From 36b35d5d807b7e57aff7d08e63de8b17731ee211 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Tue, 15 Sep 2015 12:30:08 +0530 Subject: [PATCH] powerpc/mm: Recompute hash value after a failed update If we had secondary hash flag set, we ended up modifying hash value in the updatepp code path. Hence with a failed updatepp we will be using a wrong hash value for the following hash insert. Fix this by recomputing hash before insert. Without this patch we can end up with using wrong slot number in linux pte. That can result in us missing an hash pte update or invalidate which can cause memory corruption or even machine check. Fixes: 6d492ecc6489 ("powerpc/THP: Add code to handle HPTE faults for hugepages") Cc: stable@vger.kernel.org # v3.11+ Signed-off-by: Aneesh Kumar K.V Reviewed-by: Paul Mackerras Signed-off-by: Michael Ellerman --- arch/powerpc/mm/hugepage-hash64.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/mm/hugepage-hash64.c b/arch/powerpc/mm/hugepage-hash64.c index 43dafb9..4d87122 100644 --- a/arch/powerpc/mm/hugepage-hash64.c +++ b/arch/powerpc/mm/hugepage-hash64.c @@ -85,7 +85,6 @@ int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid, BUG_ON(index >= 4096); vpn = hpt_vpn(ea, vsid, ssize); - hash = hpt_hash(vpn, shift, ssize); hpte_slot_array = get_hpte_slot_array(pmdp); if (psize == MMU_PAGE_4K) { /* @@ -101,6 +100,7 @@ int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid, valid = hpte_valid(hpte_slot_array, index); if (valid) { /* update the hpte bits */ + hash = hpt_hash(vpn, shift, ssize); hidx = hpte_hash_index(hpte_slot_array, index); if (hidx & _PTEIDX_SECONDARY) hash = ~hash; @@ -126,6 +126,7 @@ int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid, if (!valid) { unsigned long hpte_group; + hash = hpt_hash(vpn, shift, ssize); /* insert new entry */ pa = pmd_pfn(__pmd(old_pmd)) << PAGE_SHIFT; new_pmd |= _PAGE_HASHPTE; -- 2.7.4