win: Retrieve thread context for x64

Retrieve context and save to thread context. NtQueryInformationThread
is no longer required (right now?) because to retrieve the CONTEXT, the
thread needs to be Suspend/ResumeThread'd anyway, and the return value
of SuspendThread is the previous SuspendCount.

I haven't handle the x86 case yet -- that would ideally be via
Wow64GetThreadContext (I think) but unfortunately that's Vista+, so I'll
likely need to to a bit of fiddling to get that sorted out. (It's actually
likely going to be NtQueryInformationThread again, but one thing at a
time for now.)

R=cpu@chromium.org, rsesek@chromium.org
TBR=mark@chromium.org
BUG=crashpad:1

Review URL: https://codereview.chromium.org/1133203002

snapshot/win/process_reader_win.cc

@@ -64,22 +64,6 @@ NTSTATUS NtOpenThread(PHANDLE thread_handle,
                         static_cast<const void*>(client_id));
 }
 
-NTSTATUS NtQueryInformationThread(HANDLE thread_handle,
-                                  THREADINFOCLASS thread_information_class,
-                                  PVOID thread_information,
-                                  ULONG thread_information_length,
-                                  PULONG return_length) {
-  static decltype(::NtQueryInformationThread)* nt_query_information_thread =
-      reinterpret_cast<decltype(::NtQueryInformationThread)*>(GetProcAddress(
-          LoadLibrary(L"ntdll.dll"), "NtQueryInformationThread"));
-  DCHECK(nt_query_information_thread);
-  return nt_query_information_thread(thread_handle,
-                                     thread_information_class,
-                                     thread_information,
-                                     thread_information_length,
-                                     return_length);
-}
-
 // Copied from ntstatus.h because um/winnt.h conflicts with general inclusion of
 // ntstatus.h.
 #define STATUS_BUFFER_TOO_SMALL ((NTSTATUS)0xC0000023L)
@@ -153,63 +137,69 @@ process_types::SYSTEM_PROCESS_INFORMATION<Traits>* GetProcessInformation(
 }
 
 template <class Traits>
-uint32_t GetThreadSuspendCount(
+HANDLE OpenThread(const process_types::SYSTEM_EXTENDED_THREAD_INFORMATION<
-    const process_types::SYSTEM_EXTENDED_THREAD_INFORMATION<Traits>&
+    Traits>& thread_info) {
-        thread_info) {
+  HANDLE handle;
-  // Wait reason values are from KWAIT_REASON in wdm.h. We don't need all of
+  ACCESS_MASK query_access = THREAD_GET_CONTEXT | THREAD_SUSPEND_RESUME;
-  // them, so just declare the one we need.
-  const ULONG kWaitReasonSuspended = 5;
-
-  // Kernel mode enumerations for thread state come from
-  // http://www.nirsoft.net/kernel_struct/vista/KTHREAD_STATE.html and
-  // https://msdn.microsoft.com/en-us/library/system.diagnostics.threadstate(v=vs.110).aspx
-  const ULONG kThreadStateWaiting = 5;
-  const ULONG kThreadStateGateWait = 8;
-
-  bool suspended = (thread_info.ThreadState == kThreadStateWaiting ||
-                    thread_info.ThreadState == kThreadStateGateWait) &&
-                   thread_info.WaitReason == kWaitReasonSuspended;
-  if (!suspended)
-    return 0;
-
-  HANDLE thread_handle;
-  ACCESS_MASK query_access = THREAD_QUERY_LIMITED_INFORMATION;
   OBJECT_ATTRIBUTES object_attributes;
   InitializeObjectAttributes(&object_attributes, nullptr, 0, nullptr, nullptr);
   NTSTATUS status = crashpad::NtOpenThread(
-      &thread_handle, query_access, &object_attributes, &thread_info.ClientId);
+      &handle, query_access, &object_attributes, &thread_info.ClientId);
   if (!NT_SUCCESS(status)) {
-    LOG(WARNING) << "couldn't open thread to retrieve suspend count";
+    LOG(ERROR) << "NtOpenThread failed";
-    // Fall back to something semi-reasonable. We know we're suspended at this
+    return nullptr;
-    // point, so just return 1.
-    return 1;
   }
+  return handle;
+}
 
-  // Take ownership of this handle so we close on exit. NtClose and CloseHandle
+// It's necessary to suspend the thread to grab CONTEXT. SuspendThread has a
-  // are identical.
+// side-effect of returning the SuspendCount of the thread on success, so we
-  ScopedKernelHANDLE handle(thread_handle);
+// fill out these two pieces of semi-unrelated data in the same function.
+template <class Traits>
+void FillThreadContextAndSuspendCount(
+    const process_types::SYSTEM_EXTENDED_THREAD_INFORMATION<Traits>&
+        thread_info,
+    ProcessReaderWin::Thread* thread) {
 
