 const struct cond_sigargs sigargs[];
864 };
865
866 struct cond_except
867 {
868 unsigned int cond;
869 const struct Exception_Data *except;
870 unsigned int needs_adjust; /* 1 = adjust PC, 0 = no adjust */
871 const struct cond_subtests *subtests;
872 };
873
874 struct descriptor_s
875 {
876 unsigned short len, mbz;
877 __char_ptr32 adr;
878 };
879
880 /* Conditions that don't have an Ada exception counterpart must raise
881 Non_Ada_Error. Since this is defined in s-auxdec, it should only be
882 referenced by user programs, not the compiler or tools. Hence the
883 #ifdef IN_RTS. */
884
885 #ifdef IN_RTS
886
887 #define Status_Error ada__io_exceptions__status_error
888 extern struct Exception_Data Status_Error;
889
890 #define Mode_Error ada__io_exceptions__mode_error
891 extern struct Exception_Data Mode_Error;
892
893 #define Name_Error ada__io_exceptions__name_error
894 extern struct Exception_Data Name_Error;
895
896 #define Use_Error ada__io_exceptions__use_error
897 extern struct Exception_Data Use_Error;
898
899 #define Device_Error ada__io_exceptions__device_error
900 extern struct Exception_Data Device_Error;
901
902 #define End_Error ada__io_exceptions__end_error
903 extern struct Exception_Data End_Error;
904
905 #define Data_Error ada__io_exceptions__data_error
906 extern struct Exception_Data Data_Error;
907
908 #define Layout_Error ada__io_exceptions__layout_error
909 extern struct Exception_Data Layout_Error;
910
911 #define Non_Ada_Error system__aux_dec__non_ada_error
912 extern struct Exception_Data Non_Ada_Error;
913
914 #define Coded_Exception system__vms_exception_table__coded_exception
915 extern struct Exception_Data *Coded_Exception (void *);
916
917 #define Base_Code_In system__vms_exception_table__base_code_in
918 extern void *Base_Code_In (void *);
919
920 /* DEC Ada exceptions are not defined in a header file, so they
921 must be declared. */
922
923 #define ADA$_ALREADY_OPEN 0x0031a594
924 #define ADA$_CONSTRAINT_ERRO 0x00318324
925 #define ADA$_DATA_ERROR 0x003192c4
926 #define ADA$_DEVICE_ERROR 0x003195e4
927 #define ADA$_END_ERROR 0x00319904
928 #define ADA$_FAC_MODE_MISMAT 0x0031a8b3
929 #define ADA$_IOSYSFAILED 0x0031af04
930 #define ADA$_KEYSIZERR 0x0031aa3c
931 #define ADA$_KEY_MISMATCH 0x0031a8e3
932 #define ADA$_LAYOUT_ERROR 0x00319c24
933 #define ADA$_LINEXCMRS 0x0031a8f3
934 #define ADA$_MAXLINEXC 0x0031a8eb
935 #define ADA$_MODE_ERROR 0x00319f44
936 #define ADA$_MRN_MISMATCH 0x0031a8db
937 #define ADA$_MRS_MISMATCH 0x0031a8d3
938 #define ADA$_NAME_ERROR 0x0031a264
939 #define ADA$_NOT_OPEN 0x0031a58c
940 #define ADA$_ORG_MISMATCH 0x0031a8bb
941 #define ADA$_PROGRAM_ERROR 0x00318964
942 #define ADA$_RAT_MISMATCH 0x0031a8cb
943 #define ADA$_RFM_MISMATCH 0x0031a8c3
944 #define ADA$_STAOVF 0x00318cac
945 #define ADA$_STATUS_ERROR 0x0031a584
946 #define ADA$_STORAGE_ERROR 0x00318c84
947 #define ADA$_UNSUPPORTED 0x0031a8ab
948 #define ADA$_USE_ERROR 0x0031a8a4
949
950 /* DEC Ada specific conditions. */
951 static const struct cond_except dec_ada_cond_except_table [] =
952 {
953 {ADA$_PROGRAM_ERROR, &program_error, 0, 0},
954 {ADA$_USE_ERROR, &Use_Error, 0, 0},
955 {ADA$_KEYSIZERR, &program_error, 0, 0},
956 {ADA$_STAOVF, &storage_error, 0, 0},
957 {ADA$_CONSTRAINT_ERRO, &constraint_error, 0, 0},
958 {ADA$_IOSYSFAILED, &Device_Error, 0, 0},
959 {ADA$_LAYOUT_ERROR, &Layout_Error, 0, 0},
960 {ADA$_STORAGE_ERROR, &storage_error, 0, 0},
961 {ADA$_DATA_ERROR, &Data_Error, 0, 0},
962 {ADA$_DEVICE_ERROR, &Device_Error, 0, 0},
963 {ADA$_END_ERROR, &End_Error, 0, 0},
964 {ADA$_MODE_ERROR, &Mode_Error, 0, 0},
965 {ADA$_NAME_ERROR, &Name_Error, 0, 0},
966 {ADA$_STATUS_ERROR, &Status_Error, 0, 0},
967 {ADA$_NOT_OPEN, &Use_Error, 0, 0},
968 {ADA$_ALREADY_OPEN, &Use_Error, 0, 0},
969 {ADA$_USE_ERROR, &Use_Error, 0, 0},
970 {ADA$_UNSUPPORTED, &Use_Error, 0, 0},
971 {ADA$_FAC_MODE_MISMAT, &Use_Error, 0, 0},
972 {ADA$_ORG_MISMATCH, &Use_Error, 0, 0},
973 {ADA$_RFM_MISMATCH, &Use_Error, 0, 0},
974 {ADA$_RAT_MISMATCH, &Use_Error, 0, 0},
975 {ADA$_MRS_MISMATCH, &Use_Error, 0, 0},
976 {ADA$_MRN_MISMATCH, &Use_Error, 0, 0},
977 {ADA$_KEY_MISMATCH, &Use_Error, 0, 0},
978 {ADA$_MAXLINEXC, &constraint_error, 0, 0},
979 {ADA$_LINEXCMRS, &constraint_error, 0, 0},
980
981 #if 0
982 /* Already handled by a pragma Import_Exception
983 in Aux_IO_Exceptions */
984 {ADA$_LOCK_ERROR, &Lock_Error, 0, 0},
985 {ADA$_EXISTENCE_ERROR, &Existence_Error, 0, 0},
986 {ADA$_KEY_ERROR, &Key_Error, 0, 0},
987 #endif
988
989 {0, 0, 0, 0}
990 };
991
992 #endif /* IN_RTS */
993
994 /* Non-DEC Ada specific conditions that map to Ada exceptions. */
995
996 /* Subtest for ACCVIO Constraint_Error, kept for compatibility,
997 in hindsight should have just made ACCVIO == Storage_Error. */
998 #define ACCVIO_VIRTUAL_ADDR 3
999 static const struct cond_subtests accvio_c_e =
1000 {1, /* number of subtests below */
1001 {
1002 { ACCVIO_VIRTUAL_ADDR, 0 }
1003 }
1004 };
1005
1006 /* Macro flag to adjust PC which gets off by one for some conditions,
1007 not sure if this is reliably true, PC could be off by more for
1008 HPARITH for example, unless a trapb is inserted. */
1009 #define NEEDS_ADJUST 1
1010
1011 static const struct cond_except system_cond_except_table [] =
1012 {
1013 {MTH$_FLOOVEMAT, &constraint_error, 0, 0},
1014 {SS$_INTDIV, &constraint_error, 0, 0},
1015 {SS$_HPARITH, &constraint_error, NEEDS_ADJUST, 0},
1016 {SS$_ACCVIO, &constraint_error, NEEDS_ADJUST, &accvio_c_e},
1017 {SS$_ACCVIO, &storage_error, NEEDS_ADJUST, 0},
1018 {SS$_STKOVF, &storage_error, NEEDS_ADJUST, 0},
1019 {0, 0, 0, 0}
1020 };
1021
1022 /* To deal with VMS conditions and their mapping to Ada exceptions,
1023 the __gnat_error_handler routine below is installed as an exception
1024 vector having precedence over DEC frame handlers. Some conditions
1025 still need to be handled by such handlers, however, in which case
1026 __gnat_error_handler needs to return SS$_RESIGNAL. Consider for
1027 instance the use of a third party library compiled with DECAda and
1028 performing its own exception handling internally.
1029
1030 To allow some user-level flexibility, which conditions should be
1031 resignaled is controlled by a predicate function, provided with the
1032 condition value and returning a boolean indication stating whether
1033 this condition should be resignaled or not.
1034
1035 That predicate function is called indirectly, via a function pointer,
1036 by __gnat_error_handler, and changing that pointer is allowed to the
1037 user code by way of the __gnat_set_resignal_predicate interface.
1038
1039 The user level function may then implement what it likes, including
1040 for instance the maintenance of a dynamic data structure if the set
1041 of to be resignalled conditions has to change over the program's
1042 lifetime.
