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 v2 03/10] arm64: mm: Permit contiguous descriptors to be rewritten
Date: Mon, 26 Jan 2026 10:26:34 +0100 [thread overview]
Message-ID: <20260126092630.1800589-15-ardb+git@google.com> (raw)
In-Reply-To: <20260126092630.1800589-12-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 | 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
next prev parent reply other threads:[~2026-01-26 9:27 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-26 9:26 [PATCH v2 00/10] arm64: Unmap linear alias of kernel data/bss Ard Biesheuvel
2026-01-26 9:26 ` [PATCH v2 01/10] arm64: Move the zero page to rodata Ard Biesheuvel
2026-01-27 9:34 ` Ryan Roberts
2026-01-27 9:49 ` Ard Biesheuvel
2026-01-27 10:03 ` Ryan Roberts
2026-01-27 10:50 ` Ard Biesheuvel
2026-01-26 9:26 ` [PATCH v2 02/10] arm64: Move fixmap page tables to end of kernel image Ard Biesheuvel
2026-01-27 9:42 ` Ryan Roberts
2026-01-26 9:26 ` Ard Biesheuvel [this message]
2026-01-27 9:45 ` [PATCH v2 03/10] arm64: mm: Permit contiguous descriptors to be rewritten Ryan Roberts
2026-01-27 15:03 ` Ard Biesheuvel
2026-01-27 16:59 ` Ryan Roberts
2026-01-27 17:02 ` Ard Biesheuvel
2026-01-27 17:37 ` Ryan Roberts
2026-01-26 9:26 ` [PATCH v2 04/10] arm64: mm: Preserve existing table mappings when mapping DRAM Ard Biesheuvel
2026-01-27 9:58 ` Ryan Roberts
2026-01-26 9:26 ` [PATCH v2 05/10] arm64: mm: Preserve non-contiguous descriptors " Ard Biesheuvel
2026-01-27 9:58 ` Ryan Roberts
2026-01-26 9:26 ` [PATCH v2 06/10] arm64: mm: Remove bogus stop condition from map_mem() loop Ard Biesheuvel
2026-01-27 10:06 ` Ryan Roberts
2026-01-26 9:26 ` [PATCH v2 07/10] arm64: mm: Drop redundant pgd_t* argument from map_mem() Ard Biesheuvel
2026-01-27 10:10 ` Ryan Roberts
2026-01-26 9:26 ` [PATCH v2 08/10] arm64: mm: Don't abuse memblock NOMAP to check for overlaps Ard Biesheuvel
2026-01-27 10:21 ` Ryan Roberts
2026-01-27 10:27 ` Ard Biesheuvel
2026-01-27 10:39 ` Ryan Roberts
2026-01-27 10:47 ` Ard Biesheuvel
2026-01-27 11:00 ` Ryan Roberts
2026-01-27 11:03 ` Ard Biesheuvel
2026-01-27 11:09 ` Ryan Roberts
2026-01-26 9:26 ` [PATCH v2 09/10] arm64: mm: Map the kernel data/bss read-only in the linear map Ard Biesheuvel
2026-01-27 10:33 ` Ryan Roberts
2026-01-27 10:36 ` Ard Biesheuvel
2026-01-27 10:41 ` Ryan Roberts
2026-01-26 9:26 ` [PATCH v2 10/10] arm64: mm: Unmap kernel data/bss entirely from " Ard Biesheuvel
2026-01-27 10:50 ` Ryan Roberts
2026-01-27 10:54 ` Ard Biesheuvel
2026-01-27 11:02 ` Ryan Roberts
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