From: peterz@infradead.org (Peter Zijlstra)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC] arm64:change jump_label to use branch instruction, not use NOP instr
Date: Fri, 31 Jul 2015 09:52:59 +0200 [thread overview]
Message-ID: <20150731075259.GR25159@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <94E2034B-9DE4-4ADF-8B2F-197D38A363CF@gmail.com>
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.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: yalin wang <yalin.wang2010@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>, Ingo Molnar <mingo@kernel.org>,
anton@samba.org, mark.rutland@arm.com,
linux-arm-kernel@lists.infradead.org,
open list <linux-kernel@vger.kernel.org>,
jbaron@akamai.com
Subject: Re: [RFC] arm64:change jump_label to use branch instruction, not use NOP instr
Date: Fri, 31 Jul 2015 09:52:59 +0200 [thread overview]
Message-ID: <20150731075259.GR25159@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <94E2034B-9DE4-4ADF-8B2F-197D38A363CF@gmail.com>
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.
next prev parent reply other threads:[~2015-07-31 7:52 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-31 7:41 [RFC] arm64:change jump_label to use branch instruction, not use NOP instr yalin wang
2015-07-31 7:41 ` yalin wang
2015-07-31 7:52 ` Peter Zijlstra [this message]
2015-07-31 7:52 ` Peter Zijlstra
2015-07-31 9:25 ` yalin wang
2015-07-31 9:25 ` yalin wang
2015-07-31 9:33 ` Peter Zijlstra
2015-07-31 9:33 ` Peter Zijlstra
2015-07-31 10:14 ` Will Deacon
2015-07-31 10:14 ` Will Deacon
2015-08-01 10:00 ` yalin wang
2015-08-01 10:00 ` yalin wang
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