1 /*
2 * Copyright 2012, 2013 SAP AG. 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 "loadlib_aix.hpp"
27 #include "memory/allocation.hpp"
28 #include "memory/allocation.inline.hpp"
29 // For CritSect
30 #include "misc_aix.hpp"
31 #include "porting_aix.hpp"
32 #include "runtime/os.hpp"
33 #include "utilities/debug.hpp"
34
35 #include <demangle.h>
36 #include <sys/debug.h>
37
38 //////////////////////////////////
39 // Provide implementation for dladdr based on LoadedLibraries pool and
40 // traceback table scan (see getFuncName).
41
42 // Search traceback table in stack,
43 // return procedure name from trace back table.
44 #define MAX_FUNC_SEARCH_LEN 0x10000
45 // Any PC below this value is considered toast.
46 #define MINIMUM_VALUE_FOR_PC ((unsigned int*)0x1024)
47
48 #define PTRDIFF_BYTES(p1,p2) (((ptrdiff_t)p1) - ((ptrdiff_t)p2))
49
50 // Unfortunately, the interface of dladdr makes the implementator
51 // responsible for maintaining memory for function name/library
52 // name. I guess this is because most OS's keep those values as part
53 // of the mapped executable image ready to use. On AIX, this doesn't
54 // work, so I have to keep the returned strings. For now, I do this in
55 // a primitive string map. Should this turn out to be a performance
56 // problem, a better hashmap has to be used.
57 class fixed_strings {
58 struct node : public CHeapObj<mtInternal> {
59 char* v;
60 node* next;
61 };
62
63 node* first;
64
65 public:
66
67 fixed_strings() : first(0) {}
68 ~fixed_strings() {
69 node* n = first;
70 while (n) {
71 node* p = n;
72 n = n->next;
73 os::free(p->v);
74 delete p;
75 }
76 }
77
78 char* intern(const char* s) {
79 for (node* n = first; n; n = n->next) {
80 if (strcmp(n->v, s) == 0) {
81 return n->v;
82 }
83 }
84 node* p = new node;
85 p->v = os::strdup_check_oom(s);
86 p->next = first;
87 first = p;
88 return p->v;
89 }
90 };
91
92 static fixed_strings dladdr_fixed_strings;
93
94 // Given a code pointer, returns the function name and the displacement.
95 // Function looks for the traceback table at the end of the function.
96 extern "C" int getFuncName(
97 codeptr_t pc, // [in] program counter
98 char* p_name, size_t namelen, // [out] optional: function name ("" if not available)
99 int* p_displacement, // [out] optional: displacement (-1 if not available)
100 const struct tbtable** p_tb, // [out] optional: ptr to traceback table to get further
101 // information (NULL if not available)
102 char* p_errmsg, size_t errmsglen,// [out] optional: user provided buffer for error messages
103 bool demangle // [in] whether to demangle the name
104 ) {
105 struct tbtable* tb = 0;
106 unsigned int searchcount = 0;
107
108 // initialize output parameters
109 if (p_name && namelen > 0) {
110 *p_name = '\0';
111 }
112 if (p_errmsg && errmsglen > 0) {
113 *p_errmsg = '\0';
114 }
115 if (p_displacement) {
116 *p_displacement = -1;
117 }
118 if (p_tb) {
119 *p_tb = NULL;
120 }
121
122 // weed out obvious bogus states
123 if (pc < MINIMUM_VALUE_FOR_PC) {
124 ERRBYE("invalid program counter");
125 }
126
127 // We see random but frequent crashes in this function since some months mainly on shutdown
128 // (-XX:+DumpInfoAtExit). It appears the page we are reading is randomly disappearing while
129 // we read it (?).
130 // As the pc cannot be trusted to be anything sensible lets make all reads via SafeFetch. Also
131 // bail if this is not a text address right now.
132 if (!LoadedLibraries::find_for_text_address(pc, NULL)) {
133 ERRBYE("not a text address");
134 }
135
136 // .. (Note that is_readable_pointer returns true if safefetch stubs are not there yet;
137 // in that case I try reading the traceback table unsafe - I rather risk secondary crashes in
138 // error files than not having a callstack.)
