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| author | Michael Ellerman <mpe@ellerman.id.au> | 2016-05-06 08:47:12 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2016-05-11 13:54:05 +0200 |
| commit | aac55d7573c5d46ed9a62818d5d3e69dd2060105 (patch) | |
| tree | 6f9cf35965279f1e1d7f55056ed3848cd35d5ddb /arch | |
| parent | powerpc/mm/hash64: Factor out hash preload psize check (diff) | |
| download | linux-aac55d7573c5d46ed9a62818d5d3e69dd2060105.tar.xz linux-aac55d7573c5d46ed9a62818d5d3e69dd2060105.zip | |
powerpc/mm/hash64: Fix subpage protection with 4K HPTE config
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 0x3fffad4b0000 (p=13,sp=0,w=0), want=fault, got=pass !
4520890210: (4520826495): Failed at 0x3fffad5b0000 (p=29,sp=0,w=0), want=fault, got=pass !
4521574251: (4521510536): Failed at 0x3fffad6b0000 (p=45,sp=0,w=0), want=fault, got=pass !
4522258324: (4522194609): Failed at 0x3fffad7b0000 (p=61,sp=0,w=0), want=fault, got=pass !
This is because hash preload wrongly inserts the HPTE entry for subpage
0 without looking at the subpage protection information.
Fix it by teaching should_hash_preload() not to preload if we have
subpage protection configured for that range.
It appears this has been broken since it was introduced in 2008.
Fixes: fa28237cfcc5 ("[POWERPC] Provide a way to protect 4k subpages when using 64k pages")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
[mpe: Rework into should_hash_preload() to avoid build fails w/SLICES=n]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/mm/hash_utils_64.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index fbe747ed8c2d..59268969a0bc 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -1325,8 +1325,16 @@ int __hash_page(unsigned long ea, unsigned long msr, unsigned long trap, #ifdef CONFIG_PPC_MM_SLICES static bool should_hash_preload(struct mm_struct *mm, unsigned long ea) { + int psize = get_slice_psize(mm, ea); + /* We only prefault standard pages for now */ - if (unlikely(get_slice_psize(mm, ea) != mm->context.user_psize)) + if (unlikely(psize != mm->context.user_psize)) + return false; + + /* + * Don't prefault if subpage protection is enabled for the EA. + */ + if (unlikely((psize == MMU_PAGE_4K) && subpage_protection(mm, ea))) return false; return true; |