| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 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/pgtable.h> |
| 14 | #include <asm/pgalloc.h> |
| 15 | #include <asm/cacheflush.h> |
| 16 | #include <asm/machdep.h> |
| 17 | |
| 18 | extern long hpte_insert_repeating(unsigned long hash, unsigned long vpn, |
| 19 | unsigned long pa, unsigned long rlags, |
| 20 | unsigned long vflags, int psize, int ssize); |
| 21 | |
| 22 | int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid, |
| 23 | pte_t *ptep, unsigned long trap, unsigned long flags, |
| 24 | int ssize, unsigned int shift, unsigned int mmu_psize) |
| 25 | { |
| 26 | real_pte_t rpte; |
| 27 | unsigned long vpn; |
| 28 | unsigned long old_pte, new_pte; |
| 29 | unsigned long rflags, pa, sz; |
| 30 | long slot, offset; |
| 31 | |
| 32 | BUG_ON(shift != mmu_psize_defs[mmu_psize].shift); |
| 33 | |
| 34 | /* Search the Linux page table for a match with va */ |
| 35 | vpn = hpt_vpn(ea, vsid, ssize); |
| 36 | |
| 37 | /* At this point, we have a pte (old_pte) which can be used to build |
| 38 | * or update an HPTE. There are 2 cases: |
| 39 | * |
| 40 | * 1. There is a valid (present) pte with no associated HPTE (this is |
| 41 | * the most common case) |
| 42 | * 2. There is a valid (present) pte with an associated HPTE. The |
| 43 | * current values of the pp bits in the HPTE prevent access |
| 44 | * because we are doing software DIRTY bit management and the |
| 45 | * page is currently not DIRTY. |
| 46 | */ |
| 47 | |
| 48 | |
| 49 | do { |
| 50 | old_pte = pte_val(*ptep); |
| 51 | /* If PTE busy, retry the access */ |
| 52 | if (unlikely(old_pte & H_PAGE_BUSY)) |
| 53 | return 0; |
| 54 | /* If PTE permissions don't match, take page fault */ |
| 55 | if (unlikely(!check_pte_access(access, old_pte))) |
| 56 | return 1; |
| 57 | |
| 58 | /* Try to lock the PTE, add ACCESSED and DIRTY if it was |
| 59 | * a write access */ |
| 60 | new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED; |
| 61 | if (access & _PAGE_WRITE) |
| 62 | new_pte |= _PAGE_DIRTY; |
| 63 | } while(!pte_xchg(ptep, __pte(old_pte), __pte(new_pte))); |
| 64 | |
| 65 | rflags = htab_convert_pte_flags(new_pte); |
| 66 | if (unlikely(mmu_psize == MMU_PAGE_16G)) |
| 67 | offset = PTRS_PER_PUD; |
| 68 | else |
| 69 | offset = PTRS_PER_PMD; |
| 70 | rpte = __real_pte(__pte(old_pte), ptep, offset); |
| 71 | |
| 72 | sz = ((1UL) << shift); |
| 73 | if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) |
| 74 | /* No CPU has hugepages but lacks no execute, so we |
| 75 | * don't need to worry about that case */ |
| 76 | rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap); |
| 77 | |
| 78 | /* Check if pte already has an hpte (case 2) */ |
| 79 | if (unlikely(old_pte & H_PAGE_HASHPTE)) { |
| 80 | /* There MIGHT be an HPTE for this pte */ |
| 81 | unsigned long gslot; |
| 82 | |
| 83 | gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0); |
| 84 | if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, mmu_psize, |
| 85 | mmu_psize, ssize, flags) == -1) |
| 86 | old_pte &= ~_PAGE_HPTEFLAGS; |
| 87 | } |
| 88 | |
| 89 | if (likely(!(old_pte & H_PAGE_HASHPTE))) { |
| 90 | unsigned long hash = hpt_hash(vpn, shift, ssize); |
| 91 | |
| 92 | pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT; |
| 93 | |
| 94 | /* clear HPTE slot informations in new PTE */ |
| 95 | new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE; |
| 96 | |
| 97 | slot = hpte_insert_repeating(hash, vpn, pa, rflags, 0, |
| 98 | mmu_psize, ssize); |
| 99 | |
| 100 | /* |
| 101 | * Hypervisor failure. Restore old pte and return -1 |
| 102 | * similar to __hash_page_* |
| 103 | */ |
| 104 | if (unlikely(slot == -2)) { |
| 105 | *ptep = __pte(old_pte); |
| 106 | hash_failure_debug(ea, access, vsid, trap, ssize, |
| 107 | mmu_psize, mmu_psize, old_pte); |
| 108 | return -1; |
| 109 | } |
| 110 | |
| 111 | new_pte |= pte_set_hidx(ptep, rpte, 0, slot, offset); |
| 112 | } |
| 113 | |
| 114 | /* |
| 115 | * No need to use ldarx/stdcx here |
| 116 | */ |
| 117 | *ptep = __pte(new_pte & ~H_PAGE_BUSY); |
| 118 | return 0; |
| 119 | } |