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Adds a Flag to Perserve Address Offset in dump_syms
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By default, the .code section start address is normalized to zero,
and subsequently the address of all functions and lines are adjusted
accordingly. This change adds a command line flag that perserves the
original addresses. This is a requirement for those that may wish to use
the crash resolver, but do not have a minidump file to work with (most commonly in firmware).

TEST=make check
BUG=b:328511413

Change-Id: Id7c477196ffed7fd319029b28ed2607192249c6c
Reviewed-on: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/5519154
Reviewed-by: Rob Barnes <robbarnes@google.com>
Reviewed-by: Ivan Penkov <ivanpe@google.com>
Reviewed-by: Ivan Penkov <ivanpe@chromium.org>
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Sean Carpenter authored and Ivan Penkov committed May 8, 2024
1 parent f88a1aa commit 6fe410d
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Showing 7 changed files with 76 additions and 17 deletions.
2 changes: 1 addition & 1 deletion src/common/linux/dump_symbols.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1280,7 +1280,7 @@ bool WriteSymbolFile(const string& load_path,
&module))
return false;

bool result = module->Write(sym_stream, options.symbol_data);
bool result = module->Write(sym_stream, options.symbol_data, options.preserve_load_address);
delete module;
return result;
}
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7 changes: 5 additions & 2 deletions src/common/linux/dump_symbols.h
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Original file line number Diff line number Diff line change
Expand Up @@ -48,14 +48,17 @@ class Module;
struct DumpOptions {
DumpOptions(SymbolData symbol_data,
bool handle_inter_cu_refs,
bool enable_multiple_field)
bool enable_multiple_field,
bool preserve_load_address)
: symbol_data(symbol_data),
handle_inter_cu_refs(handle_inter_cu_refs),
enable_multiple_field(enable_multiple_field) {}
enable_multiple_field(enable_multiple_field),
preserve_load_address(preserve_load_address) {}

SymbolData symbol_data;
bool handle_inter_cu_refs;
bool enable_multiple_field;
bool preserve_load_address;
};

// Find all the debugging information in OBJ_FILE, an ELF executable
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6 changes: 3 additions & 3 deletions src/common/linux/dump_symbols_unittest.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -95,7 +95,7 @@ TYPED_TEST(DumpSymbols, Invalid) {
Elf32_Ehdr header;
memset(&header, 0, sizeof(header));
Module* module;
DumpOptions options(ALL_SYMBOL_DATA, true, false);
DumpOptions options(ALL_SYMBOL_DATA, true, false, false);
EXPECT_FALSE(ReadSymbolDataInternal(reinterpret_cast<uint8_t*>(&header),
"foo",
"Linux",
Expand Down Expand Up @@ -132,7 +132,7 @@ TYPED_TEST(DumpSymbols, SimplePublic) {
this->GetElfContents(elf);

Module* module;
DumpOptions options(ALL_SYMBOL_DATA, true, false);
DumpOptions options(ALL_SYMBOL_DATA, true, false, false);
EXPECT_TRUE(ReadSymbolDataInternal(this->elfdata,
"foo",
"Linux",
Expand Down Expand Up @@ -189,7 +189,7 @@ TYPED_TEST(DumpSymbols, SimpleBuildID) {
this->GetElfContents(elf);

Module* module;
DumpOptions options(ALL_SYMBOL_DATA, true, false);
DumpOptions options(ALL_SYMBOL_DATA, true, false, false);
EXPECT_TRUE(ReadSymbolDataInternal(this->elfdata,
"foo",
"Linux",
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23 changes: 15 additions & 8 deletions src/common/module.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -380,7 +380,7 @@ bool Module::AddressIsInModule(Address address) const {
return false;
}

bool Module::Write(std::ostream& stream, SymbolData symbol_data) {
bool Module::Write(std::ostream& stream, SymbolData symbol_data, bool preserve_load_address) {
stream << "MODULE " << os_ << " " << architecture_ << " "
<< id_ << " " << name_ << "\n";
if (!stream.good())
Expand All @@ -390,6 +390,13 @@ bool Module::Write(std::ostream& stream, SymbolData symbol_data) {
stream << "INFO CODE_ID " << code_id_ << "\n";
}

