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