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[fuchsia] fix module names for executables and loadable modules

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On Fuchsia, executables and loadable modules don't have a name at build
time so we use "<_>" as module name to index their symbols on the crash
server. We need to use the same dummy value at run time.

Bug: fuchsia/DX-1193
Tested: `fx run-test crashpad_test`

Change-Id: Ie926a6d26cb52679ccfac767db098c9fbfd21dd8
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/1548230
Commit-Queue: Francois Rousseau <frousseau@google.com>
Reviewed-by: Scott Graham <scottmg@chromium.org>
This commit is contained in:
Francois Rousseau 2019-04-01 13:38:26 -07:00 committed by Commit Bot
parent 439f50fb11
commit b0373799ba
2 changed files with 46 additions and 20 deletions
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52
snapshot/fuchsia/process_reader_fuchsia.cc
View File

@ -130,19 +130,6 @@ void ProcessReaderFuchsia::InitializeModules() {
// retrieves (some of) the data into internal structures. It may be worth
// trying to refactor/upstream some of this into Fuchsia.
std::string app_name;
{
char name[ZX_MAX_NAME_LEN];
zx_status_t status =
process_->get_property(ZX_PROP_NAME, name, sizeof(name));
if (status != ZX_OK) {
LOG(ERROR) << "zx_object_get_property ZX_PROP_NAME";
return;
}
app_name = name;
}
// Starting from the ld.so's _dl_debug_addr, read the link_map structure and
// walk the list to fill out modules_.
@ -204,19 +191,44 @@ void ProcessReaderFuchsia::InitializeModules() {
LOG(ERROR) << "ReadCString name";
}
// The vDSO is libzircon.so, but it's not actually loaded normally, it's
// injected by the kernel, so doesn't have a normal name. When dump_syms is
// run on libzircon.so, it uses that file name, and in order for the crash
// server to match symbols both the debug id and the name of the binary have
// to match. So, map from "<vDSO>" to "libzircon.so" so that symbol
// resolution works correctly.
// Debug symbols are indexed by module name x build-id on the crash server.
// The module name in the indexed Breakpad files is set at build time. So
// Crashpad needs to use the same module name at run time for symbol
// resolution to work properly.
//
// TODO(fuchsia/DX-1234): once Crashpad switches to elf-search, the
// following overwrites won't be necessary as only shared libraries will
// have a soname at runtime, just like at build time.
//
// * For shared libraries, the soname is used as module name at build time,
// which is the dsoname here except for libzircon.so (because it is
// injected by the kernel, its load name is "<vDSO>" and Crashpad needs to
// replace it for symbol resolution to work properly).
if (dsoname == "<vDSO>") {
dsoname = "libzircon.so";
}
// * For executables and loadable modules, the dummy value "<_>" is used as
// module name at build time. This is because executable and loadable
// modules don't have a name on Fuchsia. So we need to use the same dummy
// value at build and run times.
// Most executables have an empty dsoname. Loadable modules (and some rare
// executables) have a non-empty dsoname starting with a specific prefix,
// which Crashpas can use to identify loadable modules and clear the
// dsoname for them.
static constexpr const char kLoadableModuleLoadNamePrefix[] = "<VMO#";
// Pre-C++ 20 std::basic_string::starts_with
if (dsoname.compare(0,
strlen(kLoadableModuleLoadNamePrefix),
kLoadableModuleLoadNamePrefix) == 0) {
dsoname = "";
}
Module module;
if (dsoname.empty()) {
module.name = app_name;
// This value must be kept in sync with what is used at build time to
// index symbols for executables and loadable modules.
// See fuchsia/DX-1193 for more details.
module.name = "<_>";
module.type = ModuleSnapshot::kModuleTypeExecutable;
} else {
module.name = dsoname;

14
snapshot/fuchsia/process_reader_fuchsia_test.cc
View File

@ -41,11 +41,25 @@ TEST(ProcessReaderFuchsia, SelfBasic) {
EXPECT_STREQ(kTestMemory, buffer);
const auto& modules = process_reader.Modules();
// The process should have at least one module, the executable, and then some
// shared libraries, no loadable modules.
EXPECT_GT(modules.size(), 0u);
size_t num_executables = 0u;
size_t num_shared_libraries = 0u;
for (const auto& module : modules) {
EXPECT_FALSE(module.name.empty());
EXPECT_NE(module.type, ModuleSnapshot::kModuleTypeUnknown);
if (module.type == ModuleSnapshot::kModuleTypeExecutable) {
EXPECT_EQ(module.name, "<_>");
num_executables++;
} else if (module.type == ModuleSnapshot::kModuleTypeSharedLibrary) {
EXPECT_NE(module.name, "<_>");
num_shared_libraries++;
}
}
EXPECT_EQ(num_executables, 1u);
EXPECT_EQ(num_shared_libraries, modules.size() - num_executables);
const auto& threads = process_reader.Threads();
EXPECT_GT(threads.size(), 0u);