[ltt-dev] [PATCH 0/3] Support for user space rcu for ARM < v7

[ltt-dev] [PATCH 0/3] Support for user space rcu for ARM < v7

[Jason Wessel]

This patch makes the ARM support in user space rcu a bit more generic
by renaming the headers and adding a test case for the dmb
instruction.  On a arch that does not have dmb the generic fallback to
the compiler barrier appears to work fine.

This patch set was tested on ARMv5, ARMv6 and ARMv7.

Comments are welcome.

Thanks,
Jason.

--
The following changes since commit 34cfb3e3e6e8f876e1fbe091d715c6893b907ed7:
  Mathieu Desnoyers (1):
        URCU list: remove leftover namespace clash (list_t type removed)

Jason Wessel (3):
      Make armv7l headers generic for the arm architecture
      Change the arm headers to remove all the references to v7
      Add a test for the dmb instruction on ARM

 configure.ac                                       |   22 +++++++++++++++++++-
 urcu/{arch_armv7l.h => arch_arm.h}                 |   10 +++++---
 urcu/{uatomic_arch_armv7l.h => uatomic_arch_arm.h} |    8 +++---
 3 files changed, 31 insertions(+), 9 deletions(-)
 rename urcu/{arch_armv7l.h => arch_arm.h} (87%)
 rename urcu/{uatomic_arch_armv7l.h => uatomic_arch_arm.h} (88%)

[ltt-dev] [PATCH 1/3] Make armv7l headers generic for the arm architecture

[Jason Wessel]

This commit simply moves the files named *armv7l* to *arm*

Signed-off-by: Jason Wessel <jason.wessel at windriver.com>
---
 configure.ac               |    2 +-
 urcu/arch_arm.h            |   56 ++++++++++++++++++++++++++++++++++++++++++++
 urcu/arch_armv7l.h         |   56 --------------------------------------------
 urcu/uatomic_arch_arm.h    |   50 +++++++++++++++++++++++++++++++++++++++
 urcu/uatomic_arch_armv7l.h |   50 ---------------------------------------
 5 files changed, 107 insertions(+), 107 deletions(-)
 create mode 100644 urcu/arch_arm.h
 delete mode 100644 urcu/arch_armv7l.h
 create mode 100644 urcu/uatomic_arch_arm.h
 delete mode 100644 urcu/uatomic_arch_armv7l.h

diff --git a/configure.ac b/configure.ac
index 02780e7..69ce396 100644
--- a/configure.ac
+++ b/configure.ac
@@ -52,7 +52,7 @@ case $host_cpu in
 	sparc64) ARCHTYPE="sparc64" ;;
 	alpha*) ARCHTYPE="alpha" ;;
 	ia64) ARCHTYPE="gcc" ;;
-	armv7l) ARCHTYPE="armv7l" ;;
+	arm*) ARCHTYPE="arm" ;;
 	*) ARCHTYPE="unknown";;
 esac
 