1043
1044 ??? This is not a perfect solution to deal with the possible
1045 interactions between the GNAT and the DECAda exception handling
1046 models and better (more general) schemes are studied. This is so
1047 just provided as a convenient workaround in the meantime, and
1048 should be use with caution since the implementation has been kept
1049 very simple. */
1050
1051 typedef int resignal_predicate (int code);
1052
1053 static const int * const cond_resignal_table [] =
1054 {
1055 &C$_SIGKILL,
1056 (int *)CMA$_EXIT_THREAD,
1057 &SS$_DEBUG,
1058 &LIB$_KEYNOTFOU,
1059 &LIB$_ACTIMAGE,
1060 (int *) RDB$_STREAM_EOF,
1061 (int *) FDL$_UNPRIKW,
1062 0
1063 };
1064
1065 static const int facility_resignal_table [] =
1066 {
1067 0x1380000, /* RDB */
1068 0x2220000, /* SQL */
1069 0
1070 };
1071
1072 /* Default GNAT predicate for resignaling conditions. */
1073
1074 static int
1075 __gnat_default_resignal_p (int code)
1076 {
1077 int i, iexcept;
1078
1079 for (i = 0; facility_resignal_table [i]; i++)
1080 if ((code & FAC_MASK) == facility_resignal_table [i])
1081 return 1;
1082
1083 for (i = 0, iexcept = 0;
1084 cond_resignal_table [i]
1085 && !(iexcept = LIB$MATCH_COND (&code, &cond_resignal_table [i]));
1086 i++);
1087
1088 return iexcept;
1089 }
1090
1091 /* Static pointer to predicate that the __gnat_error_handler exception
1092 vector invokes to determine if it should resignal a condition. */
1093
1094 static resignal_predicate *__gnat_resignal_p = __gnat_default_resignal_p;
1095
1096 /* User interface to change the predicate pointer to PREDICATE. Reset to
1097 the default if PREDICATE is null. */
1098
1099 void
1100 __gnat_set_resignal_predicate (resignal_predicate *predicate)
1101 {
1102 if (predicate == NULL)
1103 __gnat_resignal_p = __gnat_default_resignal_p;
1104 else
1105 __gnat_resignal_p = predicate;
1106 }
1107
1108 /* Should match System.Parameters.Default_Exception_Msg_Max_Length. */
1109 #define Default_Exception_Msg_Max_Length 512
1110
1111 /* Action routine for SYS$PUTMSG. There may be multiple
1112 conditions, each with text to be appended to MESSAGE
1113 and separated by line termination. */
1114 static int
1115 copy_msg (struct descriptor_s *msgdesc, char *message)
1116 {
1117 int len = strlen (message);
1118 int copy_len;
1119
1120 /* Check for buffer overflow and skip. */
1121 if (len > 0 && len <= Default_Exception_Msg_Max_Length - 3)
1122 {
1123 strcat (message, "\r\n");
1124 len += 2;
1125 }
1126
1127 /* Check for buffer overflow and truncate if necessary. */
1128 copy_len = (len + msgdesc->len <= Default_Exception_Msg_Max_Length - 1 ?
1129 msgdesc->len :
1130 Default_Exception_Msg_Max_Length - 1 - len);
1131 strncpy (&message [len], msgdesc->adr, copy_len);
1132 message [len + copy_len] = 0;
1133
1134 return 0;
1135 }
1136
1137 /* Scan TABLE for a match for the condition contained in SIGARGS,
1138 and return the entry, or the empty entry if no match found. */
1139 static const struct cond_except *
1140 scan_conditions ( int *sigargs, const struct cond_except *table [])
1141 {
1142 int i;
1143 struct cond_except entry;
1144
1145 /* Scan the exception condition table for a match and fetch
1146 the associated GNAT exception pointer. */
1147 for (i = 0; (*table) [i].cond; i++)
1148 {
1149 unsigned int match = LIB$MATCH_COND (&sigargs [1], &(*table) [i].cond);
1150 const struct cond_subtests *subtests = (*table) [i].subtests;
1151
1152 if (match)
1153 {
1154 if (!subtests)
1155 {
1156 return &(*table) [i];
1157 }
1158 else
1159 {
1160 unsigned int ii;
1161 int num = (*subtests).num;
1162
1163 /* Perform subtests to differentiate exception. */
1164 for (ii = 0; ii < num; ii++)
1165 {
1166 unsigned int arg = (*subtests).sigargs [ii].sigarg;
1167 unsigned int argval = (*subtests).sigargs [ii].sigargval;
1168
1169 if (sigargs [arg] != argval)
1170 {
1171 num = 0;
1172 break;
1173 }
1174 }
1175
1176 /* All subtests passed. */
1177 if (num == (*subtests).num)
1178 return &(*table) [i];
1179 }
1180 }
1181 }
1182
1183 /* No match, return the null terminating entry. */
1184 return &(*table) [i];
1185 }
1186
1187 /* __gnat_handle_vms_condtition is both a frame based handler
1188 for the runtime, and an exception vector for the compiler. */
1189 long
1190 __gnat_handle_vms_condition (int *sigargs, void *mechargs)
1191 {
1192 struct Exception_Data *exception = 0;
1193 unsigned int needs_adjust = 0;
1194 void *base_code;
1195 struct descriptor_s gnat_facility = {4, 0, "GNAT"};
1196 char message [Default_Exception_Msg_Max_Length];
1197
1198 const char *msg = "";
1199
1200 /* Check for conditions to resignal which aren't effected by pragma
1201 Import_Exception. */
1202 if (__gnat_resignal_p (sigargs [1]))
1203 return SS$_RESIGNAL;
1204 #ifndef IN_RTS
1205 /* toplev.c handles this for compiler. */
1206 if (sigargs [1] == SS$_HPARITH)
1207 return SS$_RESIGNAL;
1208 #endif
1209
1210 #ifdef IN_RTS
1211 /* See if it's an imported exception. Beware that registered exceptions
1212 are bound to their base code, with the severity bits masked off. */
1213 base_code = Base_Code_In ((void *) sigargs[1]);
1214 exception = Coded_Exception (base_code);
1215 #endif
1216
1217 if (exception == 0)
1218 #ifdef IN_RTS
1219 {
1220 int i;
1221 struct cond_except cond;
1222 const struct cond_except *cond_table;
1223 const struct cond_except *cond_tables [] = {dec_ada_cond_except_table,
1224 system_cond_except_table,
1225 0};
1226 unsigned int ctrlc = SS$_CONTROLC;
1227 unsigned int *sigint = &C$_SIGINT;
1228 int ctrlc_match = LIB$MATCH_COND (&sigargs [1], &ctrlc);
1229 int sigint_match = LIB$MATCH_COND (&sigargs [1], &sigint);
1230
1231 extern int SYS$DCLAST (void (*astadr)(), unsigned long long astprm,
1232 unsigned int acmode);
1233
1234 /* If SS$_CONTROLC has been imported as an exception, it will take
1235 priority over a Ctrl/C handler. See above. SIGINT has a
1236 different condition value due to it's DECCCRTL roots and it's
1237 the condition that gets raised for a "kill -INT". */
1238 if ((ctrlc_match || sigint_match) && __gnat_ctrl_c_handler)
1239 {
1240 SYS$DCLAST (__gnat_ctrl_c_handler, 0, 0);
1241 return SS$_CONTINUE;
1242 }
1243
1244 i = 0;
1245 while ((cond_table = cond_tables[i++]) && !exception)
1246 {
1247 cond = *scan_conditions (sigargs, &cond_table);
1248 exception = (struct Exception_Data *) cond.except;
1249 }
1250
1251 if (exception)
1252 needs_adjust = cond.needs_adjust;
1253 else
1254 /* User programs expect Non_Ada_Error to be raised if no match,
1255 reference DEC Ada test CXCONDHAN. */
1256 exception = &Non_Ada_Error;
1257 }
1258 #else
1259 {
1260 /* Pretty much everything is just a program error in the compiler */
1261 exception = &program_error;
1262 }
1263 #endif
1264
1265 message[0] = 0;
1266 /* Subtract PC & PSL fields as per ABI for SYS$PUTMSG. */
1267 sigargs[0] -= 2;
1268
1269 extern int SYS$PUTMSG (void *, int (*)(), void *, unsigned long long);
1270
1271 /* If it was a DEC Ada specific condtiion, make it GNAT otherwise
1272 keep the old facility. */
1273 if (sigargs [1] & FAC_MASK == DECADA_M_FACILITY)
1274 SYS$PUTMSG (sigargs, copy_msg, &gnat_facility,
1275 (unsigned long long ) message);
1276 else
1277 SYS$PUTMSG (sigargs, copy_msg, 0,
1278 (unsigned long long ) message);
1279
1280 /* Add back PC & PSL fields as per ABI for SYS$PUTMSG. */
