/*
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* Copyright IBM Corporation, 2013
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* Author Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of version 2.1 of the GNU Lesser General Public License
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*
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*/
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/*
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* PPC64 THP Support for hash based MMUs
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*/
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#include <linux/mm.h>
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#include <asm/machdep.h>
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int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
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pmd_t *pmdp, unsigned long trap, unsigned long flags,
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int ssize, unsigned int psize)
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{
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unsigned int index, valid;
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unsigned char *hpte_slot_array;
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unsigned long rflags, pa, hidx;
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unsigned long old_pmd, new_pmd;
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int ret, lpsize = MMU_PAGE_16M;
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unsigned long vpn, hash, shift, slot;
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/*
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* atomically mark the linux large page PMD busy and dirty
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*/
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do {
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pmd_t pmd = READ_ONCE(*pmdp);
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old_pmd = pmd_val(pmd);
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/* If PMD busy, retry the access */
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if (unlikely(old_pmd & H_PAGE_BUSY))
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return 0;
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/* If PMD permissions don't match, take page fault */
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if (unlikely(!check_pte_access(access, old_pmd)))
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return 1;
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/*
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* Try to lock the PTE, add ACCESSED and DIRTY if it was
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* a write access
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*/
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new_pmd = old_pmd | H_PAGE_BUSY | _PAGE_ACCESSED;
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if (access & _PAGE_WRITE)
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new_pmd |= _PAGE_DIRTY;
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} while (!pmd_xchg(pmdp, __pmd(old_pmd), __pmd(new_pmd)));
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/*
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* Make sure this is thp or devmap entry
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*/
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if (!(old_pmd & (H_PAGE_THP_HUGE | _PAGE_DEVMAP)))
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return 0;
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rflags = htab_convert_pte_flags(new_pmd);
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#if 0
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if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
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/*
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* No CPU has hugepages but lacks no execute, so we
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* don't need to worry about that case
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*/
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rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
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}
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#endif
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/*
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* Find the slot index details for this ea, using base page size.
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*/
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shift = mmu_psize_defs[psize].shift;
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index = (ea & ~HPAGE_PMD_MASK) >> shift;
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BUG_ON(index >= PTE_FRAG_SIZE);
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vpn = hpt_vpn(ea, vsid, ssize);
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hpte_slot_array = get_hpte_slot_array(pmdp);
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if (psize == MMU_PAGE_4K) {
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/*
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* invalidate the old hpte entry if we have that mapped via 64K
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* base page size. This is because demote_segment won't flush
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* hash page table entries.
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*/
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if ((old_pmd & H_PAGE_HASHPTE) && !(old_pmd & H_PAGE_COMBO)) {
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flush_hash_hugepage(vsid, ea, pmdp, MMU_PAGE_64K,
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ssize, flags);
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/*
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* With THP, we also clear the slot information with
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* respect to all the 64K hash pte mapping the 16MB
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* page. They are all invalid now. This make sure we
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* don't find the slot valid when we fault with 4k
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* base page size.
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*
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*/
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memset(hpte_slot_array, 0, PTE_FRAG_SIZE);
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}
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}
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valid = hpte_valid(hpte_slot_array, index);
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if (valid) {
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/* update the hpte bits */
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hash = hpt_hash(vpn, shift, ssize);
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hidx = hpte_hash_index(hpte_slot_array, index);
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if (hidx & _PTEIDX_SECONDARY)
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hash = ~hash;
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slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
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slot += hidx & _PTEIDX_GROUP_IX;
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ret = mmu_hash_ops.hpte_updatepp(slot, rflags, vpn,
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psize, lpsize, ssize, flags);
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/*
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* We failed to update, try to insert a new entry.
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*/
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if (ret == -1) {
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/*
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* large pte is marked busy, so we can be sure
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* nobody is looking at hpte_slot_array. hence we can
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* safely update this here.
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*/
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valid = 0;
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hpte_slot_array[index] = 0;
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}
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}
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if (!valid) {
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unsigned long hpte_group;
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hash = hpt_hash(vpn, shift, ssize);
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/* insert new entry */
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pa = pmd_pfn(__pmd(old_pmd)) << PAGE_SHIFT;
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new_pmd |= H_PAGE_HASHPTE;
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repeat:
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hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
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/* Insert into the hash table, primary slot */
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slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
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psize, lpsize, ssize);
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/*
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* Primary is full, try the secondary
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*/
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if (unlikely(slot == -1)) {
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hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
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slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
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rflags,
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HPTE_V_SECONDARY,
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psize, lpsize, ssize);
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if (slot == -1) {
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if (mftb() & 0x1)
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hpte_group = (hash & htab_hash_mask) *
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HPTES_PER_GROUP;
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mmu_hash_ops.hpte_remove(hpte_group);
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goto repeat;
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}
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}
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/*
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* Hypervisor failure. Restore old pmd and return -1
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* similar to __hash_page_*
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*/
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if (unlikely(slot == -2)) {
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*pmdp = __pmd(old_pmd);
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hash_failure_debug(ea, access, vsid, trap, ssize,
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psize, lpsize, old_pmd);
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return -1;
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}
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/*
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* large pte is marked busy, so we can be sure
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* nobody is looking at hpte_slot_array. hence we can
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* safely update this here.
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*/
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mark_hpte_slot_valid(hpte_slot_array, index, slot);
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}
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/*
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* Mark the pte with H_PAGE_COMBO, if we are trying to hash it with
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* base page size 4k.
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*/
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if (psize == MMU_PAGE_4K)
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new_pmd |= H_PAGE_COMBO;
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/*
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* The hpte valid is stored in the pgtable whose address is in the
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* second half of the PMD. Order this against clearing of the busy bit in
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* huge pmd.
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*/
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smp_wmb();
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*pmdp = __pmd(new_pmd & ~H_PAGE_BUSY);
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return 0;
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}
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