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powerpc/pkeys: Avoid using lockless page table walk

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Fetch pkey from vma instead of linux page table. Also document the fact that in
some cases the pkey returned in siginfo won't be the same as the one we took
keyfault on. Even with linux page table walk, we can end up in a similar scenario.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-2-aneesh.kumar@linux.ibm.com
This commit is contained in:
Aneesh Kumar K.V
2020-05-05 12:47:08 +05:30
committed by Michael Ellerman
parent 93a98695f2
commit fe4a6856cb
3 changed files with 60 additions and 56 deletions
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24
arch/powerpc/mm/book3s64/hash_utils.c
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@ -1671,30 +1671,6 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
hash_preload(vma->vm_mm, address, is_exec, trap);
}
#ifdef CONFIG_PPC_MEM_KEYS
/*
* Return the protection key associated with the given address and the
* mm_struct.
*/
u16 get_mm_addr_key(struct mm_struct *mm, unsigned long address)
{
pte_t *ptep;
u16 pkey = 0;
unsigned long flags;
if (!mm || !mm->pgd)
return 0;
local_irq_save(flags);
ptep = find_linux_pte(mm->pgd, address, NULL, NULL);
if (ptep)
pkey = pte_to_pkey_bits(pte_val(READ_ONCE(*ptep)));
local_irq_restore(flags);
return pkey;
}
#endif /* CONFIG_PPC_MEM_KEYS */
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
static inline void tm_flush_hash_page(int local)
{