1281 sigargs[0] += 2;
1282 msg = message;
1283
1284 if (needs_adjust)
1285 __gnat_adjust_context_for_raise (sigargs [1], (void *)mechargs);
1286
1287 Raise_From_Signal_Handler (exception, msg);
1288 }
1289
1290 #if defined (IN_RTS) && defined (__IA64)
1291 /* Called only from adasigio.b32. This is a band aid to avoid going
1292 through the VMS signal handling code which results in a 0x8000 per
1293 handled exception memory leak in P2 space (see VMS source listing
1294 sys/lis/exception.lis) due to the allocation of working space that
1295 is expected to be deallocated upon return from the condition handler,
1296 which doesn't return in GNAT compiled code. */
1297 void
1298 GNAT$STOP (int *sigargs)
1299 {
1300 /* Note that there are no mechargs. We rely on the fact that condtions
1301 raised from DEClib I/O do not require an "adjust". Also the count
1302 will be off by 2, since LIB$STOP didn't get a chance to add the
1303 PC and PSL fields, so we bump it so PUTMSG comes out right. */
1304 sigargs [0] += 2;
1305 __gnat_handle_vms_condition (sigargs, 0);
1306 }
1307 #endif
1308
1309 void
1310 __gnat_install_handler (void)
1311 {
1312 long prvhnd ATTRIBUTE_UNUSED;
1313
1314 #if !defined (IN_RTS)
1315 extern int SYS$SETEXV (unsigned int vector, int (*addres)(),
1316 unsigned int accmode, void *(*(prvhnd)));
1317 SYS$SETEXV (1, __gnat_handle_vms_condition, 3, &prvhnd);
1318 #endif
1319
1320 __gnat_handler_installed = 1;
1321 }
1322
1323 /* __gnat_adjust_context_for_raise for Alpha - see comments along with the
1324 default version later in this file. */
1325
1326 #if defined (IN_RTS) && defined (__alpha__)
1327
1328 #include <vms/chfctxdef.h>
1329 #include <vms/chfdef.h>
1330
1331 #define HAVE_GNAT_ADJUST_CONTEXT_FOR_RAISE
1332
1333 void
1334 __gnat_adjust_context_for_raise (int signo ATTRIBUTE_UNUSED, void *ucontext)
1335 {
1336 if (signo == SS$_HPARITH)
1337 {
1338 /* Sub one to the address of the instruction signaling the condition,
1339 located in the sigargs array. */
1340
1341 CHF$MECH_ARRAY * mechargs = (CHF$MECH_ARRAY *) ucontext;
1342 CHF$SIGNAL_ARRAY * sigargs
1343 = (CHF$SIGNAL_ARRAY *) mechargs->chf$q_mch_sig_addr;
1344
1345 int vcount = sigargs->chf$is_sig_args;
1346 int * pc_slot = & (&sigargs->chf$l_sig_name)[vcount-2];
1347
1348 (*pc_slot)--;
1349 }
1350 }
1351
1352 #endif
1353
1354 /* __gnat_adjust_context_for_raise for ia64. */
1355
1356 #if defined (IN_RTS) && defined (__IA64)
1357
1358 #include <vms/chfctxdef.h>
1359 #include <vms/chfdef.h>
1360
1361 #define HAVE_GNAT_ADJUST_CONTEXT_FOR_RAISE
1362
1363 typedef unsigned long long u64;
1364
1365 void
1366 __gnat_adjust_context_for_raise (int signo ATTRIBUTE_UNUSED, void *ucontext)
1367 {
1368 /* Add one to the address of the instruction signaling the condition,
1369 located in the 64bits sigargs array. */
1370
1371 CHF$MECH_ARRAY * mechargs = (CHF$MECH_ARRAY *) ucontext;
1372
1373 CHF64$SIGNAL_ARRAY *chfsig64
1374 = (CHF64$SIGNAL_ARRAY *) mechargs->chf$ph_mch_sig64_addr;
1375
1376 u64 * post_sigarray
1377 = (u64 *)chfsig64 + 1 + chfsig64->chf64$l_sig_args;
1378
1379 u64 * ih_pc_loc = post_sigarray - 2;
1380
1381 (*ih_pc_loc) ++;
1382 }
1383
1384 #endif
1385
1386 /* Easier interface for LIB$GET_LOGICAL: put the equivalence of NAME into BUF,
1387 always NUL terminated. In case of error or if the result is longer than
1388 LEN (length of BUF) an empty string is written info BUF. */
1389
1390 static void
1391 __gnat_vms_get_logical (const char *name, char *buf, int len)
1392 {
1393 struct descriptor_s name_desc, result_desc;
1394 int status;
1395 unsigned short rlen;
1396
1397 /* Build the descriptor for NAME. */
1398 name_desc.len = strlen (name);
1399 name_desc.mbz = 0;
1400 name_desc.adr = (char *)name;
1401
1402 /* Build the descriptor for the result. */
1403 result_desc.len = len;
1404 result_desc.mbz = 0;
1405 result_desc.adr = buf;
1406
1407 status = LIB$GET_LOGICAL (&name_desc, &result_desc, &rlen);
1408
1409 if ((status & 1) == 1 && rlen < len)
1410 buf[rlen] = 0;
1411 else
1412 buf[0] = 0;
1413 }
1414
1415 /* Size of a page on ia64 and alpha VMS. */
1416 #define VMS_PAGESIZE 8192
1417
1418 /* User mode. */
1419 #define PSL__C_USER 3
1420
1421 /* No access. */
1422 #define PRT__C_NA 0
1423
1424 /* Descending region. */
1425 #define VA__M_DESCEND 1
1426
1427 /* Get by virtual address. */
1428 #define VA___REGSUM_BY_VA 1
1429
1430 /* Memory region summary. */
1431 struct regsum
1432 {
1433 unsigned long long q_region_id;
1434 unsigned int l_flags;
1435 unsigned int l_region_protection;
1436 void *pq_start_va;
1437 unsigned long long q_region_size;
1438 void *pq_first_free_va;
1439 };
1440
1441 extern int SYS$GET_REGION_INFO (unsigned int, unsigned long long *,
1442 void *, void *, unsigned int,
1443 void *, unsigned int *);
1444 extern int SYS$EXPREG_64 (unsigned long long *, unsigned long long,
1445 unsigned int, unsigned int, void **,
1446 unsigned long long *);
1447 extern int SYS$SETPRT_64 (void *, unsigned long long, unsigned int,
1448 unsigned int, void **, unsigned long long *,
1449 unsigned int *);
1450
1451 /* Add a guard page in the memory region containing ADDR at ADDR +/- SIZE.
1452 (The sign depends on the kind of the memory region). */
1453
1454 static int
1455 __gnat_set_stack_guard_page (void *addr, unsigned long size)
1456 {
1457 int status;
1458 void *ret_va;
1459 unsigned long long ret_len;
1460 unsigned int ret_prot;
1461 void *start_va;
1462 unsigned long long length;
1463 unsigned int retlen;
1464 struct regsum buffer;
1465
1466 /* Get the region for ADDR. */
1467 status = SYS$GET_REGION_INFO
1468 (VA___REGSUM_BY_VA, NULL, addr, NULL, sizeof (buffer), &buffer, &retlen);
1469
1470 if ((status & 1) != 1)
1471 return -1;
1472
1473 /* Extend the region. */
1474 status = SYS$EXPREG_64 (&buffer.q_region_id,
1475 size, 0, 0, &start_va, &length);
1476
1477 if ((status & 1) != 1)
1478 return -1;
1479
1480 /* Create a guard page. */
1481 if (!(buffer.l_flags & VA__M_DESCEND))
1482 start_va = (void *)((unsigned long long)start_va + length - VMS_PAGESIZE);
1483
1484 status = SYS$SETPRT_64 (start_va, VMS_PAGESIZE, PSL__C_USER, PRT__C_NA,
1485 &ret_va, &ret_len, &ret_prot);
1486
1487 if ((status & 1) != 1)
1488 return -1;
1489 return 0;
1490 }
1491
1492 /* Read logicals to limit the stack(s) size. */
1493
1494 static void
1495 __gnat_set_stack_limit (void)
1496 {
1497 #ifdef __ia64__
1498 void *sp;
1499 unsigned long size;
1500 char value[16];
1501 char *e;
1502
1503 /* The main stack. */
1504 __gnat_vms_get_logical ("GNAT_STACK_SIZE", value, sizeof (value));
1505 size = strtoul (value, &e, 0);
1506 if (e > value && *e == 0)
1507 {
1508 asm ("mov %0=sp" : "=r" (sp));
1509 __gnat_set_stack_guard_page (sp, size * 1024);
1510 }
1511
1512 /* The register stack. */
1513 __gnat_vms_get_logical ("GNAT_RBS_SIZE", value, sizeof (value));
1514 size = strtoul (value, &e, 0);
1515 if (e > value && *e == 0)
1516 {
1517 asm ("mov %0=ar.bsp" : "=r" (sp));
1518 __gnat_set_stack_guard_page (sp, size * 1024);
1519 }
1520 #endif
1521 }
1522
1523 #ifdef IN_RTS
1524 extern int SYS$IEEE_SET_FP_CONTROL (void *, void *, void *);
1525 #define K_TRUE 1
1526 #define __int64 long long
1527 #define __NEW_STARLET
1528 #include <vms/ieeedef.h>
1529 #endif
1530
1531 /* Feature logical name and global variable address pair.
