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[simgrid.git] / 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 }