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a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=1360; i=ardb@kernel.org; h=from:subject; bh=zgVblspip5ZINNAWS3J63kCjniwJXU0OYP5r0DXGxEI=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JIUtyVfJJkczPYfGm/hd8+FL02y7q1vnc3l5lLz2B/bWeR ZyU8q+OUhYGMS4GWTFFFoHZf9/tPD1RqtZ5lizMHFYmkCEMXJwCMJGrFxn+e55rMk6KmS+o8qjx TFPydss+tp/hHKtbs3vkHc/PO8RoyvA/WrE+UfB50QXpS/Hr3nSqW/oxK2XsCGS8dSmZxXNHTQs /AA== X-Mailer: git-send-email 2.54.0.823.g6e5bcc1fc9-goog Message-ID: <20260529150150.1670604-21-ardb+git@google.com> Subject: [PATCH v7 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 , Kevin Brodsky , 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" 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)); /* -- 2.54.0.823.g6e5bcc1fc9-goog