-  // From ntddk.h. winternl.h defines THREADINFOCLASS, but only one value.
+  // Don't suspend the thread if it's this thread. This is really only for test
-  const int kThreadSuspendCount = 35;
+  // binaries, as we won't be walking ourselves, in general.
-  ULONG suspend_count;
+  bool is_current_thread = thread_info.ClientId.UniqueThread ==
-  status = crashpad::NtQueryInformationThread(
+                           reinterpret_cast<process_types::TEB<Traits>*>(
-      handle.get(),
+                               NtCurrentTeb())->ClientId.UniqueThread;
-      static_cast<THREADINFOCLASS>(kThreadSuspendCount),
+
-      &suspend_count,
+  ScopedKernelHANDLE thread_handle(OpenThread(thread_info));
-      sizeof(suspend_count),
+
-      nullptr);
+  // TODO(scottmg): Handle cross-bitness in this function.
-  if (!NT_SUCCESS(status)) {
+
-    LOG(WARNING) << "NtQueryInformationThread failed" << std::hex << status;
+  if (is_current_thread) {
-    return 1;
+    thread->suspend_count = 0;
+    RtlCaptureContext(&thread->context);
+  } else {
+    DWORD previous_suspend_count = SuspendThread(thread_handle.get());
+    if (previous_suspend_count == -1) {
+      PLOG(ERROR) << "SuspendThread failed";
+      return;
+    }
+    thread->suspend_count = previous_suspend_count;
+
+    memset(&thread->context, 0, sizeof(thread->context));
+    thread->context.ContextFlags = CONTEXT_ALL;
+    if (!GetThreadContext(thread_handle.get(), &thread->context)) {
+      PLOG(ERROR) << "GetThreadContext failed";
+      return;
+    }
+
+    if (!ResumeThread(thread_handle.get())) {
+      PLOG(ERROR) << "ResumeThread failed";
+    }
   }
-
-  return suspend_count;
 }
 
 }  // namespace
 
 ProcessReaderWin::Thread::Thread()
-    : id(0),
+    : context(),
+      id(0),
       teb(0),
       stack_region_address(0),
       stack_region_size(0),
@@ -250,7 +240,8 @@ bool ProcessReaderWin::ReadMemory(WinVMAddress at,
                          base::checked_cast<SIZE_T>(num_bytes),
                          &bytes_read) ||
       num_bytes != bytes_read) {
-    PLOG(ERROR) << "ReadMemory at " << at << " of " << num_bytes << " failed";
+    PLOG(ERROR) << "ReadMemory at 0x" << std::hex << at << std::dec << " of "
+                << num_bytes << " bytes failed";
     return false;
   }
   return true;
@@ -304,7 +295,8 @@ const std::vector<ProcessReaderWin::Thread>& ProcessReaderWin::Threads() {
         thread_info = process_information->Threads[i];
     Thread thread;
     thread.id = thread_info.ClientId.UniqueThread;
-    thread.suspend_count = GetThreadSuspendCount(thread_info);
+
+    FillThreadContextAndSuspendCount(thread_info, &thread);
 
     // TODO(scottmg): I believe we could reverse engineer the PriorityClass from
     // the Priority, BasePriority, and
@@ -323,8 +315,8 @@ const std::vector<ProcessReaderWin::Thread>& ProcessReaderWin::Threads() {
     // its stack fields.
     process_types::NT_TIB<SizeTraits> tib;
     if (ReadMemory(thread_info.TebBase, sizeof(tib), &tib)) {
-      thread.stack_region_address = tib.StackBase;
       // Note, "backwards" because of direction of stack growth.
+      thread.stack_region_address = tib.StackLimit;
       thread.stack_region_size = tib.StackBase - tib.StackLimit;
     }
     threads_.push_back(thread);

snapshot/win/process_reader_win.h

@@ -34,6 +34,7 @@ class ProcessReaderWin {
     Thread();
     ~Thread() {}
 
+    CONTEXT context;
     uint64_t id;
     WinVMAddress teb;
     WinVMAddress stack_region_address;

snapshot/win/process_reader_win_test.cc

@@ -43,6 +43,28 @@ TEST(ProcessReaderWin, SelfBasic) {
   EXPECT_STREQ(kTestMemory, buffer);
 }
 
+TEST(ProcessReaderWin, SelfOneThread) {
+  ProcessReaderWin process_reader;
+  ASSERT_TRUE(process_reader.Initialize(GetCurrentProcess()));
+
+  const std::vector<ProcessReaderWin::Thread>& threads =
+      process_reader.Threads();
+
+  // If other tests ran in this process previously, threads may have been
+  // created and may still be running. This check must look for at least one
+  // thread, not exactly one thread.
+  ASSERT_GE(threads.size(), 1u);
+
+  EXPECT_EQ(GetThreadId(GetCurrentThread()), threads[0].id);
+#if defined(ARCH_CPU_64_BITS)
+  EXPECT_NE(0, threads[0].context.Rip);
+#else
+  EXPECT_NE(0, threads[0].context.Eip);
+#endif
+
+  EXPECT_EQ(0, threads[0].suspend_count);
+}
+
 }  // namespace
 }  // namespace test
 }  // namespace crashpad

