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 /*

  * Copyright 2012, 2013 SAP AG. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "asm/assembler.hpp"

 #include "loadlib_aix.hpp"

 #include "porting_aix.hpp"

 #include "utilities/debug.hpp"

 #include <demangle.h>

 #include <sys/debug.h>

 //////////////////////////////////

 // Provide implementation for dladdr based on LoadedLibraries pool and

 // traceback table scan (see getFuncName).

 // Search traceback table in stack,

 // return procedure name from trace back table.

 #define MAX_FUNC_SEARCH_LEN 0x10000

 // Any PC below this value is considered toast.

 #define MINIMUM_VALUE_FOR_PC ((unsigned int*)0x1024)

 #define PTRDIFF_BYTES(p1,p2) (((ptrdiff_t)p1) - ((ptrdiff_t)p2))

 // Align a pointer without having to cast.

 inline char* align_ptr_up(char* ptr, intptr_t alignment) {

   return (char*) align_size_up((intptr_t)ptr, alignment);

 }

 // Trace if verbose to tty.

 // I use these now instead of the Xtrace system because the latter is

 // not available at init time, hence worthless. Until we fix this, all

 // tracing here is done with -XX:+Verbose.

 #define trcVerbose(fmt, ...) { \

   if (Verbose) { \

     fprintf(stderr, fmt, ##__VA_ARGS__); \

     fputc('\n', stderr); fflush(stderr); \

   } \

 }

 #define ERRBYE(s) { trcVerbose(s); return -1; }

 // Unfortunately, the interface of dladdr makes the implementator

 // responsible for maintaining memory for function name/library

 // name. I guess this is because most OS's keep those values as part

 // of the mapped executable image ready to use. On AIX, this doesn't

 // work, so I have to keep the returned strings. For now, I do this in

 // a primitive string map. Should this turn out to be a performance

 // problem, a better hashmap has to be used.

 class fixed_strings {

   struct node {

     char* v;

     node* next;

   };

   node* first;

   public:

   fixed_strings() : first(0) {}

   ~fixed_strings() {

     node* n = first;

     while (n) {

       node* p = n;

       n = n->next;

       free(p->v);

       delete p;

     }

   }

   char* intern(const char* s) {

     for (node* n = first; n; n = n->next) {

       if (strcmp(n->v, s) == 0) {

         return n->v;

       }

     }

     node* p = new node;

     p->v = strdup(s);

     p->next = first;

     first = p;

     return p->v;

   }

 };

 static fixed_strings dladdr_fixed_strings;

 // Given a code pointer, returns the function name and the displacement.

 // Function looks for the traceback table at the end of the function.

 extern "C" int getFuncName(

     codeptr_t pc,                    // [in] program counter

     char* p_name, size_t namelen,    // [out] optional: function name ("" if not available)

     int* p_displacement,             // [out] optional: displacement (-1 if not available)

     const struct tbtable** p_tb,     // [out] optional: ptr to traceback table to get further

                                      //                 information (NULL if not available)

     char* p_errmsg, size_t errmsglen // [out] optional: user provided buffer for error messages

   ) {

   struct tbtable* tb = 0;

   unsigned int searchcount = 0;

   // initialize output parameters

   if (p_name && namelen > 0) {

     *p_name = '\0';

   }

   if (p_errmsg && errmsglen > 0) {

     *p_errmsg = '\0';

   }

   if (p_displacement) {

     *p_displacement = -1;

   }

   if (p_tb) {

     *p_tb = NULL;

   }

   // weed out obvious bogus states

   if (pc < MINIMUM_VALUE_FOR_PC) {

     ERRBYE("invalid program counter");

   }

   codeptr_t pc2 = pc;

   // make sure the pointer is word aligned.

   pc2 = (codeptr_t) align_ptr_up((char*)pc2, 4);

   // Find start of traceback table.

   // (starts after code, is marked by word-aligned (32bit) zeros)

   while ((*pc2 != NULL) && (searchcount++ < MAX_FUNC_SEARCH_LEN)) {

     pc2++;

   }

   if (*pc2 != 0) {

     ERRBYE("could not find traceback table within 5000 bytes of program counter");

   }

   //

   // Set up addressability to the traceback table

   //

   tb = (struct tbtable*) (pc2 + 1);

   // Is this really a traceback table? No way to be sure but

   // some indicators we can check.

   if (tb->tb.lang >= 0xf && tb->tb.lang <= 0xfb) {

     // Language specifiers, go from 0 (C) to 14 (Objective C).

     // According to spec, 0xf-0xfa reserved, 0xfb-0xff reserved for ibm.

