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