Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. 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 <unistd.h>

 #include <sys/procfs.h>

 #include <search.h>

 #include <stdlib.h>

 #include <string.h>

 #include "symtab.h"

 #include "salibelf.h"

 // ----------------------------------------------------

 // functions for symbol lookups

 // ----------------------------------------------------

 struct elf_section {

   ELF_SHDR   *c_shdr;

   void       *c_data;

 };

 struct elf_symbol {

   char *name;

   uintptr_t offset;

   uintptr_t size;

 };

 typedef struct symtab {

   char *strs;

   size_t num_symbols;

   struct elf_symbol *symbols;

   struct hsearch_data *hash_table;

 } symtab_t;

 // Directory that contains global debuginfo files.  In theory it

 // should be possible to change this, but in a Java environment there

 // is no obvious place to put a user interface to do it.  Maybe this

 // could be set with an environment variable.

 static const char debug_file_directory[] = "/usr/lib/debug";

 /* The CRC used in gnu_debuglink, retrieved from

    http://sourceware.org/gdb/current/onlinedocs/gdb/Separate-Debug-Files.html#Separate-Debug-Files. */

 unsigned int gnu_debuglink_crc32 (unsigned int crc,

                                   unsigned char *buf, size_t len)

 {

   static const unsigned int crc32_table[256] =

     {

       0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,

       0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,

       0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,

       0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,

       0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,

       0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,

       0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,

       0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,

       0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,

       0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,

       0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,

       0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,

       0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,

       0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,

       0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,

       0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,

       0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,

       0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,

       0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,

       0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,

       0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,

       0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,

       0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,

       0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,

       0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,

       0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,

       0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,

       0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,

       0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,

       0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,

       0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,

       0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,

       0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,

       0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,

       0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,

       0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,

       0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,

       0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,

       0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,

       0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,

       0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,

       0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,

       0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,

       0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,

       0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,

       0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,

       0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,

       0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,

       0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,

       0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,

       0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,

       0x2d02ef8d

     };

   unsigned char *end;

   crc = ~crc & 0xffffffff;

   for (end = buf + len; buf < end; ++buf)

     crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8);

   return ~crc & 0xffffffff;

 }

 /* Open a debuginfo file and check its CRC.  If it exists and the CRC

    matches return its fd.  */

 static int

 open_debug_file (const char *pathname, unsigned int crc)

 {

   unsigned int file_crc = 0;

   unsigned char buffer[8 * 1024];

   int fd = pathmap_open(pathname);

   if (fd < 0)

     return -1;

   lseek(fd, 0, SEEK_SET);

   for (;;) {

     int len = read(fd, buffer, sizeof buffer);

     if (len <= 0)

       break;

     file_crc = gnu_debuglink_crc32(file_crc, buffer, len);

   }

   if (crc == file_crc)

     return fd;

   else {

     close(fd);

     return -1;

   }

 }

 /* Find an ELF section.  */

 static struct elf_section *find_section_by_name(char *name,

                                                 int fd,

                                                 ELF_EHDR *ehdr,

                                                 ELF_SHDR *shbuf,

                                                 struct elf_section *scn_cache)

 {

   ELF_SHDR* cursct = NULL;

   char *strtab;

   int cnt;

   if (scn_cache[ehdr->e_shstrndx].c_data == NULL) {

     if ((scn_cache[ehdr->e_shstrndx].c_data

          = read_section_data(fd, ehdr, cursct)) == NULL) {

       return NULL;

     }

   }

   strtab = scn_cache[ehdr->e_shstrndx].c_data;

   for (cursct = shbuf, cnt = 0;

        cnt < ehdr->e_shnum;

        cnt++, cursct++) {

     if (strcmp(cursct->sh_name + strtab, name) == 0) {

       scn_cache[cnt].c_data = read_section_data(fd, ehdr, cursct);

       return &scn_cache[cnt];

     }

   }

   return NULL;

