RFC: CACAO PR157 ARM memory barrier patch

[Dr Andrew John Hughes]

On 14:59 Fri 11 Mar     , Xerxes Rånby wrote:
> Hi
> 
> The attached patch makes CACAO SMP safe on ARM by fixing
> CACAO PR157: ARM SMP Assertion thinlock failed.
> http://server.complang.tuwien.ac.at/cgi-bin/bugzilla/show_bug.cgi?id=157
> 
> Ok to push to IcedTea6 HEAD and 1.10 branch?
> 
> Cheers
> Xerxes

Has this been submitted to CACAO upstream?

> Index: icedtea6/Makefile.am
> ===================================================================
> --- icedtea6.orig/Makefile.am	2011-03-11 14:42:48.041904260 +0100
> +++ icedtea6/Makefile.am	2011-03-11 14:44:10.788407289 +0100
> @@ -352,6 +352,7 @@
>  	patches/cacao/arm-arch-defines.patch \
>  	patches/cacao/jsig.patch \
>  	patches/cacao/memory.patch \
> +	patches/cacao/arm-memory-barrier.patch \
>  	patches/cacao/ignore-unknown-options.patch
>  endif
>  
> Index: icedtea6/patches/cacao/arm-memory-barrier.patch
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ icedtea6/patches/cacao/arm-memory-barrier.patch	2011-03-11 14:42:15.401877441 +0100
> @@ -0,0 +1,45 @@
> +Index: cacao/cacao/src/vm/jit/arm/md-atomic.hpp
> +===================================================================
> +--- cacao.orig/cacao/src/vm/jit/arm/md-atomic.hpp	2011-03-04 22:44:20.000000000 +0100
> ++++ cacao/cacao/src/vm/jit/arm/md-atomic.hpp	2011-03-04 23:02:52.000000000 +0100
> +@@ -63,13 +63,21 @@
> + 	return Atomic::generic_compare_and_swap(p, oldval, newval);
> + }
> + 
> ++/**
> ++ * ARM Kernel helper for memory barrier.
> ++ * Using __asm __volatile ("":::"memory") does not work reliable on ARM
> ++ * and gcc __sync_synchronize(); implementation does not use the kernel
> ++ * helper for all gcc versions so it is unreliable to use as well.
> ++ */
> ++typedef void (__kernel_dmb_t) (void);
> ++#define __kernel_dmb (*(__kernel_dmb_t *) 0xffff0fa0)
> + 
> + /**
> +  * A memory barrier.
> +  */
> + inline void memory_barrier(void)
> + {
> +-	__asm__ __volatile__ ("" : : : "memory");
> ++	__kernel_dmb();
> + }
> + 
> + 
> +@@ -78,7 +86,7 @@
> +  */
> + inline void write_memory_barrier(void)
> + {
> +-	__asm__ __volatile__ ("" : : : "memory");
> ++	__kernel_dmb();
> + }
> + 
> + 
> +@@ -87,7 +95,7 @@
> +  */
> + inline void instruction_barrier(void)
> + {
> +-	__asm__ __volatile__ ("" : : : "memory");
> ++	__kernel_dmb();
> + }
> + 
> + }
> Index: icedtea6/ChangeLog
> ===================================================================
> --- icedtea6.orig/ChangeLog	2011-03-11 14:47:54.401413208 +0100
> +++ icedtea6/ChangeLog	2011-03-11 14:49:25.112411060 +0100
> @@ -1,3 +1,10 @@
> +2011-03-11  Xerxes Ranby  <xerxes at zafena.se>
> +
> +	CACAO PR157: ARM SMP Assertion thinlock failed.
> +	* NEWS: Updated.
> +	* Makefile.am: Add new CACAO patch.
> +	* patches/cacao/arm-memory-barrier.patch: New patch.
> +
>  2011-03-09  Pavel Tisnovsky  <ptisnovs at redhat.com>
>  
>  	* Makefile.am: Add new patch.
> Index: icedtea6/NEWS
> ===================================================================
> --- icedtea6.orig/NEWS	2011-03-11 14:44:25.312465536 +0100
> +++ icedtea6/NEWS	2011-03-11 14:47:49.732425447 +0100
> @@ -18,6 +18,7 @@
>      hotspot) with the jtreg_checks argument:
>      make check jtreg_checks="langtools hotspot".
>      If none is provided make check runs all testsuites.
> +  - CACAO PR157: ARM SMP Assertion thinlock failed.
>  
>  New in release 1.10 (2011-XX-XX):
>  


-- 
Andrew :)

Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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