     ERRBYE("not a traceback table");

   }

   // Existence of fields in the tbtable extension are contingent upon

   // specific fields in the base table.  Check for their existence so

   // that we can address the function name if it exists.

   pc2 = (codeptr_t) tb +

     sizeof(struct tbtable_short)/sizeof(int);

   if (tb->tb.fixedparms != 0 || tb->tb.floatparms != 0)

     pc2++;

   if (tb->tb.has_tboff == TRUE) {

     // I want to know the displacement

     const unsigned int tb_offset = *pc2;

     codeptr_t start_of_procedure =

     (codeptr_t)(((char*)tb) - 4 - tb_offset);  // (-4 to omit leading 0000)

     // Weed out the cases where we did find the wrong traceback table.

     if (pc < start_of_procedure) {

       ERRBYE("could not find (the real) traceback table within 5000 bytes of program counter");

     }

     // return the displacement

     if (p_displacement) {

       (*p_displacement) = (int) PTRDIFF_BYTES(pc, start_of_procedure);

     }

     pc2++;

   } else {

     // return -1 for displacement

     if (p_displacement) {

       (*p_displacement) = -1;

     }

   }

   if (tb->tb.int_hndl == TRUE)

     pc2++;

   if (tb->tb.has_ctl == TRUE)

     pc2 += (*pc2) + 1; // don't care

   //

   // return function name if it exists.

   //

   if (p_name && namelen > 0) {

     if (tb->tb.name_present) {

       char buf[256];

       const short l = MIN2<short>(*((short*)pc2), sizeof(buf) - 1);

       memcpy(buf, (char*)pc2 + sizeof(short), l);

       buf[l] = '\0';

       p_name[0] = '\0';

       // If it is a C++ name, try and demangle it using the Demangle interface (see demangle.h).

       char* rest;

       Name* const name = Demangle(buf, rest);

       if (name) {

         const char* const demangled_name = name->Text();

         if (demangled_name) {

           strncpy(p_name, demangled_name, namelen-1);

           p_name[namelen-1] = '\0';

         }

         delete name;

       }

       // Fallback: if demangling did not work, just provide the unmangled name.

       if (p_name[0] == '\0') {

         strncpy(p_name, buf, namelen-1);

         p_name[namelen-1] = '\0';

       }

     } else {

       strncpy(p_name, "<nameless function>", namelen-1);

       p_name[namelen-1] = '\0';

     }

   }

   // Return traceback table, if user wants it.

   if (p_tb) {

     (*p_tb) = tb;

   }

   return 0;

 }

 // Special implementation of dladdr for Aix based on LoadedLibraries

 // Note: dladdr returns non-zero for ok, 0 for error!

 // Note: dladdr is not posix, but a non-standard GNU extension. So this tries to

 //   fulfill the contract of dladdr on Linux (see http://linux.die.net/man/3/dladdr)

 // Note: addr may be both an AIX function descriptor or a real code pointer

 //   to the entry of a function.

 extern "C"

 int dladdr(void* addr, Dl_info* info) {

   if (!addr) {

     return 0;

   }

   assert(info, "");

   int rc = 0;

   const char* const ZEROSTRING = "";

   // Always return a string, even if a "" one. Linux dladdr manpage

   // does not say anything about returning NULL

   info->dli_fname = ZEROSTRING;

   info->dli_sname = ZEROSTRING;

   info->dli_saddr = NULL;

   address p = (address) addr;

   const LoadedLibraryModule* lib = NULL;

   enum { noclue, code, data } type = noclue;

   trcVerbose("dladdr(%p)...", p);

   // Note: input address may be a function. I accept both a pointer to

   // the entry of a function and a pointer to the function decriptor.

   // (see ppc64 ABI)

   lib = LoadedLibraries::find_for_text_address(p);

   if (lib) {

     type = code;

   }

   if (!lib) {

     // Not a pointer into any text segment. Is it a function descriptor?

     const FunctionDescriptor* const pfd = (const FunctionDescriptor*) p;

     p = pfd->entry();

     if (p) {

       lib = LoadedLibraries::find_for_text_address(p);

       if (lib) {

         type = code;

       }

     }

   }

   if (!lib) {

     // Neither direct code pointer nor function descriptor. A data ptr?

     p = (address)addr;

     lib = LoadedLibraries::find_for_data_address(p);

     if (lib) {

       type = data;

     }

   }

   // If we did find the shared library this address belongs to (either

   // code or data segment) resolve library path and, if possible, the

   // symbol name.

   if (lib) {

     const char* const interned_libpath =

       dladdr_fixed_strings.intern(lib->get_fullpath());

     if (interned_libpath) {

       info->dli_fname = interned_libpath;

     }

     if (type == code) {

       // For code symbols resolve function name and displacement. Use

       // displacement to calc start of function.

       char funcname[256] = "";

       int displacement = 0;

       if (getFuncName((codeptr_t) p, funcname, sizeof(funcname), &displacement,

                       NULL, NULL, 0) == 0) {

         if (funcname[0] != '\0') {

           const char* const interned = dladdr_fixed_strings.intern(funcname);

           info->dli_sname = interned;

           trcVerbose("... function name: %s ...", interned);

         }

         // From the displacement calculate the start of the function.

         if (displacement != -1) {

           info->dli_saddr = p - displacement;

         } else {

           info->dli_saddr = p;

         }

       } else {

         // No traceback table found. Just assume the pointer is it.

         info->dli_saddr = p;

       }

     } else if (type == data) {

       // For data symbols.

       info->dli_saddr = p;

     } else {

       ShouldNotReachHere();

     }

     rc = 1; // success: return 1 [sic]

   }

   // sanity checks.

   if (rc) {

     assert(info->dli_fname, "");

     assert(info->dli_sname, "");

     assert(info->dli_saddr, "");

   }

   return rc; // error: return 0 [sic]

 }