#include <algorithm>
#include <memory>
+#include <utility>
#include <cstdlib>
#define DW_LANG_Objc DW_LANG_ObjC /* fix spelling error in older dwarf.h */
int attribute)
{
Dwarf_Attribute attr;
- if (!dwarf_attr_integrate(die, attribute, &attr)) {
+ if (!dwarf_attr_integrate(die, attribute, &attr))
return nullptr;
- } else {
+ else
return dwarf_formstring(&attr);
- }
}
/** \brief Get the linkage name of a DIE.
if (low_pc) {
// DW_AT_high_pc:
Dwarf_Attribute attr;
- if (!dwarf_attr_integrate(die, DW_AT_high_pc, &attr)) {
+ if (!dwarf_attr_integrate(die, DW_AT_high_pc, &attr))
xbt_die("Missing DW_AT_high_pc matching with DW_AT_low_pc");
- }
Dwarf_Sword offset;
Dwarf_Addr high_pc;
Dwarf_Die child;
int res;
for (res = dwarf_child(die, &child); res == 0;
- res = dwarf_siblingof(&child, &child)) {
+ res = dwarf_siblingof(&child, &child))
MC_dwarf_handle_die(info, &child, unit, frame, ns);
- }
}
static void MC_dwarf_handle_die(simgrid::mc::ObjectInformation* info, Dwarf_Die * die,
}
static
-Elf64_Half MC_dwarf_elf_type(Dwarf* dwarf)
+Elf64_Half get_type(Elf* elf)
{
- Elf* elf = dwarf_getelf(dwarf);
Elf64_Ehdr* ehdr64 = elf64_getehdr(elf);
if (ehdr64)
return ehdr64->e_type;
xbt_die("Could not get ELF heeader");
}
-/** \brief Populate the debugging informations of the given ELF object
- *
- * Read the DWARf information of the EFFL object and populate the
- * lists of types, variables, functions.
- */
static
-void MC_dwarf_get_variables(simgrid::mc::ObjectInformation* info)
+void read_dwarf_info(simgrid::mc::ObjectInformation* info, Dwarf* dwarf)
{
- int fd = open(info->file_name.c_str(), O_RDONLY);
- if (fd < 0)
- xbt_die("Could not open file %s", info->file_name.c_str());
- Dwarf *dwarf = dwarf_begin(fd, DWARF_C_READ);
- if (dwarf == nullptr)
- xbt_die("Missing debugging information in %s\n"
- "Your program and its dependencies must have debugging information.\n"
- "You might want to recompile with -g or install the suitable debugging package.\n",
- info->file_name.c_str());
-
- Elf64_Half elf_type = MC_dwarf_elf_type(dwarf);
- if (elf_type == ET_EXEC)
- info->flags |= simgrid::mc::ObjectInformation::Executable;
-
// For each compilation unit:
Dwarf_Off offset = 0;
Dwarf_Off next_offset = 0;
MC_dwarf_handle_children(info, &unit_die, &unit_die, nullptr, NULL);
offset = next_offset;
}
+}
+
+/** Get the build-id (NT_GNU_BUILD_ID) from the ELF file
+ *
+ * Return an empty vector is none is found.
+ */
+static
+std::vector<char> get_build_id(Elf* elf)
+{
+ size_t phnum;
+ if (elf_getphdrnum (elf, &phnum) != 0)
+ xbt_die("Could not read program headers");
+ for (size_t i = 0; i < phnum; ++i) {
+ GElf_Phdr phdr_temp;
+ GElf_Phdr *phdr = gelf_getphdr(elf, i, &phdr_temp);
+ if (phdr->p_type != PT_NOTE)
+ continue;
+ Elf_Data* data = elf_getdata_rawchunk(elf, phdr->p_offset, phdr->p_filesz, ELF_T_NHDR);
+ size_t pos = 0;
+ while (1) {
+ GElf_Nhdr nhdr;
+ size_t name_pos;
+ size_t desc_pos;
+ pos = gelf_getnote(data, pos, &nhdr, &name_pos, &desc_pos);
+ if (nhdr.n_type == NT_GNU_BUILD_ID
+ && nhdr.n_namesz == sizeof("GNU")
+ && memcmp((char*) data->d_buf + name_pos, "GNU", sizeof("GNU")) == 0) {
+ char* start = (char*) data->d_buf + desc_pos;
+ char* end = (char*) start + nhdr.n_descsz;
+ return std::vector<char>(start, end);
+ }
+ }
+ }
+ return std::vector<char>();
+}
+static char hexdigits[16] = {
+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+ 'a', 'b', 'c', 'd', 'e', 'f'
+};
+
+static inline
+std::array<char, 2> to_hex(std::uint8_t byte)
+{
+ return { hexdigits[byte >> 4], hexdigits[byte & 0xF] };
+}
+
+/** Hexadecimal representation of some binary data */
+static