139 #define CHECK_POINTER_READABLE(p) \
140 if (!MiscUtils::is_readable_pointer(p)) { \
141 ERRBYE("pc not readable"); \
142 }
143
144 codeptr_t pc2 = pc;
145
146 // Make sure the pointer is word aligned.
147 pc2 = (codeptr_t) align_ptr_up((char*)pc2, 4);
148 CHECK_POINTER_READABLE(pc2)
149
150 // Find start of traceback table.
151 // (starts after code, is marked by word-aligned (32bit) zeros)
152 while ((*pc2 != NULL) && (searchcount++ < MAX_FUNC_SEARCH_LEN)) {
153 CHECK_POINTER_READABLE(pc2)
154 pc2++;
155 }
156 if (*pc2 != 0) {
157 ERRBYE("no traceback table found");
158 }
159 //
160 // Set up addressability to the traceback table
161 //
162 tb = (struct tbtable*) (pc2 + 1);
163
164 // Is this really a traceback table? No way to be sure but
165 // some indicators we can check.
166 if (tb->tb.lang >= 0xf && tb->tb.lang <= 0xfb) {
167 // Language specifiers, go from 0 (C) to 14 (Objective C).
168 // According to spec, 0xf-0xfa reserved, 0xfb-0xff reserved for ibm.
169 ERRBYE("no traceback table found");
170 }
171
172 // Existence of fields in the tbtable extension are contingent upon
173 // specific fields in the base table. Check for their existence so
174 // that we can address the function name if it exists.
175 pc2 = (codeptr_t) tb +
176 sizeof(struct tbtable_short)/sizeof(int);
177 if (tb->tb.fixedparms != 0 || tb->tb.floatparms != 0)
178 pc2++;
179
180 CHECK_POINTER_READABLE(pc2)
181
182 if (tb->tb.has_tboff == TRUE) {
183
184 // I want to know the displacement
185 const unsigned int tb_offset = *pc2;
186 codeptr_t start_of_procedure =
187 (codeptr_t)(((char*)tb) - 4 - tb_offset); // (-4 to omit leading 0000)
188
189 // Weed out the cases where we did find the wrong traceback table.
190 if (pc < start_of_procedure) {
191 ERRBYE("no traceback table found");
192 }
193
194 // return the displacement
195 if (p_displacement) {
196 (*p_displacement) = (int) PTRDIFF_BYTES(pc, start_of_procedure);
197 }
198
199 pc2++;
200 } else {
201 // return -1 for displacement
202 if (p_displacement) {
203 (*p_displacement) = -1;
204 }
205 }
206
207 if (tb->tb.int_hndl == TRUE)
208 pc2++;
209
210 if (tb->tb.has_ctl == TRUE)
211 pc2 += (*pc2) + 1; // don't care
212
213 CHECK_POINTER_READABLE(pc2)
214
215 //
216 // return function name if it exists.
217 //
218 if (p_name && namelen > 0) {
219 if (tb->tb.name_present) {
220 // Copy name from text because it may not be zero terminated.
221 // 256 is good enough for most cases; do not use large buffers here.
222 char buf[256];
223 const short l = MIN2<short>(*((short*)pc2), sizeof(buf) - 1);
224 // Be very careful.
225 int i = 0; char* const p = (char*)pc2 + sizeof(short);
226 while (i < l && MiscUtils::is_readable_pointer(p + i)) {
227 buf[i] = p[i];
228 i++;
229 }
230 buf[i] = '\0';
231
232 p_name[0] = '\0';
233
234 // If it is a C++ name, try and demangle it using the Demangle interface (see demangle.h).
235 if (demangle) {
236 char* rest;
237 Name* const name = Demangle(buf, rest);
238 if (name) {
239 const char* const demangled_name = name->Text();
240 if (demangled_name) {
241 strncpy(p_name, demangled_name, namelen-1);
242 p_name[namelen-1] = '\0';
243 }
244 delete name;
245 }
246 }
247
248 // Fallback: if demangling did not work, just provide the unmangled name.
