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Re: [PATCH] powerpc: Revert to default atomic ops in elision code
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: libc-alpha at sourceware dot org
- Date: Thu, 13 Aug 2015 19:05:27 -0300
- Subject: Re: [PATCH] powerpc: Revert to default atomic ops in elision code
- Authentication-results: sourceware.org; auth=none
- References: <55CD0A41 dot 6000002 at linux dot vnet dot ibm dot com>
Good to hear it does not need to require different synchronization for TLE
implementation. Does all ISA 2.07 implementations (currently only POWER8
afaik) implement this?
On 13-08-2015 18:21, Paul E. Murphy wrote:
> Power ISA 2.07B section B.5.5 relaxed the barrier requirement around a
> TLE enabled lock. It is now identical to a traditional lock.
>
> 2015-08-07 Paul E. Murphy <murphyp@linux.vnet.ibm.com>
>
> * sysdeps/unix/sysv/linux/powerpc/elision-lock.c
> (__arch_compare_and_exchange_val_32_acq): Remove and use common
> definition. ISA 2.07B no longer requires full sync.
> ---
> sysdeps/unix/sysv/linux/powerpc/elision-lock.c | 21 ---------------------
> 1 files changed, 0 insertions(+), 21 deletions(-)
>
> diff --git a/sysdeps/unix/sysv/linux/powerpc/elision-lock.c b/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
> index 7f9bcc2..26d272e 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
> +++ b/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
> @@ -23,27 +23,6 @@
> #include <elision-conf.h>
> #include "htm.h"
>
> -/* PowerISA 2.0.7 Section B.5.5 defines isync to be insufficient as a
> - barrier in acquire mechanism for HTM operations, a strong 'sync' is
> - required. */
> -#undef __arch_compare_and_exchange_val_32_acq
> -#define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
> - ({ \
> - __typeof (*(mem)) __tmp; \
> - __typeof (mem) __memp = (mem); \
> - __asm __volatile ( \
> - "1: lwarx %0,0,%1" MUTEX_HINT_ACQ "\n" \
> - " cmpw %0,%2\n" \
> - " bne 2f\n" \
> - " stwcx. %3,0,%1\n" \
> - " bne- 1b\n" \
> - "2: sync" \
> - : "=&r" (__tmp) \
> - : "b" (__memp), "r" (oldval), "r" (newval) \
> - : "cr0", "memory"); \
> - __tmp; \
> - })
> -
> #if !defined(LLL_LOCK) && !defined(EXTRAARG)
> /* Make sure the configuration code is always linked in for static
> libraries. */
>