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/*
* Copyright IBM Corporation, 2015
* Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.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>
/*
* Return true, if the entry has a slot value which
* the software considers as invalid.
*/
static inline bool hpte_soft_invalid(unsigned long hidx)
{
return ((hidx & 0xfUL) == 0xfUL);
}
/*
* index from 0 - 15
*/
bool __rpte_sub_valid(real_pte_t rpte, unsigned long index)
{
return !(hpte_soft_invalid(__rpte_to_hidx(rpte, index)));
}
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 int subpg_index;
unsigned long rflags, pa;
unsigned long old_pte, new_pte, subpg_pte;
unsigned long vpn, hash, slot, gslot;
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 | H_PAGE_COMBO;
if (access & _PAGE_WRITE)
new_pte |= _PAGE_DIRTY;
} while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
/*
* Handle the subpage protection bits
*/
subpg_pte = new_pte & ~subpg_prot;
rflags = htab_convert_pte_flags(subpg_pte);
if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
/*
* No CPU has hugepages but lacks no execute, so we
* don't need to worry about that case
*/
rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
}
subpg_index = (ea & (PAGE_SIZE - 1)) >> shift;
vpn = hpt_vpn(ea, vsid, ssize);
rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
/*
*None of the sub 4k page is hashed
*/
if (!(old_pte & H_PAGE_HASHPTE))
goto htab_insert_hpte;
/*
* Check if the pte was already inserted into the hash table
* as a 64k HW page, and invalidate the 64k HPTE if so.
*/
if (!(old_pte & H_PAGE_COMBO)) {
flush_hash_page(vpn, rpte, MMU_PAGE_64K, ssize, flags);
/*
* clear the old slot details from the old and new pte.
* On hash insert failure we use old pte value and we don't
* want slot information there if we have a insert failure.
*/
old_pte &= ~H_PAGE_HASHPTE;
new_pte &= ~H_PAGE_HASHPTE;
goto htab_insert_hpte;
}
/*
* Check for sub page valid and update
*/
if (__rpte_sub_valid(rpte, subpg_index)) {
int ret;
gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte,
subpg_index);
ret = mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn,
MMU_PAGE_4K, MMU_PAGE_4K,
ssize, flags);
/*
* If we failed because typically the HPTE wasn't really here
* we try an insertion.
*/
if (ret == -1)
goto htab_insert_hpte;
*ptep = __pte(new_pte & ~H_PAGE_BUSY);
return 0;
}
htab_insert_hpte:
/*
* Initialize all hidx entries to invalid value, the first time
* the PTE is about to allocate a 4K HPTE.
*/
if (!(old_pte & H_PAGE_COMBO))
rpte.hidx = INVALID_RPTE_HIDX;
/*
* handle H_PAGE_4K_PFN case
*/
if (old_pte & H_PAGE_4K_PFN) {
/*
* All the sub 4k page have the same
* physical address.
*/
pa = pte_pfn(__pte(old_pte)) << HW_PAGE_SHIFT;
} else {
pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
pa += (subpg_index << 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)) {
bool soft_invalid;
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);
soft_invalid = hpte_soft_invalid(slot);
if (unlikely(soft_invalid)) {
/*
* We got a valid slot from a hardware point of view.
* but we cannot use it, because we use this special
* value; as defined by hpte_soft_invalid(), to track
* invalid slots. We cannot use it. So invalidate it.
*/
gslot = slot & _PTEIDX_GROUP_IX;
mmu_hash_ops.hpte_invalidate(hpte_group + gslot, vpn,
MMU_PAGE_4K, MMU_PAGE_4K,
ssize, 0);
}
if (unlikely(slot == -1 || soft_invalid)) {
/*
* For soft invalid slot, let's ensure that we release a
* slot from the primary, with the hope that we will
* acquire that slot next time we try. This will ensure
* that we do not get the same soft-invalid slot.
*/
if (soft_invalid || (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 |= pte_set_hidx(ptep, rpte, subpg_index, slot, PTRS_PER_PTE);
new_pte |= H_PAGE_HASHPTE;
*ptep = __pte(new_pte & ~H_PAGE_BUSY);
return 0;
}
int __hash_page_64K(unsigned long ea, unsigned long access,
unsigned long vsid, pte_t *ptep, unsigned long trap,
unsigned long flags, int ssize)
{
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_64K].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;
/*
* Check if PTE has the cache-inhibit bit set
* If so, bail out and refault as a 4k page
*/
if (!mmu_has_feature(MMU_FTR_CI_LARGE_PAGE) &&
unlikely(pte_ci(pte)))
return 0;
/*
* Try to lock the PTE, add ACCESSED and DIRTY if it was
* a write access.
*/
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)));
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)) {
unsigned long gslot;
/*
* There MIGHT be an HPTE for this pte
*/
gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0);
if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_64K,
MMU_PAGE_64K, 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_64K, MMU_PAGE_64K,
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_64K,
MMU_PAGE_64K, 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_64K, MMU_PAGE_64K, 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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