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Date: Fri, 2 May 2025 18:57:40 +0100
From: Catalin Marinas <catalin.marinas@arm.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Yeoreum Yun <yeoreum.yun@arm.com>, will@kernel.org, nathan@kernel.org,
	nick.desaulniers+lkml@gmail.com, morbo@google.com,
	justinstitt@google.com, broonie@kernel.org, maz@kernel.org,
	oliver.upton@linux.dev, frederic@kernel.org, joey.gouly@arm.com,
	james.morse@arm.com, hardevsinh.palaniya@siliconsignals.io,
	shameerali.kolothum.thodi@huawei.com, ryan.roberts@arm.com,
	linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
	llvm@lists.linux.dev, stable@vger.kernel.org
Subject: Re: [PATCH] arm64/cpufeature: annotate arm64_use_ng_mappings with
 ro_after_init to prevent wrong idmap generation
Message-ID: <aBUHlGvZuI2O0bbs@arm.com>
References: <20250502145755.3751405-1-yeoreum.yun@arm.com>
 <CAMj1kXEoYcS6YPU0mBdvijDRK6ZVB7mPYZsCVpz7sYotabrxtQ@mail.gmail.com>
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In-Reply-To: <CAMj1kXEoYcS6YPU0mBdvijDRK6ZVB7mPYZsCVpz7sYotabrxtQ@mail.gmail.com>

On Fri, May 02, 2025 at 06:41:33PM +0200, Ard Biesheuvel wrote:
> Making arm64_use_ng_mappings __ro_after_init seems like a useful
> change by itself, so I am not objecting to that. But we don't solve it
> more fundamentally, please at least add a big fat comment why it is
> important that the variable remains there.

Maybe something like the section reference checker we use for __init -
verify that the early C code does not refer anything in the BSS section.

-- 
Catalin