hash_4k.c

  1/*
  2 * Copyright IBM Corporation, 2015
  3 * Author Aneesh Kumar K.V <aneesh.kumar@linux.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
 19#include "internal.h"
 20
 21int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
 22		   pte_t *ptep, unsigned long trap, unsigned long flags,
 23		   int ssize, int subpg_prot)
 24{
 25	real_pte_t rpte;
 26	unsigned long hpte_group;
 27	unsigned long rflags, pa;
 28	unsigned long old_pte, new_pte;
 29	unsigned long vpn, hash, slot;
 30	unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
 31
 32	/*
 33	 * atomically mark the linux large page PTE busy and dirty
 34	 */
 35	do {
 36		pte_t pte = READ_ONCE(*ptep);
 37
 38		old_pte = pte_val(pte);
 39		/* If PTE busy, retry the access */
 40		if (unlikely(old_pte & H_PAGE_BUSY))
 41			return 0;
 42		/* If PTE permissions don't match, take page fault */
 43		if (unlikely(!check_pte_access(access, old_pte)))
 44			return 1;
 45		/*
 46		 * Try to lock the PTE, add ACCESSED and DIRTY if it was
 47		 * a write access. Since this is 4K insert of 64K page size
 48		 * also add H_PAGE_COMBO
 49		 */
 50		new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
 51		if (access & _PAGE_WRITE)
 52			new_pte |= _PAGE_DIRTY;
 53	} while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
 54
 55	/*
 56	 * PP bits. _PAGE_USER is already PP bit 0x2, so we only
 57	 * need to add in 0x1 if it's a read-only user page
 58	 */
 59	rflags = htab_convert_pte_flags(new_pte, flags);
 60	rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
 61
 62	if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
 63	    !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
 64		rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
 65
 66	vpn  = hpt_vpn(ea, vsid, ssize);
 67	if (unlikely(old_pte & H_PAGE_HASHPTE)) {
 68		/*
 69		 * There MIGHT be an HPTE for this pte
 70		 */
 71		unsigned long gslot = pte_get_hash_gslot(vpn, shift, ssize,
 72							 rpte, 0);
 73
 74		if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_4K,
 75					       MMU_PAGE_4K, ssize, flags) == -1)
 76			old_pte &= ~_PAGE_HPTEFLAGS;
 77	}
 78
 79	if (likely(!(old_pte & H_PAGE_HASHPTE))) {
 80
 81		pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
 82		hash = hpt_hash(vpn, shift, ssize);
 83
 84repeat:
 85		hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 86
 87		/* Insert into the hash table, primary slot */
 88		slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
 89						MMU_PAGE_4K, MMU_PAGE_4K, ssize);
 90		/*
 91		 * Primary is full, try the secondary
 92		 */
 93		if (unlikely(slot == -1)) {
 94			hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
 95			slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
 96							rflags,
 97							HPTE_V_SECONDARY,
 98							MMU_PAGE_4K,
 99							MMU_PAGE_4K, ssize);
100			if (slot == -1) {
101				if (mftb() & 0x1)
102					hpte_group = (hash & htab_hash_mask) *
103							HPTES_PER_GROUP;
104				mmu_hash_ops.hpte_remove(hpte_group);
105				/*
106				 * FIXME!! Should be try the group from which we removed ?
107				 */
108				goto repeat;
109			}
110		}
111		/*
112		 * Hypervisor failure. Restore old pte and return -1
113		 * similar to __hash_page_*
114		 */
115		if (unlikely(slot == -2)) {
116			*ptep = __pte(old_pte);
117			hash_failure_debug(ea, access, vsid, trap, ssize,
118					   MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
119			return -1;
120		}
121		new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
122		new_pte |= pte_set_hidx(ptep, rpte, 0, slot, PTRS_PER_PTE);
123
124		if (stress_hpt())
125			hpt_do_stress(ea, hpte_group);
126	}
127	*ptep = __pte(new_pte & ~H_PAGE_BUSY);
128	return 0;
129}