1532 If we ever add another feature logical to this list, the
1533 feature struct will need to be enhanced to take into account
1534 possible values for *gl_addr. */
1535 struct feature {
1536 const char *name;
1537 int *gl_addr;
1538 };
1539
1540 /* Default values for GNAT features set by environment or binder. */
1541 int __gl_heap_size = 64;
1542
1543 /* Default float format is 'I' meaning IEEE. If gnatbind detetcts that a
1544 VAX Float format is specified, it will set this global variable to 'V'.
1545 Subsequently __gnat_set_features will test the variable and if set for
1546 VAX Float will call a Starlet function to enable trapping for invalid
1547 operation, drivide by zero, and overflow. This will prevent the VMS runtime
1548 (specifically OTS$CHECK_FP_MODE) from complaining about inconsistent
1549 floating point settings in a mixed language program. Ideally the setting
1550 would be determined at link time based on setttings in the object files,
1551 however the VMS linker seems to take the setting from the first object
1552 in the link, e.g. pcrt0.o which is float representation neutral. */
1553 char __gl_float_format = 'I';
1554
1555 /* Array feature logical names and global variable addresses. */
1556 static const struct feature features[] =
1557 {
1558 {"GNAT$NO_MALLOC_64", &__gl_heap_size},
1559 {0, 0}
1560 };
1561
1562 void
1563 __gnat_set_features (void)
1564 {
1565 int i;
1566 char buff[16];
1567 #ifdef IN_RTS
1568 IEEE clrmsk, setmsk, prvmsk;
1569
1570 clrmsk.ieee$q_flags = 0LL;
1571 setmsk.ieee$q_flags = 0LL;
1572 #endif
1573
1574 /* Loop through features array and test name for enable/disable. */
1575 for (i = 0; features[i].name; i++)
1576 {
1577 __gnat_vms_get_logical (features[i].name, buff, sizeof (buff));
1578
1579 if (strcmp (buff, "ENABLE") == 0
1580 || strcmp (buff, "TRUE") == 0
1581 || strcmp (buff, "1") == 0)
1582 *features[i].gl_addr = 32;
1583 else if (strcmp (buff, "DISABLE") == 0
1584 || strcmp (buff, "FALSE") == 0
1585 || strcmp (buff, "0") == 0)
1586 *features[i].gl_addr = 64;
1587 }
1588
1589 /* Features to artificially limit the stack size. */
1590 __gnat_set_stack_limit ();
1591
1592 #ifdef IN_RTS
1593 if (__gl_float_format == 'V')
1594 {
1595 setmsk.ieee$v_trap_enable_inv = K_TRUE;
1596 setmsk.ieee$v_trap_enable_dze = K_TRUE;
1597 setmsk.ieee$v_trap_enable_ovf = K_TRUE;
1598 SYS$IEEE_SET_FP_CONTROL (&clrmsk, &setmsk, &prvmsk);
1599 }
1600 #endif
1601
1602 __gnat_features_set = 1;
1603 }
1604
1605 /* Return true if the VMS version is 7.x. */
1606
1607 extern unsigned int LIB$GETSYI (int *, ...);
1608
1609 #define SYI$_VERSION 0x1000
1610
1611 int
1612 __gnat_is_vms_v7 (void)
1613 {
1614 struct descriptor_s desc;
1615 char version[8];
1616 int status;
1617 int code = SYI$_VERSION;
1618
1619 desc.len = sizeof (version);
1620 desc.mbz = 0;
1621 desc.adr = version;
1622
1623 status = LIB$GETSYI (&code, 0, &desc);
1624 if ((status & 1) == 1 && version[1] == '7' && version[2] == '.')
1625 return 1;
1626 else
1627 return 0;
1628 }
1629
1630 /*******************/
1631 /* FreeBSD Section */
1632 /*******************/
1633
1634 #elif defined (__FreeBSD__) || defined (__DragonFly__)
1635
1636 #include <signal.h>
1637 #include <sys/ucontext.h>
1638 #include <unistd.h>
1639
1640 static void
1641 __gnat_error_handler (int sig,
1642 siginfo_t *si ATTRIBUTE_UNUSED,
1643 void *ucontext ATTRIBUTE_UNUSED)
1644 {
1645 struct Exception_Data *exception;
1646 const char *msg;
1647
1648 switch (sig)
1649 {
1650 case SIGFPE:
1651 exception = &constraint_error;
1652 msg = "SIGFPE";
1653 break;
1654
1655 case SIGILL:
1656 exception = &constraint_error;
1657 msg = "SIGILL";
1658 break;
1659
1660 case SIGSEGV:
1661 exception = &storage_error;
1662 msg = "stack overflow or erroneous memory access";
1663 break;
1664
1665 case SIGBUS:
1666 exception = &storage_error;
1667 msg = "SIGBUS: possible stack overflow";
1668 break;
1669
1670 default:
1671 exception = &program_error;
1672 msg = "unhandled signal";
1673 }
1674
1675 Raise_From_Signal_Handler (exception, msg);
1676 }
1677
1678 void
1679 __gnat_install_handler (void)
1680 {
1681 struct sigaction act;
1682
1683 /* Set up signal handler to map synchronous signals to appropriate
1684 exceptions. Make sure that the handler isn't interrupted by another
1685 signal that might cause a scheduling event! */
1686
1687 act.sa_sigaction
1688 = (void (*)(int, struct __siginfo *, void*)) __gnat_error_handler;
1689 act.sa_flags = SA_NODEFER | SA_RESTART | SA_SIGINFO;
1690 (void) sigemptyset (&act.sa_mask);
1691
1692 (void) sigaction (SIGILL, &act, NULL);
1693 (void) sigaction (SIGFPE, &act, NULL);
1694 (void) sigaction (SIGSEGV, &act, NULL);
1695 (void) sigaction (SIGBUS, &act, NULL);
1696
1697 __gnat_handler_installed = 1;
1698 }
1699
1700 /*************************************/
1701 /* VxWorks Section (including Vx653) */
1702 /*************************************/
1703
1704 #elif defined(__vxworks)
1705
1706 #include <signal.h>
1707 #include <taskLib.h>
1708 #if defined (__i386__) && !defined (VTHREADS)
1709 #include <sysLib.h>
1710 #endif
1711
1712 #ifndef __RTP__
1713 #include <intLib.h>
1714 #include <iv.h>
1715 #endif
1716
1717 #if defined (ARMEL) && (_WRS_VXWORKS_MAJOR == 6) && !defined(__RTP__)
1718 #include <vmLib.h>
1719 #endif
1720
1721 #ifdef VTHREADS
1722 #include "private/vThreadsP.h"
1723 #endif
1724
1725 #ifndef __RTP__
1726
1727 /* Directly vectored Interrupt routines are not supported when using RTPs. */
1728
1729 extern int __gnat_inum_to_ivec (int);
1730
1731 /* This is needed by the GNAT run time to handle Vxworks interrupts. */
1732 int
1733 __gnat_inum_to_ivec (int num)
1734 {
1735 return (int) ((long) INUM_TO_IVEC ((long) num));
1736 }
1737 #endif
1738
1739 #if !defined(__alpha_vxworks) && ((_WRS_VXWORKS_MAJOR != 6) && (_WRS_VXWORKS_MAJOR != 7)) && !defined(__RTP__)
1740
1741 /* getpid is used by s-parint.adb, but is not defined by VxWorks, except
1742 on Alpha VxWorks and VxWorks 6.x (including RTPs). */
1743
1744 extern long getpid (void);
1745
1746 long
1747 getpid (void)
1748 {
1749 return taskIdSelf ();
1750 }
1751 #endif
1752
1753 /* VxWorks 653 vThreads expects the field excCnt to be zeroed when a signal is.
