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From: Catalin Marinas <catalin.marinas@arm.com>
To: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Amit Daniel Kachhap <amit.kachhap@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/3] arm64: Make NOP handling a whitelist
Date: Wed, 22 Apr 2020 18:27:43 +0100	[thread overview]
Message-ID: <20200422172743.GG3585@gaia> (raw)
In-Reply-To: <20200324194822.15682-1-broonie@kernel.org>

On Tue, Mar 24, 2020 at 07:48:19PM +0000, Mark Brown wrote:
> Currently we default to assuming any unrecognized instruction in the
> hint space can be safely handled as a NOP.  This is not robust and any
> code that really wants a NOP should be using the explicitly defined NOP
> so let's instead invert this and whitelist those instructions which it
> is safe to handle as NOPs.
> 
> Mark Brown (3):
>   arm64: insn: Don't assume unrecognized HINTs are NOPs
>   arm64: insn: Add constants for PAC and BTI instruction decode
>   arm64: insn: Report PAC and BTI instructions as NOPs
> 
>  arch/arm64/include/asm/insn.h | 22 ++++++++++++++++++++--
>  arch/arm64/kernel/insn.c      | 32 ++++++++++++++++++++++++--------
>  2 files changed, 44 insertions(+), 10 deletions(-)

IIRC, we concluded [1] there is no problem for PAC and BTI instruction
in the NOP space. For this series:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

[1] https://lore.kernel.org/linux-arm-kernel/20200312184211.GA3849205@arrakis.emea.arm.com/

-- 
Catalin

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      parent reply	other threads:[~2020-04-22 17:27 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24 19:48 [PATCH 0/3] arm64: Make NOP handling a whitelist Mark Brown
2020-03-24 19:48 ` [PATCH 1/3] arm64: insn: Don't assume unrecognized HINTs are NOPs Mark Brown
2020-03-24 19:48 ` [PATCH 2/3] arm64: insn: Add constants for PAC and BTI instruction decode Mark Brown
2020-04-28 11:43   ` Mark Brown
2020-04-28 13:33     ` Will Deacon
2020-03-24 19:48 ` [PATCH 3/3] arm64: insn: Report PAC and BTI instructions as NOPs Mark Brown
2020-04-22 17:27 ` Catalin Marinas [this message]

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