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, "Missing frame context for register operation DW_OP_reg%i", dwarf_register);
  43     return Location(dwarf_register_to_libunwind(dwarf_register));
  44   }
  45
  46   simgrid::dwarf::ExpressionStack stack;
  47   simgrid::dwarf::execute(expression, context, stack);
  48   return Location((void*) stack.top());
  49 }
  50
  51 // TODO, move this in a method of LocationList
  52 static simgrid::dwarf::DwarfExpression const* find_expression(
  53     simgrid::dwarf::LocationList const& locations, unw_word_t ip)
  54 {
  55   for (simgrid::dwarf::LocationListEntry const& entry : locations)
  56     if (entry.valid_for_ip(ip))
  57       return &entry.expression();
  58   return nullptr;
  59 }
  60
  61 Location resolve(
  62   simgrid::dwarf::LocationList const& locations,
  63   simgrid::mc::ObjectInformation* object_info,
  64   unw_cursor_t * c,
  65   void *frame_pointer_address,
  66   simgrid::mc::AddressSpace* address_space,
  67   int process_index)
  68 {
  69   unw_word_t ip = 0;
  70   if (c && unw_get_reg(c, UNW_REG_IP, &ip))
  71     xbt_die("Could not resolve IP");
  72   simgrid::dwarf::DwarfExpression const* expression =
  73     find_expression(locations, ip);
  74   if (!expression)
  75     xbt_die("Could not resolve location");
  76   return simgrid::dwarf::resolve(
  77           *expression, object_info, c,
  78           frame_pointer_address, address_space, process_index);
  79 }
  80
  81 LocationList location_list(
  82   simgrid::mc::ObjectInformation& info,
  83   Dwarf_Attribute& attr)
  84 {
  85   LocationList locations;
  86   std::ptrdiff_t offset = 0;
  87   while (1) {
  88     Dwarf_Addr base;
  89     Dwarf_Addr start;
  90     Dwarf_Addr end;
  91     Dwarf_Op *ops;
  92     std::size_t len;
  93
  94     offset = dwarf_getlocations(&attr, offset, &base, &start, &end, &ops, &len);
  95
  96     if (offset == 0)
  97       break;
  98     else if (offset == -1)
  99       xbt_die("Error while loading location list");
 100
 101     std::uint64_t base_address = (std::uint64_t) info.base_address();
 102
 103     LocationListEntry::range_type range;
 104     if (start == 0)
 105       // If start == 0, this is not a location list:
 106       range = { 0, UINT64_MAX };
 107     else
 108       range =  { base_address + start, base_address + end };
 109
 110     locations.push_back({ DwarfExpression(ops, ops+len), range });
 111   }
 112
 113   return locations;
 114 }
 115 }
 116 }