From: Paolo Bonzini <pbonz...@redhat.com>
Fast TLS is not available on some platforms, but it is always nice to
use it. This wrapper implementation falls back to pthread_get/setspecific
on POSIX systems that lack __thread, but uses the dynamic linker's TLS
support on Linux and Windows.
The user shall call alloc_foo() in every thread that needs to access the
variable---exactly once and before any access. foo is the name of the
variable as passed to DECLARE_TLS and DEFINE_TLS. Then, get_foo() will
return the address of the variable. It is guaranteed to remain the same
across the lifetime of a thread, so you can cache it.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
configure | 21 +++++++
include/qemu/tls.h | 139 +++++++++++++++++++++++++++++++++++++++++++++++
tests/Makefile | 3 +
tests/test-tls.c | 87 +++++++++++++++++++++++++++++
util/qemu-thread-win32.c | 17 ++++++
5 files changed, 267 insertions(+)
create mode 100644 include/qemu/tls.h
create mode 100644 tests/test-tls.c
diff --git a/configure b/configure
index 1654413..c679386 100755
--- a/configure
+++ b/configure
@@ -284,6 +284,7 @@ fi
ar="${AR-${cross_prefix}ar}"
as="${AS-${cross_prefix}as}"
cpp="${CPP-$cc -E}"
+nm="${NM-${cross_prefix}nm}"
objcopy="${OBJCOPY-${cross_prefix}objcopy}"
ld="${LD-${cross_prefix}ld}"
libtool="${LIBTOOL-${cross_prefix}libtool}"
@@ -3157,6 +3158,22 @@ if test "$trace_backend" = "dtrace"; then
fi
##########################################
+# check for TLS runtime
+
+# Some versions of mingw include the "magic" definitions that make
+# TLS work, some don't. Check for it.
+
+if test "$mingw32" = yes; then
+ cat > $TMPC << EOF
+int main(void) {}
+EOF
+ compile_prog "" ""
+ if $nm $TMPE | grep _tls_used > /dev/null 2>&1; then
+ mingw32_tls_runtime=yes
+ fi
+fi
+
+##########################################
# check and set a backend for coroutine
# We prefer ucontext, but it's not always possible. The fallback
@@ -3615,6 +3632,9 @@ if test "$mingw32" = "yes" ; then
version_micro=0
echo
"CONFIG_FILEVERSION=$version_major,$version_minor,$version_subminor,$version_micro"
>> $config_host_mak
echo
"CONFIG_PRODUCTVERSION=$version_major,$version_minor,$version_subminor,$version_micro"
>> $config_host_mak
+ if test "$mingw32_tls_runtime" = yes; then
+ echo "CONFIG_MINGW32_TLS_RUNTIME=y" >> $config_host_mak
+ fi
else
echo "CONFIG_POSIX=y" >> $config_host_mak
fi
@@ -4040,6 +4060,7 @@ echo "OBJCC=$objcc" >> $config_host_mak
echo "AR=$ar" >> $config_host_mak
echo "AS=$as" >> $config_host_mak
echo "CPP=$cpp" >> $config_host_mak
+echo "NM=$nm" >> $config_host_mak
echo "OBJCOPY=$objcopy" >> $config_host_mak
echo "LD=$ld" >> $config_host_mak
echo "WINDRES=$windres" >> $config_host_mak
diff --git a/include/qemu/tls.h b/include/qemu/tls.h
new file mode 100644
index 0000000..7fd0632
--- /dev/null
+++ b/include/qemu/tls.h
@@ -0,0 +1,139 @@
+/*
+ * Abstraction layer for defining and using TLS variables
+ *
+ * Copyright (c) 2011, 2013 Red Hat, Inc
+ * Copyright (c) 2011 Linaro Limited
+ *
+ * Authors:
+ * Paolo Bonzini <pbonz...@redhat.com>
+ * Peter Maydell <peter.mayd...@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef QEMU_TLS_H
+#define QEMU_TLS_H
+
+#if defined __linux__
+#define DECLARE_TLS(type, x) \
+extern __thread typeof(type) x; \
+ \
+static inline typeof(type) *get_##x(void) \
+{ \
+ return &x; \
+} \
+ \
+static inline typeof(type) *alloc_##x(void) \
+{ \
+ return &x; \
+} \
+ \
+extern int dummy_##__LINE__
+
+#define DEFINE_TLS(type, x) \
+__thread typeof(type) x
+
+#elif defined CONFIG_POSIX
+typedef struct QEMUTLSValue {
+ pthread_key_t k;
+ pthread_once_t o;
+} QEMUTLSValue;
+
+#define DECLARE_TLS(type, x) \