// load_address is subtracted from each line. If we use zero instead, we
// preserve the original addresses present in the ELF binary.
Address load_offset = load_address_;
if (preserve_load_address) {
load_offset = 0;
}

if (symbol_data & SYMBOLS_AND_FILES) {
// Get all referenced inline origins.
set<InlineOrigin*, InlineOriginCompare> inline_origins;
Expand All @@ -406,13 +413,13 @@ bool Module::Write(std::ostream& stream, SymbolData symbol_data) {
return ReportError();
}
}

// Write out inline origins.
for (InlineOrigin* origin : inline_origins) {
stream << "INLINE_ORIGIN " << origin->id << " " << origin->name << "\n";
if (!stream.good())
return ReportError();
}

// Write out functions and their inlines and lines.
for (FunctionSet::const_iterator func_it = functions_.begin();
func_it != functions_.end(); ++func_it) {
Expand All @@ -421,7 +428,7 @@ bool Module::Write(std::ostream& stream, SymbolData symbol_data) {
for (auto range_it = func->ranges.cbegin();
range_it != func->ranges.cend(); ++range_it) {
stream << "FUNC " << (func->is_multiple ? "m " : "") << hex
<< (range_it->address - load_address_) << " " << range_it->size
<< (range_it->address - load_offset) << " " << range_it->size
<< " " << func->parameter_size << " " << func->name << dec
<< "\n";

Expand All @@ -434,7 +441,7 @@ bool Module::Write(std::ostream& stream, SymbolData symbol_data) {
stream << in->inline_nest_level << " " << in->call_site_line << " "
<< in->getCallSiteFileID() << " " << in->origin->id << hex;
for (const Range& r : in->ranges)
stream << " " << (r.address - load_address_) << " " << r.size;
stream << " " << (r.address - load_offset) << " " << r.size;
stream << dec << "\n";
};
Module::Inline::InlineDFS(func->inlines, write_inline);
Expand All @@ -445,7 +452,7 @@ bool Module::Write(std::ostream& stream, SymbolData symbol_data) {
(line_it->address >= range_it->address) &&
(line_it->address < (range_it->address + range_it->size))) {
stream << hex
<< (line_it->address - load_address_) << " "
<< (line_it->address - load_offset) << " "
<< line_it->size << " "
<< dec
<< line_it->number << " "
Expand All @@ -464,7 +471,7 @@ bool Module::Write(std::ostream& stream, SymbolData symbol_data) {
extern_it != externs_.end(); ++extern_it) {
Extern* ext = extern_it->get();
stream << "PUBLIC " << (ext->is_multiple ? "m " : "") << hex
<< (ext->address - load_address_) << " 0 " << ext->name << dec
<< (ext->address - load_offset) << " 0 " << ext->name << dec
<< "\n";
}
}
Expand All @@ -475,7 +482,7 @@ bool Module::Write(std::ostream& stream, SymbolData symbol_data) {
frame_it != stack_frame_entries_.end(); ++frame_it) {
StackFrameEntry* entry = frame_it->get();
stream << "STACK CFI INIT " << hex
<< (entry->address - load_address_) << " "
<< (entry->address - load_offset) << " "
<< entry->size << " " << dec;
if (!stream.good()
|| !WriteRuleMap(entry->initial_rules, stream))
Expand All @@ -487,7 +494,7 @@ bool Module::Write(std::ostream& stream, SymbolData symbol_data) {
for (RuleChangeMap::const_iterator delta_it = entry->rule_changes.begin();
delta_it != entry->rule_changes.end(); ++delta_it) {
stream << "STACK CFI " << hex
<< (delta_it->first - load_address_) << " " << dec;
<< (delta_it->first - load_offset) << " " << dec;
if (!stream.good()
|| !WriteRuleMap(delta_it->second, stream))
return ReportError();
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5 changes: 3 additions & 2 deletions src/common/module.h
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Original file line number Diff line number Diff line change
Expand Up @@ -421,8 +421,9 @@ class Module {
// If symbol_data is CFI then:
// - all CFI records.
// Addresses in the output are all relative to the load address
// established by SetLoadAddress.
bool Write(std::ostream& stream, SymbolData symbol_data);
// established by SetLoadAddress, unless preserve_load_address
// is equal to true, in which case each address will remain unchanged.
bool Write(std::ostream& stream, SymbolData symbol_data, bool preserve_load_address = false);

