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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=KZBlPQ1sPDbrJhxD9GJVH5ERW4UKB3ReLaGE3w6Rs7y5sqoZtBJxYyDPoySmzUimS O2W2ca7Bx0rNnlTgvtXYIkX9i8isJ3q6U5bEoSdMuy+joC8i+kcUX/Pz9lnXt+pwSX DREPzwlNeterBeiJ8pRPWspZwsPTrQUst6s1cJdo= Message-ID: <82091dd4-9d11-4054-89ec-99aadaeec7b2@arm.com> Date: Tue, 28 Apr 2026 16:16:20 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 01/15] arm64: mm: Map the linear alias of text/rodata as tagged To: Ard Biesheuvel , linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, Ard Biesheuvel , Ryan Roberts , Anshuman Khandual , Liz Prucka , Seth Jenkins , Kees Cook , Mike Rapoport , David Hildenbrand , Andrew Morton , linux-mm@kvack.org, linux-hardening@vger.kernel.org References: <20260427153416.2103979-17-ardb+git@google.com> <20260427153416.2103979-18-ardb+git@google.com> From: Kevin Brodsky Content-Language: en-GB In-Reply-To: <20260427153416.2103979-18-ardb+git@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: xoyau4kkgfydzqsirf95txg1bwkpwd4t X-Rspamd-Queue-Id: 8268B4000C X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1777385789-274322 X-HE-Meta: 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 SYkTgnsv jzYGnsQt132RmEObpi3oDSPdiGiBkel3qsJ6T86sXCjn9JH8POmhnL35B1wuXjoXThnzHanWwkcdb2Lhhj7WjUG29CdnentEQoQPmXKeN+pSVmHIWC5ze8Y7dwPxnw0VZ4FV0iSvwsdHyE4WhtbGnXhl6qAicQvfnmyYxfabHKd7OnPFzjmDA8bspM0DAT5F7i1RhAQbwldmYgEQhR2zvXAqOuhQ8lbrUVr8pjYyeEp57mnGEKSWBMEIboyI2DSmmWzSaN5Df7rWUOENEenC+bBB1WxWMKQfTy7ULoO7BgwhMtUVtKeG376mE7pxi3r3TkaQuuAebNVxQWUPXpvJbjT+SkLkAzLifucyF29H6t3MyssI= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 27/04/2026 17:34, Ard Biesheuvel wrote: > From: Ard Biesheuvel > > Before moving the empty_zero_page into the __ro_after_init section, make > sure it has the memory-tagged type. This is needed to ensure that > cpu_enable_mte() will be able to initialize the tags correctly. mark_linear_text_alias_ro() is called after all features have been detected and enabled, so do we actually need this? AFAICT the lines that matter for cpu_enable_mte() are those, in map_mem():     __map_memblock(pgdp, kernel_start, kernel_end,                PAGE_KERNEL, NO_CONT_MAPPINGS); It is probably this call that needs to be changed to use pgprot_tagged(PAGE_KERNEL). - Kevin > Signed-off-by: Ard Biesheuvel > --- > arch/arm64/mm/mmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index dd85e093ffdb..f084993024ab 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1049,7 +1049,7 @@ void __init mark_linear_text_alias_ro(void) > */ > update_mapping_prot(__pa_symbol(_text), (unsigned long)lm_alias(_text), > (unsigned long)__init_begin - (unsigned long)_text, > - PAGE_KERNEL_RO); > + pgprot_tagged(PAGE_KERNEL_RO)); > } > > #ifdef CONFIG_KFENCE