* [Qemu-devel] [PATCH 2/2] enable TLS in build and activate test-tls in make check
2013-08-15 15:26 [Qemu-devel] [RFC PATCH 0/2] v2.1 RCU Implementation for QEMU Mike Day
2013-08-15 15:26 ` [Qemu-devel] [PATCH 1/2] fixed tests/Makefile to correctly link rcutorture Mike Day
@ 2013-08-15 15:26 ` Mike Day
1 sibling, 0 replies; 3+ messages in thread
From: Mike Day @ 2013-08-15 15:26 UTC (permalink / raw)
To: qemu-devel; +Cc: Mike Day, Paolo Bonzini
From: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Mike Day <ncmike@ncultra.org>
---
configure | 63 ++++++++++++++++++++++----
include/qemu/tls.h | 127 +++++++++++++++++++++++++++++++++++++++++++++--------
include/qom/cpu.h | 2 +-
tests/Makefile | 2 +-
tests/test-tls.c | 87 ++++++++++++++++++++++++++++++++++++
5 files changed, 252 insertions(+), 29 deletions(-)
create mode 100644 tests/test-tls.c
diff --git a/configure b/configure
index 18fa608..baf61c8 100755
--- a/configure
+++ b/configure
@@ -285,6 +285,7 @@ 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}"
@@ -1241,6 +1242,29 @@ if compile_prog "-Werror -fno-gcse" "" ; then
TRANSLATE_OPT_CFLAGS=-fno-gcse
fi
+##########################################
+# Using __thread is either faster than pthread_get/setspecific,
+# or (if using GCC's "emutls" feature) exactly the same. So
+# we always use it if available.
+
+cat > $TMPC << EOF
+__thread int x;
+
+int main(void)
+{
+ x = 42;
+ return x;
+}
+EOF
+if compile_prog "-Werror" "" ; then
+ tls=yes
+else
+ tls=no
+fi
+
+##########################################
+# Position Independent executables
+
if test "$static" = "yes" ; then
if test "$pie" = "yes" ; then
error_exit "static and pie are mutually incompatible"
@@ -1260,19 +1284,18 @@ if test "$pie" = ""; then
fi
if test "$pie" != "no" ; then
+ if test "$CONFIG_TLS" = yes; then
+ THREAD=__thread
+ else
+ THREAD=
+ fi
cat > $TMPC << EOF
-
-#ifdef __linux__
-# define THREAD __thread
-#else
-# define THREAD
-#endif
-
-static THREAD int tls_var;
+static $THREAD int tls_var;
int main(void) { return tls_var; }
EOF
+ unset THREAD
if compile_prog "-fPIE -DPIE" "-pie"; then
QEMU_CFLAGS="-fPIE -DPIE $QEMU_CFLAGS"
LDFLAGS="-pie $LDFLAGS"
@@ -3184,6 +3207,22 @@ if test "$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) { return 0; }
+EOF
+ compile_prog "" ""
+ if $nm $TMPE | grep _tls_used > /dev/null 2>&1; then
+ mingw32_tls_runtime=yes
+ fi
+fi
+
+##########################################
# check and set a backend for coroutine
# We prefer ucontext, but it's not always possible. The fallback
@@ -3677,6 +3716,9 @@ if test "$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" >> $config_host_mak
fi
@@ -3979,6 +4021,10 @@ if test "$cpuid_h" = "yes" ; then
echo "CONFIG_CPUID_H=y" >> $config_host_mak
fi
+if test "$tls" = "yes" ; then
+ echo "CONFIG_TLS=y" >> $config_host_mak
+fi
+
if test "$int128" = "yes" ; then
echo "CONFIG_INT128=y" >> $config_host_mak
fi
@@ -4107,6 +4153,7 @@ echo "OBJCC=$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" >> $config_host_mak
diff --git a/include/qemu/tls.h b/include/qemu/tls.h
index b92ea9d..c878aaa 100644
--- a/include/qemu/tls.h
+++ b/include/qemu/tls.h
@@ -1,7 +1,7 @@
/*
* Abstraction layer for defining and using TLS variables
*
- * Copyright (c) 2011 Red Hat, Inc
+ * Copyright (c) 2011, 2013 Red Hat, Inc
* Copyright (c) 2011 Linaro Limited
*
* Authors:
@@ -25,28 +25,117 @@
#ifndef QEMU_TLS_H
#define QEMU_TLS_H
-/* Per-thread variables. Note that we only have implementations
- * which are really thread-local on Linux; the dummy implementations
- * define plain global variables.
