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  1. /* DWARF 1 find nearest line (_bfd_dwarf1_find_nearest_line).
  2.    Copyright (C) 1998-2015 Free Software Foundation, Inc.
  3.  
  4.    Written by Gavin Romig-Koch of Cygnus Solutions (gavin@cygnus.com).
  5.  
  6.    This file is part of BFD.
  7.  
  8.    This program is free software; you can redistribute it and/or modify
  9.    it under the terms of the GNU General Public License as published by
  10.    the Free Software Foundation; either version 3 of the License, or (at
  11.    your option) any later version.
  12.  
  13.    This program is distributed in the hope that it will be useful, but
  14.    WITHOUT ANY WARRANTY; without even the implied warranty of
  15.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.    General Public License for more details.
  17.  
  18.    You should have received a copy of the GNU General Public License
  19.    along with this program; if not, write to the Free Software
  20.    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21.    MA 02110-1301, USA.  */
  22.  
  23. #include "sysdep.h"
  24. #include "bfd.h"
  25. #include "libiberty.h"
  26. #include "libbfd.h"
  27. #include "elf-bfd.h"
  28. #include "elf/dwarf.h"
  29.  
  30. /* dwarf1_debug is the starting point for all dwarf1 info.  */
  31.  
  32. struct dwarf1_debug
  33. {
  34.   /* The bfd we are working with.  */
  35.   bfd* abfd;
  36.  
  37.   /* Pointer to the symbol table.  */
  38.   asymbol** syms;
  39.  
  40.   /* List of already parsed compilation units.  */
  41.   struct dwarf1_unit* lastUnit;
  42.  
  43.   /* The buffer for the .debug section.
  44.      Zero indicates that the .debug section failed to load.  */
  45.   bfd_byte *debug_section;
  46.  
  47.   /* Pointer to the end of the .debug_info section memory buffer.  */
  48.   bfd_byte *debug_section_end;
  49.  
  50.   /* The buffer for the .line section.  */
  51.   bfd_byte *line_section;
  52.  
  53.   /* End of that buffer.  */
  54.   bfd_byte *line_section_end;
  55.  
  56.   /* The current or next unread die within the .debug section.  */
  57.   bfd_byte *currentDie;
  58. };
  59.  
  60. /* One dwarf1_unit for each parsed compilation unit die.  */
  61.  
  62. struct dwarf1_unit
  63. {
  64.   /* Linked starting from stash->lastUnit.  */
  65.   struct dwarf1_unit* prev;
  66.  
  67.   /* Name of the compilation unit.  */
  68.   char *name;
  69.  
  70.   /* The highest and lowest address used in the compilation unit.  */
  71.   unsigned long low_pc;
  72.   unsigned long high_pc;
  73.  
  74.   /* Does this unit have a statement list?  */
  75.   int has_stmt_list;
  76.  
  77.   /* If any, the offset of the line number table in the .line section.  */
  78.   unsigned long stmt_list_offset;
  79.  
  80.   /* If non-zero, a pointer to the first child of this unit.  */
  81.   bfd_byte *first_child;
  82.  
  83.   /* How many line entries?  */
  84.   unsigned long line_count;
  85.  
  86.   /* The decoded line number table (line_count entries).  */
  87.   struct linenumber* linenumber_table;
  88.  
  89.   /* The list of functions in this unit.  */
  90.   struct dwarf1_func* func_list;
  91. };
  92.  
  93. /* One dwarf1_func for each parsed function die.  */
  94.  
  95. struct dwarf1_func
  96. {
  97.   /* Linked starting from aUnit->func_list.  */
  98.   struct dwarf1_func* prev;
  99.  
  100.   /* Name of function.  */
  101.   char* name;
  102.  
  103.   /* The highest and lowest address used in the compilation unit.  */
  104.   unsigned long low_pc;
  105.   unsigned long high_pc;
  106. };
  107.  
  108. /* Used to return info about a parsed die.  */
  109. struct die_info
  110. {
  111.   unsigned long length;
  112.   unsigned long sibling;
  113.   unsigned long low_pc;
  114.   unsigned long high_pc;
  115.   unsigned long stmt_list_offset;
  116.  
  117.   char* name;
  118.  
  119.   int has_stmt_list;
  120.  
  121.   unsigned short tag;
  122. };
  123.  
  124. /* Parsed line number information.  */
  125. struct linenumber
  126. {
  127.   /* First address in the line.  */
  128.   unsigned long addr;
  129.  
