Mac x86_64: Mach exception support

src/trusted/service_runtime/osx/mach_thread_map.h

+/*
+ * Copyright (c) 2013 The Native Client Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef NATIVE_CLIENT_SERVICE_RUNTIME_OSX_MACH_THREAD_MAP_H_
+#define NATIVE_CLIENT_SERVICE_RUNTIME_OSX_MACH_THREAD_MAP_H_ 1
+
+#if NACL_OSX
+
+#include <mach/mach.h>
+
+#include "native_client/src/include/nacl_base.h"
+#include "native_client/src/include/nacl_compiler_annotations.h"
+#include "native_client/src/shared/platform/nacl_check.h"
+#include "native_client/src/trusted/service_runtime/nacl_tls.h"
+
+EXTERN_C_BEGIN
+
+#if NACL_ARCH(NACL_BUILD_ARCH) != NACL_x86 || NACL_BUILD_SUBARCH != 32

[Mark Seaborn, 2013/02/14 23:55:02]

Probably better to say:
#if NACL_ARCH(NACL_BUILD_ARCH) == NACL_x86 && NACL_BUILD_SUBARCH = 64
since if we ever handled ARM here, we might use a combination of pc and r9 to
recover the thread identity.

+
+/*
+ * Retrieves the Native Client thread index for a given Mach thread, or
+ * NACL_TLS_INDEX_INVALID if the Mach thread is unknown to Native Client.
+ */
+size_t NaClGetThreadIndexForMachThread(mach_port_t mach_thread);
+
+/*
+ * Establishes a mapping from the currently executing Mach thread to the
+ * given Native Client thread index.
+ */
+void NaClSetCurrentMachThreadForThreadIndex(size_t nacl_thread_index);

[Mark Seaborn, 2013/02/14 23:55:02]

Elsewhere, thread indexes are all uint32_t

+
+/*
+ * Clears any existing mapping to any Mach thread for the given Native Client
+ * thread index. A thread's mapping must be cleared by itself, not by another
+ * thread.
+ */
+void NaClClearMachThreadForThreadIndex(size_t nacl_thread_index);
+
+#else
+
+static INLINE size_t NaClGetThreadIndexForMachThread(mach_port_t mach_thread) {
+  /*
+   * This could be implemented for 32-bit x86 by using thread_get_state to
+   * obtain the thread's state and returning %gs >> 3. It's left unimplemented
+   * because the only prospective call sites already have access to the thread
+   * state and thus %gs themselves, and directing them through this function
+   * would add system call overhead for a redundant thread_get_state.
+   */
+  UNREFERENCED_PARAMETER(mach_thread);
+  CHECK(0);

[Mark Seaborn, 2013/02/14 23:55:02]

I'd suggest omitting this function definition since it's not used on x86-32 and
doesn't work there.

+  /* NOTREACHED */
+  return NACL_TLS_INDEX_INVALID;
+}
+
+static INLINE void NaClSetCurrentMachThreadForThreadIndex(
+    size_t nacl_thread_index) {
+  /* No-op for 32-bit x86. */

[Mark Seaborn, 2013/02/14 23:55:02]

Nit: '32-bit x86' -> 'x86-32' (since that's the usual term in the NaCl
codebase).

+  UNREFERENCED_PARAMETER(nacl_thread_index);
+}
+
+static INLINE void NaClClearMachThreadForThreadIndex(size_t nacl_thread_index) {
+  /* No-op for 32-bit x86. */
+  UNREFERENCED_PARAMETER(nacl_thread_index);
+}
+
+#endif
+
+EXTERN_C_END
+
+#endif  /* NACL_OSX */
+
+#endif  /* NATIVE_CLIENT_SERVICE_RUNTIME_OSX_MACH_THREAD_MAP_H_ */