+#ifdef CONFIG_WIN32
+
+/* Do not use GCC's "emutls" path on Windows, it is slower.
+ *
+ * The initial contents of TLS variables are placed in the .tls section.
+ * The linker takes all section starting with ".tls$", 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.
*
- * This means that for the moment use should be restricted to
- * per-VCPU variables, which are OK because:
- * - the only -user mode supporting multiple VCPU threads is linux-user
- * - TCG system mode is single-threaded regarding VCPUs
- * - KVM system mode is multi-threaded but limited to Linux
+ * _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.
*
- * TODO: proper implementations via Win32 .tls sections and
- * POSIX pthread_getspecific.
+ * 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.
*/
-#ifdef __linux__
-#define DECLARE_TLS(type, x) extern DEFINE_TLS(type, x)
-#define DEFINE_TLS(type, x) __thread __typeof__(type) tls__##x
-#define tls_var(x) tls__##x
+
+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$QEMU"))); \
+ \
+static inline typeof(type) *tls_get_##x(void) \
+{ \
+ return tls_var((ULONG_PTR)&(tls_##x) - (ULONG_PTR)&_tls_start); \
+} \
+ \
+static inline typeof(type) *tls_alloc_##x(void) \
+{ \
+ typeof(type) *addr = get_##x(); \
+ memset((void *)addr, 0, sizeof(type)); \
+ return addr; \
+} \
+ \
+extern int glue(dummy_, __LINE__)
+
+#define DEFINE_TLS(type, x) \
+typeof(type) tls_##x __attribute__((section(".tls$QEMU")))
+
+#elif defined CONFIG_TLS
+#define DECLARE_TLS(type, x) \
+extern __thread typeof(type) x; \
+ \
+static inline typeof(type) *tls_get_##x(void) \
+{ \
+ return &x; \
+} \
+ \
+static inline typeof(type) *tls_alloc_##x(void) \
+{ \
+ return &x; \
+} \
+ \
+extern int glue(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 tls_init_##x(void); \
+ \
+static inline typeof(type) *tls_get_##x(void) \
+{ \
+ return pthread_getspecific(x.k); \
+} \
+ \
+static inline typeof(type) *tls_alloc_##x(void) \
+{ \
+ void *datum = g_malloc0(sizeof(type)); \
+ pthread_once(&x.o, tls_init_##x); \
+ pthread_setspecific(x.k, datum); \
+ return datum; \
+} \
+ \
+extern int glue(dummy_, __LINE__)
+
+#define DEFINE_TLS(type, x) \
+void tls_init_##x(void) { \
+ pthread_key_create(&x.k, g_free); \
+} \
+ \
+QEMUTLSValue x = { .o = PTHREAD_ONCE_INIT }
+
#else
-/* Dummy implementations which define plain global variables */
-#define DECLARE_TLS(type, x) extern DEFINE_TLS(type, x)
-#define DEFINE_TLS(type, x) __typeof__(type) tls__##x
-#define tls_var(x) tls__##x
+#error No TLS abstraction available on this platform
#endif
#endif
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 0d6e95c..5d0d40b 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -203,7 +203,7 @@ struct CPUState {
extern CPUState *first_cpu;
DECLARE_TLS(CPUState *, current_cpu);
-#define current_cpu tls_var(current_cpu)
+//#define current_cpu tls_var(current_cpu)
/**
* cpu_paging_enabled:
diff --git a/tests/Makefile b/tests/Makefile
index 4d68d28..d1defbb 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -47,7 +47,7 @@ gcov-files-test-mul64-y = util/host-utils.c
check-unit-y += tests/test-tls$(EXESUF)
# all code tested by test-tls is inside tls.h
gcov-files-test-tls-y =
-check-unit-y += tests/test-int128$(EXESUF)
+#check-unit-y += tests/test-int128$(EXESUF)
# all code tested by test-int128 is inside int128.h
gcov-files-test-int128-y =
check-unit-y += tests/rcutorture$(EXESUF)
diff --git a/tests/test-tls.c b/tests/test-tls.c
new file mode 100644
index 0000000..26a9ec7
--- /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 <pbonzini@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 = tls_alloc_cnt();
+ volatile long long **p_ret = arg;
+ long long exp = 0;
+
+ g_assert(tls_get_cnt() == p_cnt);
+ *p_ret = p_cnt;
+ g_assert(*p_cnt == 0);
+ while (atomic_mb_read(&stop) == 0) {
+ exp++;
+ (*p_cnt)++;
+ g_assert(*tls_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();
+}
--
1.8.3.1
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