src/mc/inspect/LocationList.cpp

   1 /* Copyright (c) 2004-2019. The SimGrid Team. All rights reserved.          */
   2
   3 /* This program is free software; you can redistribute it and/or modify it
   4  * under the terms of the license (GNU LGPL) which comes with this package. */
   5
   6 #include <cstddef>
   7 #include <cstdint>
   8 #include <utility>
   9
  10 #include "xbt/asserts.h"
  11 #include "xbt/sysdep.h"
  12
  13 #include <libunwind.h>
  14
  15 #include "src/mc/LocationList.hpp"
  16 #include "src/mc/ObjectInformation.hpp"
  17 #include "src/mc/mc_dwarf.hpp"
  18
  19 namespace simgrid {
  20 namespace dwarf {
  21
  22 /** Resolve a location expression */
  23 Location resolve(simgrid::dwarf::DwarfExpression const& expression, simgrid::mc::ObjectInformation* object_info,
  24                  unw_cursor_t* c, void* frame_pointer_address, simgrid::mc::AddressSpace* address_space,
  25                  int process_index)
  26 {
  27   simgrid::dwarf::ExpressionContext context;
  28   context.frame_base    = frame_pointer_address;
  29   context.cursor        = c;
  30   context.address_space = address_space;
  31   context.object_info   = object_info;
  32   context.process_index = process_index;
  33
  34   if (not expression.empty() && expression[0].atom >= DW_OP_reg0 && expression[0].atom <= DW_OP_reg31) {
  35     int dwarf_register = expression[0].atom - DW_OP_reg0;
  36     xbt_assert(c, "Missing frame context for register operation DW_OP_reg%i", dwarf_register);
  37     return Location(dwarf_register_to_libunwind(dwarf_register));
  38   }
  39
  40   simgrid::dwarf::ExpressionStack stack;
  41   simgrid::dwarf::execute(expression, context, stack);
  42   return Location((void*)stack.top());
  43 }
  44
  45 // TODO, move this in a method of LocationList
  46 static simgrid::dwarf::DwarfExpression const* find_expression(simgrid::dwarf::LocationList const& locations,
  47                                                               unw_word_t ip)
  48 {
  49   for (simgrid::dwarf::LocationListEntry const& entry : locations)
  50     if (entry.valid_for_ip(ip))
  51       return &entry.expression();
  52   return nullptr;
  53 }
  54
  55 Location resolve(simgrid::dwarf::LocationList const& locations, simgrid::mc::ObjectInformation* object_info,
  56                  unw_cursor_t* c, void* frame_pointer_address, simgrid::mc::AddressSpace* address_space,
  57                  int process_index)
  58 {
  59   unw_word_t ip = 0;
  60   if (c && unw_get_reg(c, UNW_REG_IP, &ip))
  61     xbt_die("Could not resolve IP");
  62   simgrid::dwarf::DwarfExpression const* expression = find_expression(locations, ip);
  63   if (not expression)
  64     xbt_die("Could not resolve location");
  65   return simgrid::dwarf::resolve(*expression, object_info, c, frame_pointer_address, address_space, process_index);
  66 }
  67
  68 LocationList location_list(simgrid::mc::ObjectInformation& info, Dwarf_Attribute& attr)
  69 {
  70   LocationList locations;
  71   std::ptrdiff_t offset = 0;
  72   while (1) {
  73     Dwarf_Addr base;
  74     Dwarf_Addr start;
  75     Dwarf_Addr end;
  76     Dwarf_Op* ops;
  77     std::size_t len;
  78
  79     offset = dwarf_getlocations(&attr, offset, &base, &start, &end, &ops, &len);
  80
  81     if (offset == 0)
  82       break;
  83     else if (offset == -1)
  84       xbt_die("Error while loading location list");
  85
  86     std::uint64_t base_address = (std::uint64_t)info.base_address();
  87
  88     LocationListEntry::range_type range;
  89     if (start == 0)
  90       // If start == 0, this is not a location list:
  91       range = {0, UINT64_MAX};
  92     else
  93       range = {base_address + start, base_address + end};
  94
  95     locations.push_back({DwarfExpression(ops, ops + len), range});
  96   }
  97
  98   return locations;
  99 }
 100 } // namespace dwarf
 101 } // namespace simgrid