1 /*
2 * Copyright (c) 2012, 2013 SAP SE. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "asm/assembler.hpp"
26 #include "compiler/disassembler.hpp"
27 #include "loadlib_aix.hpp"
28 #include "memory/allocation.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "misc_aix.hpp"
31 #include "porting_aix.hpp"
32 #include "runtime/os.hpp"
33 #include "runtime/thread.hpp"
34 #include "utilities/align.hpp"
35 #include "utilities/debug.hpp"
36
37 #include <demangle.h>
38 #include <sys/debug.h>
39 #include <pthread.h>
40 #include <ucontext.h>
41
42 //////////////////////////////////
43 // Provide implementation for dladdr based on LoadedLibraries pool and
44 // traceback table scan
45
46 // Search traceback table in stack,
47 // return procedure name from trace back table.
48 #define MAX_FUNC_SEARCH_LEN 0x10000
49
50 #define PTRDIFF_BYTES(p1,p2) (((ptrdiff_t)p1) - ((ptrdiff_t)p2))
51
52 // Typedefs for stackslots, stack pointers, pointers to op codes.
53 typedef unsigned long stackslot_t;
54 typedef stackslot_t* stackptr_t;
55 typedef unsigned int* codeptr_t;
56
57 // Unfortunately, the interface of dladdr makes the implementator
58 // responsible for maintaining memory for function name/library
59 // name. I guess this is because most OS's keep those values as part
60 // of the mapped executable image ready to use. On AIX, this doesn't
61 // work, so I have to keep the returned strings. For now, I do this in
62 // a primitive string map. Should this turn out to be a performance
63 // problem, a better hashmap has to be used.
64 class fixed_strings {
65 struct node : public CHeapObj<mtInternal> {
66 char* v;
67 node* next;
68 };
69
70 node* first;
71
72 public:
73
74 fixed_strings() : first(0) {}
75 ~fixed_strings() {
76 node* n = first;
77 while (n) {
78 node* p = n;
79 n = n->next;
80 os::free(p->v);
81 delete p;
82 }
83 }
84
85 char* intern(const char* s) {
86 for (node* n = first; n; n = n->next) {
87 if (strcmp(n->v, s) == 0) {
88 return n->v;
89 }
90 }
91 node* p = new node;
92 p->v = os::strdup_check_oom(s);
93 p->next = first;
94 first = p;
95 return p->v;
96 }
97 };
98
99 static fixed_strings dladdr_fixed_strings;
100
101 bool AixSymbols::get_function_name (
102 address pc0, // [in] program counter
103 char* p_name, size_t namelen, // [out] optional: function name ("" if not available)
104 int* p_displacement, // [out] optional: displacement (-1 if not available)
105 const struct tbtable** p_tb, // [out] optional: ptr to traceback table to get further
106 // information (NULL if not available)
107 bool demangle // [in] whether to demangle the name
108 ) {
109 struct tbtable* tb = 0;
110 unsigned int searchcount = 0;
111
112 // initialize output parameters
113 if (p_name && namelen > 0) {
114 *p_name = '\0';
115 }
116 if (p_displacement) {
117 *p_displacement = -1;
118 }
119 if (p_tb) {
120 *p_tb = NULL;
121 }
122
123 codeptr_t pc = (codeptr_t)pc0;
124
125 // weed out obvious bogus states
126 if (pc < (codeptr_t)0x1000) {
127 trcVerbose("invalid program counter");
128 return false;
129 }
130
131 // We see random but frequent crashes in this function since some months mainly on shutdown
132 // (-XX:+DumpInfoAtExit). It appears the page we are reading is randomly disappearing while
133 // we read it (?).
134 // As the pc cannot be trusted to be anything sensible lets make all reads via SafeFetch. Also
135 // bail if this is not a text address right now.
136 if (!LoadedLibraries::find_for_text_address(pc, NULL)) {
137 trcVerbose("not a text address");
138 return false;
139 }
140
141 // .. (Note that is_readable_pointer returns true if safefetch stubs are not there yet;
142 // in that case I try reading the traceback table unsafe - I rather risk secondary crashes in
143 // error files than not having a callstack.)
