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 <cstddef>
   8 #include <cstdint>
   9 #include <utility>
  10
  11 #include <xbt/asserts.h>
  12 #include <xbt/sysdep.h>
  13
  14 #include <libunwind.h>
  15
  16 #include "src/mc/mc_dwarf.hpp"
  17 #include "src/mc/ObjectInformation.hpp"
  18 #include "src/mc/LocationList.hpp"
  19
  20 namespace simgrid {
  21 namespace dwarf {
  22
  23 /** Resolve a location expression */
  24 Location resolve(
  25                       simgrid::dwarf::DwarfExpression const& expression,
  26                       simgrid::mc::ObjectInformation* object_info,
  27                       unw_cursor_t * c,
  28                       void *frame_pointer_address,
  29                       simgrid::mc::AddressSpace* address_space, int process_index)
  30 {
  31   simgrid::dwarf::ExpressionContext context;
  32   context.frame_base = frame_pointer_address;
  33   context.cursor = c;
  34   context.address_space = address_space;
  35   context.object_info = object_info;
  36   context.process_index = process_index;
  37
  38   if (!expression.empty()
  39       && expression[0].atom >= DW_OP_reg0
  40       && expression[0].atom <= DW_OP_reg31) {
  41     int dwarf_register = expression[0].atom - DW_OP_reg0;
  42     xbt_assert(c,
  43       "Missing frame context for register operation DW_OP_reg%i",
  44       dwarf_register);
  45     return Location(dwarf_register_to_libunwind(dwarf_register));
  46   }
  47
  48   simgrid::dwarf::ExpressionStack stack;
  49   simgrid::dwarf::execute(expression, context, stack);
  50   return Location((void*) stack.top());
  51 }
  52
  53 // TODO, move this in a method of LocationList
  54 static simgrid::dwarf::DwarfExpression const* find_expression(
  55     simgrid::dwarf::LocationList const& locations, unw_word_t ip)
  56 {
  57   for (simgrid::dwarf::LocationListEntry const& entry : locations)
  58     if (entry.valid_for_ip(ip))
  59       return &entry.expression();
  60   return nullptr;
  61 }
  62
  63 Location resolve(
  64   simgrid::dwarf::LocationList const& locations,
  65   simgrid::mc::ObjectInformation* object_info,
  66   unw_cursor_t * c,
  67   void *frame_pointer_address,
  68   simgrid::mc::AddressSpace* address_space,
  69   int process_index)
  70 {
  71   unw_word_t ip = 0;
  72   if (c && unw_get_reg(c, UNW_REG_IP, &ip))
  73     xbt_die("Could not resolve IP");
  74   simgrid::dwarf::DwarfExpression const* expression =
  75     find_expression(locations, ip);
  76   if (!expression)
  77     xbt_die("Could not resolve location");
  78   return simgrid::dwarf::resolve(
  79           *expression, object_info, c,
  80           frame_pointer_address, address_space, process_index);
  81 }
  82
  83 LocationList location_list(
  84   simgrid::mc::ObjectInformation& info,
  85   Dwarf_Attribute& attr)
  86 {
  87   LocationList locations;
  88   std::ptrdiff_t offset = 0;
  89   while (1) {
  90
  91     Dwarf_Addr base, start, end;
  92     Dwarf_Op *ops;
  93     std::size_t len;
  94
  95     offset = dwarf_getlocations(
  96       &attr, offset, &base, &start, &end, &ops, &len);
  97
  98     if (offset == 0)
  99       break;
 100     else if (offset == -1)
 101       xbt_die("Error while loading location list");
 102
 103     std::uint64_t base_address = (std::uint64_t) info.base_address();
 104
 105     LocationListEntry::range_type range;
 106     if (start == 0)
 107       // If start == 0, this is not a location list:
 108       range = { 0, UINT64_MAX };
 109     else
 110       range =  { base_address + start, base_address + end };
 111
 112     locations.push_back({ DwarfExpression(ops, ops+len), range });
 113   }
 114
 115   return locations;
 116 }
 117
 118
 119 }
 120 }