Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Fix Introspection issues #6424

Merged
merged 1 commit into from
Nov 17, 2021
Merged

Fix Introspection issues #6424

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
89 changes: 63 additions & 26 deletions src/Introspection.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@

#include <cstdio>
#include <iostream>
#include <map>
#include <sstream>
#include <string>

Expand Down Expand Up @@ -77,7 +78,7 @@ class DebugSections {
EntryFormat() = default;
vector<FieldFormat> fields;
};
vector<EntryFormat> entry_formats;
map<uint64_t, EntryFormat> entry_formats;

struct LiveRange {
uint64_t pc_begin, pc_end;
Expand Down Expand Up @@ -940,7 +941,7 @@ class DebugSections {

void parse_object_file(llvm::object::ObjectFile *obj) {
// Look for the debug_info, debug_abbrev, debug_line, and debug_str sections
llvm::StringRef debug_info, debug_abbrev, debug_str, debug_line, debug_ranges;
llvm::StringRef debug_info, debug_abbrev, debug_str, debug_line, debug_line_str, debug_ranges;

#ifdef __APPLE__
std::string prefix = "__";
Expand All @@ -963,6 +964,8 @@ class DebugSections {
debug_abbrev = *e;
} else if (name == prefix + "debug_str") {
debug_str = *e;
} else if (name == prefix + "debug_line_str") {
debug_line_str = *e;
} else if (name == prefix + "debug_line") {
debug_line = *e;
} else if (name == prefix + "debug_ranges") {
Expand All @@ -976,6 +979,7 @@ class DebugSections {
debug_str.empty() ||
debug_line.empty() ||
debug_ranges.empty()) {
// It's OK for debug_line_str to be empty
debug(2) << "Debugging sections not found\n";
working = false;
return;
Expand All @@ -985,7 +989,10 @@ class DebugSections {
// Parse the debug_info section to populate the functions and local variables
llvm::DataExtractor extractor(debug_info, true, obj->getBytesInAddress());
llvm::DataExtractor debug_abbrev_extractor(debug_abbrev, true, obj->getBytesInAddress());
parse_debug_info(extractor, debug_abbrev_extractor, debug_str, debug_ranges);
parse_debug_info(extractor, debug_abbrev_extractor, debug_str, debug_line_str, debug_ranges);
if (!working) {
return;
}
}

{
Expand Down Expand Up @@ -1019,18 +1026,19 @@ class DebugSections {
if (!name && !form) {
break;
}
//printf(" name = %lu, form = %lu\n", name, form);
// printf(" name = %lu, form = %lu\n", name, form);

FieldFormat f_fmt(name, form);
fmt.fields.push_back(f_fmt);
}
entry_formats.push_back(fmt);
entry_formats[fmt.code] = std::move(fmt);
}
}

void parse_debug_info(const llvm::DataExtractor &e,
const llvm::DataExtractor &debug_abbrev,
llvm::StringRef debug_str,
llvm::StringRef debug_line_str,
llvm::StringRef debug_ranges) {
// Offset into the section
llvm_offset_t off = 0;
Expand All @@ -1053,6 +1061,11 @@ class DebugSections {
} else {
dwarf_64 = false;
}
// clang-format off
const auto parse_offset = dwarf_64 ?
[](const llvm::DataExtractor &e, llvm_offset_t *off) -> uint64_t { return e.getU64(off); } :
[](const llvm::DataExtractor &e, llvm_offset_t *off) -> uint64_t { return e.getU32(off); };
// clang-format on

if (!unit_length) {
// A zero-length compilation unit indicates the end of
Expand All @@ -1063,16 +1076,35 @@ class DebugSections {
uint64_t start_of_unit = off;

uint16_t dwarf_version = e.getU16(&off);
// DWARF v4 and lower is well-tested; DWARF v5 is very lightly
// tested and is almost certainly incomplete.
internal_assert(dwarf_version <= 5); // We haven't tested on anything larger

