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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=VZYMMPruwp21m0Xl4JeKfECbeTob5+cc9VVBwFqewef4YFQpd9Inm1HT5mWQ5/6XG ItElSh4Ig+yLgjTKWv4g3SNaz5OOVx2Ve3sKphhXFiZ/dF5OXmmvFug+NBjU9oGbIA 5KSpb9He9n9hVC8WDP9z/KmEA1lJ8qPdpTJ9HzCk= Message-ID: <21a547ae-7121-4cd1-b203-4d8182eb7cc9@arm.com> Date: Wed, 29 Apr 2026 15:57:29 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 15/15] arm64: mm: Remap linear aliases of the fixmap page tables read-only 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> <20260427153416.2103979-32-ardb+git@google.com> From: Kevin Brodsky Content-Language: en-GB In-Reply-To: <20260427153416.2103979-32-ardb+git@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: B68664000B X-Stat-Signature: b95qqc64sy96dhtjhmfhgjwhcp5fackq X-Rspam-User: X-HE-Tag: 1777471056-885826 X-HE-Meta: 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 COl+lnwW 6ouZhc+e4sFLuUIHZjOQZ6lbYG425gSE7D4GiLl7b9geTvbKwNwpBJwU7EkPYN0WguxJPOHsbm9XiNnqlHOP8h3r9Phj3M0jYl0eijO7G0MzgRU390mPxeUihduNtVE2E9IKlrwLTTWbgkjxWDnd2RJjmFiHFxiigribpn+yXe+PsMqu9PNezG+PzgE2991dWcTBXlR13ELB/paDPxPOUIegduqL09BO2OJY3Rat1qylt3ZaU7IHzeYC8EvyMd+XPpZhW+2k/N6EKgrCmfcpiFxlqsSAuWRAar+/NB3xbj9nlhRGK3U2cH36u0g== 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: > [...] > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 84d81bae07a7..e76fe5b0c5fe 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1076,6 +1076,11 @@ void __init mark_linear_text_alias_ro(void) > (unsigned long)__init_begin - (unsigned long)_text, > pgprot_tagged(PAGE_KERNEL_RO)); > > + /* Map the fixmap PTE table at __fixmap_pgdir_start R/O in linear map too */ > + update_mapping_prot(__pa_symbol(__fixmap_pgdir_start), > + (unsigned long)lm_alias(__fixmap_pgdir_start), > + PAGE_SIZE, pgprot_tagged(PAGE_KERNEL_RO)); Is that definitely just one page? > + > remap_linear_data_alias(true); > > if (IS_ENABLED(CONFIG_HIBERNATION)) {