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 "memory/allocation.hpp"
27 #include "loadlib_aix.hpp"
28 #include "porting_aix.hpp"
29 #include "utilities/debug.hpp"
30
31 #include <demangle.h>
32 #include <sys/debug.h>
33
34 //////////////////////////////////
35 // Provide implementation for dladdr based on LoadedLibraries pool and
36 // traceback table scan (see getFuncName).
37
38 // Search traceback table in stack,
39 // return procedure name from trace back table.
40 #define MAX_FUNC_SEARCH_LEN 0x10000
41 // Any PC below this value is considered toast.
42 #define MINIMUM_VALUE_FOR_PC ((unsigned int*)0x1024)
43
44 #define PTRDIFF_BYTES(p1,p2) (((ptrdiff_t)p1) - ((ptrdiff_t)p2))
45
46 // Align a pointer without having to cast.
47 inline char* align_ptr_up(char* ptr, intptr_t alignment) {
48 return (char*) align_size_up((intptr_t)ptr, alignment);
49 }
50
51 // Trace if verbose to tty.
52 // I use these now instead of the Xtrace system because the latter is
53 // not available at init time, hence worthless. Until we fix this, all
54 // tracing here is done with -XX:+Verbose.
55 #define trcVerbose(fmt, ...) { \
56 if (Verbose) { \
57 fprintf(stderr, fmt, ##__VA_ARGS__); \
58 fputc('\n', stderr); fflush(stderr); \
59 } \
60 }
61 #define ERRBYE(s) { trcVerbose(s); return -1; }
62
63 // Unfortunately, the interface of dladdr makes the implementator
64 // responsible for maintaining memory for function name/library
65 // name. I guess this is because most OS's keep those values as part
66 // of the mapped executable image ready to use. On AIX, this doesn't
67 // work, so I have to keep the returned strings. For now, I do this in
68 // a primitive string map. Should this turn out to be a performance
69 // problem, a better hashmap has to be used.
70 class fixed_strings {
71 struct node : public CHeapObj<mtInternal> {
72 char* v;
73 node* next;
74 };
75
76 node* first;
77
78 public:
79
80 fixed_strings() : first(0) {}
81 ~fixed_strings() {
82 node* n = first;
83 while (n) {
84 node* p = n;
85 n = n->next;
86 free(p->v);
87 delete p;
88 }
89 }
90
91 char* intern(const char* s) {
92 for (node* n = first; n; n = n->next) {
93 if (strcmp(n->v, s) == 0) {
94 return n->v;
95 }
96 }
97 node* p = new node;
98 p->v = strdup(s);
99 p->next = first;
100 first = p;
101 return p->v;
102 }
103 };
104
105 static fixed_strings dladdr_fixed_strings;
106
107 // Given a code pointer, returns the function name and the displacement.
108 // Function looks for the traceback table at the end of the function.
109 extern "C" int getFuncName(
110 codeptr_t pc, // [in] program counter
111 char* p_name, size_t namelen, // [out] optional: function name ("" if not available)
112 int* p_displacement, // [out] optional: displacement (-1 if not available)
113 const struct tbtable** p_tb, // [out] optional: ptr to traceback table to get further
114 // information (NULL if not available)
115 char* p_errmsg, size_t errmsglen // [out] optional: user provided buffer for error messages
116 ) {
117 struct tbtable* tb = 0;
118 unsigned int searchcount = 0;
119
120 // initialize output parameters
121 if (p_name && namelen > 0) {
122 *p_name = '\0';
123 }
124 if (p_errmsg && errmsglen > 0) {
125 *p_errmsg = '\0';
126 }
127 if (p_displacement) {
128 *p_displacement = -1;
129 }
130 if (p_tb) {
131 *p_tb = NULL;
132 }
133
134 // weed out obvious bogus states
135 if (pc < MINIMUM_VALUE_FOR_PC) {
136 ERRBYE("invalid program counter");
137 }
138
139 codeptr_t pc2 = pc;
140
141 // make sure the pointer is word aligned.
142 pc2 = (codeptr_t) align_ptr_up((char*)pc2, 4);
143
144 // Find start of traceback table.
145 // (starts after code, is marked by word-aligned (32bit) zeros)
146 while ((*pc2 != NULL) && (searchcount++ < MAX_FUNC_SEARCH_LEN)) {
147 pc2++;
148 }
149 if (*pc2 != 0) {
150 ERRBYE("could not find traceback table within 5000 bytes of program counter");
151 }
152 //
153 // Set up addressability to the traceback table
154 //
155 tb = (struct tbtable*) (pc2 + 1);
156
157 // Is this really a traceback table? No way to be sure but
158 // some indicators we can check.
159 if (tb->tb.lang >= 0xf && tb->tb.lang <= 0xfb) {
160 // Language specifiers, go from 0 (C) to 14 (Objective C).
161 // According to spec, 0xf-0xfa reserved, 0xfb-0xff reserved for ibm.
162 ERRBYE("not a traceback table");
163 }
164
165 // Existence of fields in the tbtable extension are contingent upon
166 // specific fields in the base table. Check for their existence so
167 // that we can address the function name if it exists.
168 pc2 = (codeptr_t) tb +
169 sizeof(struct tbtable_short)/sizeof(int);
170 if (tb->tb.fixedparms != 0 || tb->tb.floatparms != 0)
171 pc2++;
172
173 if (tb->tb.has_tboff == TRUE) {
174
175 // I want to know the displacement
176 const unsigned int tb_offset = *pc2;
177 codeptr_t start_of_procedure =
178 (codeptr_t)(((char*)tb) - 4 - tb_offset); // (-4 to omit leading 0000)
179
180 // Weed out the cases where we did find the wrong traceback table.
