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/*
* Copyright IBM Corporation, 2013
* 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 2.1 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.
*
*/
/*
* PPC64 THP Support for hash based MMUs
*/
#include <linux/mm.h>
#include <asm/machdep.h>
int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
pmd_t *pmdp, unsigned long trap, unsigned long flags,
int ssize, unsigned int psize)
{
unsigned int index, valid;
unsigned char *hpte_slot_array;
unsigned long rflags, pa, hidx;
unsigned long old_pmd, new_pmd;
int ret, lpsize = MMU_PAGE_16M;
unsigned long vpn, hash, shift, slot;
/*
* atomically mark the linux large page PMD busy and dirty
*/
do {
pmd_t pmd = ACCESS_ONCE(*pmdp);
old_pmd = pmd_val(pmd);
/* If PMD busy, retry the access */
if (unlikely(old_pmd & _PAGE_BUSY))
return 0;
/* If PMD is trans splitting retry the access */
if (unlikely(old_pmd & _PAGE_SPLITTING))
return 0;
/* If PMD permissions don't match, take page fault */
if (unlikely(access & ~old_pmd))
return 1;
/*
* Try to lock the PTE, add ACCESSED and DIRTY if it was
* a write access
*/
new_pmd = old_pmd | _PAGE_BUSY | _PAGE_ACCESSED;
if (access & _PAGE_RW)
new_pmd |= _PAGE_DIRTY;
} while (old_pmd != __cmpxchg_u64((unsigned long *)pmdp,
old_pmd, new_pmd));
/*
* 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 = new_pmd & _PAGE_USER;
if ((new_pmd & _PAGE_USER) && !((new_pmd & _PAGE_RW) &&
(new_pmd & _PAGE_DIRTY)))
rflags |= 0x1;
/*
* _PAGE_EXEC -> HW_NO_EXEC since it's inverted
*/
rflags |= ((new_pmd & _PAGE_EXEC) ? 0 : HPTE_R_N);
#if 0
if (!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);
}
#endif
/*
* Find the slot index details for this ea, using base page size.
*/
shift = mmu_psize_defs[psize].shift;
index = (ea & ~HPAGE_PMD_MASK) >> shift;
BUG_ON(index >= 4096);
vpn = hpt_vpn(ea, vsid, ssize);
hash = hpt_hash(vpn, shift, ssize);
hpte_slot_array = get_hpte_slot_array(pmdp);
if (psize == MMU_PAGE_4K) {
/*
* invalidate the old hpte entry if we have that mapped via 64K
* base page size. This is because demote_segment won't flush
* hash page table entries.
*/
if ((old_pmd & _PAGE_HASHPTE) && !(old_pmd & _PAGE_COMBO))
flush_hash_hugepage(vsid, ea, pmdp, MMU_PAGE_64K,
ssize, flags);
}
valid = hpte_valid(hpte_slot_array, index);
if (valid) {
/* update the hpte bits */
hidx = hpte_hash_index(hpte_slot_array, index);
if (hidx & _PTEIDX_SECONDARY)
hash = ~hash;
slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
slot += hidx & _PTEIDX_GROUP_IX;
ret = ppc_md.hpte_updatepp(slot, rflags, vpn,
psize, lpsize, ssize, flags);
/*
* We failed to update, try to insert a new entry.
*/
if (ret == -1) {
/*
* large pte is marked busy, so we can be sure
* nobody is looking at hpte_slot_array. hence we can
* safely update this here.
*/
valid = 0;
hpte_slot_array[index] = 0;
}
}
if (!valid) {
unsigned long hpte_group;
/* insert new entry */
pa = pmd_pfn(__pmd(old_pmd)) << PAGE_SHIFT;
new_pmd |= _PAGE_HASHPTE;
/* Add in WIMG bits */
rflags |= (new_pmd & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
_PAGE_GUARDED));
/*
* enable the memory coherence always
*/
rflags |= HPTE_R_M;
repeat:
hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
/* Insert into the hash table, primary slot */
slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
psize, lpsize, ssize);
/*
* Primary is full, try the secondary
*/
if (unlikely(slot == -1)) {
hpte_group = ((~hash & htab_hash_mask) *
HPTES_PER_GROUP) & ~0x7UL;
slot = ppc_md.hpte_insert(hpte_group, vpn, pa,
rflags, HPTE_V_SECONDARY,
psize, lpsize, ssize);
if (slot == -1) {
if (mftb() & 0x1)
hpte_group = ((hash & htab_hash_mask) *
HPTES_PER_GROUP) & ~0x7UL;
ppc_md.hpte_remove(hpte_group);
goto repeat;
}
}
/*
* Hypervisor failure. Restore old pmd and return -1
* similar to __hash_page_*
*/
if (unlikely(slot == -2)) {
*pmdp = __pmd(old_pmd);
hash_failure_debug(ea, access, vsid, trap, ssize,
psize, lpsize, old_pmd);
return -1;
}
/*
* large pte is marked busy, so we can be sure
* nobody is looking at hpte_slot_array. hence we can
* safely update this here.
*/
mark_hpte_slot_valid(hpte_slot_array, index, slot);
}
/*
* Mark the pte with _PAGE_COMBO, if we are trying to hash it with
* base page size 4k.
*/
if (psize == MMU_PAGE_4K)
new_pmd |= _PAGE_COMBO;
/*
* The hpte valid is stored in the pgtable whose address is in the
* second half of the PMD. Order this against clearing of the busy bit in
* huge pmd.
*/
smp_wmb();
*pmdp = __pmd(new_pmd & ~_PAGE_BUSY);
return 0;
}
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