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Fri, 20 Mar 2026 07:59:59 -0700 (PDT) Date: Fri, 20 Mar 2026 15:59:37 +0100 In-Reply-To: <20260320145934.2349881-15-ardb+git@google.com> Mime-Version: 1.0 References: <20260320145934.2349881-15-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=1340; i=ardb@kernel.org; h=from:subject; bh=RNseX4mRXVBWe3ByFtnF7vDF/KyNT++5b73PmV91ziY=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JIXNvwq2EdddL5C1WvNOwK94xj3Pq40+BMyeKKn7+bJ8Qu 499zbLpHaUsDGJcDLJiiiwCs/++23l6olSt8yxZmDmsTCBDGLg4BWAim9cx/Hfgi/mWLLjsk9uN F+teaatVvZ0RbGgj9CG4gPVB1aX0S3wMf7hu3pPafatOKSa/zt88y3a55KMrpRVVNqt75DvYwwq v8QEA X-Mailer: git-send-email 2.53.0.959.g497ff81fa9-goog Message-ID: <20260320145934.2349881-17-ardb+git@google.com> Subject: [PATCH v3 02/13] arm64: mm: Preserve existing table mappings when mapping DRAM 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" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260320_080002_642536_5200C1DD X-CRM114-Status: GOOD ( 10.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Ard Biesheuvel Instead of blindly overwriting an existing table entry when mapping DRAM regions, take care not to replace a pre-existing table entry with a block entry. This permits the logic of mapping the kernel's linear alias to be simplified in a subsequent patch. Reviewed-by: Ryan Roberts Signed-off-by: Ard Biesheuvel --- arch/arm64/mm/mmu.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 795743913ce5..9927b55022d8 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -262,7 +262,8 @@ static int init_pmd(pmd_t *pmdp, unsigned long addr, unsigned long end, /* try section mapping first */ if (((addr | next | phys) & ~PMD_MASK) == 0 && - (flags & NO_BLOCK_MAPPINGS) == 0) { + (flags & NO_BLOCK_MAPPINGS) == 0 && + !pmd_table(old_pmd)) { pmd_set_huge(pmdp, phys, prot); /* @@ -385,7 +386,8 @@ static int alloc_init_pud(p4d_t *p4dp, unsigned long addr, unsigned long end, */ if (pud_sect_supported() && ((addr | next | phys) & ~PUD_MASK) == 0 && - (flags & NO_BLOCK_MAPPINGS) == 0) { + (flags & NO_BLOCK_MAPPINGS) == 0 && + !pud_table(old_pud)) { pud_set_huge(pudp, phys, prot); /* -- 2.53.0.959.g497ff81fa9-goog