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From: Will Deacon <will.deacon@arm.com>
To: Jiang Liu <liuj97@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	Sandeepa Prabhu <sandeepa.prabhu@linaro.org>,
	Jiang Liu <jiang.liu@huawei.com>,
	Marc Zyngier <Marc.Zyngier@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 1/7] arm64: introduce basic aarch64 instruction decoding helpers
Date: Thu, 17 Oct 2013 10:43:19 +0100	[thread overview]
Message-ID: <20131017094318.GC18765@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <525EC98A.6090802@gmail.com>

On Wed, Oct 16, 2013 at 06:14:50PM +0100, Jiang Liu wrote:
> On 10/16/2013 11:36 PM, Jiang Liu wrote:
> > On 10/16/2013 06:51 PM, Will Deacon wrote:
> >> Take care here:
> >>
> >> 	- This doesn't guarantee that CPUs exclusively see new_insn (they
> >> 	  may see old_insn, even after patching)
> > Good point. Still need some synchronization mechanism lighter than
> > stop_machine(). How about kick_all_cpus_sync(), which should be lighter
> > than stop_machine()?
> For jump label, x86 uses three smp_call_function() to replace a
> stop_machine(). Seems it's valuable for us to use just one
> kick_all_cpus_sync() to avoid a stop_machine().

Yes, the exception return after handling the IPI from kick_all_cpus_sync
should be enough to synchronise the pipeline, providing that all cache
maintenance by the CPU writing the new instructions has completed (if you're
using flush_icache_range then you're fine).

Will

  reply	other threads:[~2013-10-17  9:44 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-16  3:18 [PATCH v3 0/7] Optimize jump label implementation for ARM64 Jiang Liu
2013-10-16  3:18 ` [PATCH v3 1/7] arm64: introduce basic aarch64 instruction decoding helpers Jiang Liu
2013-10-16 10:51   ` Will Deacon
2013-10-16 15:36     ` Jiang Liu
2013-10-16 17:14       ` Jiang Liu
2013-10-17  9:43         ` Will Deacon [this message]
2013-10-16  3:18 ` [PATCH v3 2/7] arm64: introduce interfaces to hotpatch kernel and module code Jiang Liu
2013-10-16 11:11   ` Will Deacon
2013-10-16 16:15     ` Jiang Liu
2013-10-16  3:18 ` [PATCH v3 3/7] arm64: move encode_insn_immediate() from module.c to insn.c Jiang Liu
2013-10-16 11:22   ` Will Deacon
2013-10-16 16:33     ` Jiang Liu
2013-10-16  3:18 ` [PATCH v3 4/7] arm64: introduce aarch64_insn_gen_{nop|branch_imm}() helper functions Jiang Liu
2013-10-16  3:18 ` [PATCH v3 5/7] arm64, jump label: detect %c support for ARM64 Jiang Liu
2013-10-16  3:18 ` [PATCH v3 6/7] arm64, jump label: optimize jump label implementation Jiang Liu
2013-10-16 11:46   ` Will Deacon
2013-10-16 17:11     ` Jiang Liu
2013-10-17  9:39       ` Will Deacon
2013-10-17 14:40         ` Jiang Liu
2013-10-17 15:27           ` Steven Rostedt
2013-10-18  3:31             ` Jiang Liu (Gerry)
2013-10-18 10:02               ` Will Deacon
2013-10-16  3:18 ` [PATCH v3 7/7] jump_label: use defined macros instead of hard-coding for better readability Jiang Liu

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