144 #define CHECK_POINTER_READABLE(p) \
145 if (!os::is_readable_pointer(p)) { \
146 trcVerbose("pc not readable"); \
147 return false; \
148 }
149
150 codeptr_t pc2 = (codeptr_t) pc;
151
152 // Make sure the pointer is word aligned.
153 pc2 = (codeptr_t) align_up((char*)pc2, 4);
154 CHECK_POINTER_READABLE(pc2)
155
156 // Find start of traceback table.
157 // (starts after code, is marked by word-aligned (32bit) zeros)
158 while ((*pc2 != NULL) && (searchcount++ < MAX_FUNC_SEARCH_LEN)) {
159 CHECK_POINTER_READABLE(pc2)
160 pc2++;
161 }
162 if (*pc2 != 0) {
163 trcVerbose("no traceback table found");
164 return false;
165 }
166 //
167 // Set up addressability to the traceback table
168 //
169 tb = (struct tbtable*) (pc2 + 1);
170
171 // Is this really a traceback table? No way to be sure but
172 // some indicators we can check.
173 if (tb->tb.lang >= 0xf && tb->tb.lang <= 0xfb) {
174 // Language specifiers, go from 0 (C) to 14 (Objective C).
175 // According to spec, 0xf-0xfa reserved, 0xfb-0xff reserved for ibm.
176 trcVerbose("no traceback table found");
177 return false;
178 }
179
180 // Existence of fields in the tbtable extension are contingent upon
181 // specific fields in the base table. Check for their existence so
182 // that we can address the function name if it exists.
183 pc2 = (codeptr_t) tb +
184 sizeof(struct tbtable_short)/sizeof(int);
185 if (tb->tb.fixedparms != 0 || tb->tb.floatparms != 0)
186 pc2++;
187
188 CHECK_POINTER_READABLE(pc2)
189
190 if (tb->tb.has_tboff == TRUE) {
191
192 // I want to know the displacement
193 const unsigned int tb_offset = *pc2;
194 codeptr_t start_of_procedure =
195 (codeptr_t)(((char*)tb) - 4 - tb_offset); // (-4 to omit leading 0000)
196
197 // Weed out the cases where we did find the wrong traceback table.
198 if (pc < start_of_procedure) {
199 trcVerbose("no traceback table found");
200 return false;
201 }
202
203 // return the displacement
204 if (p_displacement) {
205 (*p_displacement) = (int) PTRDIFF_BYTES(pc, start_of_procedure);
206 }
207
208 pc2++;
209 } else {
210 // return -1 for displacement
211 if (p_displacement) {
212 (*p_displacement) = -1;
213 }
214 }
215
216 if (tb->tb.int_hndl == TRUE)
217 pc2++;
218
219 if (tb->tb.has_ctl == TRUE)
220 pc2 += (*pc2) + 1; // don't care
221
222 CHECK_POINTER_READABLE(pc2)
223
224 //
225 // return function name if it exists.
226 //
227 if (p_name && namelen > 0) {
228 if (tb->tb.name_present) {
229 // Copy name from text because it may not be zero terminated.
230 const short l = MIN2<short>(*((short*)pc2), namelen - 1);
231 // Be very careful.
232 int i = 0; char* const p = (char*)pc2 + sizeof(short);
233 while (i < l && os::is_readable_pointer(p + i)) {
234 p_name[i] = p[i];
235 i++;
236 }
237 p_name[i] = '\0';
238
239 // If it is a C++ name, try and demangle it using the Demangle interface (see demangle.h).
240 if (demangle) {
241 char* rest;
242 Name* const name = Demangle(p_name, rest);
243 if (name) {
244 const char* const demangled_name = name->Text();
245 if (demangled_name) {
246 strncpy(p_name, demangled_name, namelen-1);
247 p_name[namelen-1] = '\0';
248 }
249 delete name;
250 }
251 }
252 } else {
253 strncpy(p_name, "<nameless function>", namelen-1);
254 p_name[namelen-1] = '\0';
255 }
256 }
257
258 // Return traceback table, if user wants it.