+extern QEMUTLSValue x; \
+extern void init_##x(void); \
+ \
+static inline typeof(type) *get_##x(void) \
+{ \
+ return pthread_getspecific(x.k); \
+} \
+ \
+static inline typeof(type) *alloc_##x(void) \
+{ \
+ void *datum = g_malloc0(sizeof(type)); \
+ pthread_once(&x.o, init_##x); \
+ pthread_setspecific(x.k, datum); \
+ return datum; \
+} \
+ \
+extern int dummy_##__LINE__
+
+#define DEFINE_TLS(type, x) \
+void init_##x(void) { \
+ pthread_key_create(&x.k, g_free); \
+} \
+ \
+QEMUTLSValue x = { .o = PTHREAD_ONCE_INIT }
+
+#elif defined CONFIG_WIN32
+
+/* The initial contents of TLS variables are placed in the .tls section.
+ * The linker takes all section starting with ".tls$", sorts them and puts
+ * the contents in a single ".tls" section. qemu-thread-win32.c defines
+ * special symbols in .tls$000 and .tls$ZZZ that represent the beginning
+ * and end of TLS memory. The linker and run-time library then cooperate
+ * to copy memory between those symbols in the TLS area of new threads.
+ *
+ * _tls_index holds the number of our module. The executable should be
+ * zero, DLLs are numbered 1 and up. The loader fills it in for us.
+ *
+ * Thus, Teb->ThreadLocalStoragePointer[_tls_index] is the base of
+ * the TLS segment for this (thread, module) pair. Each segment has
+ * the same layout as this module's .tls segment and is initialized
+ * with the content of the .tls segment; 0 is the _tls_start variable.
+ * So, get_##x passes us the offset of the passed variable relative to
+ * _tls_start, and we return that same offset plus the base of segment.
+ */
+
+typedef struct _TEB {
+ NT_TIB NtTib;
+ void *EnvironmentPointer;
+ void *x[3];
+ char **ThreadLocalStoragePointer;
+} TEB, *PTEB;
+
+extern int _tls_index;
+extern int _tls_start;
+
+static inline void *tls_var(size_t offset)
+{
+ PTEB Teb = NtCurrentTeb();
+ return (char *)(Teb->ThreadLocalStoragePointer[_tls_index]) + offset;
+}
+
+#define DECLARE_TLS(type, x) \
+extern typeof(type) tls_##x __attribute__((section(".tls$QEMU"))); \
+ \
+static inline typeof(type) *get_##x(void) \
+{ \
+ return tls_var((ULONG_PTR)&(tls_##x) - (ULONG_PTR)&_tls_start); \
+} \
+ \
+static inline typeof(type) *alloc_##x(void) \
+{ \
+ typeof(type) *addr = get_##x(); \
+ memset((void *)addr, 0, sizeof(type)); \
+ return addr; \
+} \
+ \
+extern int dummy_##__LINE__
+
+#define DEFINE_TLS(type, x) \
+typeof(type) tls_##x __attribute__((section(".tls$QEMU")))
+
+#else
+#error No TLS abstraction available on this platform
+#endif
+
+#endif
diff --git a/tests/Makefile b/tests/Makefile
index c107489..1f5156a 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -42,6 +42,8 @@ check-unit-y += tests/test-xbzrle$(EXESUF)
gcov-files-test-xbzrle-y = xbzrle.c
check-unit-y += tests/test-cutils$(EXESUF)
gcov-files-test-cutils-y += util/cutils.c
+check-unit-y += tests/test-tls$(EXESUF)
+gcov-files-test-tls-y +=
check-unit-y += tests/test-mul64$(EXESUF)
gcov-files-test-mul64-y = util/host-utils.c
@@ -98,6 +100,7 @@ tests/test-hbitmap$(EXESUF): tests/test-hbitmap.o
libqemuutil.a libqemustub.a
tests/test-x86-cpuid$(EXESUF): tests/test-x86-cpuid.o
tests/test-xbzrle$(EXESUF): tests/test-xbzrle.o xbzrle.o page_cache.o
libqemuutil.a
tests/test-cutils$(EXESUF): tests/test-cutils.o util/cutils.o
+tests/test-tls$(EXESUF): tests/test-tls.o libqemuutil.a
tests/test-qapi-types.c tests/test-qapi-types.h :\
$(SRC_PATH)/qapi-schema-test.json $(SRC_PATH)/scripts/qapi-types.py
diff --git a/tests/test-tls.c b/tests/test-tls.c
new file mode 100644
index 0000000..54e981d
--- /dev/null
+++ b/tests/test-tls.c
@@ -0,0 +1,87 @@
+/*
+ * Unit-tests for TLS wrappers
+ *
+ * Copyright (C) 2013 Red Hat Inc.
