[Qemu-devel] [PATCH v3 0/3] TLS abstraction layer for thread-local cpu_single_env on Linux

[Qemu-devel] [PATCH v3 0/3] TLS abstraction layer for thread-local cpu_single_env on Linux

[Peter Maydell]

These patches add enough of the TLS abstraction layer to allow us
to make cpu_single_env thread-local on Linux systems. This fixes
the regression described in bug 823902 for the 1.0 release; we
can add the Win32 and POSIX implementations later.

I haven't included Paolo's "Prepare Windows port for thread-local
cpu_single_env" patch -- it would be safe to do so but it isn't
necessary until we actually implement TLS for Win32.

Changes v1->v2:
 * fix Paolo's email address
 * split the darwin-user change out into a separate patch
 * drop the 'tls_' prefix from the cpu_single_env tls var name
Changes v2->v3:
 * minor rearrangement of copyright notice in comment
 * added a missing Signed-off-by
 * fixed the name of the multiple-include-guard #define

Paolo Bonzini (2):
  darwin-user/main.c: Drop unused cpu_single_env definition
  Make cpu_single_env thread-local

Peter Maydell (1):
  qemu-tls.h: Add abstraction layer for TLS variables

 cpu-all.h          |    4 +++-
 darwin-user/main.c |    2 --
 exec.c             |    2 +-
 qemu-tls.h         |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 56 insertions(+), 4 deletions(-)
 create mode 100644 qemu-tls.h

[Qemu-devel] [PATCH v3 1/3] qemu-tls.h: Add abstraction layer for TLS variables

[Peter Maydell]

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>
---
 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
-- 
1.7.1

[Qemu-devel] [PATCH v3 2/3] darwin-user/main.c: Drop unused cpu_single_env definition

[Peter Maydell]

From: Paolo Bonzini <pbonzini@redhat.com>

Drop the cpu_single_env definition as it is unused.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.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;
-- 
1.7.1

[Qemu-devel] [PATCH v3 3/3] Make cpu_single_env thread-local

[Peter Maydell]

From: Paolo Bonzini <pbonzini@redhat.com>

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>
---
 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 9dc4edb..18e26cb 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.  */
-- 
1.7.1

Re: [Qemu-devel] [PATCH v3 0/3] TLS abstraction layer for thread-local cpu_single_env on Linux

[Peter Maydell]

An early ping since I have no idea who counts as the submaintainer
for this patchset and it definitely needs to go in for 1.0...

thanks
-- PMM

On 28 October 2011 10:52, Peter Maydell <peter.maydell@linaro.org> wrote:
> These patches add enough of the TLS abstraction layer to allow us
> to make cpu_single_env thread-local on Linux systems. This fixes
> the regression described in bug 823902 for the 1.0 release; we
> can add the Win32 and POSIX implementations later.
>
> I haven't included Paolo's "Prepare Windows port for thread-local
> cpu_single_env" patch -- it would be safe to do so but it isn't
> necessary until we actually implement TLS for Win32.
>
> Changes v1->v2:
>  * fix Paolo's email address
>  * split the darwin-user change out into a separate patch
>  * drop the 'tls_' prefix from the cpu_single_env tls var name
> Changes v2->v3:
>  * minor rearrangement of copyright notice in comment
>  * added a missing Signed-off-by
>  * fixed the name of the multiple-include-guard #define
>
> Paolo Bonzini (2):
>  darwin-user/main.c: Drop unused cpu_single_env definition
>  Make cpu_single_env thread-local
>
> Peter Maydell (1):
>  qemu-tls.h: Add abstraction layer for TLS variables
>
>  cpu-all.h          |    4 +++-
>  darwin-user/main.c |    2 --
>  exec.c             |    2 +-
>  qemu-tls.h         |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 56 insertions(+), 4 deletions(-)
>  create mode 100644 qemu-tls.h

Re: [Qemu-devel] [PATCH v3 0/3] TLS abstraction layer for thread-local cpu_single_env on Linux

[Jan Kiszka]

On 2011-10-31 14:40, Peter Maydell wrote:
> An early ping since I have no idea who counts as the submaintainer
> for this patchset and it definitely needs to go in for 1.0...