1754 handled. The VxWorks version of longjmp does this; GCC's builtin_longjmp
1755 doesn't. */
1756 void
1757 __gnat_clear_exception_count (void)
1758 {
1759 #ifdef VTHREADS
1760 WIND_TCB *currentTask = (WIND_TCB *) taskIdSelf();
1761
1762 currentTask->vThreads.excCnt = 0;
1763 #endif
1764 }
1765
1766 /* Handle different SIGnal to exception mappings in different VxWorks
1767 versions. */
1768 void
1769 __gnat_map_signal (int sig, siginfo_t *si ATTRIBUTE_UNUSED,
1770 void *sc ATTRIBUTE_UNUSED)
1771 {
1772 struct Exception_Data *exception;
1773 const char *msg;
1774
1775 switch (sig)
1776 {
1777 case SIGFPE:
1778 exception = &constraint_error;
1779 msg = "SIGFPE";
1780 break;
1781 #ifdef VTHREADS
1782 #ifdef __VXWORKSMILS__
1783 case SIGILL:
1784 exception = &storage_error;
1785 msg = "SIGILL: possible stack overflow";
1786 break;
1787 case SIGSEGV:
1788 exception = &storage_error;
1789 msg = "SIGSEGV";
1790 break;
1791 case SIGBUS:
1792 exception = &program_error;
1793 msg = "SIGBUS";
1794 break;
1795 #else
1796 case SIGILL:
1797 exception = &constraint_error;
1798 msg = "Floating point exception or SIGILL";
1799 break;
1800 case SIGSEGV:
1801 exception = &storage_error;
1802 msg = "SIGSEGV";
1803 break;
1804 case SIGBUS:
1805 exception = &storage_error;
1806 msg = "SIGBUS: possible stack overflow";
1807 break;
1808 #endif
1809 #elif (_WRS_VXWORKS_MAJOR >= 6)
1810 case SIGILL:
1811 exception = &constraint_error;
1812 msg = "SIGILL";
1813 break;
1814 #ifdef __RTP__
1815 /* In RTP mode a SIGSEGV is most likely due to a stack overflow,
1816 since stack checking uses the probing mechanism. */
1817 case SIGSEGV:
1818 exception = &storage_error;
1819 msg = "SIGSEGV: possible stack overflow";
1820 break;
1821 case SIGBUS:
1822 exception = &program_error;
1823 msg = "SIGBUS";
1824 break;
1825 #else
1826 /* VxWorks 6 kernel mode with probing. SIGBUS for guard page hit */
1827 case SIGSEGV:
1828 exception = &storage_error;
1829 msg = "SIGSEGV";
1830 break;
1831 case SIGBUS:
1832 exception = &storage_error;
1833 msg = "SIGBUS: possible stack overflow";
1834 break;
1835 #endif
1836 #else
1837 /* VxWorks 5: a SIGILL is most likely due to a stack overflow,
1838 since stack checking uses the stack limit mechanism. */
1839 case SIGILL:
1840 exception = &storage_error;
1841 msg = "SIGILL: possible stack overflow";
1842 break;
1843 case SIGSEGV:
1844 exception = &storage_error;
1845 msg = "SIGSEGV";
1846 break;
1847 case SIGBUS:
1848 exception = &program_error;
1849 msg = "SIGBUS";
1850 break;
1851 #endif
1852 default:
1853 exception = &program_error;
1854 msg = "unhandled signal";
1855 }
1856
1857 /* On ARM VxWorks 6.x, the guard page is left un-armed by the kernel
1858 after being violated, so subsequent violations aren't detected.
1859 so we retrieve the address of the guard page from the TCB and compare it
1860 with the page that is violated (pREG 12 in the context) and re-arm that
1861 page if there's a match. Additionally we're are assured this is a
1862 genuine stack overflow condition and and set the message and exception
1863 to that effect. */
1864 #if defined (ARMEL) && (_WRS_VXWORKS_MAJOR == 6) && !defined(__RTP__)
1865
1866 /* We re-arm the guard page by marking it invalid */
1867
1868 #define PAGE_SIZE 4096
1869 #define REG_IP 12
1870
1871 if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL)
1872 {
1873 TASK_ID tid = taskIdSelf ();
1874 WIND_TCB *pTcb = taskTcb (tid);
1875 unsigned long violated_page
1876 = ((struct sigcontext *) sc)->sc_pregs->r[REG_IP] & ~(PAGE_SIZE - 1);
1877
1878 if ((unsigned long) (pTcb->pStackEnd - PAGE_SIZE) == violated_page)
1879 {
1880 vmStateSet (NULL, violated_page,
1881 PAGE_SIZE, VM_STATE_MASK_VALID, VM_STATE_VALID_NOT);
1882 exception = &storage_error;
1883
1884 switch (sig)
1885 {
1886 case SIGSEGV:
1887 msg = "SIGSEGV: stack overflow";
1888 break;
1889 case SIGBUS:
1890 msg = "SIGBUS: stack overflow";
1891 break;
1892 case SIGILL:
1893 msg = "SIGILL: stack overflow";
1894 break;
1895 }
1896 }
1897 }
1898 #endif /* defined (ARMEL) && (_WRS_VXWORKS_MAJOR == 6) && !defined(__RTP__) */
1899
1900 __gnat_clear_exception_count ();
1901 Raise_From_Signal_Handler (exception, msg);
1902 }
1903
1904 #if defined (__i386__) && !defined (VTHREADS) && _WRS_VXWORKS_MAJOR < 7
1905
1906 extern void
1907 __gnat_vxsim_error_handler (int sig, siginfo_t *si, void *sc);
1908
1909 static int is_vxsim = 0;
1910 #endif
1911
1912 #if defined (ARMEL) && (_WRS_VXWORKS_MAJOR >= 7)
1913
1914 /* ARM-vx7 case with arm unwinding exceptions */
1915 #define HAVE_GNAT_ADJUST_CONTEXT_FOR_RAISE
1916
1917 #include <arch/../regs.h>
1918 #ifndef __RTP__
1919 #include <sigLib.h>
1920 #else
1921 #include <signal.h>
1922 #include <regs.h>
1923 #include <ucontext.h>
1924 #endif /* __RTP__ */
1925
1926 void
1927 __gnat_adjust_context_for_raise (int signo ATTRIBUTE_UNUSED,
1928 void *sc ATTRIBUTE_UNUSED)
1929 {
1930 /* In case of ARM exceptions, the registers context have the PC pointing
1931 to the instruction that raised the signal. However the unwinder expects
1932 the instruction to be in the range ]PC,PC+1]. */
1933 uintptr_t *pc_addr;
1934 #ifdef __RTP__
1935 mcontext_t *mcontext = &((ucontext_t *) sc)->uc_mcontext;
1936 pc_addr = (uintptr_t*)&mcontext->regs.pc;
1937 #else
1938 struct sigcontext * sctx = (struct sigcontext *) sc;
1939 pc_addr = (uintptr_t*)&sctx->sc_pregs->pc;
1940 #endif
1941 /* ARM Bump has to be an even number because of odd/even architecture. */
1942 *pc_addr += 2;
1943 }
1944 #endif /* ARMEL && _WRS_VXWORKS_MAJOR >= 7 */
1945
1946 /* Tasking and Non-tasking signal handler. Map SIGnal to Ada exception
1947 propagation after the required low level adjustments. */
1948
1949 static void
1950 __gnat_error_handler (int sig, siginfo_t *si, void *sc)
1951 {
1952 sigset_t mask;
1953
1954 /* VxWorks on e500v2 clears the SPE bit of the MSR when entering CPU
1955 exception state. To allow the handler and exception to work properly
1956 when they contain SPE instructions, we need to set it back before doing
1957 anything else.
1958 This mechanism is only need in kernel mode. */
1959 #if !(defined (__RTP__) || defined (CERT)) && ((CPU == PPCE500V2) || (CPU == PPC85XX))
1960 register unsigned msr;
1961 /* Read the MSR value */
1962 asm volatile ("mfmsr %0" : "=r" (msr));
1963 /* Force the SPE bit */
1964 msr |= 0x02000000;
1965 /* Store to MSR */
1966 asm volatile ("mtmsr %0" : : "r" (msr));
1967 #endif
1968
1969 /* VxWorks will always mask out the signal during the signal handler and
1970 will reenable it on a longjmp. GNAT does not generate a longjmp to
1971 return from a signal handler so the signal will still be masked unless
1972 we unmask it. */
1973 sigprocmask (SIG_SETMASK, NULL, &mask);
1974 sigdelset (&mask, sig);
1975 sigprocmask (SIG_SETMASK, &mask, NULL);
1976
1977 #if defined (__ARMEL__) || defined (__PPC__) || defined (__i386__) || defined (__x86_64__)
1978 /* On certain targets, kernel mode, we process signals through a Call Frame
1979 Info trampoline, voiding the need for myriads of fallback_frame_state
1980 variants in the ZCX runtime. We have no simple way to distinguish ZCX
1981 from SJLJ here, so we do this for SJLJ as well even though this is not
1982 necessary. This only incurs a few extra instructions and a tiny
1983 amount of extra stack usage. */
1984
1985 #ifdef HAVE_GNAT_ADJUST_CONTEXT_FOR_RAISE
1986 /* We need to sometimes to adjust the PC in case of signals so that it
1987 doesn't reference the exception that actually raised the signal but the
1988 instruction before it. */
1989 __gnat_adjust_context_for_raise (sig, sc);
1990 #endif
1991
1992 #if defined (__i386__) && !defined (VTHREADS) && (__WRS_VXWORKS_MAJOR < 7)
1993 /* On x86, the vxsim signal context is subtly different and is processeed
1994 by a handler compiled especially for vxsim.