 }

 /* Look for a ".gnu_debuglink" section.  If one exists, try to open a

    suitable debuginfo file.  */

 static int open_file_from_debug_link(const char *name,

                                      int fd,

                                      ELF_EHDR *ehdr,

                                      ELF_SHDR *shbuf,

                                      struct elf_section *scn_cache)

 {

   int debug_fd;

   struct elf_section *debug_link = find_section_by_name(".gnu_debuglink", fd, ehdr,

                                                         shbuf, scn_cache);

   if (debug_link == NULL)

     return -1;

   char *debug_filename = debug_link->c_data;

   int offset = (strlen(debug_filename) + 4) >> 2;

   static unsigned int crc;

   crc = ((unsigned int*)debug_link->c_data)[offset];

   char *debug_pathname = malloc(strlen(debug_filename)

                                 + strlen(name)

                                 + strlen(".debug/")

                                 + strlen(debug_file_directory)

                                 + 2);

   strcpy(debug_pathname, name);

   char *last_slash = strrchr(debug_pathname, '/');

   if (last_slash == NULL)

     return -1;

   /* Look in the same directory as the object.  */

   strcpy(last_slash+1, debug_filename);

   debug_fd = open_debug_file(debug_pathname, crc);

   if (debug_fd >= 0) {

     free(debug_pathname);

     return debug_fd;

   }

   /* Look in a subdirectory named ".debug".  */

   strcpy(last_slash+1, ".debug/");

   strcat(last_slash, debug_filename);

   debug_fd = open_debug_file(debug_pathname, crc);

   if (debug_fd >= 0) {

     free(debug_pathname);

     return debug_fd;

   }

   /* Look in /usr/lib/debug + the full pathname.  */

   strcpy(debug_pathname, debug_file_directory);

   strcat(debug_pathname, name);

   last_slash = strrchr(debug_pathname, '/');

   strcpy(last_slash+1, debug_filename);

   debug_fd = open_debug_file(debug_pathname, crc);

   if (debug_fd >= 0) {

     free(debug_pathname);

     return debug_fd;

   }

   free(debug_pathname);

   return -1;

 }

 static struct symtab* build_symtab_internal(int fd, const char *filename, bool try_debuginfo);

 /* Look for a ".gnu_debuglink" section.  If one exists, try to open a

    suitable debuginfo file and read a symbol table from it.  */

 static struct symtab *build_symtab_from_debug_link(const char *name,

                                      int fd,

                                      ELF_EHDR *ehdr,

                                      ELF_SHDR *shbuf,

                                      struct elf_section *scn_cache)

 {

   fd = open_file_from_debug_link(name, fd, ehdr, shbuf, scn_cache);

   if (fd >= 0) {

     struct symtab *symtab = build_symtab_internal(fd, NULL, /* try_debuginfo */ false);

     close(fd);

     return symtab;

   }

   return NULL;

 }

 // Given a build_id, find the associated debuginfo file

 static char *

 build_id_to_debug_filename (size_t size, unsigned char *data)

 {

   char *filename, *s;

   filename = malloc(strlen (debug_file_directory) + (sizeof "/.build-id/" - 1) + 1

                     + 2 * size + (sizeof ".debug" - 1) + 1);

   s = filename + sprintf (filename, "%s/.build-id/", debug_file_directory);

   if (size > 0)

     {

       size--;

       s += sprintf (s, "%02x", *data++);

     }

   if (size > 0)

     *s++ = '/';

   while (size-- > 0)

     s += sprintf (s, "%02x", *data++);

   strcpy (s, ".debug");

   return filename;

 }

 // Read a build ID note.  Try to open any associated debuginfo file

 // and return its symtab

 static struct symtab* build_symtab_from_build_id(Elf64_Nhdr *note)

 {

   int fd;

   struct symtab *symtab = NULL;

   unsigned char *bytes

     = (unsigned char*)(note+1) + note->n_namesz;

   unsigned char *filename

     = (build_id_to_debug_filename (note->n_descsz, bytes));

   fd = pathmap_open(filename);

   if (fd >= 0) {

     symtab = build_symtab_internal(fd, NULL, /* try_debuginfo */ false);

     close(fd);