I think it's rather a central system this touches. So it's likely a
super-maintainer thing.

Anyway, you have my ack on these patches as well.

Thanks,
Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

Re: [Qemu-devel] [PATCH v3 0/3] TLS abstraction layer for thread-local cpu_single_env on Linux

[Anthony Liguori]

On 10/31/2011 08:40 AM, Peter Maydell wrote:
> An early ping since I have no idea who counts as the submaintainer
> for this patchset and it definitely needs to go in for 1.0...

I'm in the process of testing them and will apply provided nothing breaks.

Regards,

Anthony Liguori

>
> thanks
> -- PMM
>
> On 28 October 2011 10:52, Peter Maydell<peter.maydell@linaro.org>  wrote:
>> These patches add enough of the TLS abstraction layer to allow us
>> to make cpu_single_env thread-local on Linux systems. This fixes
>> the regression described in bug 823902 for the 1.0 release; we
>> can add the Win32 and POSIX implementations later.
>>
>> I haven't included Paolo's "Prepare Windows port for thread-local
>> cpu_single_env" patch -- it would be safe to do so but it isn't
>> necessary until we actually implement TLS for Win32.
>>
>> Changes v1->v2:
>>   * fix Paolo's email address
>>   * split the darwin-user change out into a separate patch
>>   * drop the 'tls_' prefix from the cpu_single_env tls var name
>> Changes v2->v3:
>>   * minor rearrangement of copyright notice in comment
>>   * added a missing Signed-off-by
>>   * fixed the name of the multiple-include-guard #define
>>
>> Paolo Bonzini (2):
>>   darwin-user/main.c: Drop unused cpu_single_env definition
>>   Make cpu_single_env thread-local
>>
>> Peter Maydell (1):
>>   qemu-tls.h: Add abstraction layer for TLS variables
>>
>>   cpu-all.h          |    4 +++-
>>   darwin-user/main.c |    2 --
>>   exec.c             |    2 +-
>>   qemu-tls.h         |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   4 files changed, 56 insertions(+), 4 deletions(-)
>>   create mode 100644 qemu-tls.h
>
>

Re: [Qemu-devel] [PATCH v3 0/3] TLS abstraction layer for thread-local cpu_single_env on Linux

[Anthony Liguori]

On 10/28/2011 04:52 AM, Peter Maydell wrote:
> These patches add enough of the TLS abstraction layer to allow us
> to make cpu_single_env thread-local on Linux systems. This fixes
> the regression described in bug 823902 for the 1.0 release; we
> can add the Win32 and POSIX implementations later.
>
> I haven't included Paolo's "Prepare Windows port for thread-local
> cpu_single_env" patch -- it would be safe to do so but it isn't
> necessary until we actually implement TLS for Win32.

Applied all.  Thanks.

Regards,

Anthony Liguori

>
> Changes v1->v2:
>   * fix Paolo's email address
>   * split the darwin-user change out into a separate patch
>   * drop the 'tls_' prefix from the cpu_single_env tls var name
> Changes v2->v3:
>   * minor rearrangement of copyright notice in comment
>   * added a missing Signed-off-by
>   * fixed the name of the multiple-include-guard #define
>
> Paolo Bonzini (2):
>    darwin-user/main.c: Drop unused cpu_single_env definition
>    Make cpu_single_env thread-local
>
> Peter Maydell (1):
>    qemu-tls.h: Add abstraction layer for TLS variables
>
>   cpu-all.h          |    4 +++-
>   darwin-user/main.c |    2 --
>   exec.c             |    2 +-
>   qemu-tls.h         |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 56 insertions(+), 4 deletions(-)
>   create mode 100644 qemu-tls.h
>
>
>