1995 Vxsim is not supported anymore on our vxworks-7 port. */
1996
1997 if (is_vxsim)
1998 __gnat_vxsim_error_handler (sig, si, sc);
1999 #endif
2000
2001 # include "sigtramp.h"
2002
2003 __gnat_sigtramp (sig, (void *)si, (void *)sc,
2004 (__sigtramphandler_t *)&__gnat_map_signal);
2005
2006 #else
2007 __gnat_map_signal (sig, si, sc);
2008 #endif
2009 }
2010
2011 #if defined(__leon__) && defined(_WRS_KERNEL)
2012 /* For LEON VxWorks we need to install a trap handler for stack overflow */
2013
2014 extern void excEnt (void);
2015 /* VxWorks exception handler entry */
2016
2017 struct trap_entry {
2018 unsigned long inst_first;
2019 unsigned long inst_second;
2020 unsigned long inst_third;
2021 unsigned long inst_fourth;
2022 };
2023 /* Four instructions representing entries in the trap table */
2024
2025 struct trap_entry *trap_0_entry;
2026 /* We will set the location of the entry for software trap 0 in the trap
2027 table. */
2028 #endif
2029
2030 void
2031 __gnat_install_handler (void)
2032 {
2033 struct sigaction act;
2034 char *model ATTRIBUTE_UNUSED;
2035
2036 /* Setup signal handler to map synchronous signals to appropriate
2037 exceptions. Make sure that the handler isn't interrupted by another
2038 signal that might cause a scheduling event! */
2039
2040 act.sa_sigaction = __gnat_error_handler;
2041 act.sa_flags = SA_SIGINFO | SA_ONSTACK;
2042 sigemptyset (&act.sa_mask);
2043
2044 /* For VxWorks, install all signal handlers, since pragma Interrupt_State
2045 applies to vectored hardware interrupts, not signals. */
2046 sigaction (SIGFPE, &act, NULL);
2047 sigaction (SIGILL, &act, NULL);
2048 sigaction (SIGSEGV, &act, NULL);
2049 sigaction (SIGBUS, &act, NULL);
2050
2051 #if defined(__leon__) && defined(_WRS_KERNEL)
2052 /* Specific to the LEON VxWorks kernel run-time library */
2053
2054 /* For stack checking the compiler triggers a software trap 0 (ta 0) in
2055 case of overflow (we use the stack limit mechanism). We need to install
2056 the trap handler here for this software trap (the OS does not handle
2057 it) as if it were a data_access_exception (trap 9). We do the same as
2058 if we put in the trap table a VXSPARC_BAD_TRAP(9). Software trap 0 is
2059 located at vector 0x80, and each entry takes 4 words. */
2060
2061 trap_0_entry = (struct trap_entry *)(intVecBaseGet () + 0x80 * 4);
2062
2063 /* mov 0x9, %l7 */
2064
2065 trap_0_entry->inst_first = 0xae102000 + 9;
2066
2067 /* sethi %hi(excEnt), %l6 */
2068
2069 /* The 22 most significant bits of excEnt are obtained shifting 10 times
2070 to the right. */
2071
2072 trap_0_entry->inst_second = 0x2d000000 + ((unsigned long)excEnt >> 10);
2073
2074 /* jmp %l6+%lo(excEnt) */
2075
2076 /* The 10 least significant bits of excEnt are obtained by masking */
2077
2078 trap_0_entry->inst_third = 0x81c5a000 + ((unsigned long)excEnt & 0x3ff);
2079
2080 /* rd %psr, %l0 */
2081
2082 trap_0_entry->inst_fourth = 0xa1480000;
2083 #endif
2084
2085 #if defined (__i386__) && !defined (VTHREADS) && _WRS_VXWORKS_MAJOR != 7
2086 /* By experiment, found that sysModel () returns the following string
2087 prefix for vxsim when running on Linux and Windows. */
2088 model = sysModel ();
2089 if ((strncmp (model, "Linux", 5) == 0)
2090 || (strncmp (model, "Windows", 7) == 0))
2091 is_vxsim = 1;
2092 #endif
2093
2094 __gnat_handler_installed = 1;
2095 }
2096
2097 #define HAVE_GNAT_INIT_FLOAT
2098
2099 void
2100 __gnat_init_float (void)
2101 {
2102 /* Disable overflow/underflow exceptions on the PPC processor, needed
2103 to get correct Ada semantics. Note that for AE653 vThreads, the HW
2104 overflow settings are an OS configuration issue. The instructions
2105 below have no effect. */
2106 #if defined (_ARCH_PPC) && !defined (_SOFT_FLOAT) && (!defined (VTHREADS) || defined (__VXWORKSMILS__))
2107 #if defined (__SPE__)
2108 {
2109 /* For e500v2, do nothing and leave the responsibility to install the
2110 handler and enable the exceptions to the BSP. */
2111 }
2112 #else
2113 asm ("mtfsb0 25");
2114 asm ("mtfsb0 26");
2115 #endif
2116 #endif
2117
2118 #if (defined (__i386__) && !defined (VTHREADS))
2119 /* This is used to properly initialize the FPU on an x86 for each
2120 process thread. Is this needed for x86_64 ??? */
2121 asm ("finit");
2122 #endif
2123
2124 /* Similarly for SPARC64. Achieved by masking bits in the Trap Enable Mask
2125 field of the Floating-point Status Register (see the SPARC Architecture
2126 Manual Version 9, p 48). */
2127 #if defined (sparc64)
2128
2129 #define FSR_TEM_NVM (1 << 27) /* Invalid operand */
2130 #define FSR_TEM_OFM (1 << 26) /* Overflow */
2131 #define FSR_TEM_UFM (1 << 25) /* Underflow */
2132 #define FSR_TEM_DZM (1 << 24) /* Division by Zero */
2133 #define FSR_TEM_NXM (1 << 23) /* Inexact result */
2134 {
2135 unsigned int fsr;
2136
2137 __asm__("st %%fsr, %0" : "=m" (fsr));
2138 fsr &= ~(FSR_TEM_OFM | FSR_TEM_UFM);
2139 __asm__("ld %0, %%fsr" : : "m" (fsr));
2140 }
2141 #endif
2142 }
2143
2144 /* This subprogram is called by System.Task_Primitives.Operations.Enter_Task
2145 (if not null) when a new task is created. It is initialized by
2146 System.Stack_Checking.Operations.Initialize_Stack_Limit.
2147 The use of a hook avoids to drag stack checking subprograms if stack
2148 checking is not used. */
2149 void (*__gnat_set_stack_limit_hook)(void) = (void (*)(void))0;
2150
2151 /******************/
2152 /* NetBSD Section */
2153 /******************/
2154
2155 #elif defined(__NetBSD__)
2156
2157 #include <signal.h>
2158 #include <unistd.h>
2159
2160 static void
2161 __gnat_error_handler (int sig)
2162 {
2163 struct Exception_Data *exception;
2164 const char *msg;
2165
2166 switch(sig)
2167 {
2168 case SIGFPE:
2169 exception = &constraint_error;
2170 msg = "SIGFPE";
2171 break;
2172 case SIGILL:
2173 exception = &constraint_error;
2174 msg = "SIGILL";
2175 break;
2176 case SIGSEGV:
2177 exception = &storage_error;
2178 msg = "stack overflow or erroneous memory access";
2179 break;
2180 case SIGBUS:
2181 exception = &constraint_error;
2182 msg = "SIGBUS";
2183 break;
2184 default:
2185 exception = &program_error;
2186 msg = "unhandled signal";
2187 }
2188
2189 Raise_From_Signal_Handler (exception, msg);
2190 }
2191
2192 void
2193 __gnat_install_handler (void)
2194 {
2195 struct sigaction act;
2196
2197 act.sa_handler = __gnat_error_handler;
2198 act.sa_flags = SA_NODEFER | SA_RESTART;
2199 sigemptyset (&act.sa_mask);
2200
2201 /* Do not install handlers if interrupt state is "System". */
2202 if (__gnat_get_interrupt_state (SIGFPE) != 's')
2203 sigaction (SIGFPE, &act, NULL);
2204 if (__gnat_get_interrupt_state (SIGILL) != 's')
2205 sigaction (SIGILL, &act, NULL);
2206 if (__gnat_get_interrupt_state (SIGSEGV) != 's')
2207 sigaction (SIGSEGV, &act, NULL);
2208 if (__gnat_get_interrupt_state (SIGBUS) != 's')
2209 sigaction (SIGBUS, &act, NULL);
2210
2211 __gnat_handler_installed = 1;
2212 }
2213
2214 /*******************/
2215 /* OpenBSD Section */
2216 /*******************/
2217
2218 #elif defined(__OpenBSD__)
2219
2220 #include <signal.h>
2221 #include <unistd.h>
2222
2223 static void
2224 __gnat_error_handler (int sig)
2225 {
2226 struct Exception_Data *exception;
2227 const char *msg;
2228
2229 switch(sig)
2230 {
2231 case SIGFPE:
2232 exception = &constraint_error;
2233 msg = "SIGFPE";
2234 break;
2235 case SIGILL:
2236 exception = &constraint_error;
2237 msg = "SIGILL";
2238 break;
2239 case SIGSEGV:
2240 exception = &storage_error;
2241 msg = "stack overflow or erroneous memory access";
2242 break;
2243 case SIGBUS:
2244 exception = &constraint_error;
2245 msg = "SIGBUS";
2246 break;
2247 default:
2248 exception = &program_error;
2249 msg = "unhandled signal";
2250 }
2251
2252 Raise_From_Signal_Handler (exception, msg);
2253 }
2254
2255 void
2256 __gnat_install_handler (void)
2257 {
2258 struct sigaction act;
2259
2260 act.sa_handler = __gnat_error_handler;
2261 act.sa_flags = SA_NODEFER | SA_RESTART;
2262 sigemptyset (&act.sa_mask);
2263
2264 /* Do not install handlers if interrupt state is "System" */
2265 if (__gnat_get_interrupt_state (SIGFPE) != 's')
2266 sigaction (SIGFPE, &act, NULL);
2267 if (__gnat_get_interrupt_state (SIGILL) != 's')
2268 sigaction (SIGILL, &act, NULL);
2269 if (__gnat_get_interrupt_state (SIGSEGV) != 's')
2270 sigaction (SIGSEGV, &act, NULL);
2271 if (__gnat_get_interrupt_state (SIGBUS) != 's')
2272 sigaction (SIGBUS, &act, NULL);
2273
2274 __gnat_handler_installed = 1;
2275 }
2276
2277 /******************/
2278 /* Darwin Section */
2279 /******************/
2280
2281 #elif defined(__APPLE__)
2282
2283 #include <TargetConditionals.h>
2284 #include <signal.h>
2285 #include <stdlib.h>
2286 #include <sys/syscall.h>
2287 #include <sys/sysctl.h>
2288
2289 /* This must be in keeping with System.OS_Interface.Alternate_Stack_Size. */
2290 char __gnat_alternate_stack[32 * 1024]; /* 1 * MINSIGSTKSZ */
2291
2292 /* Defined in xnu unix_signal.c.
