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From: Mark Rutland <mark.rutland@arm.com>
To: unlisted-recipients:; (no To-header on input)
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	James Morse <james.morse@arm.com>,
	Quentin Perret <qperret@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH 2/4] arm64: implement support for static call trampolines
Date: Wed, 27 Oct 2021 13:47:44 +0100	[thread overview]
Message-ID: <20211027124744.GE54628@C02TD0UTHF1T.local> (raw)
In-Reply-To: <7d807624275a4938871f8e433e510e3c@AcuMS.aculab.com>

On Tue, Oct 26, 2021 at 11:06:11AM +0000, David Laight wrote:
> From: Mark Rutland
> > Sent: 26 October 2021 11:37
> ...
> > My preference overall is to keep the trampoline self-contained, and I'd
> > prefer to keep the RET inline in the trampoline rather than trying to
> > factor it out so that all the control-flow is clearly in one place.
> > 
> > So I'd prefer that we have the sequence as-is:
> > 
> > | 0:	.quad 0x0
> > | 	bti	c
> > | 	< insn >
> > | 	ldr	x16, 0b
> > | 	cbz	x16, 1f
> > | 	br	x16
> > | 1:	ret
> 
> What is wrong with:
> 0:	.quad 1f
> 	bti	c
> 	< insn >
> 	ldr	x16, 0b
> 	br	x16
> 1:	bti	c
> 	ret
> 
> Self-contained and reasonably easy to read.

FWIW, that would work for me too.

Thanks,
Mark.

  reply	other threads:[~2021-10-27 12:47 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-25 12:20 [PATCH 0/4] arm64: Support dynamic preemption v2 Frederic Weisbecker
2021-10-25 12:20 ` [PATCH 1/4] sched/preempt: Prepare for supporting !CONFIG_GENERIC_ENTRY dynamic preemption Frederic Weisbecker
2021-10-25 12:21 ` [PATCH 2/4] arm64: implement support for static call trampolines Frederic Weisbecker
2021-10-25 13:56   ` Peter Zijlstra
2021-10-25 14:08     ` Ard Biesheuvel
2021-10-25 14:19       ` Peter Zijlstra
2021-10-25 14:44         ` Peter Zijlstra
2021-10-25 14:55           ` Ard Biesheuvel
2021-10-25 15:03             ` Peter Zijlstra
2021-10-25 15:10               ` Ard Biesheuvel
2021-10-26 10:36                 ` Mark Rutland
2021-10-26 10:45                   ` Peter Zijlstra
2021-10-26 11:06                   ` David Laight
2021-10-27 12:47                     ` Mark Rutland [this message]
2021-10-25 15:03             ` David Laight
2021-10-25 14:25   ` David Laight
2021-10-25 14:31     ` Ard Biesheuvel
2021-10-25 14:38       ` David Laight
2021-10-25 12:21 ` [PATCH 3/4] arm64: Implement IRQ exit preemption static call for dynamic preemption Frederic Weisbecker
2021-10-25 12:21 ` [PATCH 4/4] arm64: Implement HAVE_PREEMPT_DYNAMIC Frederic Weisbecker
  -- strict thread matches above, loose matches on Subject: below --
2021-09-20 23:32 [PATCH 0/4] arm64: Support dynamic preemption Frederic Weisbecker
2021-09-20 23:32 ` [PATCH 2/4] arm64: implement support for static call trampolines Frederic Weisbecker
2021-09-21  7:09   ` Peter Zijlstra
2021-09-21 14:44     ` Ard Biesheuvel
2021-09-21 15:08       ` Peter Zijlstra
2021-09-21 15:33       ` Mark Rutland
2021-09-21 15:55         ` Ard Biesheuvel
2021-09-21 16:28           ` Mark Rutland
2021-09-25 17:46             ` David Laight
2021-09-27  8:58               ` Mark Rutland
2021-09-21 16:10   ` Ard Biesheuvel

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