Patchwork [1/2] exec: do not use qemu/tls.h

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Submitter Stefan Hajnoczi
Date July 1, 2013, 9:35 a.m.
Message ID <1372671341-19855-2-git-send-email-stefanha@redhat.com>
Download mbox | patch
Permalink /patch/256040/
State New
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Comments

Stefan Hajnoczi - July 1, 2013, 9:35 a.m.
From: Paolo Bonzini <pbonzini@redhat.com>

The next patch will change qemu/tls.h to support more platforms, but at
some performance cost.  Declare cpu_single_env directly instead of using
the tls.h abstractions.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 exec.c                 | 10 ++++++++--
 include/exec/cpu-all.h | 14 +++++++++++---
 include/qemu/tls.h     | 52 --------------------------------------------------
 3 files changed, 19 insertions(+), 57 deletions(-)
 delete mode 100644 include/qemu/tls.h
Peter Maydell - July 1, 2013, 9:51 a.m.
On 1 July 2013 10:35, Stefan Hajnoczi <stefanha@redhat.com> wrote:
> From: Paolo Bonzini <pbonzini@redhat.com>
>
> The next patch will change qemu/tls.h to support more platforms, but at
> some performance cost.  Declare cpu_single_env directly instead of using
> the tls.h abstractions.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  exec.c                 | 10 ++++++++--
>  include/exec/cpu-all.h | 14 +++++++++++---
>  include/qemu/tls.h     | 52 --------------------------------------------------
>  3 files changed, 19 insertions(+), 57 deletions(-)
>  delete mode 100644 include/qemu/tls.h
>
> diff --git a/exec.c b/exec.c
> index c49806c..02263db 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -70,9 +70,15 @@ static MemoryRegion io_mem_unassigned;
>  #endif
>
>  CPUArchState *first_cpu;
> +
>  /* current CPU in the current thread. It is only valid inside
> -   cpu_exec() */
> -DEFINE_TLS(CPUArchState *,cpu_single_env);
> + * cpu_exec().  See comment in include/exec/cpu-all.h.  */
> +#if defined CONFIG_KVM || (defined CONFIG_USER_ONLY && defined CONFIG_USE_NPTL)
> +__thread CPUArchState *cpu_single_env;
> +#else
> +CPUArchState *cpu_single_env;
> +#endif

This is still wrong, as per my review comments on the previous
version.

-- PMM
Paolo Bonzini - July 1, 2013, 10:15 a.m.
Il 01/07/2013 11:51, Peter Maydell ha scritto:
> On 1 July 2013 10:35, Stefan Hajnoczi <stefanha@redhat.com> wrote:
>> From: Paolo Bonzini <pbonzini@redhat.com>
>>
>> The next patch will change qemu/tls.h to support more platforms, but at
>> some performance cost.  Declare cpu_single_env directly instead of using
>> the tls.h abstractions.
>>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>>  exec.c                 | 10 ++++++++--
>>  include/exec/cpu-all.h | 14 +++++++++++---
>>  include/qemu/tls.h     | 52 --------------------------------------------------
>>  3 files changed, 19 insertions(+), 57 deletions(-)
>>  delete mode 100644 include/qemu/tls.h
>>
>> diff --git a/exec.c b/exec.c
>> index c49806c..02263db 100644
>> --- a/exec.c
>> +++ b/exec.c
>> @@ -70,9 +70,15 @@ static MemoryRegion io_mem_unassigned;
>>  #endif
>>
>>  CPUArchState *first_cpu;
>> +
>>  /* current CPU in the current thread. It is only valid inside
>> -   cpu_exec() */
>> -DEFINE_TLS(CPUArchState *,cpu_single_env);
>> + * cpu_exec().  See comment in include/exec/cpu-all.h.  */
>> +#if defined CONFIG_KVM || (defined CONFIG_USER_ONLY && defined CONFIG_USE_NPTL)
>> +__thread CPUArchState *cpu_single_env;
>> +#else
>> +CPUArchState *cpu_single_env;
>> +#endif
> 
> This is still wrong, as per my review comments on the previous
> version.

I'm replying there.

Paolo
Andreas Färber - July 1, 2013, 10:47 a.m.
Am 01.07.2013 11:35, schrieb Stefan Hajnoczi:
> From: Paolo Bonzini <pbonzini@redhat.com>
> 
> The next patch will change qemu/tls.h to support more platforms, but at
> some performance cost.  Declare cpu_single_env directly instead of using
> the tls.h abstractions.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  exec.c                 | 10 ++++++++--
>  include/exec/cpu-all.h | 14 +++++++++++---
>  include/qemu/tls.h     | 52 --------------------------------------------------
>  3 files changed, 19 insertions(+), 57 deletions(-)
>  delete mode 100644 include/qemu/tls.h
> 
> diff --git a/exec.c b/exec.c
> index c49806c..02263db 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -70,9 +70,15 @@ static MemoryRegion io_mem_unassigned;
>  #endif
>  
>  CPUArchState *first_cpu;
> +
>  /* current CPU in the current thread. It is only valid inside
> -   cpu_exec() */
> -DEFINE_TLS(CPUArchState *,cpu_single_env);
> + * cpu_exec().  See comment in include/exec/cpu-all.h.  */
> +#if defined CONFIG_KVM || (defined CONFIG_USER_ONLY && defined CONFIG_USE_NPTL)
> +__thread CPUArchState *cpu_single_env;
> +#else
> +CPUArchState *cpu_single_env;
> +#endif