2293 Tell the kernel to re-use alt stack when delivering a signal. */
2294 #define UC_RESET_ALT_STACK 0x80000000
2295
2296 #if !(defined (__arm__) || defined (__arm64__) || TARGET_IPHONE_SIMULATOR)
2297 #include <mach/mach_vm.h>
2298 #include <mach/mach_init.h>
2299 #include <mach/vm_statistics.h>
2300 #endif
2301
2302 #ifdef __arm64__
2303 #include <sys/ucontext.h>
2304 #include "sigtramp.h"
2305 #endif
2306
2307 /* Return true if ADDR is within a stack guard area. */
2308 static int
2309 __gnat_is_stack_guard (mach_vm_address_t addr)
2310 {
2311 #if !(defined (__arm__) || defined (__arm64__) || TARGET_IPHONE_SIMULATOR)
2312 kern_return_t kret;
2313 vm_region_submap_info_data_64_t info;
2314 mach_vm_address_t start;
2315 mach_vm_size_t size;
2316 natural_t depth;
2317 mach_msg_type_number_t count;
2318
2319 count = VM_REGION_SUBMAP_INFO_COUNT_64;
2320 start = addr;
2321 size = -1;
2322 depth = 9999;
2323 kret = mach_vm_region_recurse (mach_task_self (), &start, &size, &depth,
2324 (vm_region_recurse_info_t) &info, &count);
2325 if (kret == KERN_SUCCESS
2326 && addr >= start && addr < (start + size)
2327 && info.protection == VM_PROT_NONE
2328 && info.user_tag == VM_MEMORY_STACK)
2329 return 1;
2330 return 0;
2331 #else
2332 /* Pagezero for arm. */
2333 return addr >= 4096;
2334 #endif
2335 }
2336
2337 #define HAVE_GNAT_ADJUST_CONTEXT_FOR_RAISE
2338
2339 #if defined (__x86_64__)
2340 static int
2341 __darwin_major_version (void)
2342 {
2343 static int cache = -1;
2344 if (cache < 0)
2345 {
2346 int mib[2] = {CTL_KERN, KERN_OSRELEASE};
2347 size_t len;
2348
2349 /* Find out how big the buffer needs to be (and set cache to 0
2350 on failure). */
2351 if (sysctl (mib, 2, NULL, &len, NULL, 0) == 0)
2352 {
2353 char release[len];
2354 sysctl (mib, 2, release, &len, NULL, 0);
2355 /* Darwin releases are of the form L.M.N where L is the major
2356 version, so strtol will return L. */
2357 cache = (int) strtol (release, NULL, 10);
2358 }
2359 else
2360 {
2361 cache = 0;
2362 }
2363 }
2364 return cache;
2365 }
2366 #endif
2367
2368 void
2369 __gnat_adjust_context_for_raise (int signo ATTRIBUTE_UNUSED,
2370 void *ucontext ATTRIBUTE_UNUSED)
2371 {
2372 #if defined (__x86_64__)
2373 if (__darwin_major_version () < 12)
2374 {
2375 /* Work around radar #10302855, where the unwinders (libunwind or
2376 libgcc_s depending on the system revision) and the DWARF unwind
2377 data for sigtramp have different ideas about register numbering,
2378 causing rbx and rdx to be transposed. */
2379 ucontext_t *uc = (ucontext_t *)ucontext;
2380 unsigned long t = uc->uc_mcontext->__ss.__rbx;
2381
2382 uc->uc_mcontext->__ss.__rbx = uc->uc_mcontext->__ss.__rdx;
2383 uc->uc_mcontext->__ss.__rdx = t;
2384 }
2385 #elif defined(__arm64__)
2386 /* Even though the CFI is marked as a signal frame, we need this. */
2387 ucontext_t *uc = (ucontext_t *)ucontext;
2388 uc->uc_mcontext->__ss.__pc++;
2389 #endif
2390 }
2391
2392 static void
2393 __gnat_map_signal (int sig, siginfo_t *si, void *mcontext ATTRIBUTE_UNUSED)
2394 {
2395 struct Exception_Data *exception;
2396 const char *msg;
2397
2398 switch (sig)
2399 {
2400 case SIGSEGV:
2401 case SIGBUS:
2402 if (__gnat_is_stack_guard ((unsigned long)si->si_addr))
2403 {
2404 #ifdef __arm64__
2405 /* ??? This is a kludge to make stack checking work. The problem is
2406 that the trampoline doesn't restore LR and, consequently, doesn't
2407 make it possible to unwind past an interrupted frame which hasn"t
2408 saved LR on the stack yet. Therefore, for probes in the prologue
2409 (32-bit probes as opposed to standard 64-bit probes), we make the
2410 unwinder skip the not-yet-established frame altogether. */
2411 mcontext_t mc = (mcontext_t)mcontext;
2412 if (!(*(unsigned int *)(mc->__ss.__pc-1) & ((unsigned int)1 << 30)))
2413 mc->__ss.__pc = mc->__ss.__lr;
2414 #endif
2415 exception = &storage_error;
2416 msg = "stack overflow";
2417 }
2418 else
2419 {
2420 exception = &constraint_error;
2421 msg = "erroneous memory access";
2422 }
2423
2424 /* Reset the use of alt stack, so that the alt stack will be used
2425 for the next signal delivery.