259 if (p_tb) {
260 (*p_tb) = tb;
261 }
262
263 return true;
264
265 }
266
267 bool AixSymbols::get_module_name(address pc,
268 char* p_name, size_t namelen) {
269
270 if (p_name && namelen > 0) {
271 p_name[0] = '\0';
272 loaded_module_t lm;
273 if (LoadedLibraries::find_for_text_address(pc, &lm) != NULL) {
274 strncpy(p_name, lm.shortname, namelen);
275 p_name[namelen - 1] = '\0';
276 return true;
277 }
278 }
279
280 return false;
281 }
282
283 // Special implementation of dladdr for Aix based on LoadedLibraries
284 // Note: dladdr returns non-zero for ok, 0 for error!
285 // Note: dladdr is not posix, but a non-standard GNU extension. So this tries to
286 // fulfill the contract of dladdr on Linux (see http://linux.die.net/man/3/dladdr)
287 // Note: addr may be both an AIX function descriptor or a real code pointer
288 // to the entry of a function.
289 extern "C"
290 int dladdr(void* addr, Dl_info* info) {
291
292 if (!addr) {
293 return 0;
294 }
295
296 assert(info, "");
297
298 int rc = 0;
299
300 const char* const ZEROSTRING = "";
301
302 // Always return a string, even if a "" one. Linux dladdr manpage
303 // does not say anything about returning NULL
304 info->dli_fname = ZEROSTRING;
305 info->dli_sname = ZEROSTRING;
306 info->dli_saddr = NULL;
307
308 address p = (address) addr;
309 loaded_module_t lm;
310 bool found = false;
311
312 enum { noclue, code, data } type = noclue;
313
314 trcVerbose("dladdr(%p)...", p);
315
316 // Note: input address may be a function. I accept both a pointer to
317 // the entry of a function and a pointer to the function decriptor.
318 // (see ppc64 ABI)
319 found = LoadedLibraries::find_for_text_address(p, &lm);
320 if (found) {
321 type = code;
322 }
323
324 if (!found) {
325 // Not a pointer into any text segment. Is it a function descriptor?
326 const FunctionDescriptor* const pfd = (const FunctionDescriptor*) p;
327 p = pfd->entry();
328 if (p) {
329 found = LoadedLibraries::find_for_text_address(p, &lm);
330 if (found) {
331 type = code;
332 }
333 }
334 }
335
336 if (!found) {
337 // Neither direct code pointer nor function descriptor. A data ptr?
338 p = (address)addr;
339 found = LoadedLibraries::find_for_data_address(p, &lm);
340 if (found) {
341 type = data;
342 }
343 }
344
345 // If we did find the shared library this address belongs to (either
346 // code or data segment) resolve library path and, if possible, the
347 // symbol name.
348 if (found) {
349
350 // No need to intern the libpath, that one is already interned one layer below.
351 info->dli_fname = lm.path;
352
353 if (type == code) {
354
355 // For code symbols resolve function name and displacement. Use
356 // displacement to calc start of function.
357 char funcname[256] = "";
358 int displacement = 0;
359
360 if (AixSymbols::get_function_name(p, funcname, sizeof(funcname),
361 &displacement, NULL, true)) {
362 if (funcname[0] != '\0') {
363 const char* const interned = dladdr_fixed_strings.intern(funcname);
364 info->dli_sname = interned;
365 trcVerbose("... function name: %s ...", interned);
366 }
367
368 // From the displacement calculate the start of the function.
369 if (displacement != -1) {
370 info->dli_saddr = p - displacement;
371 } else {
372 info->dli_saddr = p;
373 }
374 } else {
375
376 // No traceback table found. Just assume the pointer is it.
377 info->dli_saddr = p;
378
379 }
380
381 } else if (type == data) {
382
383 // For data symbols.
384 info->dli_saddr = p;
385
386 } else {
387 ShouldNotReachHere();
388 }
389
390 rc = 1; // success: return 1 [sic]
391
392 }
393
394 // sanity checks.
395 if (rc) {
396 assert(info->dli_fname, "");
397 assert(info->dli_sname, "");
398 assert(info->dli_saddr, "");
399 }
400
401 return rc; // error: return 0 [sic]
402
403 }
404
405 /////////////////////////////////////////////////////////////////////////////
406 // Native callstack dumping
407
408 // Print the traceback table for one stack frame.