  130.   /* The line number.  */
  131.   unsigned long linenumber;
  132. };
  133.  
  134. /* Find the form of an attr, from the attr field.  */
  135. #define FORM_FROM_ATTR(attr)    ((attr) & 0xF)  /* Implicitly specified.  */
  136.  
  137. /* Return a newly allocated dwarf1_unit.  It should be cleared and
  138.    then attached into the 'stash' at 'stash->lastUnit'.  */
  139.  
  140. static struct dwarf1_unit*
  141. alloc_dwarf1_unit (struct dwarf1_debug* stash)
  142. {
  143.   bfd_size_type amt = sizeof (struct dwarf1_unit);
  144.  
  145.   struct dwarf1_unit* x = (struct dwarf1_unit *) bfd_zalloc (stash->abfd, amt);
  146.   if (x)
  147.     {
  148.       x->prev = stash->lastUnit;
  149.       stash->lastUnit = x;
  150.     }
  151.  
  152.   return x;
  153. }
  154.  
  155. /* Return a newly allocated dwarf1_func.  It must be cleared and
  156.    attached into 'aUnit' at 'aUnit->func_list'.  */
  157.  
  158. static struct dwarf1_func *
  159. alloc_dwarf1_func (struct dwarf1_debug* stash, struct dwarf1_unit* aUnit)
  160. {
  161.   bfd_size_type amt = sizeof (struct dwarf1_func);
  162.  
  163.   struct dwarf1_func* x = (struct dwarf1_func *) bfd_zalloc (stash->abfd, amt);
  164.   if (x)
  165.     {
  166.       x->prev = aUnit->func_list;
  167.       aUnit->func_list = x;
  168.     }
  169.  
  170.   return x;
  171. }
  172.  
  173. /* parse_die - parse a Dwarf1 die.
  174.    Parse the die starting at 'aDiePtr' into 'aDieInfo'.
  175.    'abfd' must be the bfd from which the section that 'aDiePtr'
  176.    points to was pulled from.
  177.  
  178.    Return FALSE if the die is invalidly formatted; TRUE otherwise.  */
  179.  
  180. static bfd_boolean
  181. parse_die (bfd *             abfd,
  182.            struct die_info * aDieInfo,
  183.            bfd_byte *        aDiePtr,
  184.            bfd_byte *        aDiePtrEnd)
  185. {
  186.   bfd_byte *this_die = aDiePtr;
  187.   bfd_byte *xptr = this_die;
  188.  
  189.   memset (aDieInfo, 0, sizeof (* aDieInfo));
  190.  
  191.   /* First comes the length.  */
  192.   aDieInfo->length = bfd_get_32 (abfd, (bfd_byte *) xptr);
  193.   xptr += 4;
  194.   if (aDieInfo->length == 0
  195.       || (this_die + aDieInfo->length) >= aDiePtrEnd)
  196.     return FALSE;
  197.   if (aDieInfo->length < 6)
  198.     {
  199.       /* Just padding bytes.  */
  200.       aDieInfo->tag = TAG_padding;
  201.       return TRUE;
  202.     }
  203.  
  204.   /* Then the tag.  */
  205.   aDieInfo->tag = bfd_get_16 (abfd, (bfd_byte *) xptr);
  206.   xptr += 2;
  207.  
  208.   /* Then the attributes.  */
  209.   while (xptr < (this_die + aDieInfo->length))
  210.     {
  211.       unsigned short attr;
  212.  
  213.       /* Parse the attribute based on its form.  This section
  214.          must handle all dwarf1 forms, but need only handle the
  215.          actual attributes that we care about.  */
  216.       attr = bfd_get_16 (abfd, (bfd_byte *) xptr);
  217.       xptr += 2;
  218.  