// Place the name in the global set of strings. Return a StringView points to
// a string inside the pool.
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43 changes: 43 additions & 0 deletions src/common/module_unittest.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -175,6 +175,49 @@ TEST(Module, WriteRelativeLoadAddress) {
contents.c_str());
}

TEST(Module, WritePreserveLoadAddress) {
stringstream s;
Module m(MODULE_NAME, MODULE_OS, MODULE_ARCH, MODULE_ID);
// Set the load address to something. Doesn't matter what.
// The goal of this test is to demonstrate that the load
// address does not impact any of the generated addresses
// when the preserve_load_address option is equal to true.
m.SetLoadAddress(0x1337ULL);

Module::File* file = m.FindFile("filename-a.cc");
Module::Function* function = new Module::Function(
"do_stuff", 0x110ULL);
Module::Range range(0x110ULL, 0x210ULL);
function->ranges.push_back(range);
function->parameter_size = 0x50ULL;
Module::Line line1 = { 0x110ULL, 0x1ULL,
file, 20ULL };
function->lines.push_back(line1);
m.AddFunction(function);

// Some stack information.
auto entry = std::make_unique<Module::StackFrameEntry>();
entry->address = 0x200ULL;
entry->size = 0x55ULL;
entry->initial_rules[".cfa"] = "some call frame info";
entry->rule_changes[0x201ULL][".s0"] =
"some rules change call frame info";
m.AddStackFrameEntry(std::move(entry));

bool preserve_load_address = true;
m.Write(s, ALL_SYMBOL_DATA, preserve_load_address);
string contents = s.str();
EXPECT_STREQ("MODULE os-name architecture id-string name with spaces\n"
"FILE 0 filename-a.cc\n"
"FUNC 110 210 50 do_stuff\n"
"110 1 20 0\n"
"STACK CFI INIT 200 55"
" .cfa: some call frame info\n"
"STACK CFI 201"
" .s0: some rules change call frame info\n",
contents.c_str());
}

TEST(Module, WriteOmitUnusedFiles) {
Module m(MODULE_NAME, MODULE_OS, MODULE_ARCH, MODULE_ID);

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7 changes: 6 additions & 1 deletion src/tools/linux/dump_syms/dump_syms.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,8 @@ int usage(const char* self) {
google_breakpad::BaseName(self).c_str());
fprintf(stderr, "Options:\n");
fprintf(stderr, " -i: Output module header information only.\n");
fprintf(stderr, " -a Preserve the load address - Do not normalize "
"the load address to zero.\n");
fprintf(stderr, " -c Do not generate CFI section\n");
fprintf(stderr, " -d Generate INLINE/INLINE_ORIGIN records\n");
fprintf(stderr, " -r Do not handle inter-compilation "
Expand All @@ -69,6 +71,7 @@ int usage(const char* self) {
int main(int argc, char** argv) {
if (argc < 2)
return usage(argv[0]);
bool preserve_load_address = false;
bool header_only = false;
bool cfi = true;
bool handle_inlines = false;
Expand All @@ -82,6 +85,8 @@ int main(int argc, char** argv) {
argv[arg_index][0] == '-') {
if (strcmp("-i", argv[arg_index]) == 0) {
header_only = true;
} else if (strcmp("-a", argv[arg_index]) == 0) {
preserve_load_address = true;
} else if (strcmp("-c", argv[arg_index]) == 0) {
cfi = false;
} else if (strcmp("-d", argv[arg_index]) == 0) {
Expand Down Expand Up @@ -143,7 +148,7 @@ int main(int argc, char** argv) {
SymbolData symbol_data = (handle_inlines ? INLINES : NO_DATA) |
(cfi ? CFI : NO_DATA) | SYMBOLS_AND_FILES;
google_breakpad::DumpOptions options(symbol_data, handle_inter_cu_refs,
enable_multiple_field);
enable_multiple_field, preserve_load_address);
if (!WriteSymbolFile(binary, obj_name, obj_os, debug_dirs, options,
std::cout)) {
fprintf(saved_stderr, "Failed to write symbol file.\n");
Expand Down

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