src/mc/inspect/LocationList.cpp

   1 /* Copyright (c) 2004-2021. 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 "src/mc/inspect/LocationList.hpp"
   7 #include "src/mc/inspect/ObjectInformation.hpp"
   8 #include "src/mc/inspect/mc_dwarf.hpp"
   9
  10 #include "xbt/asserts.h"
  11 #include "xbt/sysdep.h"
  12
  13 #include <cstddef>
  14 #include <cstdint>
  15 #include <libunwind.h>
  16 #include <utility>
  17
  18 namespace simgrid {
  19 namespace dwarf {
  20
  21 /** Resolve a location expression */
  22 Location resolve(simgrid::dwarf::DwarfExpression const& expression, simgrid::mc::ObjectInformation* object_info,
  23                  unw_cursor_t* c, void* frame_pointer_address, const simgrid::mc::AddressSpace* address_space)
  24 {
  25   simgrid::dwarf::ExpressionContext context;
  26   context.frame_base    = frame_pointer_address;
  27   context.cursor        = c;
  28   context.address_space = address_space;
  29   context.object_info   = object_info;
  30
  31   if (not expression.empty() && expression[0].atom >= DW_OP_reg0 && expression[0].atom <= DW_OP_reg31) {
  32     int dwarf_register = expression[0].atom - DW_OP_reg0;
  33     xbt_assert(c, "Missing frame context for register operation DW_OP_reg%i", dwarf_register);
  34     return Location(dwarf_register_to_libunwind(dwarf_register));
  35   }
  36
  37   simgrid::dwarf::ExpressionStack stack;
  38   simgrid::dwarf::execute(expression, context, stack);
  39   return Location((void*)stack.top());
  40 }
  41
  42 // TODO, move this in a method of LocationList
  43 static simgrid::dwarf::DwarfExpression const* find_expression(simgrid::dwarf::LocationList const& locations,
  44                                                               unw_word_t ip)
  45 {
  46   for (simgrid::dwarf::LocationListEntry const& entry : locations)
  47     if (entry.valid_for_ip(ip))
  48       return &entry.expression();
  49   return nullptr;
  50 }
  51
  52 Location resolve(simgrid::dwarf::LocationList const& locations, simgrid::mc::ObjectInformation* object_info,
  53                  unw_cursor_t* c, void* frame_pointer_address, const simgrid::mc::AddressSpace* address_space)
  54 {
  55   unw_word_t ip = 0;
  56   if (c && unw_get_reg(c, UNW_REG_IP, &ip))
  57     xbt_die("Could not resolve IP");
  58   simgrid::dwarf::DwarfExpression const* expression = find_expression(locations, ip);
  59   if (not expression)
  60     xbt_die("Could not resolve location");
  61   return simgrid::dwarf::resolve(*expression, object_info, c, frame_pointer_address, address_space);
  62 }
  63
  64 LocationList location_list(const simgrid::mc::ObjectInformation& info, Dwarf_Attribute& attr)
  65 {
  66   LocationList locations;
  67   std::ptrdiff_t offset = 0;
  68   while (true) {
  69     Dwarf_Addr base;
  70     Dwarf_Addr start;
  71     Dwarf_Addr end;
  72     Dwarf_Op* ops;
  73     std::size_t len;
  74
  75     offset = dwarf_getlocations(&attr, offset, &base, &start, &end, &ops, &len);
  76
  77     if (offset == 0)
  78       break;
  79     else if (offset == -1)
  80       xbt_die("Error while loading location list");
  81
  82     auto base_address = reinterpret_cast<std::uint64_t>(info.base_address());
  83
  84     LocationListEntry::range_type range;
  85     if (start == 0)
  86       // If start == 0, this is not a location list:
  87       range = {0, UINT64_MAX};
  88     else
  89       range = {base_address + start, base_address + end};
  90
  91     locations.emplace_back(DwarfExpression(ops, ops + len), range);
  92   }
  93
  94   return locations;
  95 }
  96 } // namespace dwarf
  97 } // namespace simgrid