   }

   free(filename);

   return symtab;

 }

 // read symbol table from given fd.  If try_debuginfo) is true, also

 // try to open an associated debuginfo file

 static struct symtab* build_symtab_internal(int fd, const char *filename, bool try_debuginfo) {

   ELF_EHDR ehdr;

   char *names = NULL;

   struct symtab* symtab = NULL;

   // Reading of elf header

   struct elf_section *scn_cache = NULL;

   int cnt = 0;

   ELF_SHDR* shbuf = NULL;

   ELF_SHDR* cursct = NULL;

   ELF_PHDR* phbuf = NULL;

   ELF_PHDR* phdr = NULL;

   int sym_section = SHT_DYNSYM;

   uintptr_t baseaddr = (uintptr_t)-1;

   lseek(fd, (off_t)0L, SEEK_SET);

   if (! read_elf_header(fd, &ehdr)) {

     // not an elf

     return NULL;

   }

   // read ELF header

   if ((shbuf = read_section_header_table(fd, &ehdr)) == NULL) {

     goto quit;

   }

   baseaddr = find_base_address(fd, &ehdr);

   scn_cache = (struct elf_section *)

               calloc(ehdr.e_shnum * sizeof(struct elf_section), 1);

   if (scn_cache == NULL) {

     goto quit;

   }

   for (cursct = shbuf, cnt = 0; cnt < ehdr.e_shnum; cnt++) {

     scn_cache[cnt].c_shdr = cursct;

     if (cursct->sh_type == SHT_SYMTAB || cursct->sh_type == SHT_STRTAB

         || cursct->sh_type == SHT_NOTE || cursct->sh_type == SHT_DYNSYM) {

       if ( (scn_cache[cnt].c_data = read_section_data(fd, &ehdr, cursct)) == NULL) {

          goto quit;

       }

     }

     if (cursct->sh_type == SHT_SYMTAB) {

       // Full symbol table available so use that

       sym_section = cursct->sh_type;

     }

     cursct++;

   }

   for (cnt = 1; cnt < ehdr.e_shnum; cnt++) {

     ELF_SHDR *shdr = scn_cache[cnt].c_shdr;

     if (shdr->sh_type == sym_section) {

       ELF_SYM  *syms;

       int j, n, rslt;

       size_t size;

       // FIXME: there could be multiple data buffers associated with the

       // same ELF section. Here we can handle only one buffer. See man page

       // for elf_getdata on Solaris.

       // guarantee(symtab == NULL, "multiple symtab");

       symtab = (struct symtab*)calloc(1, sizeof(struct symtab));

       if (symtab == NULL) {

          goto quit;

       }

       // the symbol table

       syms = (ELF_SYM *)scn_cache[cnt].c_data;

       // number of symbols

       n = shdr->sh_size / shdr->sh_entsize;

       // create hash table, we use hcreate_r, hsearch_r and hdestroy_r to

       // manipulate the hash table.

       symtab->hash_table = (struct hsearch_data*) calloc(1, sizeof(struct hsearch_data));

       rslt = hcreate_r(n, symtab->hash_table);

       // guarantee(rslt, "unexpected failure: hcreate_r");

       // shdr->sh_link points to the section that contains the actual strings

       // for symbol names. the st_name field in ELF_SYM is just the

       // string table index. we make a copy of the string table so the

       // strings will not be destroyed by elf_end.

       size = scn_cache[shdr->sh_link].c_shdr->sh_size;

       symtab->strs = (char *)malloc(size);

       memcpy(symtab->strs, scn_cache[shdr->sh_link].c_data, size);

       // allocate memory for storing symbol offset and size;

       symtab->num_symbols = n;

       symtab->symbols = (struct elf_symbol *)calloc(n , sizeof(struct elf_symbol));

       // copy symbols info our symtab and enter them info the hash table

       for (j = 0; j < n; j++, syms++) {

         ENTRY item, *ret;

         char *sym_name = symtab->strs + syms->st_name;