uint64_t debug_abbrev_offset = 0;
if (dwarf_64) {
debug_abbrev_offset = e.getU64(&off);
uint8_t address_size = 0;
if (dwarf_version == 5) {
constexpr uint8_t DW_UT_compile = 0x01;
// constexpr uint8_t DW_UT_type = 0x02;
// constexpr uint8_t DW_UT_partial = 0x03;
constexpr uint8_t DW_UT_skeleton = 0x04;
// constexpr uint8_t DW_UT_split_compile = 0x05;
// constexpr uint8_t DW_UT_split_type = 0x06;
const uint8_t unit_type = e.getU8(&off);
internal_assert(unit_type == DW_UT_compile || unit_type == DW_UT_skeleton) << unit_type;

address_size = e.getU8(&off);
debug_abbrev_offset = parse_offset(e, &off);

if (unit_type == DW_UT_skeleton) {
(void)e.getU64(&off);
}
} else {
debug_abbrev_offset = e.getU32(&off);
debug_abbrev_offset = parse_offset(e, &off);
address_size = e.getU8(&off);
}
parse_debug_abbrev(debug_abbrev, debug_abbrev_offset);

uint8_t address_size = e.getU8(&off);
internal_assert(address_size == sizeof(uintptr_t));

vector<pair<FunctionInfo, int>> func_stack;
vector<pair<TypeInfo, int>> type_stack;
Expand Down Expand Up @@ -1147,9 +1179,16 @@ class DebugSections {
continue;
}

internal_assert(abbrev_code <= entry_formats.size());
const EntryFormat &fmt = entry_formats[abbrev_code - 1];
internal_assert(fmt.code == abbrev_code);
auto it = entry_formats.find(abbrev_code);
if (it == entry_formats.end()) {
// Either the DWARF is malformed or we are parsing it incorrectly.
// (This has only been reported when compiling with TSAN enabled,
// so either is quite possible.)
debug(2) << "Unspecified abbrev_code, ignoring introspection\n";
working = false;
return;
}
const EntryFormat &fmt = it->second;

LocalVariable var;
GlobalVariable gvar;
Expand Down Expand Up @@ -1274,12 +1313,7 @@ class DebugSections {
}
case 14: // strp (offset into debug_str section. 4 bytes in dwarf 32, 8 in dwarf 64)
{
uint64_t offset;
if (dwarf_64) {
offset = e.getU64(&off);
} else {
offset = e.getU32(&off);
}
uint64_t offset = parse_offset(e, &off);
val = 0;
payload = (const uint8_t *)(debug_str.data() + offset);
break;
Expand Down Expand Up @@ -1331,11 +1365,7 @@ class DebugSections {
}
case 23: // sec_offset
{
if (dwarf_64) {
val = e.getU64(&off);
} else {
val = e.getU32(&off);
}
val = parse_offset(e, &off);
break;
}
case 24: // exprloc
Expand All @@ -1353,14 +1383,21 @@ class DebugSections {
// Just the existence of this field is information apparently? There's no data.
break;
}
case 31: // line_strp (offset into debug_line_str section. 4 bytes in dwarf 32, 8 in dwarf 64)
{
uint64_t offset = parse_offset(e, &off);
val = 0;
payload = (const uint8_t *)(debug_line_str.data() + offset);
break;
}
case 32: // ref_sig8
{
// 64-bit type signature for a reference in its own type unit
val = e.getU64(&off);
break;
}
default:
internal_error << "Unknown form";
internal_error << "Unknown form " << fmt.fields[i].form;
break;
}

Expand Down Expand Up @@ -1861,7 +1898,7 @@ class DebugSections {
if (!f.pc_begin ||
!f.pc_end ||
f.name.empty()) {
//debug(5) << "Dropping " << f.name << "\n";
// debug(5) << "Dropping " << f.name << "\n";
continue;
}

Expand All @@ -1870,7 +1907,7 @@ class DebugSections {
if (!v.name.empty() && v.type && v.stack_offset != no_location) {
vars.push_back(v);
} else {
//debug(5) << "Dropping " << v.name << "\n";
// debug(5) << "Dropping " << v.name << "\n";
}
}
f.variables.clear();
Expand Down