linux-kernel - Re: [RFC] arm64:change jump_label to use branch instruction, not use NOP instr

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Message-Id: <8F6A71B0-C7DB-4505-BEE2-79967FC91A8F@gmail.com>
Date:	Fri, 31 Jul 2015 17:25:02 +0800
From:	yalin wang <yalin.wang2010@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Ingo Molnar <mingo@...nel.org>, anton@...ba.org,
	mark.rutland@....com, linux-arm-kernel@...ts.infradead.org,
	open list <linux-kernel@...r.kernel.org>, jbaron@...mai.com
Subject: Re: [RFC] arm64:change jump_label to use branch instruction, not use NOP instr


> On Jul 31, 2015, at 15:52, Peter Zijlstra <peterz@...radead.org> wrote:
> 
> On Fri, Jul 31, 2015 at 03:41:37PM +0800, yalin wang wrote:
>> This change a little arch_static_branch(), use b . + 4 for false
>> return, why? According to aarch64 TRM, if both source and dest
>> instr are branch instr, can patch the instr directly, don't need
>> all cpu to do ISB for sync, this means we can call
>> aarch64_insn_patch_text_nosync() during patch_text(),
>> will improve the performance when change a static_key.
> 
> This doesn't parse.. What?
> 
> Also, this conflicts with the jump label patches I've got.


this is arch depend , you can see aarch64_insn_patch_text( ) for more info,
if aarch64_insn_hotpatch_safe() is true, will patch the text directly.

what is your git branch base? i make the patch based on linux-next branch,
maybe a little delay than yours , could you share your branch git address?
i can make a new based on yours .

Thanks

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