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/*
* Copyright IBM Corporation, 2015
* Author Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of version 2 of the GNU Lesser General Public License
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*
*/
#include <linux/mm.h>
#include <asm/machdep.h>
#include <asm/mmu.h>
int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
pte_t *ptep, unsigned long trap, unsigned long flags,
int ssize, int subpg_prot)
{
real_pte_t rpte;
unsigned long hpte_group;
unsigned long rflags, pa;
unsigned long old_pte, new_pte;
unsigned long vpn, hash, slot;
unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
/*
* atomically mark the linux large page PTE busy and dirty
*/
do {
pte_t pte = READ_ONCE(*ptep);
old_pte = pte_val(pte);
/* If PTE busy, retry the access */
if (unlikely(old_pte & H_PAGE_BUSY))
return 0;
/* If PTE permissions don't match, take page fault */
if (unlikely(!check_pte_access(access, old_pte)))
return 1;
/*
* Try to lock the PTE, add ACCESSED and DIRTY if it was
* a write access. Since this is 4K insert of 64K page size
* also add H_PAGE_COMBO
*/
new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
if (access & _PAGE_WRITE)
new_pte |= _PAGE_DIRTY;
} while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
/*
* PP bits. _PAGE_USER is already PP bit 0x2, so we only
* need to add in 0x1 if it's a read-only user page
*/
rflags = htab_convert_pte_flags(new_pte);
rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
!cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
vpn = hpt_vpn(ea, vsid, ssize);
if (unlikely(old_pte & H_PAGE_HASHPTE)) {
/*
* There MIGHT be an HPTE for this pte
*/
unsigned long gslot = pte_get_hash_gslot(vpn, shift, ssize,
rpte, 0);
if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_4K,
MMU_PAGE_4K, ssize, flags) == -1)
old_pte &= ~_PAGE_HPTEFLAGS;
}
if (likely(!(old_pte & H_PAGE_HASHPTE))) {
pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
hash = hpt_hash(vpn, shift, ssize);
repeat:
hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
/* Insert into the hash table, primary slot */
slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
MMU_PAGE_4K, MMU_PAGE_4K, ssize);
/*
* Primary is full, try the secondary
*/
if (unlikely(slot == -1)) {
hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
rflags,
HPTE_V_SECONDARY,
MMU_PAGE_4K,
MMU_PAGE_4K, ssize);
if (slot == -1) {
if (mftb() & 0x1)
hpte_group = (hash & htab_hash_mask) *
HPTES_PER_GROUP;
mmu_hash_ops.hpte_remove(hpte_group);
/*
* FIXME!! Should be try the group from which we removed ?
*/
goto repeat;
}
}
/*
* Hypervisor failure. Restore old pte and return -1
* similar to __hash_page_*
*/
if (unlikely(slot == -2)) {
*ptep = __pte(old_pte);
hash_failure_debug(ea, access, vsid, trap, ssize,
MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
return -1;
}
new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
new_pte |= pte_set_hidx(ptep, rpte, 0, slot, PTRS_PER_PTE);
}
*ptep = __pte(new_pte & ~H_PAGE_BUSY);
return 0;
}
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