409 static void print_tbtable (outputStream* st, const struct tbtable* p_tb) {
410
411 if (p_tb == NULL) {
412 st->print("<null>");
413 return;
414 }
415
416 switch(p_tb->tb.lang) {
417 case TB_C: st->print("C"); break;
418 case TB_FORTRAN: st->print("FORTRAN"); break;
419 case TB_PASCAL: st->print("PASCAL"); break;
420 case TB_ADA: st->print("ADA"); break;
421 case TB_PL1: st->print("PL1"); break;
422 case TB_BASIC: st->print("BASIC"); break;
423 case TB_LISP: st->print("LISP"); break;
424 case TB_COBOL: st->print("COBOL"); break;
425 case TB_MODULA2: st->print("MODULA2"); break;
426 case TB_CPLUSPLUS: st->print("C++"); break;
427 case TB_RPG: st->print("RPG"); break;
428 case TB_PL8: st->print("PL8"); break;
429 case TB_ASM: st->print("ASM"); break;
430 case TB_HPJ: st->print("HPJ"); break;
431 default: st->print("unknown");
432 }
433 st->print(" ");
434
435 if (p_tb->tb.globallink) {
436 st->print("globallink ");
437 }
438 if (p_tb->tb.is_eprol) {
439 st->print("eprol ");
440 }
441 if (p_tb->tb.int_proc) {
442 st->print("int_proc ");
443 }
444 if (p_tb->tb.tocless) {
445 st->print("tocless ");
446 }
447 if (p_tb->tb.fp_present) {
448 st->print("fp_present ");
449 }
450 if (p_tb->tb.int_hndl) {
451 st->print("interrupt_handler ");
452 }
453 if (p_tb->tb.uses_alloca) {
454 st->print("uses_alloca ");
455 }
456 if (p_tb->tb.saves_cr) {
457 st->print("saves_cr ");
458 }
459 if (p_tb->tb.saves_lr) {
460 st->print("saves_lr ");
461 }
462 if (p_tb->tb.stores_bc) {
463 st->print("stores_bc ");
464 }
465 if (p_tb->tb.fixup) {
466 st->print("fixup ");
467 }
468 if (p_tb->tb.fpr_saved > 0) {
469 st->print("fpr_saved:%d ", p_tb->tb.fpr_saved);
470 }
471 if (p_tb->tb.gpr_saved > 0) {
472 st->print("gpr_saved:%d ", p_tb->tb.gpr_saved);
473 }
474 if (p_tb->tb.fixedparms > 0) {
475 st->print("fixedparms:%d ", p_tb->tb.fixedparms);
476 }
477 if (p_tb->tb.floatparms > 0) {
478 st->print("floatparms:%d ", p_tb->tb.floatparms);
479 }
480 if (p_tb->tb.parmsonstk > 0) {
481 st->print("parmsonstk:%d", p_tb->tb.parmsonstk);
482 }
483 }
484
485 // Print information for pc (module, function, displacement, traceback table)
486 // on one line.
487 static void print_info_for_pc (outputStream* st, codeptr_t pc, char* buf,
488 size_t buf_size, bool demangle) {
489 const struct tbtable* tb = NULL;
490 int displacement = -1;
491
492 if (!os::is_readable_pointer(pc)) {
493 st->print("(invalid)");
494 return;
495 }
496
497 if (AixSymbols::get_module_name((address)pc, buf, buf_size)) {
498 st->print("%s", buf);
499 } else {
500 st->print("(unknown module)");
501 }
502 st->print("::");
503 if (AixSymbols::get_function_name((address)pc, buf, buf_size,
504 &displacement, &tb, demangle)) {
505 st->print("%s", buf);
506 } else {
507 st->print("(unknown function)");
508 }
509 if (displacement == -1) {
510 st->print("+?");
511 } else {
512 st->print("+0x%x", displacement);
513 }
514 if (tb) {
515 st->fill_to(64);
516 st->print(" (");
517 print_tbtable(st, tb);
518 st->print(")");
519 }
520 }
521
522 static void print_stackframe(outputStream* st, stackptr_t sp, char* buf,
523 size_t buf_size, bool demangle) {
524
525 stackptr_t sp2 = sp;
526
527 // skip backchain
528
529 sp2++;
530
531 // skip crsave
532
533 sp2++;
534
535 // retrieve lrsave. That is the only info I need to get the function/displacement
536
537 codeptr_t lrsave = (codeptr_t) *(sp2);
538 st->print (PTR64_FORMAT " - " PTR64_FORMAT " ", sp2, lrsave);
539
540 if (lrsave != NULL) {
541 print_info_for_pc(st, lrsave, buf, buf_size, demangle);
542 }
543
544 }
545
546 // Function to check a given stack pointer against given stack limits.
