1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * PPC64 Huge TLB Page Support for hash based MMUs (POWER4 and later) 4 * 5 * Copyright (C) 2003 David Gibson, IBM Corporation. 6 * 7 * Based on the IA-32 version: 8 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com> 9 */ 10 11 #include <linux/mm.h> 12 #include <linux/hugetlb.h> 13 #include <asm/cacheflush.h> 14 #include <asm/machdep.h> 15 16 unsigned int hpage_shift; 17 EXPORT_SYMBOL(hpage_shift); 18 19 #ifdef CONFIG_PPC_64S_HASH_MMU 20 int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid, 21 pte_t *ptep, unsigned long trap, unsigned long flags, 22 int ssize, unsigned int shift, unsigned int mmu_psize) 23 { 24 real_pte_t rpte; 25 unsigned long vpn; 26 unsigned long old_pte, new_pte; 27 unsigned long rflags, pa; 28 long slot, offset; 29 30 BUG_ON(shift != mmu_psize_defs[mmu_psize].shift); 31 32 /* Search the Linux page table for a match with va */ 33 vpn = hpt_vpn(ea, vsid, ssize); 34 35 /* 36 * At this point, we have a pte (old_pte) which can be used to build 37 * or update an HPTE. There are 2 cases: 38 * 39 * 1. There is a valid (present) pte with no associated HPTE (this is 40 * the most common case) 41 * 2. There is a valid (present) pte with an associated HPTE. The 42 * current values of the pp bits in the HPTE prevent access 43 * because we are doing software DIRTY bit management and the 44 * page is currently not DIRTY. 45 */ 46 47 48 do { 49 old_pte = pte_val(*ptep); 50 /* If PTE busy, retry the access */ 51 if (unlikely(old_pte & H_PAGE_BUSY)) 52 return 0; 53 /* If PTE permissions don't match, take page fault */ 54 if (unlikely(!check_pte_access(access, old_pte))) 55 return 1; 56 57 /* 58 * Try to lock the PTE, add ACCESSED and DIRTY if it was 59 * a write access 60 */ 61 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED; 62 if (access & _PAGE_WRITE) 63 new_pte |= _PAGE_DIRTY; 64 } while(!pte_xchg(ptep, __pte(old_pte), __pte(new_pte))); 65 66 /* Make sure this is a hugetlb entry */ 67 if (old_pte & (H_PAGE_THP_HUGE | _PAGE_DEVMAP)) 68 return 0; 69 70 rflags = htab_convert_pte_flags(new_pte, flags); 71 if (unlikely(mmu_psize == MMU_PAGE_16G)) 72 offset = PTRS_PER_PUD; 73 else 74 offset = PTRS_PER_PMD; 75 rpte = __real_pte(__pte(old_pte), ptep, offset); 76 77 if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) 78 /* 79 * No CPU has hugepages but lacks no execute, so we 80 * don't need to worry about that case 81 */ 82 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap); 83 84 /* Check if pte already has an hpte (case 2) */ 85 if (unlikely(old_pte & H_PAGE_HASHPTE)) { 86 /* There MIGHT be an HPTE for this pte */ 87 unsigned long gslot; 88 89 gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0); 90 if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, mmu_psize, 91 mmu_psize, ssize, flags) == -1) 92 old_pte &= ~_PAGE_HPTEFLAGS; 93 } 94 95 if (likely(!(old_pte & H_PAGE_HASHPTE))) { 96 unsigned long hash = hpt_hash(vpn, shift, ssize); 97 98 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT; 99 100 /* clear HPTE slot informations in new PTE */ 101 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE; 102 103 slot = hpte_insert_repeating(hash, vpn, pa, rflags, 0, 104 mmu_psize, ssize); 105 106 /* 107 * Hypervisor failure. Restore old pte and return -1 108 * similar to __hash_page_* 109 */ 110 if (unlikely(slot == -2)) { 111 *ptep = __pte(old_pte); 112 hash_failure_debug(ea, access, vsid, trap, ssize, 113 mmu_psize, mmu_psize, old_pte); 114 return -1; 115 } 116 117 new_pte |= pte_set_hidx(ptep, rpte, 0, slot, offset); 118 } 119 120 /* 121 * No need to use ldarx/stdcx here 122 */ 123 *ptep = __pte(new_pte & ~H_PAGE_BUSY); 124 return 0; 125 } 126 #endif 127 128 pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma, 129 unsigned long addr, pte_t *ptep) 130 { 131 unsigned long pte_val; 132 /* 133 * Clear the _PAGE_PRESENT so that no hardware parallel update is 134 * possible. Also keep the pte_present true so that we don't take 135 * wrong fault. 136 */ 137 pte_val = pte_update(vma->vm_mm, addr, ptep, 138 _PAGE_PRESENT, _PAGE_INVALID, 1); 139 140 return __pte(pte_val); 141 } 142 143 void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, 144 pte_t *ptep, pte_t old_pte, pte_t pte) 145 { 146 147 if (radix_enabled()) 148 return radix__huge_ptep_modify_prot_commit(vma, addr, ptep, 149 old_pte, pte); 150 set_huge_pte_at(vma->vm_mm, addr, ptep, pte); 151 } 152 153 void __init hugetlbpage_init_default(void) 154 { 155 /* Set default large page size. Currently, we pick 16M or 1M 156 * depending on what is available 157 */ 158 if (mmu_psize_defs[MMU_PAGE_16M].shift) 159 hpage_shift = mmu_psize_defs[MMU_PAGE_16M].shift; 160 else if (mmu_psize_defs[MMU_PAGE_1M].shift) 161 hpage_shift = mmu_psize_defs[MMU_PAGE_1M].shift; 162 else if (mmu_psize_defs[MMU_PAGE_2M].shift) 163 hpage_shift = mmu_psize_defs[MMU_PAGE_2M].shift; 164 } 165