  219.       switch (FORM_FROM_ATTR (attr))
  220.         {
  221.         case FORM_DATA2:
  222.           xptr += 2;
  223.           break;
  224.         case FORM_DATA4:
  225.         case FORM_REF:
  226.           if (attr == AT_sibling)
  227.             aDieInfo->sibling = bfd_get_32 (abfd, (bfd_byte *) xptr);
  228.           else if (attr == AT_stmt_list)
  229.             {
  230.               aDieInfo->stmt_list_offset = bfd_get_32 (abfd, (bfd_byte *) xptr);
  231.               aDieInfo->has_stmt_list = 1;
  232.             }
  233.           xptr += 4;
  234.           break;
  235.         case FORM_DATA8:
  236.           xptr += 8;
  237.           break;
  238.         case FORM_ADDR:
  239.           if (attr == AT_low_pc)
  240.             aDieInfo->low_pc = bfd_get_32 (abfd, (bfd_byte *) xptr);
  241.           else if (attr == AT_high_pc)
  242.             aDieInfo->high_pc = bfd_get_32 (abfd, (bfd_byte *) xptr);
  243.           xptr += 4;
  244.           break;
  245.         case FORM_BLOCK2:
  246.           xptr += 2 + bfd_get_16 (abfd, (bfd_byte *) xptr);
  247.           break;
  248.         case FORM_BLOCK4:
  249.           xptr += 4 + bfd_get_32 (abfd, (bfd_byte *) xptr);
  250.           break;
  251.         case FORM_STRING:
  252.           if (attr == AT_name)
  253.             aDieInfo->name = (char *) xptr;
  254.           xptr += strlen ((char *) xptr) + 1;
  255.           break;
  256.         }
  257.     }
  258.  
  259.   return TRUE;
  260. }
  261.  
  262. /* Parse a dwarf1 line number table for 'aUnit->stmt_list_offset'
  263.    into 'aUnit->linenumber_table'.  Return FALSE if an error
  264.    occurs; TRUE otherwise.  */
  265.  
  266. static bfd_boolean
  267. parse_line_table (struct dwarf1_debug* stash, struct dwarf1_unit* aUnit)
  268. {
  269.   bfd_byte *xptr;
  270.  
  271.   /* Load the ".line" section from the bfd if we haven't already.  */
  272.   if (stash->line_section == 0)
  273.     {
  274.       asection *msec;
  275.       bfd_size_type size;
  276.  
  277.       msec = bfd_get_section_by_name (stash->abfd, ".line");
  278.       if (! msec)
  279.         return FALSE;
  280.  
  281.       size = msec->rawsize ? msec->rawsize : msec->size;
  282.       stash->line_section
  283.         = bfd_simple_get_relocated_section_contents
  284.         (stash->abfd, msec, NULL, stash->syms);
  285.  
  286.       if (! stash->line_section)
  287.         return FALSE;
  288.  
  289.       stash->line_section_end = stash->line_section + size;
  290.     }
  291.  
  292.   xptr = stash->line_section + aUnit->stmt_list_offset;
  293.   if (xptr < stash->line_section_end)
  294.     {
  295.       unsigned long eachLine;
  296.       bfd_byte *tblend;
  297.       unsigned long base;
  298.       bfd_size_type amt;
  299.  
  300.       /* First comes the length.  */
  301.       tblend = bfd_get_32 (stash->abfd, (bfd_byte *) xptr) + xptr;
  302.       xptr += 4;
  303.  
  304.       /* Then the base address for each address in the table.  */
  305.       base = bfd_get_32 (stash->abfd, (bfd_byte *) xptr);
  306.       xptr += 4;
  307.  
  308.       /* How many line entrys?
  309.          10 = 4 (line number) + 2 (pos in line) + 4 (address in line).  */
  310.       aUnit->line_count = (tblend - xptr) / 10;
  311.  
  312.       /* Allocate an array for the entries.  */
  313.       amt = sizeof (struct linenumber) * aUnit->line_count;
  314.       aUnit->linenumber_table = (struct linenumber *) bfd_alloc (stash->abfd,
  315.                                                                  amt);
  316.       if (!aUnit->linenumber_table)
  317.         return FALSE;
  318.  
  319.       for (eachLine = 0; eachLine < aUnit->line_count; eachLine++)
  320.         {
  321.           /* A line number.  */
  322.           aUnit->linenumber_table[eachLine].linenumber
  323.             = bfd_get_32 (stash->abfd, (bfd_byte *) xptr);
  324.           xptr += 4;
  325.  
  326.           /* Skip the position within the line.  */
  327.           xptr += 2;
  328.  
  329.           /* And finally the address.  */
  330.           aUnit->linenumber_table[eachLine].addr
  331.             = base + bfd_get_32 (stash->abfd, (bfd_byte *) xptr);
  332.           xptr += 4;
  333.         }
  334.     }
  335.  
  336.   return TRUE;
  337. }
  338.  
  339. /* Parse each function die in a compilation unit 'aUnit'.
  340.    The first child die of 'aUnit' should be in 'aUnit->first_child',
  341.    the result is placed in 'aUnit->func_list'.