547 static bool is_valid_stackpointer(stackptr_t sp, stackptr_t stack_base, size_t stack_size) {
548 if (((uintptr_t)sp) & 0x7) {
549 return false;
550 }
551 if (sp > stack_base) {
552 return false;
553 }
554 if (sp < (stackptr_t) ((address)stack_base - stack_size)) {
555 return false;
556 }
557 return true;
558 }
559
560 // Returns true if function is a valid codepointer.
561 static bool is_valid_codepointer(codeptr_t p) {
562 if (!p) {
563 return false;
564 }
565 if (((uintptr_t)p) & 0x3) {
566 return false;
567 }
568 if (LoadedLibraries::find_for_text_address(p, NULL) == NULL) {
569 return false;
570 }
571 return true;
572 }
573
574 // Function tries to guess if the given combination of stack pointer, stack base
575 // and stack size is a valid stack frame.
576 static bool is_valid_frame (stackptr_t p, stackptr_t stack_base, size_t stack_size) {
577
578 if (!is_valid_stackpointer(p, stack_base, stack_size)) {
579 return false;
580 }
581
582 // First check - the occurrence of a valid backchain pointer up the stack, followed by a
583 // valid codeptr, counts as a good candidate.
584 stackptr_t sp2 = (stackptr_t) *p;
585 if (is_valid_stackpointer(sp2, stack_base, stack_size) && // found a valid stack pointer in the stack...
586 ((sp2 - p) > 6) && // ... pointing upwards and not into my frame...
587 is_valid_codepointer((codeptr_t)(*(sp2 + 2)))) // ... followed by a code pointer after two slots...
588 {
589 return true;
590 }
591
592 return false;
593 }
594
595 // Try to relocate a stack back chain in a given stack.
596 // Used in callstack dumping, when the backchain is broken by an overwriter
597 static stackptr_t try_find_backchain (stackptr_t last_known_good_frame,
598 stackptr_t stack_base, size_t stack_size)
599 {
600 if (!is_valid_stackpointer(last_known_good_frame, stack_base, stack_size)) {
601 return NULL;
602 }
603
604 stackptr_t sp = last_known_good_frame;
605
606 sp += 6; // Omit next fixed frame slots.
607 while (sp < stack_base) {
608 if (is_valid_frame(sp, stack_base, stack_size)) {
609 return sp;
610 }
611 sp ++;
612 }
613
614 return NULL;
615 }
616
617 static void decode_instructions_at_pc(const char* header,
618 codeptr_t pc, int num_before,
619 int num_after, outputStream* st) {
620 // TODO: PPC port Disassembler::decode(pc, 16, 16, st);
621 }
622
623
624 void AixNativeCallstack::print_callstack_for_context(outputStream* st, const ucontext_t* context,
625 bool demangle, char* buf, size_t buf_size) {
626
627 #define MAX_CALLSTACK_DEPTH 50
628
629 unsigned long* sp;
630 unsigned long* sp_last;
631 int frame;
632
633 // To print the first frame, use the current value of iar:
634 // current entry indicated by iar (the current pc)
635 codeptr_t cur_iar = 0;
636 stackptr_t cur_sp = 0;
637 codeptr_t cur_rtoc = 0;
638 codeptr_t cur_lr = 0;
639
640 const ucontext_t* uc = (const ucontext_t*) context;
641
642 // fallback: use the current context
643 ucontext_t local_context;
644 if (!uc) {
645 st->print_cr("No context given, using current context.");
646 if (getcontext(&local_context) == 0) {
647 uc = &local_context;
648 } else {
649 st->print_cr("No context given and getcontext failed. ");
650 return;
651 }
652 }
653
654 cur_iar = (codeptr_t)uc->uc_mcontext.jmp_context.iar;
655 cur_sp = (stackptr_t)uc->uc_mcontext.jmp_context.gpr[1];
656 cur_rtoc = (codeptr_t)uc->uc_mcontext.jmp_context.gpr[2];
657 cur_lr = (codeptr_t)uc->uc_mcontext.jmp_context.lr;
658
659 // syntax used here:
660 // n -------------- <-- stack_base, stack_to
661 // n-1 | |
662 // ... | older |
663 // ... | frames | |
664 // | | | stack grows downward
665 // ... | younger | |
666 // ... | frames | V
667 // | |
668 // |------------| <-- cur_sp, current stack ptr
669 // | |
670 // | unsused |
671 // | stack |
672 // | |
673 // . .
