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Tue, 26 May 2026 10:59:25 -0700 (PDT) Date: Tue, 26 May 2026 19:58:51 +0200 In-Reply-To: <20260526175846.2694125-17-ardb+git@google.com> Mime-Version: 1.0 References: <20260526175846.2694125-17-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=1360; i=ardb@kernel.org; h=from:subject; bh=HTVCAgvGTLScrJ2CZV4D8VSId3uhva+Scq8FVpoE17Y=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JIUv0fgzPcSP+Z1uPSc089cXOMuHXyr/rHy2TE5mx/o6dx X9ece7OjlIWBjEuBlkxRRaB2X/f7Tw9UarWeZYszBxWJpAhDFycAjARxViG/1GnxVK2TMh4vX6H yFPbSV03ey81Ml2OaYnZZ/vlkGzNih2MDIuvZ3AHycz03hNo9ypyg7OB0C2/DLkSk46sXolZjBl hfAA= X-Mailer: git-send-email 2.54.0.794.g4f17f83d09-goog Message-ID: <20260526175846.2694125-21-ardb+git@google.com> Subject: [PATCH v6 04/15] arm64: mm: Preserve existing table mappings when mapping DRAM From: Ard Biesheuvel To: 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 , Jann Horn , linux-mm@kvack.org, linux-hardening@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260526_105928_598382_7117E590 X-CRM114-Status: GOOD ( 12.00 ) 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 b2ba5b35c35f..5c827fa3cd38 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -256,7 +256,8 @@ 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)) { WARN_ON(!pmd_set_huge(pmdp, phys, prot)); /* @@ -379,7 +380,8 @@ 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)) { WARN_ON(!pud_set_huge(pudp, phys, prot)); /* -- 2.54.0.794.g4f17f83d09-goog