As indicated elsewhere, this conflicts with my pending CPUState part 10
series, which moves, renames and changes type of cpu_single_env:
http://patchwork.ozlabs.org/patch/254825/

The latest version received no further feedback after finding a better
name than cpu_single_cpu (current_cpu), first_cpu/next_cpu is ack'ed and
so are the prereqs for current_cpu, so I will pull that in as soon as
potential conflicts with ppc and memory pulls are sorted out, since
pretty invasive and a milestone towards getting rid of CPUArchState.

I'd be happy to help with rebasing this afterwards when needed.

Regards,
Andreas

> +
>  /* 0 = Do not count executed instructions.
>     1 = Precise instruction counting.
>     2 = Adaptive rate instruction counting.  */
> diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
> index 35bdf85..7e8df70 100644
> --- a/include/exec/cpu-all.h
> +++ b/include/exec/cpu-all.h
> @@ -20,7 +20,6 @@
>  #define CPU_ALL_H
>  
>  #include "qemu-common.h"
> -#include "qemu/tls.h"
>  #include "exec/cpu-common.h"
>  #include "qemu/thread.h"
>  
> @@ -358,8 +357,17 @@ CPUArchState *cpu_copy(CPUArchState *env);
>  void QEMU_NORETURN cpu_abort(CPUArchState *env, const char *fmt, ...)
>      GCC_FMT_ATTR(2, 3);
>  extern CPUArchState *first_cpu;
> -DECLARE_TLS(CPUArchState *,cpu_single_env);
> -#define cpu_single_env tls_var(cpu_single_env)
> +
> +/* This is thread-local depending on __linux__ 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
> + */
> +#if defined CONFIG_KVM || (defined CONFIG_USER_ONLY && defined CONFIG_USE_NPTL)
> +extern __thread CPUArchState *cpu_single_env;
> +#else
> +extern CPUArchState *cpu_single_env;
> +#endif
>  
>  /* Flags for use in ENV->INTERRUPT_PENDING.
>  
> diff --git a/include/qemu/tls.h b/include/qemu/tls.h
> deleted file mode 100644
> index b92ea9d..0000000
> --- a/include/qemu/tls.h
> +++ /dev/null
> @@ -1,52 +0,0 @@
> -/*
> - * 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 tls_var(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 tls_var(x)           tls__##x
> -#endif
> -
> -#endif
>

Patch

diff --git a/exec.c b/exec.c
index c49806c..02263db 100644
--- a/exec.c
+++ b/exec.c
@@ -70,9 +70,15 @@  static MemoryRegion io_mem_unassigned;
 #endif
 
 CPUArchState *first_cpu;
+
 /* current CPU in the current thread. It is only valid inside
-   cpu_exec() */
-DEFINE_TLS(CPUArchState *,cpu_single_env);
+ * cpu_exec().  See comment in include/exec/cpu-all.h.  */
+#if defined CONFIG_KVM || (defined CONFIG_USER_ONLY && defined CONFIG_USE_NPTL)
+__thread CPUArchState *cpu_single_env;
+#else
+CPUArchState *cpu_single_env;
+#endif
+
 /* 0 = Do not count executed instructions.
    1 = Precise instruction counting.
    2 = Adaptive rate instruction counting.  */
diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
index 35bdf85..7e8df70 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -20,7 +20,6 @@ 
 #define CPU_ALL_H
 
 #include "qemu-common.h"
-#include "qemu/tls.h"
 #include "exec/cpu-common.h"
 #include "qemu/thread.h"
 
@@ -358,8 +357,17 @@  CPUArchState *cpu_copy(CPUArchState *env);
 void QEMU_NORETURN cpu_abort(CPUArchState *env, const char *fmt, ...)
     GCC_FMT_ATTR(2, 3);
 extern CPUArchState *first_cpu;
-DECLARE_TLS(CPUArchState *,cpu_single_env);
-#define cpu_single_env tls_var(cpu_single_env)
+
+/* This is thread-local depending on __linux__ 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
+ */
+#if defined CONFIG_KVM || (defined CONFIG_USER_ONLY && defined CONFIG_USE_NPTL)
+extern __thread CPUArchState *cpu_single_env;
+#else
+extern CPUArchState *cpu_single_env;
+#endif
 
 /* Flags for use in ENV->INTERRUPT_PENDING.
 
diff --git a/include/qemu/tls.h b/include/qemu/tls.h
deleted file mode 100644
index b92ea9d..0000000
--- a/include/qemu/tls.h
+++ /dev/null
@@ -1,52 +0,0 @@ 
-/*
- * 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 tls_var(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 tls_var(x)           tls__##x
-#endif
-
-#endif