From 754fd932bedacfd7de35cf74da6adca89ba28089 Mon Sep 17 00:00:00 2001
From: Peter Maydell <peter.maydell@linaro.org>
Date: Fri, 28 Oct 2011 10:52:40 +0100
Subject: [PATCH 1/3] qemu-tls.h: Add abstraction layer for TLS variables

Add an abstraction layer for defining and using thread-local
variables. For the moment this is implemented only for Linux,
which means they can only be used in restricted circumstances.
The abstraction layer allows us to add POSIX and Win32 support
later.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
 qemu-tls.h |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 52 insertions(+), 0 deletions(-)
 create mode 100644 qemu-tls.h

diff --git a/qemu-tls.h b/qemu-tls.h
new file mode 100644
index 0000000..5b70f10
--- /dev/null
+++ b/qemu-tls.h
@@ -0,0 +1,52 @@
+/*
+ * Abstraction layer for defining and using TLS variables
+ *
+ * Copyright (c) 2011 Red Hat, Inc
+ * Copyright (c) 2011 Linaro Limited
+ *
+ * Authors:
+ *  Paolo Bonzini <pbonzini@redhat.com>
+ *  Peter Maydell <peter.maydell@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
+
+/* Per-thread variables. Note that we only have implementations
+ * which are really thread-local on Linux; the dummy implementations
+ * define plain global variables.
+ *
+ * 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
+ *
+ * TODO: proper implementations via Win32 .tls sections and
+ * POSIX pthread_getspecific.
+ */
+#ifdef __linux__
+#define DECLARE_TLS(type, x) extern DEFINE_TLS(type, x)
+#define DEFINE_TLS(type, x)  __thread __typeof__(type) tls__##x
+#define get_tls(x)           tls__##x
+#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 get_tls(x)           tls__##x
+#endif
+
+#endif
-- 
1.7.3.1


From 8a5f7b03a0a711ec8e04aeebe339cdb8b876794b Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 28 Oct 2011 10:52:41 +0100
Subject: [PATCH 2/3] darwin-user/main.c: Drop unused cpu_single_env definition

Drop the cpu_single_env definition as it is unused.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
 darwin-user/main.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/darwin-user/main.c b/darwin-user/main.c
index 1a881a0..c0f14f8 100644
--- a/darwin-user/main.c
+++ b/darwin-user/main.c
@@ -729,8 +729,6 @@ static void usage(void)

 /* XXX: currently only used for async signals (see signal.c) */
 CPUState *global_env;
-/* used only if single thread */
-CPUState *cpu_single_env = NULL;

 /* used to free thread contexts */
 TaskState *first_task_state;
-- 
1.7.3.1


From b3c4bbe56dc707102d3abd969f51bb2aa9c6c53d Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 28 Oct 2011 10:52:42 +0100
Subject: [PATCH 3/3] Make cpu_single_env thread-local
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Make cpu_single_env thread-local. This fixes a regression
in handling of multi-threaded programs in linux-user mode
(bug 823902).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[Peter Maydell: rename tls_cpu_single_env to cpu_single_env]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
 cpu-all.h |    4 +++-
 exec.c    |    2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/cpu-all.h b/cpu-all.h
index 42a5fa0..5f47ab8 100644
--- a/cpu-all.h
+++ b/cpu-all.h
@@ -20,6 +20,7 @@
 #define CPU_ALL_H

 #include "qemu-common.h"
+#include "qemu-tls.h"
 #include "cpu-common.h"

 /* some important defines:
@@ -334,7 +335,8 @@ void cpu_dump_statistics(CPUState *env, FILE *f, fprintf_function cpu_fprintf,
 void QEMU_NORETURN cpu_abort(CPUState *env, const char *fmt, ...)
     GCC_FMT_ATTR(2, 3);
 extern CPUState *first_cpu;
-extern CPUState *cpu_single_env;
+DECLARE_TLS(CPUState *,cpu_single_env);
+#define cpu_single_env get_tls(cpu_single_env)

 /* Flags for use in ENV->INTERRUPT_PENDING.

diff --git a/exec.c b/exec.c
index 54ecbe7..6b92198 100644
--- a/exec.c
+++ b/exec.c
@@ -120,7 +120,7 @@ static MemoryRegion *system_io;
 CPUState *first_cpu;
 /* current CPU in the current thread. It is only valid inside
    cpu_exec() */
-CPUState *cpu_single_env;
+DEFINE_TLS(CPUState *,cpu_single_env);
 /* 0 = Do not count executed instructions.
    1 = Precise instruction counting.
    2 = Adaptive rate instruction counting.  */
-- 
1.7.3.1