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

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Message-ID: <20150731075259.GR25159@twins.programming.kicks-ass.net>
Date:	Fri, 31 Jul 2015 09:52:59 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	yalin wang <yalin.wang2010@...il.com>
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 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.
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