674 // . .
675 // . .
676 // . .
677 // | |
678 // 0 -------------- <-- stack_from
679 //
680
681 // Retrieve current stack base, size from the current thread. If there is none,
682 // retrieve it from the OS.
683 stackptr_t stack_base = NULL;
684 size_t stack_size = NULL;
685 {
686 AixMisc::stackbounds_t stackbounds;
687 if (!AixMisc::query_stack_bounds_for_current_thread(&stackbounds)) {
688 st->print_cr("Cannot retrieve stack bounds.");
689 return;
690 }
691 stack_base = (stackptr_t)stackbounds.base;
692 stack_size = stackbounds.size;
693 }
694
695 st->print_cr("------ current frame:");
696 st->print("iar: " PTR64_FORMAT " ", p2i(cur_iar));
697 print_info_for_pc(st, cur_iar, buf, buf_size, demangle);
698 st->cr();
699
700 if (cur_iar && os::is_readable_pointer(cur_iar)) {
701 decode_instructions_at_pc(
702 "Decoded instructions at iar:",
703 cur_iar, 32, 16, st);
704 }
705
706 // Print out lr too, which may be interesting if we did jump to some bogus location;
707 // in those cases the new frame is not built up yet and the caller location is only
708 // preserved via lr register.
709 st->print("lr: " PTR64_FORMAT " ", p2i(cur_lr));
710 print_info_for_pc(st, cur_lr, buf, buf_size, demangle);
711 st->cr();
712
713 if (cur_lr && os::is_readable_pointer(cur_lr)) {
714 decode_instructions_at_pc(
715 "Decoded instructions at lr:",
716 cur_lr, 32, 16, st);
717 }
718
719 // Check and print sp.
720 st->print("sp: " PTR64_FORMAT " ", p2i(cur_sp));
721 if (!is_valid_stackpointer(cur_sp, stack_base, stack_size)) {
722 st->print("(invalid) ");
723 goto cleanup;
724 } else {
725 st->print("(base - 0x%X) ", PTRDIFF_BYTES(stack_base, cur_sp));
726 }
727 st->cr();
728
729 // Check and print rtoc.
730 st->print("rtoc: " PTR64_FORMAT " ", p2i(cur_rtoc));
731 if (cur_rtoc == NULL || cur_rtoc == (codeptr_t)-1 ||
732 !os::is_readable_pointer(cur_rtoc)) {
733 st->print("(invalid)");
734 } else if (((uintptr_t)cur_rtoc) & 0x7) {
735 st->print("(unaligned)");
736 }
737 st->cr();
738
739 st->print_cr("|---stackaddr----| |----lrsave------|: <function name>");
740
741 ///
742 // Walk callstack.
743 //
744 // (if no context was given, use the current stack)
745 sp = (unsigned long*)(*(unsigned long*)cur_sp); // Stack pointer
746 sp_last = cur_sp;
747
748 frame = 0;
749
750 while (frame < MAX_CALLSTACK_DEPTH) {
751
752 // Check sp.
753 bool retry = false;
754 if (sp == NULL) {
755 // The backchain pointer was NULL. This normally means the end of the chain. But the
756 // stack might be corrupted, and it may be worth looking for the stack chain.
757 if (is_valid_stackpointer(sp_last, stack_base, stack_size) && (stack_base - 0x10) > sp_last) {
758 // If we are not within <guess> 0x10 stackslots of the stack base, we assume that this
759 // is indeed not the end of the chain but that the stack was corrupted. So lets try to
760 // find the end of the chain.
