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