From 1fef81669147d63eb8c5d3627d54eadc21173a0b Mon Sep 17 00:00:00 2001 From: Andrea Parri Date: Wed, 23 Sep 2026 16:36:32 +0200 Subject: arm64: mm: Fix the break-before-make flush range for erratum 2645198 modify_prot_start_ptes() performs the break-before-make TLB invalidation required by erratum 2645198 with __flush_tlb_range(), whose third argument is the end address of the range. It passes nr * PAGE_SIZE instead of addr + nr * PAGE_SIZE, so __do_flush_tlb_range() computes the page count as (nr * PAGE_SIZE - addr) >> PAGE_SHIFT. For addr > nr * PAGE_SIZE that subtraction underflows, the page count exceeds the batching limit and the flush degenerates to flush_tlb_mm(), so a single-page mprotect broadcasts an ASID-wide invalidation and a full-range mmu notifier call. For addr <= nr * PAGE_SIZE only [addr, nr * PAGE_SIZE) is invalidated, and when the cleared batch starts below nr * PAGE_SIZE the tail is left in the TLB. The workaround then no longer covers the whole batch, and for addr == nr * PAGE_SIZE the flush is empty. On affected Cortex-A715 CPUs, this can corrupt ESR_ELx and FAR_ELx on the next instruction abort caused by a permission fault. Pass addr + nr * PAGE_SIZE as the end address. Fixes: 7efa1cd5f89b5 ("arm64: add batched versions of ptep_modify_prot_start/commit") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Andrea Parri Reviewed-by: Dev Jain Signed-off-by: Will Deacon --- 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 79d90226f..d4384131e 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -2295,7 +2295,7 @@ pte_t modify_prot_start_ptes(struct vm_area_struct *vma, unsigned long addr, * in cases where cpu is affected with errata #2645198. */ if (pte_accessible(vma->vm_mm, pte) && pte_user_exec(pte)) - __flush_tlb_range(vma, addr, nr * PAGE_SIZE, + __flush_tlb_range(vma, addr, addr + nr * PAGE_SIZE, PAGE_SIZE, 3, TLBF_NOWALKCACHE); } -- cgit v1.3.1