snapshot/win/thread_snapshot_win.cc

@@ -20,6 +20,55 @@
 namespace crashpad {
 namespace internal {
 
+namespace {
+
+void InitializeX64Context(const CONTEXT& context,
+                          CPUContextX86_64* out) {
+  out->rax = context.Rax;
+  out->rbx = context.Rbx;
+  out->rcx = context.Rcx;
+  out->rdx = context.Rdx;
+  out->rdi = context.Rdi;
+  out->rsi = context.Rsi;
+  out->rbp = context.Rbp;
+  out->rsp = context.Rsp;
+  out->r8 = context.R8;
+  out->r9 = context.R9;
+  out->r10 = context.R10;
+  out->r11 = context.R11;
+  out->r12 = context.R12;
+  out->r13 = context.R13;
+  out->r14 = context.R14;
+  out->r15 = context.R15;
+  out->rip = context.Rip;
+  out->rflags = context.EFlags;
+  out->cs = context.SegCs;
+  out->fs = context.SegFs;
+  out->gs = context.SegGs;
+
+  out->dr0 = context.Dr0;
+  out->dr1 = context.Dr1;
+  out->dr2 = context.Dr2;
+  out->dr3 = context.Dr3;
+  // DR4 and DR5 are obsolete synonyms for DR6 and DR7, see
+  // http://en.wikipedia.org/wiki/X86_debug_register.
+  out->dr4 = context.Dr6;
+  out->dr5 = context.Dr7;
+  out->dr6 = context.Dr6;
+  out->dr7 = context.Dr7;
+
+  static_assert(sizeof(out->fxsave) == sizeof(context.FltSave),
+                "types must be equivalent");
+  memcpy(&out->fxsave, &context.FltSave.ControlWord, sizeof(out->fxsave));
+}
+
+void InitializeX86Context(const CONTEXT& context,
+                          CPUContextX86* out) {
+  CHECK(false) << "TODO(scottmg) InitializeX86Context()";
+}
+
+}  // namespace
+
 ThreadSnapshotWin::ThreadSnapshotWin()
     : ThreadSnapshot(), context_(), stack_(), thread_(), initialized_() {
 }
@@ -36,13 +85,24 @@ bool ThreadSnapshotWin::Initialize(
   stack_.Initialize(
       process_reader, thread_.stack_region_address, thread_.stack_region_size);
 
+#if defined(ARCH_CPU_X86_FAMILY)
+  if (process_reader->Is64Bit()) {
+    context_.architecture = kCPUArchitectureX86_64;
+    context_.x86_64 = &context_union_.x86_64;
+    InitializeX64Context(process_reader_thread.context, context_.x86_64);
+  } else {
+    context_.architecture = kCPUArchitectureX86;
+    context_.x86 = &context_union_.x86;
+    InitializeX86Context(process_reader_thread.context, context_.x86);
+  }
+#endif
+
   INITIALIZATION_STATE_SET_VALID(initialized_);
   return true;
 }
 
 const CPUContext* ThreadSnapshotWin::Context() const {
   INITIALIZATION_STATE_DCHECK_VALID(initialized_);
-  LOG(ERROR) << "TODO(scottmg): CPUContext";
   return &context_;
 }
 

snapshot/win/thread_snapshot_win.h

@@ -60,6 +60,12 @@ class ThreadSnapshotWin final : public ThreadSnapshot {
   uint64_t ThreadSpecificDataAddress() const override;
 
  private:
+#if defined(ARCH_CPU_X86_FAMILY)
+  union {
+    CPUContextX86 x86;
+    CPUContextX86_64 x86_64;
+  } context_union_;
+#endif
   CPUContext context_;
   MemorySnapshotWin stack_;
   ProcessReaderWin::Thread thread_;

tools/generate_dump.cc

@@ -199,6 +199,7 @@ int GenerateDumpMain(int argc, char* argv[]) {
     MinidumpFileWriter minidump;
     minidump.InitializeFromSnapshot(&process_snapshot);
     if (!minidump.WriteEverything(&file_writer)) {
+      file_writer.Close();
       if (unlink(options.dump_path.c_str()) != 0) {
         PLOG(ERROR) << "unlink";
       }

util/win/process_structs.h

@@ -302,6 +302,15 @@ struct CLIENT_ID {
   typename Traits::Pointer UniqueThread;
 };
 
+// This is a partial definition of the TEB, as we do not currently use many
+// fields of it. See http://www.nirsoft.net/kernel_struct/vista/TEB.html.
+template <class Traits>
+struct TEB {
+  NT_TIB<Traits> NtTib;
+  typename Traits::Pointer EnvironmentPointer;
+  CLIENT_ID<Traits> ClientId;
+};
+
 // See https://msdn.microsoft.com/en-us/library/gg750724.aspx for the base
 // structure, and 
 // http://processhacker.sourceforge.net/doc/struct___s_y_s_t_e_m___e_x_t_e_n_d_e_d___t_h_r_e_a_d___i_n_f_o_r_m_a_t_i_o_n.html