+ *
+ * Authors:
+ * Paolo Bonzini <pbonz...@redhat.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <glib.h>
+#include <errno.h>
+#include <string.h>
+
+#include "qemu-common.h"
+#include "qemu/atomic.h"
+#include "qemu/thread.h"
+#include "qemu/tls.h"
+
+DECLARE_TLS(volatile long long, cnt);
+DEFINE_TLS(volatile long long, cnt);
+
+#define NUM_THREADS 10
+
+int stop;
+
+static void *test_thread(void *arg)
+{
+ volatile long long *p_cnt = alloc_cnt();
+ volatile long long **p_ret = arg;
+ long long exp = 0;
+
+ g_assert(get_cnt() == p_cnt);
+ *p_ret = p_cnt;
+ g_assert(*p_cnt == 0);
+ while (atomic_mb_read(&stop) == 0) {
+ exp++;
+ (*p_cnt)++;
+ g_assert(*get_cnt() == exp);
+ }
+
+ return NULL;
+}
+
+static void test_tls(void)
+{
+ volatile long long *addr[NUM_THREADS];
+ QemuThread t[NUM_THREADS];
+ int i;
+
+ for (i = 0; i < NUM_THREADS; i++) {
+ qemu_thread_create(&t[i], test_thread, &addr[i], QEMU_THREAD_JOINABLE);
+ }
+ g_usleep(1000000);
+ atomic_mb_set(&stop, 1);
+ for (i = 0; i < NUM_THREADS; i++) {
+ qemu_thread_join(&t[i]);
+ }
+ for (i = 1; i < NUM_THREADS; i++) {
+ g_assert(addr[i] != addr[i - 1]);
+ }
+}
+
+int main(int argc, char **argv)
+{
+ g_test_init(&argc, &argv, NULL);
+
+ g_test_add_func("/tls", test_tls);
+ return g_test_run();
+}
diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c
index 517878d..f75e404 100644
--- a/util/qemu-thread-win32.c
+++ b/util/qemu-thread-win32.c
@@ -16,6 +16,23 @@
#include <assert.h>
#include <limits.h>
+/* TLS support. Some versions of mingw32 provide it, others do not. */
+
+#ifndef CONFIG_MINGW32_TLS_RUNTIME
+int __attribute__((section(".tls$AAA"))) _tls_start = 0;
+int __attribute__((section(".tls$ZZZ"))) _tls_end = 0;
+int _tls_index = 0;
+
+const IMAGE_TLS_DIRECTORY _tls_used __attribute__((used, section(".rdata$T")))
= {
+ (ULONG)(ULONG_PTR) &_tls_start, /* start of tls data */
+ (ULONG)(ULONG_PTR) &_tls_end, /* end of tls data */
+ (ULONG)(ULONG_PTR) &_tls_index, /* address of tls_index */
+ (ULONG) 0, /* pointer to callbacks */
+ (ULONG) 0, /* size of tls zero fill */
+ (ULONG) 0 /* characteristics */
+};
+#endif
+
static void error_exit(int err, const char *msg)
{
char *pstr;
--
1.8.1.4