181 if (pc < start_of_procedure) {
182 ERRBYE("could not find (the real) traceback table within 5000 bytes of program counter");
183 }
184
185 // return the displacement
186 if (p_displacement) {
187 (*p_displacement) = (int) PTRDIFF_BYTES(pc, start_of_procedure);
188 }
189
190 pc2++;
191 } else {
192 // return -1 for displacement
193 if (p_displacement) {
194 (*p_displacement) = -1;
195 }
196 }
197
198 if (tb->tb.int_hndl == TRUE)
199 pc2++;
200
201 if (tb->tb.has_ctl == TRUE)
202 pc2 += (*pc2) + 1; // don't care
203
204 //
205 // return function name if it exists.
206 //
207 if (p_name && namelen > 0) {
208 if (tb->tb.name_present) {
209 char buf[256];
210 const short l = MIN2<short>(*((short*)pc2), sizeof(buf) - 1);
211 memcpy(buf, (char*)pc2 + sizeof(short), l);
212 buf[l] = '\0';
213
214 p_name[0] = '\0';
215
216 // If it is a C++ name, try and demangle it using the Demangle interface (see demangle.h).
217 char* rest;
218 Name* const name = Demangle(buf, rest);
219 if (name) {
220 const char* const demangled_name = name->Text();
221 if (demangled_name) {
222 strncpy(p_name, demangled_name, namelen-1);
223 p_name[namelen-1] = '\0';
224 }
225 delete name;
226 }
227
228 // Fallback: if demangling did not work, just provide the unmangled name.
229 if (p_name[0] == '\0') {
230 strncpy(p_name, buf, namelen-1);
231 p_name[namelen-1] = '\0';
232 }
233
234 } else {
235 strncpy(p_name, "<nameless function>", namelen-1);
236 p_name[namelen-1] = '\0';
237 }
238 }
239 // Return traceback table, if user wants it.
240 if (p_tb) {
241 (*p_tb) = tb;
242 }
243
244 return 0;
245 }
246
247 // Special implementation of dladdr for Aix based on LoadedLibraries
248 // Note: dladdr returns non-zero for ok, 0 for error!
249 // Note: dladdr is not posix, but a non-standard GNU extension. So this tries to
250 // fulfill the contract of dladdr on Linux (see http://linux.die.net/man/3/dladdr)
251 // Note: addr may be both an AIX function descriptor or a real code pointer
252 // to the entry of a function.
253 extern "C"
254 int dladdr(void* addr, Dl_info* info) {
255
256 if (!addr) {
257 return 0;
258 }
259
260 assert(info, "");
261
262 int rc = 0;
263
264 const char* const ZEROSTRING = "";
265
266 // Always return a string, even if a "" one. Linux dladdr manpage
267 // does not say anything about returning NULL
268 info->dli_fname = ZEROSTRING;
269 info->dli_sname = ZEROSTRING;
270 info->dli_saddr = NULL;
271
272 address p = (address) addr;
273 const LoadedLibraryModule* lib = NULL;
274
275 enum { noclue, code, data } type = noclue;
276
277 trcVerbose("dladdr(%p)...", p);
278
279 // Note: input address may be a function. I accept both a pointer to
280 // the entry of a function and a pointer to the function decriptor.
281 // (see ppc64 ABI)
282 lib = LoadedLibraries::find_for_text_address(p);
283 if (lib) {
284 type = code;
285 }
286
287 if (!lib) {
288 // Not a pointer into any text segment. Is it a function descriptor?
289 const FunctionDescriptor* const pfd = (const FunctionDescriptor*) p;
290 p = pfd->entry();
291 if (p) {
292 lib = LoadedLibraries::find_for_text_address(p);
293 if (lib) {
294 type = code;
295 }
296 }
297 }
298
299 if (!lib) {
300 // Neither direct code pointer nor function descriptor. A data ptr?
301 p = (address)addr;
302 lib = LoadedLibraries::find_for_data_address(p);
303 if (lib) {
304 type = data;
305 }
306 }
307
308 // If we did find the shared library this address belongs to (either
309 // code or data segment) resolve library path and, if possible, the
310 // symbol name.
311 if (lib) {
312 const char* const interned_libpath =
313 dladdr_fixed_strings.intern(lib->get_fullpath());
314 if (interned_libpath) {
315 info->dli_fname = interned_libpath;
316 }
317
318 if (type == code) {
319
320 // For code symbols resolve function name and displacement. Use
321 // displacement to calc start of function.
322 char funcname[256] = "";
323 int displacement = 0;
324
325 if (getFuncName((codeptr_t) p, funcname, sizeof(funcname), &displacement,
326 NULL, NULL, 0) == 0) {
327 if (funcname[0] != '\0') {
328 const char* const interned = dladdr_fixed_strings.intern(funcname);
329 info->dli_sname = interned;
330 trcVerbose("... function name: %s ...", interned);
331 }
332
333 // From the displacement calculate the start of the function.
334 if (displacement != -1) {
335 info->dli_saddr = p - displacement;
336 } else {
337 info->dli_saddr = p;
338 }
339 } else {
340
341 // No traceback table found. Just assume the pointer is it.
342 info->dli_saddr = p;
343
344 }
345
346 } else if (type == data) {
347
348 // For data symbols.
349 info->dli_saddr = p;
350
351 } else {
352 ShouldNotReachHere();
353 }
354
355 rc = 1; // success: return 1 [sic]
356
357 }
358
359 // sanity checks.
360 if (rc) {
361 assert(info->dli_fname, "");
362 assert(info->dli_sname, "");
363 assert(info->dli_saddr, "");
364 }
365
366 return rc; // error: return 0 [sic]
367
368 }