  342.    Return FALSE if error; TRUE otherwise.  */
  343.  
  344. static bfd_boolean
  345. parse_functions_in_unit (struct dwarf1_debug* stash, struct dwarf1_unit* aUnit)
  346. {
  347.   bfd_byte *eachDie;
  348.  
  349.   if (aUnit->first_child)
  350.     for (eachDie = aUnit->first_child;
  351.          eachDie < stash->debug_section_end;
  352.          )
  353.       {
  354.         struct die_info eachDieInfo;
  355.  
  356.         if (! parse_die (stash->abfd, &eachDieInfo, eachDie,
  357.                          stash->debug_section_end))
  358.           return FALSE;
  359.  
  360.         if (eachDieInfo.tag == TAG_global_subroutine
  361.             || eachDieInfo.tag == TAG_subroutine
  362.             || eachDieInfo.tag == TAG_inlined_subroutine
  363.             || eachDieInfo.tag == TAG_entry_point)
  364.           {
  365.             struct dwarf1_func* aFunc = alloc_dwarf1_func (stash,aUnit);
  366.             if (!aFunc)
  367.               return FALSE;
  368.  
  369.             aFunc->name = eachDieInfo.name;
  370.             aFunc->low_pc = eachDieInfo.low_pc;
  371.             aFunc->high_pc = eachDieInfo.high_pc;
  372.           }
  373.  
  374.         /* Move to next sibling, if none, end loop */
  375.         if (eachDieInfo.sibling)
  376.           eachDie = stash->debug_section + eachDieInfo.sibling;
  377.         else
  378.           break;
  379.       }
  380.  
  381.   return TRUE;
  382. }
  383.  
  384. /* Find the nearest line to 'addr' in 'aUnit'.
  385.    Return whether we found the line (or a function) without error.  */
  386.  
  387. static bfd_boolean
  388. dwarf1_unit_find_nearest_line (struct dwarf1_debug* stash,
  389.                                struct dwarf1_unit* aUnit,
  390.                                unsigned long addr,
  391.                                const char **filename_ptr,
  392.                                const char **functionname_ptr,
  393.                                unsigned int *linenumber_ptr)
  394. {
  395.   int line_p = FALSE;
  396.   int func_p = FALSE;
  397.  
  398.   if (aUnit->low_pc <= addr && addr < aUnit->high_pc)
  399.     {
  400.       if (aUnit->has_stmt_list)
  401.         {
  402.           unsigned long i;
  403.           struct dwarf1_func* eachFunc;
  404.  
  405.           if (! aUnit->linenumber_table)
  406.             {
  407.               if (! parse_line_table (stash, aUnit))
  408.                 return FALSE;
  409.             }
  410.  
  411.           if (! aUnit->func_list)
  412.             {
  413.               if (! parse_functions_in_unit (stash, aUnit))
  414.                 return FALSE;
  415.             }
  416.  
  417.           for (i = 0; i < aUnit->line_count; i++)
  418.             {
  419.               if (aUnit->linenumber_table[i].addr <= addr
  420.                   && addr < aUnit->linenumber_table[i+1].addr)
  421.                 {
  422.                   *filename_ptr = aUnit->name;
  423.                   *linenumber_ptr = aUnit->linenumber_table[i].linenumber;
  424.                   line_p = TRUE;
  425.                   break;
  426.                 }
  427.             }
  428.  
  429.           for (eachFunc = aUnit->func_list;
  430.                eachFunc;
  431.                eachFunc = eachFunc->prev)
  432.             {
  433.               if (eachFunc->low_pc <= addr
  434.                   && addr < eachFunc->high_pc)
  435.                 {
  436.                   *functionname_ptr = eachFunc->name;
  437.                   func_p = TRUE;
  438.                   break;
  439.                 }
  440.             }
  441.         }
  442.     }
  443.  
  444.   return line_p || func_p;
  445. }
  446.  
  447. /* The DWARF 1 version of find_nearest line.
  448.    Return TRUE if the line is found without error.  */
  449.  
  450. bfd_boolean
  451. _bfd_dwarf1_find_nearest_line (bfd *abfd,
  452.                                asymbol **symbols,
  453.                                asection *section,
  454.                                bfd_vma offset,
  455.                                const char **filename_ptr,
  456.                                const char **functionname_ptr,
  457.                                unsigned int *linenumber_ptr)
  458. {
  459.   struct dwarf1_debug *stash = elf_tdata (abfd)->dwarf1_find_line_info;
  460.  