+std::string to_hex(const char* data, std::size_t count)
+{
+ std::string res;
+ res.resize(2*count);
+ for (std::size_t i = 0; i < count; i++) {
+ std::array<char, 2> hex_byte = to_hex(data[i]);
+ for (int j = 0; j < 2; ++j)
+ res[2 * i + j] = hex_byte[j];
+ }
+ return std::move(res);
+}
+
+static
+std::string to_hex(std::vector<char> const& data)
+{
+ return to_hex(data.data(), data.size());
+}
+
+const char* debug_paths[] = {
+ "/usr/lib/debug/",
+ "/usr/local/lib/debug/"
+};
+
+static
+std::string find_by_build_id(std::vector<char> id)
+{
+ std::string filename;
+ for (const char* debug_path : debug_paths) {
+ filename = debug_path;
+ filename += ".build-id/" + to_hex(id.data(), 1) + '/'
+ + to_hex(id.data() + 1, id.size() - 1) + ".debug";
+ XBT_DEBUG("Checking debug file: %s", filename.c_str());
+ if (access(filename.c_str(), F_OK) == 0)
+ return std::move(filename);
+ }
+ return std::string();
+}
+
+/** \brief Populate the debugging informations of the given ELF object
+ *
+ * Read the DWARf information of the EFFL object and populate the
+ * lists of types, variables, functions.
+ */
+static
+void MC_dwarf_get_variables(simgrid::mc::ObjectInformation* info)
+{
+ if (elf_version(EV_CURRENT) == EV_NONE)
+ xbt_die("libelf initialization error");
+
+ int fd = open(info->file_name.c_str(), O_RDONLY);
+ if (fd < 0)
+ xbt_die("Could not open file %s", info->file_name.c_str());
+ Elf* elf = elf_begin(fd, ELF_C_READ, nullptr);
+ if (elf == nullptr)
+ xbt_die("Not an ELF file 1");
+ Elf_Kind kind = elf_kind(elf);
+ if (kind != ELF_K_ELF)
+ xbt_die("Not an ELF file 2");
+
+ Elf64_Half type = get_type(elf);
+ if (type == ET_EXEC)
+ info->flags |= simgrid::mc::ObjectInformation::Executable;
+
+ Dwarf* dwarf = dwarf_begin_elf (elf, DWARF_C_READ, nullptr);
+ if (dwarf != nullptr) {
+ // This is the simple case where DWARF is located in the ELF file:
+ read_dwarf_info(info, dwarf);
+ dwarf_end(dwarf);
+ elf_end(elf);
+ close(fd);
+ return;
+ }
dwarf_end(dwarf);
- close(fd);
+
+ // Try to find it with NT_GNU_BUILD_ID:
+ std::vector<char> build_id = get_build_id(elf);
+ if (!build_id.empty()) {
+ elf_end(elf);
+ close(fd);
+
+ // Find a debug file using the build id:
+ std::string debug_file = find_by_build_id(build_id);
+ if (debug_file.empty()) {
+ std::string hex = to_hex(build_id);
+ xbt_die(
+ "Missing debug info for %s with build-id %s\n"
+ "You might want to install the suitable debugging package.\n",
+ info->file_name.c_str(), hex.c_str());
+ }
+
+ // Load the DWARF info from this file:
+ XBT_DEBUG("Load DWARF for %s from %s",
+ info->file_name.c_str(), debug_file.c_str());
+ fd = open(debug_file.c_str(), O_RDONLY);
+ if (fd < 0)
+ xbt_die("Could not open file %s", debug_file.c_str());
+ Dwarf* dwarf = dwarf_begin(fd, DWARF_C_READ);
+ if (dwarf == nullptr)
+ xbt_die("No DWARF info in %s for %s",
+ debug_file.c_str(), info->file_name.c_str());
+ read_dwarf_info(info, dwarf);
+ dwarf_end(dwarf);
+ close(fd);
+ return;
+ }
+
+ // TODO, try to find DWARF info using debug-link.
+ // Is this debug-link actually used anywhere?
+
+ // Everything failes, complain loudly:
+ xbt_die("Debugging information not found for %s\n"
+ "Try recompiling with -g\n",
+ info->file_name.c_str());
}
// ***** Functions index
break;
// Resolve full_type:
- if (!subtype->name.empty() && subtype->byte_size == 0) {
+ if (!subtype->name.empty() && subtype->byte_size == 0)
for (auto const& object_info : process->object_infos) {
auto i = object_info->full_types_by_name.find(subtype->name);
if (i != object_info->full_types_by_name.end()
break;
}
}
- } else type->full_type = subtype;
+ else type->full_type = subtype;
}
}
