1/*
  2 * Copyright IBM Corporation, 2015
  3 * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
  4 *
  5 * This program is free software; you can redistribute it and/or modify it
  6 * under the terms of version 2 of the GNU Lesser General Public License
  7 * as published by the Free Software Foundation.
  8 *
  9 * This program is distributed in the hope that it would be useful, but
 10 * WITHOUT ANY WARRANTY; without even the implied warranty of
 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 12 *
 13 */
 14
 15#include <linux/mm.h>
 16#include <asm/machdep.h>
 17#include <asm/mmu.h>
 18
 19int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
 20		   pte_t *ptep, unsigned long trap, unsigned long flags,
 21		   int ssize, int subpg_prot)
 22{
 23	unsigned long hpte_group;
 24	unsigned long rflags, pa;
 25	unsigned long old_pte, new_pte;
 26	unsigned long vpn, hash, slot;
 27	unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
 28
 29	/*
 30	 * atomically mark the linux large page PTE busy and dirty
 31	 */
 32	do {
 33		pte_t pte = READ_ONCE(*ptep);
 34
 35		old_pte = pte_val(pte);
 36		/* If PTE busy, retry the access */
 37		if (unlikely(old_pte & _PAGE_BUSY))
 38			return 0;
 39		/* If PTE permissions don't match, take page fault */
 40		if (unlikely(access & ~old_pte))
 41			return 1;
 42		/*
 43		 * Try to lock the PTE, add ACCESSED and DIRTY if it was
 44		 * a write access. Since this is 4K insert of 64K page size
 45		 * also add _PAGE_COMBO
 46		 */
 47		new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED;
 48		if (access & _PAGE_RW)
 49			new_pte |= _PAGE_DIRTY;
 50	} while (old_pte != __cmpxchg_u64((unsigned long *)ptep,
 51					  old_pte, new_pte));
 52	/*
 53	 * PP bits. _PAGE_USER is already PP bit 0x2, so we only
 54	 * need to add in 0x1 if it's a read-only user page
 55	 */
 56	rflags = htab_convert_pte_flags(new_pte);
 57
 58	if (!cpu_has_feature(CPU_FTR_NOEXECUTE) &&
 59	    !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
 60		rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
 61
 62	vpn  = hpt_vpn(ea, vsid, ssize);
 63	if (unlikely(old_pte & _PAGE_HASHPTE)) {
 64		/*
 65		 * There MIGHT be an HPTE for this pte
 66		 */
 67		hash = hpt_hash(vpn, shift, ssize);
 68		if (old_pte & _PAGE_F_SECOND)
 69			hash = ~hash;
 70		slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 71		slot += (old_pte & _PAGE_F_GIX) >> _PAGE_F_GIX_SHIFT;
 72
 73		if (ppc_md.hpte_updatepp(slot, rflags, vpn, MMU_PAGE_4K,
 74					 MMU_PAGE_4K, ssize, flags) == -1)
 75			old_pte &= ~_PAGE_HPTEFLAGS;
 76	}
 77
 78	if (likely(!(old_pte & _PAGE_HASHPTE))) {
 79
 80		pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
 81		hash = hpt_hash(vpn, shift, ssize);
 82
 83repeat:
 84		hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 85
 86		/* Insert into the hash table, primary slot */
 87		slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
 88				  MMU_PAGE_4K, MMU_PAGE_4K, ssize);
 89		/*
 90		 * Primary is full, try the secondary
 91		 */
 92		if (unlikely(slot == -1)) {
 93			hpte_group = ((~hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 94			slot = ppc_md.hpte_insert(hpte_group, vpn, pa,
 95						  rflags, HPTE_V_SECONDARY,
 96						  MMU_PAGE_4K, MMU_PAGE_4K, ssize);
 97			if (slot == -1) {
 98				if (mftb() & 0x1)
 99					hpte_group = ((hash & htab_hash_mask) *
100						      HPTES_PER_GROUP) & ~0x7UL;
101				ppc_md.hpte_remove(hpte_group);
102				/*
103				 * FIXME!! Should be try the group from which we removed ?
104				 */
105				goto repeat;
106			}
107		}
108		/*
109		 * Hypervisor failure. Restore old pte and return -1
110		 * similar to __hash_page_*
111		 */
112		if (unlikely(slot == -2)) {
113			*ptep = __pte(old_pte);
114			hash_failure_debug(ea, access, vsid, trap, ssize,
115					   MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
116			return -1;
117		}
118		new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | _PAGE_HASHPTE;
119		new_pte |= (slot << _PAGE_F_GIX_SHIFT) & (_PAGE_F_SECOND | _PAGE_F_GIX);
120	}
121	*ptep = __pte(new_pte & ~_PAGE_BUSY);
122	return 0;
123}