With Linux page size of 64K and hardware only supporting 4K hpte, if we use subpage protection, we always fail for the subpage 0 as shown below (using the selftest subpage_prot test).
520175565: (4520111850): Failed at 0x0x3fffad4b0000 (p=13,sp=0,w=0), want=fault, got=pass ! 4520890210: (4520826495): Failed at 0x0x3fffad5b0000 (p=29,sp=0,w=0), want=fault, got=pass ! 4521574251: (4521510536): Failed at 0x0x3fffad6b0000 (p=45,sp=0,w=0), want=fault, got=pass ! 4522258324: (4522194609): Failed at 0x0x3fffad7b0000 (p=61,sp=0,w=0), want=fault, got=pass ! This is because hash preload wrongly insert the hpte entry for subpage 0 without looking at the subapge protection information. Don't do hash page table entry preload if we have subpage protection configured for that range. Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> --- arch/powerpc/mm/hash_utils_64.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index 262082e51db1..b5a454415215 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -1329,15 +1329,26 @@ void hash_preload(struct mm_struct *mm, unsigned long ea, unsigned long vsid; pgd_t *pgdir; pte_t *ptep; + int psize; unsigned long flags; int rc, ssize, update_flags = 0; BUG_ON(REGION_ID(ea) != USER_REGION_ID); #ifdef CONFIG_PPC_MM_SLICES - /* We only prefault standard pages for now */ - if (unlikely(get_slice_psize(mm, ea) != mm->context.user_psize)) + psize = get_slice_psize(mm, ea); + /* + * We only prefault standard pages + */ + if (psize != mm->context.user_psize) return; +#ifdef CONFIG_PPC_64K_PAGES + /* + * Don't prefault is subpage protection is enabled for that ea + */ + if ((psize == MMU_PAGE_4K) && subpage_protection(mm, ea)) + return; +#endif #endif DBG_LOW("hash_preload(mm=%p, mm->pgdir=%p, ea=%016lx, access=%lx," -- 2.7.4 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev