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Mon, 27 Apr 2026 08:35:37 -0700 (PDT) Date: Mon, 27 Apr 2026 17:34:20 +0200 In-Reply-To: <20260427153416.2103979-17-ardb+git@google.com> Mime-Version: 1.0 References: <20260427153416.2103979-17-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=1344; i=ardb@kernel.org; h=from:subject; bh=GHwWYq60lqNuozERz0S434bqDfMxYbnUraaeSVA3Tn0=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JIfN947/7X8wOXuLePiOp7MONnvXiUl5NBamL377hk804c tjhpENeRykLgxgXg6yYIovA7L/vdp6eKFXrPEsWZg4rE8gQBi5OAZjI+npGhoWiYueTlCv3njc5 eKI4u3WiW9EuwdunmA+vma0g5vHDOoKRYavEAeGovTdWuwnO7aw0j1t2v8qU20TqZU3o42gvDsX t/AA= X-Mailer: git-send-email 2.54.0.rc2.544.gc7ae2d5bb8-goog Message-ID: <20260427153416.2103979-20-ardb+git@google.com> Subject: [PATCH v4 03/15] 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 , linux-mm@kvack.org, 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-20260427_083539_576650_336AAB93 X-CRM114-Status: GOOD ( 11.52 ) 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 f084993024ab..801a54ade76f 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)) { 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)) { pud_set_huge(pudp, phys, prot); /* -- 2.54.0.rc2.544.gc7ae2d5bb8-goog