         // skip non-object and non-function symbols

         int st_type = ELF_ST_TYPE(syms->st_info);

         if ( st_type != STT_FUNC && st_type != STT_OBJECT)

            continue;

         // skip empty strings and undefined symbols

         if (*sym_name == '\0' || syms->st_shndx == SHN_UNDEF) continue;

         symtab->symbols[j].name   = sym_name;

         symtab->symbols[j].offset = syms->st_value - baseaddr;

         symtab->symbols[j].size   = syms->st_size;

         item.key = sym_name;

         item.data = (void *)&(symtab->symbols[j]);

         hsearch_r(item, ENTER, &ret, symtab->hash_table);

       }

     }

   }

   // Look for a separate debuginfo file.

   if (try_debuginfo) {

     // We prefer a debug symtab to an object's own symtab, so look in

     // the debuginfo file.  We stash a copy of the old symtab in case

     // there is no debuginfo.

     struct symtab* prev_symtab = symtab;

     symtab = NULL;

 #ifdef NT_GNU_BUILD_ID

     // First we look for a Build ID

     for (cursct = shbuf, cnt = 0;

          symtab == NULL && cnt < ehdr.e_shnum;

          cnt++) {

       if (cursct->sh_type == SHT_NOTE) {

         Elf64_Nhdr *note = (Elf64_Nhdr *)scn_cache[cnt].c_data;

         if (note->n_type == NT_GNU_BUILD_ID) {

           symtab = build_symtab_from_build_id(note);

         }

       }

       cursct++;

     }

 #endif

     // Then, if that doesn't work, the debug link

     if (symtab == NULL) {

       symtab = build_symtab_from_debug_link(filename, fd, &ehdr, shbuf,

                                             scn_cache);

     }

     // If we still haven't found a symtab, use the object's own symtab.

     if (symtab != NULL) {

       if (prev_symtab != NULL)

         destroy_symtab(prev_symtab);

     } else {

       symtab = prev_symtab;

     }

   }

 quit:

   if (shbuf) free(shbuf);

   if (phbuf) free(phbuf);

   if (scn_cache) {

     for (cnt = 0; cnt < ehdr.e_shnum; cnt++) {

       if (scn_cache[cnt].c_data != NULL) {

         free(scn_cache[cnt].c_data);

       }

     }

     free(scn_cache);

   }

   return symtab;

 }

 struct symtab* build_symtab(int fd, const char *filename) {

   return build_symtab_internal(fd, filename, /* try_debuginfo */ true);

 }

 void destroy_symtab(struct symtab* symtab) {

   if (!symtab) return;

   if (symtab->strs) free(symtab->strs);

   if (symtab->symbols) free(symtab->symbols);

   if (symtab->hash_table) {

      hdestroy_r(symtab->hash_table);

      free(symtab->hash_table);

   }

   free(symtab);

 }

 uintptr_t search_symbol(struct symtab* symtab, uintptr_t base,

                       const char *sym_name, int *sym_size) {

   ENTRY item;

   ENTRY* ret = NULL;

   // library does not have symbol table

   if (!symtab || !symtab->hash_table)

      return (uintptr_t)NULL;

   item.key = (char*) strdup(sym_name);

   hsearch_r(item, FIND, &ret, symtab->hash_table);

   if (ret) {

     struct elf_symbol * sym = (struct elf_symbol *)(ret->data);

     uintptr_t rslt = (uintptr_t) ((char*)base + sym->offset);

     if (sym_size) *sym_size = sym->size;

     free(item.key);

     return rslt;

   }

 quit:

   free(item.key);

   return (uintptr_t) NULL;

 }

 const char* nearest_symbol(struct symtab* symtab, uintptr_t offset,

                            uintptr_t* poffset) {

   int n = 0;

   if (!symtab) return NULL;

   for (; n < symtab->num_symbols; n++) {

      struct elf_symbol* sym = &(symtab->symbols[n]);

      if (sym->name != NULL &&

          offset >= sym->offset && offset < sym->offset + sym->size) {

         if (poffset) *poffset = (offset - sym->offset);

         return sym->name;

      }

   }

   return NULL;

 }