2426 The stack can't be used in case of stack checking. */
2427 syscall (SYS_sigreturn, NULL, UC_RESET_ALT_STACK);
2428 break;
2429
2430 case SIGFPE:
2431 exception = &constraint_error;
2432 msg = "SIGFPE";
2433 break;
2434
2435 default:
2436 exception = &program_error;
2437 msg = "unhandled signal";
2438 }
2439
2440 Raise_From_Signal_Handler (exception, msg);
2441 }
2442
2443 static void
2444 __gnat_error_handler (int sig, siginfo_t *si, void *ucontext)
2445 {
2446 __gnat_adjust_context_for_raise (sig, ucontext);
2447
2448 /* The Darwin libc comes with a signal trampoline, except for ARM64. */
2449 #ifdef __arm64__
2450 __gnat_sigtramp (sig, (void *)si, ucontext,
2451 (__sigtramphandler_t *)&__gnat_map_signal);
2452 #else
2453 __gnat_map_signal (sig, si, ucontext);
2454 #endif
2455 }
2456
2457 void
2458 __gnat_install_handler (void)
2459 {
2460 struct sigaction act;
2461
2462 /* Set up signal handler to map synchronous signals to appropriate
2463 exceptions. Make sure that the handler isn't interrupted by another
2464 signal that might cause a scheduling event! Also setup an alternate
2465 stack region for the handler execution so that stack overflows can be
2466 handled properly, avoiding a SEGV generation from stack usage by the
2467 handler itself (and it is required by Darwin). */
2468
2469 stack_t stack;
2470 stack.ss_sp = __gnat_alternate_stack;
2471 stack.ss_size = sizeof (__gnat_alternate_stack);
2472 stack.ss_flags = 0;
2473 sigaltstack (&stack, NULL);
2474
2475 act.sa_flags = SA_NODEFER | SA_RESTART | SA_SIGINFO;
2476 act.sa_sigaction = __gnat_error_handler;
2477 sigemptyset (&act.sa_mask);
2478
2479 /* Do not install handlers if interrupt state is "System". */
2480 if (__gnat_get_interrupt_state (SIGABRT) != 's')
2481 sigaction (SIGABRT, &act, NULL);
2482 if (__gnat_get_interrupt_state (SIGFPE) != 's')
2483 sigaction (SIGFPE, &act, NULL);
2484 if (__gnat_get_interrupt_state (SIGILL) != 's')
2485 sigaction (SIGILL, &act, NULL);
2486
2487 act.sa_flags |= SA_ONSTACK;
2488 if (__gnat_get_interrupt_state (SIGSEGV) != 's')
2489 sigaction (SIGSEGV, &act, NULL);
2490 if (__gnat_get_interrupt_state (SIGBUS) != 's')
2491 sigaction (SIGBUS, &act, NULL);
2492
2493 __gnat_handler_installed = 1;
2494 }
2495
2496 #elif defined(__ANDROID__)
2497
2498 /*******************/
2499 /* Android Section */
2500 /*******************/
2501
2502 #include <signal.h>
2503 #include <sys/ucontext.h>
2504 #include "sigtramp.h"
2505
2506 #define HAVE_GNAT_ADJUST_CONTEXT_FOR_RAISE
2507
2508 void
2509 __gnat_adjust_context_for_raise (int signo ATTRIBUTE_UNUSED, void *ucontext)
2510 {
2511 mcontext_t *mcontext = &((ucontext_t *) ucontext)->uc_mcontext;
2512
2513 /* ARM Bump has to be an even number because of odd/even architecture. */
2514 ((mcontext_t *) mcontext)->arm_pc += 2;
2515 }
2516
2517 static void
2518 __gnat_map_signal (int sig,
2519 siginfo_t *si ATTRIBUTE_UNUSED,
2520 void *mcontext ATTRIBUTE_UNUSED)
2521 {
2522 struct Exception_Data *exception;
2523 const char *msg;
2524
2525 switch (sig)
2526 {
2527 case SIGSEGV:
2528 exception = &storage_error;
2529 msg = "stack overflow or erroneous memory access";
2530 break;
2531
2532 case SIGBUS:
2533 exception = &constraint_error;
2534 msg = "SIGBUS";
2535 break;
2536
2537 case SIGFPE:
2538 exception = &constraint_error;
2539 msg = "SIGFPE";
2540 break;
2541
2542 default:
2543 exception = &program_error;
2544 msg = "unhandled signal";
2545 }
2546
2547 Raise_From_Signal_Handler (exception, msg);
2548 }
2549
2550 static void
2551 __gnat_error_handler (int sig, siginfo_t *si, void *ucontext)
2552 {
2553 __gnat_adjust_context_for_raise (sig, ucontext);
2554
2555 __gnat_sigtramp (sig, (void *) si, (void *) ucontext,
2556 (__sigtramphandler_t *)&__gnat_map_signal);
2557 }
2558
2559 /* This must be in keeping with System.OS_Interface.Alternate_Stack_Size. */
2560 char __gnat_alternate_stack[16 * 1024];
2561
2562 void
2563 __gnat_install_handler (void)
2564 {
2565 struct sigaction act;
2566
2567 /* Set up signal handler to map synchronous signals to appropriate
2568 exceptions. Make sure that the handler isn't interrupted by another
2569 signal that might cause a scheduling event! Also setup an alternate
2570 stack region for the handler execution so that stack overflows can be
2571 handled properly, avoiding a SEGV generation from stack usage by the
2572 handler itself. */
2573
2574 stack_t stack;
2575 stack.ss_sp = __gnat_alternate_stack;
2576 stack.ss_size = sizeof (__gnat_alternate_stack);
2577 stack.ss_flags = 0;
2578 sigaltstack (&stack, NULL);
2579
2580 act.sa_sigaction = __gnat_error_handler;
2581 act.sa_flags = SA_NODEFER | SA_RESTART | SA_SIGINFO;
2582 sigemptyset (&act.sa_mask);
2583
2584 sigaction (SIGABRT, &act, NULL);
2585 sigaction (SIGFPE, &act, NULL);
2586 sigaction (SIGILL, &act, NULL);
2587 sigaction (SIGBUS, &act, NULL);
2588 act.sa_flags |= SA_ONSTACK;
2589 sigaction (SIGSEGV, &act, NULL);
2590
2591 __gnat_handler_installed = 1;
2592 }
2593
2594 #else
2595
2596 /* For all other versions of GNAT, the handler does nothing. */
2597
2598 /*******************/
2599 /* Default Section */
2600 /*******************/
2601
2602 void
2603 __gnat_install_handler (void)
2604 {
2605 __gnat_handler_installed = 1;
2606 }
2607
2608 #endif
2609
2610 /*********************/
2611 /* __gnat_init_float */
2612 /*********************/
2613
2614 /* This routine is called as each process thread is created, for possible
2615 initialization of the FP processor. This version is used under INTERIX
2616 and WIN32. */
2617
2618 #if defined (_WIN32) || defined (__INTERIX) \
2619 || defined (__Lynx__) || defined(__NetBSD__) || defined(__FreeBSD__) \
2620 || defined (__OpenBSD__) || defined (__DragonFly__)
2621
2622 #define HAVE_GNAT_INIT_FLOAT
2623
2624 void
2625 __gnat_init_float (void)
2626 {
2627 #if defined (__i386__) || defined (__x86_64__)
2628
2629 /* This is used to properly initialize the FPU on an x86 for each
2630 process thread. */
2631
2632 asm ("finit");
2633
2634 #endif /* Defined __i386__ */
2635 }
2636 #endif
2637
2638 #ifndef HAVE_GNAT_INIT_FLOAT
2639
2640 /* All targets without a specific __gnat_init_float will use an empty one. */
2641 void
2642 __gnat_init_float (void)
2643 {
2644 }
2645 #endif
2646
2647 /***********************************/
2648 /* __gnat_adjust_context_for_raise */
2649 /***********************************/
2650
2651 #ifndef HAVE_GNAT_ADJUST_CONTEXT_FOR_RAISE
2652
2653 /* All targets without a specific version will use an empty one. */
2654
2655 /* Given UCONTEXT a pointer to a context structure received by a signal
2656 handler for SIGNO, perform the necessary adjustments to let the handler
2657 raise an exception. Calls to this routine are not conditioned by the
2658 propagation scheme in use. */
2659
2660 void
2661 __gnat_adjust_context_for_raise (int signo ATTRIBUTE_UNUSED,
2662 void *ucontext ATTRIBUTE_UNUSED)
2663 {
2664 /* We used to compensate here for the raised from call vs raised from signal
2665 exception discrepancy with the GCC ZCX scheme, but this now can be dealt
2666 with generically in the unwinder (see GCC PR other/26208). This however
2667 requires the use of the _Unwind_GetIPInfo routine in raise-gcc.c, which
2668 is predicated on the definition of HAVE_GETIPINFO at compile time. Only
2669 the VMS ports still do the compensation described in the few lines below.
2670
2671 *** Call vs signal exception discrepancy with GCC ZCX scheme ***
2672
2673 The GCC unwinder expects to be dealing with call return addresses, since
2674 this is the "nominal" case of what we retrieve while unwinding a regular
2675 call chain.
2676
2677 To evaluate if a handler applies at some point identified by a return
2678 address, the propagation engine needs to determine what region the
2679 corresponding call instruction pertains to. Because the return address
2680 may not be attached to the same region as the call, the unwinder always
2681 subtracts "some" amount from a return address to search the region
2682 tables, amount chosen to ensure that the resulting address is inside the
2683 call instruction.
2684
2685 When we raise an exception from a signal handler, e.g. to transform a
2686 SIGSEGV into Storage_Error, things need to appear as if the signal
2687 handler had been "called" by the instruction which triggered the signal,
2688 so that exception handlers that apply there are considered. What the
2689 unwinder will retrieve as the return address from the signal handler is
2690 what it will find as the faulting instruction address in the signal
2691 context pushed by the kernel. Leaving this address untouched looses, if
2692 the triggering instruction happens to be the very first of a region, as
2693 the later adjustments performed by the unwinder would yield an address
2694 outside that region. We need to compensate for the unwinder adjustments
2695 at some point, and this is what this routine is expected to do.
2696
2697 signo is passed because on some targets for some signals the PC in
2698 context points to the instruction after the faulting one, in which case
2699 the unwinder adjustment is still desired. */
2700 }
2701
2702 #endif
2703
2704 #ifdef __cplusplus
2705 }
2706 #endif
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