diff --git a/urcu/arch_arm.h b/urcu/arch_arm.h
new file mode 100644
index 0000000..125066b
--- /dev/null
+++ b/urcu/arch_arm.h
@@ -0,0 +1,56 @@
+#ifndef _URCU_ARCH_ARMV7L_H
+#define _URCU_ARCH_ARMV7L_H
+
+/*
+ * arch_armv7l.h: trivial definitions for the ARMv7 architecture.
+ *
+ * Copyright (c) 2010 Paul E. McKenney, IBM Corporation.
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <urcu/compiler.h>
+#include <urcu/config.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif 
+
+#define cmm_mb()    asm volatile("dmb":::"memory")
+
+#include <stdlib.h>
+#include <sys/time.h>
+
+typedef unsigned long long cycles_t;
+
+static inline cycles_t caa_get_cycles (void)
+{
+	cycles_t thetime;
+	struct timeval tv;
+
+	if (gettimeofday(&tv, NULL) != 0)
+		return 0;
+	thetime = ((cycles_t)tv.tv_sec) * 1000000ULL + ((cycles_t)tv.tv_usec);
+	return (cycles_t)thetime;
+}
+
+#ifdef __cplusplus 
+}
+#endif
+
+#include <urcu/arch_generic.h>
+
+#endif /* _URCU_ARCH_ARMV7L_H */
diff --git a/urcu/arch_armv7l.h b/urcu/arch_armv7l.h
deleted file mode 100644
index 125066b..0000000
--- a/urcu/arch_armv7l.h
+++ /dev/null
@@ -1,56 +0,0 @@
-#ifndef _URCU_ARCH_ARMV7L_H
-#define _URCU_ARCH_ARMV7L_H
-
-/*
- * arch_armv7l.h: trivial definitions for the ARMv7 architecture.
- *
- * Copyright (c) 2010 Paul E. McKenney, IBM Corporation.
- * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library 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
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include <urcu/compiler.h>
-#include <urcu/config.h>
-
-#ifdef __cplusplus
-extern "C" {
-#endif 
-
-#define cmm_mb()    asm volatile("dmb":::"memory")
-
-#include <stdlib.h>
-#include <sys/time.h>
-
-typedef unsigned long long cycles_t;
-
-static inline cycles_t caa_get_cycles (void)
-{
-	cycles_t thetime;
-	struct timeval tv;
-
-	if (gettimeofday(&tv, NULL) != 0)
-		return 0;
-	thetime = ((cycles_t)tv.tv_sec) * 1000000ULL + ((cycles_t)tv.tv_usec);
-	return (cycles_t)thetime;
-}
-
-#ifdef __cplusplus 
-}
-#endif
-
-#include <urcu/arch_generic.h>
-
-#endif /* _URCU_ARCH_ARMV7L_H */
diff --git a/urcu/uatomic_arch_arm.h b/urcu/uatomic_arch_arm.h
new file mode 100644
index 0000000..b68c818
--- /dev/null
+++ b/urcu/uatomic_arch_arm.h
@@ -0,0 +1,50 @@
+#ifndef _URCU_ARCH_UATOMIC_ARMV7L_H
+#define _URCU_ARCH_UATOMIC_ARMV7L_H
+
+/* 
+ * Atomics for ARMv7.  This approach is usable on kernels back to 2.6.15.
+ *
+ * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
+ * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
+ * Copyright (c) 1999-2004 Hewlett-Packard Development Company, L.P.
+ * Copyright (c) 2009      Mathieu Desnoyers
+ * Copyright (c) 2010      Paul E. McKenney, IBM Corporation
+ *			   (Adapted from uatomic_arch_ppc.h)
+ *
+ * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+ * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
+ *
+ * Permission is hereby granted to use or copy this program
+ * for any purpose,  provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ *
+ * Code inspired from libuatomic_ops-1.2, inherited in part from the
+ * Boehm-Demers-Weiser conservative garbage collector.
+ */
+
+#include <urcu/compiler.h>
+#include <urcu/system.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif 
+
+/* xchg */
+#define uatomic_xchg(addr, v) __sync_lock_test_and_set(addr, v)
+
+/* cmpxchg */
+#define uatomic_cmpxchg(addr, old, _new) \
+	__sync_val_compare_and_swap(addr, old, _new)
+
+/* uatomic_add_return */
+#define uatomic_add_return(addr, v) __sync_add_and_fetch(addr, v)
+
+#ifdef __cplusplus 
+}
+#endif
+
+#include <urcu/uatomic_generic.h>
+
+#endif /* _URCU_ARCH_UATOMIC_ARMV7L_H */
diff --git a/urcu/uatomic_arch_armv7l.h b/urcu/uatomic_arch_armv7l.h
deleted file mode 100644
index b68c818..0000000
--- a/urcu/uatomic_arch_armv7l.h
+++ /dev/null
@@ -1,50 +0,0 @@
-#ifndef _URCU_ARCH_UATOMIC_ARMV7L_H
-#define _URCU_ARCH_UATOMIC_ARMV7L_H
-
-/* 
- * Atomics for ARMv7.  This approach is usable on kernels back to 2.6.15.
- *
- * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
- * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
- * Copyright (c) 1999-2004 Hewlett-Packard Development Company, L.P.
- * Copyright (c) 2009      Mathieu Desnoyers
- * Copyright (c) 2010      Paul E. McKenney, IBM Corporation
- *			   (Adapted from uatomic_arch_ppc.h)
- *
- * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
- * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
- *
- * Permission is hereby granted to use or copy this program
- * for any purpose,  provided the above notices are retained on all copies.
- * Permission to modify the code and to distribute modified code is granted,
- * provided the above notices are retained, and a notice that the code was
- * modified is included with the above copyright notice.
- *
- * Code inspired from libuatomic_ops-1.2, inherited in part from the
- * Boehm-Demers-Weiser conservative garbage collector.
- */
-
-#include <urcu/compiler.h>
-#include <urcu/system.h>
-
-#ifdef __cplusplus
-extern "C" {
-#endif 
-
-/* xchg */
-#define uatomic_xchg(addr, v) __sync_lock_test_and_set(addr, v)
-
-/* cmpxchg */
-#define uatomic_cmpxchg(addr, old, _new) \
-	__sync_val_compare_and_swap(addr, old, _new)
-
-/* uatomic_add_return */
-#define uatomic_add_return(addr, v) __sync_add_and_fetch(addr, v)
-
-#ifdef __cplusplus 
-}
-#endif
-
-#include <urcu/uatomic_generic.h>
-
-#endif /* _URCU_ARCH_UATOMIC_ARMV7L_H */
-- 
1.7.0

