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