  461.   struct dwarf1_unit* eachUnit;
  462.  
  463.   /* What address are we looking for? */
  464.   unsigned long addr = (unsigned long)(offset + section->vma);
  465.  
  466.   *filename_ptr = NULL;
  467.   *functionname_ptr = NULL;
  468.   *linenumber_ptr = 0;
  469.  
  470.   if (! stash)
  471.     {
  472.       asection *msec;
  473.       bfd_size_type size = sizeof (struct dwarf1_debug);
  474.  
  475.       stash = elf_tdata (abfd)->dwarf1_find_line_info
  476.         = (struct dwarf1_debug *) bfd_zalloc (abfd, size);
  477.  
  478.       if (! stash)
  479.         return FALSE;
  480.  
  481.       msec = bfd_get_section_by_name (abfd, ".debug");
  482.       if (! msec)
  483.         /* No dwarf1 info.  Note that at this point the stash
  484.            has been allocated, but contains zeros, this lets
  485.            future calls to this function fail quicker.  */
  486.         return FALSE;
  487.  
  488.       size = msec->rawsize ? msec->rawsize : msec->size;
  489.       stash->debug_section
  490.         = bfd_simple_get_relocated_section_contents (abfd, msec, NULL,
  491.                                                      symbols);
  492.  
  493.       if (! stash->debug_section)
  494.         return FALSE;
  495.  
  496.       stash->debug_section_end = stash->debug_section + size;
  497.       stash->currentDie = stash->debug_section;
  498.       stash->abfd = abfd;
  499.       stash->syms = symbols;
  500.     }
  501.  
  502.   /* A null debug_section indicates that there was no dwarf1 info
  503.      or that an error occured while setting up the stash.  */
  504.  
  505.   if (! stash->debug_section)
  506.     return FALSE;
  507.  
  508.   /* Look at the previously parsed units to see if any contain
  509.      the addr.  */
  510.   for (eachUnit = stash->lastUnit; eachUnit; eachUnit = eachUnit->prev)
  511.     if (eachUnit->low_pc <= addr && addr < eachUnit->high_pc)
  512.       return dwarf1_unit_find_nearest_line (stash, eachUnit, addr,
  513.                                             filename_ptr,
  514.                                             functionname_ptr,
  515.                                             linenumber_ptr);
  516.  
  517.   while (stash->currentDie < stash->debug_section_end)
  518.     {
  519.       struct die_info aDieInfo;
  520.  
  521.       if (! parse_die (stash->abfd, &aDieInfo, stash->currentDie,
  522.                        stash->debug_section_end))
  523.         return FALSE;
  524.  
  525.       if (aDieInfo.tag == TAG_compile_unit)
  526.         {
  527.           struct dwarf1_unit* aUnit
  528.             = alloc_dwarf1_unit (stash);
  529.           if (!aUnit)
  530.             return FALSE;
  531.  
  532.           aUnit->name = aDieInfo.name;
  533.           aUnit->low_pc = aDieInfo.low_pc;
  534.           aUnit->high_pc = aDieInfo.high_pc;
  535.           aUnit->has_stmt_list = aDieInfo.has_stmt_list;
  536.           aUnit->stmt_list_offset = aDieInfo.stmt_list_offset;
  537.  
  538.           /* A die has a child if it's followed by a die that is
  539.              not it's sibling.  */
  540.           if (aDieInfo.sibling
  541.               && stash->currentDie + aDieInfo.length
  542.                     < stash->debug_section_end
  543.               && stash->currentDie + aDieInfo.length
  544.                     != stash->debug_section + aDieInfo.sibling)
  545.             aUnit->first_child = stash->currentDie + aDieInfo.length;
  546.           else
  547.             aUnit->first_child = 0;
  548.  
  549.           if (aUnit->low_pc <= addr && addr < aUnit->high_pc)
  550.             return dwarf1_unit_find_nearest_line (stash, aUnit, addr,
  551.                                                   filename_ptr,
  552.                                                   functionname_ptr,
  553.                                                   linenumber_ptr);
  554.         }
  555.  
  556.       if (aDieInfo.sibling != 0)
  557.         stash->currentDie = stash->debug_section + aDieInfo.sibling;
  558.       else
  559.         stash->currentDie += aDieInfo.length;
  560.     }
  561.  
  562.   return FALSE;
  563. }
  564.