[ltt-dev] [PATCH 2/3] Change the arm headers to remove all the references to v7

[Jason Wessel]

Signed-off-by: Jason Wessel <jason.wessel at windriver.com>
---
 urcu/arch_arm.h         |    8 ++++----
 urcu/uatomic_arch_arm.h |    8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/urcu/arch_arm.h b/urcu/arch_arm.h
index 125066b..e25457d 100644
--- a/urcu/arch_arm.h
+++ b/urcu/arch_arm.h
@@ -1,8 +1,8 @@
-#ifndef _URCU_ARCH_ARMV7L_H
-#define _URCU_ARCH_ARMV7L_H
+#ifndef _URCU_ARCH_ARM_H
+#define _URCU_ARCH_ARM_H
 
 /*
- * arch_armv7l.h: trivial definitions for the ARMv7 architecture.
+ * arch_arm.h: trivial definitions for the ARM architecture.
  *
  * Copyright (c) 2010 Paul E. McKenney, IBM Corporation.
  * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
@@ -53,4 +53,4 @@ static inline cycles_t caa_get_cycles (void)
 
 #include <urcu/arch_generic.h>
 
-#endif /* _URCU_ARCH_ARMV7L_H */
+#endif /* _URCU_ARCH_ARM_H */
diff --git a/urcu/uatomic_arch_arm.h b/urcu/uatomic_arch_arm.h
index b68c818..bcd21d2 100644
--- a/urcu/uatomic_arch_arm.h
+++ b/urcu/uatomic_arch_arm.h
@@ -1,8 +1,8 @@
-#ifndef _URCU_ARCH_UATOMIC_ARMV7L_H
-#define _URCU_ARCH_UATOMIC_ARMV7L_H
+#ifndef _URCU_ARCH_UATOMIC_ARM_H
+#define _URCU_ARCH_UATOMIC_ARM_H
 
 /* 
- * Atomics for ARMv7.  This approach is usable on kernels back to 2.6.15.
+ * Atomics for ARM.  This approach is usable on kernels back to 2.6.15.
  *
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -47,4 +47,4 @@ extern "C" {
 
 #include <urcu/uatomic_generic.h>
 
-#endif /* _URCU_ARCH_UATOMIC_ARMV7L_H */
+#endif /* _URCU_ARCH_UATOMIC_ARM_H */
-- 
1.7.0

[ltt-dev] [PATCH 3/3] Add a test for the dmb instruction on ARM

[Jason Wessel]

The dmb instruction is used to implement a memory barrier on modern
ARM hardware.  The older generations of processors which are included
in single processor systems can get by on the generic implementation
of the cmm_mb().  This will allow the user space rcu to work on many
other ARM systems.

Signed-off-by: Jason Wessel <jason.wessel at windriver.com>
---
 configure.ac    |   20 ++++++++++++++++++++
 urcu/arch_arm.h |    2 ++
 2 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/configure.ac b/configure.ac
index 69ce396..3e1b501 100644
--- a/configure.ac
+++ b/configure.ac
@@ -20,6 +20,7 @@ AH_TEMPLATE([CONFIG_RCU_HAVE_FENCE], [Defined when on a system that has memory f
 AH_TEMPLATE([CONFIG_RCU_HAVE_FUTEX], [Defined when on a system with futex support.])
 AH_TEMPLATE([CONFIG_RCU_COMPAT_ARCH], [Compatibility mode for i386 which lacks
 cmpxchg instruction.])
+AH_TEMPLATE([CONFIG_ARM_HAVE_DMB], [Use the dmb instruction is available for use on ARM.])
 
