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AJvYcCVAEQrHWZm+URH6NYwgwXd8s/vwvhiDkvDxhlKDa5bxw1T/02gtSqOcTj5pkFFtNLPUZr+dp+FIIeb3O/TDVIE=@vger.kernel.org X-Gm-Message-State: AOJu0YzffnryhLbxyYr3lD5JQHBfjF+6YDsSKUeT5J25EnFW+wNUYpRi 1GHFCiMrKHKb1KJlNpQ8LYFTVR0sqIu6TaW5zk4MJzqkmVZ4eluJb/5gUuhP+iGdr/bfcURJfg= = X-Received: from wmbjw6.prod.google.com ([2002:a05:600c:5746:b0:480:3842:3532]) (user=ardb job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:4689:b0:47e:e78a:c831 with SMTP id 5b1f17b1804b1-4805d0668famr63022225e9.36.1769419654312; Mon, 26 Jan 2026 01:27:34 -0800 (PST) Date: Mon, 26 Jan 2026 10:26:34 +0100 In-Reply-To: <20260126092630.1800589-12-ardb+git@google.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260126092630.1800589-12-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=874; i=ardb@kernel.org; h=from:subject; bh=Gtkmu5xUf/IdJr0kiShY6X4TSbxJqYA0pGP5tteQQSc=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JIbPc2EOMl1Oe+ZtxwpPOV9LiF4RXP+tbf+lo+TXjL389J m2duYmho5SFQYyLQVZMkUVg9t93O09PlKp1niULM4eVCWQIAxenAEzkSiQjQyt7cfCidwej5f/9 5p7Qf1Jt4vfD9tERNyW+nXLVefgp8xkjw8lZxm6uxhc5n927XLbV0/fcU+dXx87Oeyi4gG+7QvH jeEYA X-Mailer: git-send-email 2.52.0.457.g6b5491de43-goog Message-ID: <20260126092630.1800589-15-ardb+git@google.com> Subject: [PATCH v2 03/10] arm64: mm: Permit contiguous descriptors to be rewritten From: Ard Biesheuvel To: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, Ard Biesheuvel , Ryan Roberts , Anshuman Khandual , Liz Prucka , Seth Jenkins , Kees Cook , linux-hardening@vger.kernel.org Content-Type: text/plain; charset="UTF-8" From: Ard Biesheuvel Currently, pgattr_change_is_safe() is overly pedantic when it comes to descriptors with the contiguous hint attribute set, as it rejects assignments even if the old and the new value are the same. So relax the check to allow that. 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 c36422a3fae2..9d39de3cfe67 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -141,7 +141,7 @@ bool pgattr_change_is_safe(pteval_t old, pteval_t new) return false; /* live contiguous mappings may not be manipulated at all */ - if ((old | new) & PTE_CONT) + if ((old | new) & PTE_CONT && old != new) return false; /* Transitioning from Non-Global to Global is unsafe */ -- 2.52.0.457.g6b5491de43-goog