249 if (p_name[0] == '\0') {
250 strncpy(p_name, buf, namelen-1);
251 p_name[namelen-1] = '\0';
252 }
253
254 } else {
255 strncpy(p_name, "<nameless function>", namelen-1);
256 p_name[namelen-1] = '\0';
257 }
258 }
259 // Return traceback table, if user wants it.
260 if (p_tb) {
261 (*p_tb) = tb;
262 }
263
264 return 0;
265 }
266
267 // Special implementation of dladdr for Aix based on LoadedLibraries
268 // Note: dladdr returns non-zero for ok, 0 for error!
269 // Note: dladdr is not posix, but a non-standard GNU extension. So this tries to
270 // fulfill the contract of dladdr on Linux (see http://linux.die.net/man/3/dladdr)
271 // Note: addr may be both an AIX function descriptor or a real code pointer
272 // to the entry of a function.
273 extern "C"
274 int dladdr(void* addr, Dl_info* info) {
275
276 if (!addr) {
277 return 0;
278 }
279
280 assert(info, "");
281
282 int rc = 0;
283
284 const char* const ZEROSTRING = "";
285
286 // Always return a string, even if a "" one. Linux dladdr manpage
287 // does not say anything about returning NULL
288 info->dli_fname = ZEROSTRING;
289 info->dli_sname = ZEROSTRING;
290 info->dli_saddr = NULL;
291
292 address p = (address) addr;
293 loaded_module_t lm;
294 bool found = false;
295
296 enum { noclue, code, data } type = noclue;
297
298 trcVerbose("dladdr(%p)...", p);
299
300 // Note: input address may be a function. I accept both a pointer to
301 // the entry of a function and a pointer to the function decriptor.
302 // (see ppc64 ABI)
303 found = LoadedLibraries::find_for_text_address(p, &lm);
304 if (found) {
305 type = code;
306 }
307
308 if (!found) {
309 // Not a pointer into any text segment. Is it a function descriptor?
310 const FunctionDescriptor* const pfd = (const FunctionDescriptor*) p;
311 p = pfd->entry();
312 if (p) {
313 found = LoadedLibraries::find_for_text_address(p, &lm);
314 if (found) {
315 type = code;
316 }
317 }
318 }
319
320 if (!found) {
321 // Neither direct code pointer nor function descriptor. A data ptr?
322 p = (address)addr;
323 found = LoadedLibraries::find_for_data_address(p, &lm);
324 if (found) {
325 type = data;
326 }
327 }
328
329 // If we did find the shared library this address belongs to (either
330 // code or data segment) resolve library path and, if possible, the
331 // symbol name.
332 if (found) {
333
334 // No need to intern the libpath, that one is already interned one layer below.
335 info->dli_fname = lm.path;
336
337 if (type == code) {
338
339 // For code symbols resolve function name and displacement. Use
340 // displacement to calc start of function.
341 char funcname[256] = "";
342 int displacement = 0;
343
344 if (getFuncName((codeptr_t) p, funcname, sizeof(funcname), &displacement,
345 NULL, NULL, 0, false) == 0) {
346 if (funcname[0] != '\0') {
347 const char* const interned = dladdr_fixed_strings.intern(funcname);
348 info->dli_sname = interned;
349 trcVerbose("... function name: %s ...", interned);
350 }
351
352 // From the displacement calculate the start of the function.
353 if (displacement != -1) {
354 info->dli_saddr = p - displacement;
355 } else {
356 info->dli_saddr = p;
357 }
358 } else {
359
360 // No traceback table found. Just assume the pointer is it.
361 info->dli_saddr = p;
362
363 }
364
365 } else if (type == data) {
366
367 // For data symbols.
368 info->dli_saddr = p;
369
370 } else {
371 ShouldNotReachHere();
372 }
373
374 rc = 1; // success: return 1 [sic]
375
376 }
377
378 // sanity checks.
379 if (rc) {
380 assert(info->dli_fname, "");
381 assert(info->dli_sname, "");
382 assert(info->dli_saddr, "");
383 }
384
385 return rc; // error: return 0 [sic]
386
387 }