 # Checks for programs.
 AC_PROG_CC
@@ -56,6 +57,25 @@ case $host_cpu in
 	*) ARCHTYPE="unknown";;
 esac
 
+if test "x$ARCHTYPE" = "xarm" ; then
+AC_MSG_CHECKING([checking for dmb instruction])
+AC_TRY_COMPILE(
+[
+],
+[
+asm volatile("dmb":::"memory");
+],
+[
+	AC_MSG_RESULT([yes])
+	AC_DEFINE([CONFIG_ARM_HAVE_DMB], [1])
+]
+,
+[
+	AC_MSG_RESULT([no])
+]
+)
+fi
+
 UATOMICSRC=urcu/uatomic_arch_$ARCHTYPE.h
 ARCHSRC=urcu/arch_$ARCHTYPE.h
 if test "x$ARCHTYPE" != xx86 -a "x$ARCHTYPE" != xppc; then
diff --git a/urcu/arch_arm.h b/urcu/arch_arm.h
index e25457d..83cbb60 100644
--- a/urcu/arch_arm.h
+++ b/urcu/arch_arm.h
@@ -29,7 +29,9 @@
 extern "C" {
 #endif 
 
+#ifdef CONFIG_ARM_HAVE_DMB
 #define cmm_mb()    asm volatile("dmb":::"memory")
+#endif /* CONFIG_ARM_HAVE_DMB */
 
 #include <stdlib.h>
 #include <sys/time.h>
-- 
1.7.0

[ltt-dev] [PATCH 0/3] Support for user space rcu for ARM < v7

[Mathieu Desnoyers]

* Jason Wessel (jason.wessel at windriver.com) wrote:
> This patch makes the ARM support in user space rcu a bit more generic
> by renaming the headers and adding a test case for the dmb
> instruction.  On a arch that does not have dmb the generic fallback to
> the compiler barrier appears to work fine.
> 
> This patch set was tested on ARMv5, ARMv6 and ARMv7.

All merged, including your documentation patch. I create a patch to also perform
dmb when cmm_rmb/wmb are used.

Thanks,

Mathieu

> 
> Comments are welcome.
> 
> Thanks,
> Jason.
> 
> --
> The following changes since commit 34cfb3e3e6e8f876e1fbe091d715c6893b907ed7:
>   Mathieu Desnoyers (1):
>         URCU list: remove leftover namespace clash (list_t type removed)
> 
> Jason Wessel (3):
>       Make armv7l headers generic for the arm architecture
>       Change the arm headers to remove all the references to v7
>       Add a test for the dmb instruction on ARM
> 
>  configure.ac                                       |   22 +++++++++++++++++++-
>  urcu/{arch_armv7l.h => arch_arm.h}                 |   10 +++++---
>  urcu/{uatomic_arch_armv7l.h => uatomic_arch_arm.h} |    8 +++---
>  3 files changed, 31 insertions(+), 9 deletions(-)
>  rename urcu/{arch_armv7l.h => arch_arm.h} (87%)
>  rename urcu/{uatomic_arch_armv7l.h => uatomic_arch_arm.h} (88%)
> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

[ltt-dev] [PATCH 0/3] Support for user space rcu for ARM < v7

[Mathieu Desnoyers]

* Jason Wessel (jason.wessel at windriver.com) wrote:
> This patch makes the ARM support in user space rcu a bit more generic
> by renaming the headers and adding a test case for the dmb
> instruction.  On a arch that does not have dmb the generic fallback to
> the compiler barrier appears to work fine.
> 
> This patch set was tested on ARMv5, ARMv6 and ARMv7.
> 
> Comments are welcome.

I'm curious: are you planning to add support for the Thumb2 instruction set ?
With all the hardware you have access to, testing this would be pretty much
straightforward.

Thanks,

Mathieu

> 
> Thanks,
> Jason.
> 
> --
> The following changes since commit 34cfb3e3e6e8f876e1fbe091d715c6893b907ed7:
>   Mathieu Desnoyers (1):
>         URCU list: remove leftover namespace clash (list_t type removed)
> 
> Jason Wessel (3):
>       Make armv7l headers generic for the arm architecture
>       Change the arm headers to remove all the references to v7
>       Add a test for the dmb instruction on ARM
> 
>  configure.ac                                       |   22 +++++++++++++++++++-
>  urcu/{arch_armv7l.h => arch_arm.h}                 |   10 +++++---
>  urcu/{uatomic_arch_armv7l.h => uatomic_arch_arm.h} |    8 +++---
>  3 files changed, 31 insertions(+), 9 deletions(-)
>  rename urcu/{arch_armv7l.h => arch_arm.h} (87%)
>  rename urcu/{uatomic_arch_armv7l.h => uatomic_arch_arm.h} (88%)
> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com