761 st->print_cr("*** back chain pointer is NULL - end of stack or broken backchain ? ***");
762 retry = true;
763 } else {
764 st->print_cr("*** end of backchain ***");
765 goto end_walk_callstack;
766 }
767 } else if (!is_valid_stackpointer(sp, stack_base, stack_size)) {
768 st->print_cr("*** stack pointer invalid - backchain corrupted (" PTR_FORMAT ") ***", p2i(sp));
769 retry = true;
770 } else if (sp < sp_last) {
771 st->print_cr("invalid stack pointer: " PTR_FORMAT " (not monotone raising)", p2i(sp));
772 retry = true;
773 }
774
775 // If backchain is broken, try to recover, by manually scanning the stack for a pattern
776 // which looks like a valid stack.
777 if (retry) {
778 st->print_cr("trying to recover and find backchain...");
779 sp = try_find_backchain(sp_last, stack_base, stack_size);
780 if (sp) {
781 st->print_cr("found something which looks like a backchain at " PTR64_FORMAT ", after 0x%x bytes... ",
782 p2i(sp), PTRDIFF_BYTES(sp, sp_last));
783 } else {
784 st->print_cr("did not find a backchain, giving up.");
785 goto end_walk_callstack;
786 }
787 }
788
789 // Print stackframe.
790 print_stackframe(st, sp, buf, buf_size, demangle);
791 st->cr();
792 frame ++;
793
794 // Next stack frame and link area.
795 sp_last = sp;
796 sp = (unsigned long*)(*sp);
797 }
798
799 // Prevent endless loops in case of invalid callstacks.
800 if (frame == MAX_CALLSTACK_DEPTH) {
801 st->print_cr("...(stopping after %d frames.", MAX_CALLSTACK_DEPTH);
802 }
803
804 end_walk_callstack:
805
806 st->print_cr("-----------------------");
807
808 cleanup:
809
810 return;
811
812 }
813
814
815 bool AixMisc::query_stack_bounds_for_current_thread(stackbounds_t* out) {
816
817 // Information about this api can be found (a) in the pthread.h header and
818 // (b) in http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.basetechref/doc/basetrf1/pthread_getthrds_np.htm
819 //
820 // The use of this API to find out the current stack is kind of undefined.
821 // But after a lot of tries and asking IBM about it, I concluded that it is safe
822 // enough for cases where I let the pthread library create its stacks. For cases
823 // where I create an own stack and pass this to pthread_create, it seems not to
824 // work (the returned stack size in that case is 0).
825
826 pthread_t tid = pthread_self();
827 struct __pthrdsinfo pinfo;
828 char dummy[1]; // Just needed to satisfy pthread_getthrds_np.
829 int dummy_size = sizeof(dummy);
830
831 memset(&pinfo, 0, sizeof(pinfo));
832
833 const int rc = pthread_getthrds_np(&tid, PTHRDSINFO_QUERY_ALL, &pinfo,
834 sizeof(pinfo), dummy, &dummy_size);
835
836 if (rc != 0) {
837 fprintf(stderr, "pthread_getthrds_np failed (%d)\n", rc);
838 fflush(stdout);
839 return false;
840 }
841
842 // The following may happen when invoking pthread_getthrds_np on a pthread
843 // running on a user provided stack (when handing down a stack to pthread
844 // create, see pthread_attr_setstackaddr).
845 // Not sure what to do then.
846 if (pinfo.__pi_stackend == NULL || pinfo.__pi_stackaddr == NULL) {
847 fprintf(stderr, "pthread_getthrds_np - invalid values\n");
848 fflush(stdout);
849 return false;
850 }
851
852 // Note: we get three values from pthread_getthrds_np:
853 // __pi_stackaddr, __pi_stacksize, __pi_stackend
854 //
855 // high addr --------------------- base, high
856 //
857 // | pthread internal data, like ~2K
858 // |
859 // | --------------------- __pi_stackend (usually not page aligned, (xxxxF890))
860 // |
861 // |
862 // |
863 // |
864 // |
865 // |
866 // | --------------------- (__pi_stackend - __pi_stacksize)
867 // |
868 // | padding to align the following AIX guard pages, if enabled.
869 // |
870 // V --------------------- __pi_stackaddr low, base - size
871 //
872 // low addr AIX guard pages, if enabled (AIXTHREAD_GUARDPAGES > 0)
873 //
874
875 out->base = (address)pinfo.__pi_stackend;
876 address low = (address)pinfo.__pi_stackaddr;
877 out->size = out->base - low;
878 return true;
879
880 }
881
882
883
884