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Date: Mon, 14 Oct 2024 10:54:00 +0100
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Subject: Re: [PATCH] ARM: NOMMU: Fix exc_ret for stack frame type
To: Jisheng Zhang <jszhang@kernel.org>, Russell King <linux@armlinux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20241013132520.2848-1-jszhang@kernel.org>
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From: Vladimir Murzin <vladimir.murzin@arm.com>
In-Reply-To: <20241013132520.2848-1-jszhang@kernel.org>
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On 10/13/24 14:25, Jisheng Zhang wrote:
> commit 72cd4064fcca ("ARM: 8830/1: NOMMU: Toggle only bits in
> EXC_RETURN we are really care of") only sets BIT[3] for Thread mode
> and BIT[2] for PSP, it leaves BIT[4] untouched. But there's such a
> case: the pre-linux env makes use of FPU then the BIT[4] in 'lr' is
> cleared, this brings an umatch issue since the NOMMU kernel doesn't

Can pre-linux env disable FPU before passing control to kernel (which
is, as correctly pointed, doesn't know how to use FPU)?

Cheers
Vladimir