From: Ard Biesheuvel <ardb+git@google.com>
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 <ardb@kernel.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Liz Prucka <lizprucka@google.com>,
Seth Jenkins <sethjenkins@google.com>,
Kees Cook <kees@kernel.org>,
linux-hardening@vger.kernel.org
Subject: [PATCH v3 06/13] arm64: mm: Permit contiguous descriptors to be rewritten
Date: Fri, 20 Mar 2026 15:59:41 +0100 [thread overview]
Message-ID: <20260320145934.2349881-21-ardb+git@google.com> (raw)
In-Reply-To: <20260320145934.2349881-15-ardb+git@google.com>
From: Ard Biesheuvel <ardb@kernel.org>
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 <ardb@kernel.org>
---
arch/arm64/mm/mmu.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 744cf76f25aa..6780236b6cf8 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -140,10 +140,6 @@ bool pgattr_change_is_safe(pteval_t old, pteval_t new)
if (pte_pfn(__pte(old)) != pte_pfn(__pte(new)))
return false;
- /* live contiguous mappings may not be manipulated at all */
- if ((old | new) & PTE_CONT)
- return false;
-
/* Transitioning from Non-Global to Global is unsafe */
if (old & ~new & PTE_NG)
return false;
--
2.53.0.959.g497ff81fa9-goog
next prev parent reply other threads:[~2026-03-20 15:00 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-20 14:59 [PATCH v3 00/13] arm64: Unmap linear alias of kernel data/bss Ard Biesheuvel
2026-03-20 14:59 ` [PATCH v3 01/13] arm64: Move the zero page to rodata Ard Biesheuvel
2026-03-20 14:59 ` [PATCH v3 02/13] arm64: mm: Preserve existing table mappings when mapping DRAM Ard Biesheuvel
2026-03-20 14:59 ` [PATCH v3 03/13] arm64: mm: Preserve non-contiguous descriptors " Ard Biesheuvel
2026-03-20 14:59 ` [PATCH v3 04/13] arm64: mm: Remove bogus stop condition from map_mem() loop Ard Biesheuvel
2026-03-20 14:59 ` [PATCH v3 05/13] arm64: mm: Drop redundant pgd_t* argument from map_mem() Ard Biesheuvel
2026-03-20 14:59 ` Ard Biesheuvel [this message]
2026-03-20 14:59 ` [PATCH v3 07/13] arm64: mm: Use hierarchical XN mapping for the fixmap Ard Biesheuvel
2026-03-20 14:59 ` [PATCH v3 08/13] arm64: kfence: Avoid NOMAP tricks when mapping the early pool Ard Biesheuvel
2026-03-20 14:59 ` [PATCH v3 09/13] arm64: mm: Permit contiguous attribute for preliminary mappings Ard Biesheuvel
2026-03-20 14:59 ` [PATCH v3 10/13] arm64: Move fixmap page tables to end of kernel image Ard Biesheuvel
2026-03-20 14:59 ` [PATCH v3 11/13] arm64: mm: Don't abuse memblock NOMAP to check for overlaps Ard Biesheuvel
2026-03-20 14:59 ` [PATCH v3 12/13] arm64: mm: Map the kernel data/bss read-only in the linear map Ard Biesheuvel
2026-03-20 14:59 ` [PATCH v3 13/13] arm64: mm: Unmap kernel data/bss entirely from " Ard Biesheuvel
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