src/mc/LocationList.cpp

   1 /* Copyright (c) 2004-2015. The SimGrid Team.
   2  * All rights reserved.                                                     */
   3
   4 /* This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the license (GNU LGPL) which comes with this package. */
   6
   7 #include "src/mc/mc_dwarf.hpp"
   8 #include "src/mc/ObjectInformation.hpp"
   9 #include "src/mc/LocationList.hpp"
  10
  11 namespace simgrid {
  12 namespace dwarf {
  13
  14 /** Resolve a location expression */
  15 Location resolve(
  16                       simgrid::dwarf::DwarfExpression const& expression,
  17                       simgrid::mc::ObjectInformation* object_info,
  18                       unw_cursor_t * c,
  19                       void *frame_pointer_address,
  20                       simgrid::mc::AddressSpace* address_space, int process_index)
  21 {
  22   simgrid::dwarf::ExpressionContext context;
  23   context.frame_base = frame_pointer_address;
  24   context.cursor = c;
  25   context.address_space = address_space;
  26   context.object_info = object_info;
  27   context.process_index = process_index;
  28
  29   if (!expression.empty()
  30       && expression[0].atom >= DW_OP_reg0
  31       && expression[0].atom <= DW_OP_reg31) {
  32     int dwarf_register = expression[0].atom - DW_OP_reg0;
  33     xbt_assert(c,
  34       "Missing frame context for register operation DW_OP_reg%i",
  35       dwarf_register);
  36     return Location(dwarf_register_to_libunwind(dwarf_register));
  37   }
  38
  39   simgrid::dwarf::ExpressionStack stack;
  40   simgrid::dwarf::execute(expression, context, stack);
  41   return Location((void*) stack.top());
  42 }
  43
  44 // TODO, move this in a method of LocationList
  45 static simgrid::dwarf::DwarfExpression const* find_expression(
  46     simgrid::dwarf::LocationList const& locations, unw_word_t ip)
  47 {
  48   for (simgrid::dwarf::LocationListEntry const& entry : locations)
  49     if (entry.valid_for_ip(ip))
  50       return &entry.expression;
  51   return nullptr;
  52 }
  53
  54 Location resolve(
  55   simgrid::dwarf::LocationList const& locations,
  56   simgrid::mc::ObjectInformation* object_info,
  57   unw_cursor_t * c,
  58   void *frame_pointer_address,
  59   simgrid::mc::AddressSpace* address_space,
  60   int process_index)
  61 {
  62   unw_word_t ip = 0;
  63   if (c && unw_get_reg(c, UNW_REG_IP, &ip))
  64     xbt_die("Could not resolve IP");
  65   simgrid::dwarf::DwarfExpression const* expression =
  66     find_expression(locations, ip);
  67   if (!expression)
  68     xbt_die("Could not resolve location");
  69   return simgrid::dwarf::resolve(
  70           *expression, object_info, c,
  71           frame_pointer_address, address_space, process_index);
  72 }
  73
  74 simgrid::dwarf::LocationList location_list(
  75   simgrid::mc::ObjectInformation& info,
  76   Dwarf_Attribute& attr)
  77 {
  78   simgrid::dwarf::LocationList locations;
  79   std::ptrdiff_t offset = 0;
  80   while (1) {
  81
  82     Dwarf_Addr base, start, end;
  83     Dwarf_Op *ops;
  84     std::size_t len;
  85
  86     offset = dwarf_getlocations(
  87       &attr, offset, &base, &start, &end, &ops, &len);
  88
  89     if (offset == 0)
  90       return std::move(locations);
  91     else if (offset == -1)
  92       xbt_die("Error while loading location list");
  93
  94     simgrid::dwarf::LocationListEntry entry;
  95     entry.expression = simgrid::dwarf::DwarfExpression(ops, ops + len);
  96
  97     void *base_address = info.base_address();
  98
  99     // If start == 0, this is not a location list:
 100     if (start == 0) {
 101       entry.lowpc  = nullptr;
 102       entry.highpc = nullptr;
 103     } else {
 104       entry.lowpc  = (char *) base_address + start;
 105       entry.highpc = (char *) base_address + end;
 106     }
 107
 108     locations.push_back(std::move(entry));
 109   }
 110 }
 111
 112
 113 }
 114 }