From 08e445bd6a98fa09befe0cf6d67705324f913fc6 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Fri, 16 Jan 2009 23:02:54 +0100 Subject: [PATCH] [ARM] 5366/1: fix shared memory coherency with VIVT L1 + L2 caches When there are multiple L1-aliasing userland mappings of the same physical page, we currently remap each of them uncached, to prevent VIVT cache aliasing issues. (E.g. writes to one of the mappings not being immediately visible via another mapping.) However, when we do this remapping, there could still be stale data in the L2 cache, and an uncached mapping might bypass L2 and go straight to RAM. This would cause reads from such mappings to see old data (until the dirty L2 line is eventually evicted.) This issue is solved by forcing a L2 cache flush whenever the shared page is made L1 uncacheable. Ideally, we would make L1 uncacheable and L2 cacheable as L2 is PIPT. But Feroceon does not support that combination, and the TEX=5 C=0 B=0 encoding for XSc3 doesn't appear to work in practice. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King --- arch/arm/mm/fault-armv.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c index 81d0b8772de3..bc0099d5ae85 100644 --- a/arch/arm/mm/fault-armv.c +++ b/arch/arm/mm/fault-armv.c @@ -66,7 +66,10 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address) * fault (ie, is old), we can safely ignore any issues. */ if (ret && (pte_val(entry) & L_PTE_MT_MASK) != shared_pte_mask) { - flush_cache_page(vma, address, pte_pfn(entry)); + unsigned long pfn = pte_pfn(entry); + flush_cache_page(vma, address, pfn); + outer_flush_range((pfn << PAGE_SHIFT), + (pfn << PAGE_SHIFT) + PAGE_SIZE); pte_val(entry) &= ~L_PTE_MT_MASK; pte_val(entry) |= shared_pte_mask; set_pte_at(vma->vm_mm, address, pte, entry); -- 2.39.5