1 // SPDX-License-Identifier: GPL-2.0
3 * PPC64 Huge TLB Page Support for hash based MMUs (POWER4 and later)
5 * Copyright (C) 2003 David Gibson, IBM Corporation.
7 * Based on the IA-32 version:
8 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
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>
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);
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)
28 unsigned long old_pte, new_pte;
29 unsigned long rflags, pa, sz;
32 BUG_ON(shift != mmu_psize_defs[mmu_psize].shift);
34 /* Search the Linux page table for a match with va */
35 vpn = hpt_vpn(ea, vsid, ssize);
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:
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.
50 old_pte = pte_val(*ptep);
51 /* If PTE busy, retry the access */
52 if (unlikely(old_pte & H_PAGE_BUSY))
54 /* If PTE permissions don't match, take page fault */
55 if (unlikely(!check_pte_access(access, old_pte)))
58 /* Try to lock the PTE, add ACCESSED and DIRTY if it was
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)));
65 rflags = htab_convert_pte_flags(new_pte);
66 rpte = __real_pte(__pte(old_pte), ptep);
68 sz = ((1UL) << shift);
69 if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
70 /* No CPU has hugepages but lacks no execute, so we
71 * don't need to worry about that case */
72 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
74 /* Check if pte already has an hpte (case 2) */
75 if (unlikely(old_pte & H_PAGE_HASHPTE)) {
76 /* There MIGHT be an HPTE for this pte */
79 gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0);
80 if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, mmu_psize,
81 mmu_psize, ssize, flags) == -1)
82 old_pte &= ~_PAGE_HPTEFLAGS;
85 if (likely(!(old_pte & H_PAGE_HASHPTE))) {
86 unsigned long hash = hpt_hash(vpn, shift, ssize);
88 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
90 /* clear HPTE slot informations in new PTE */
91 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
93 slot = hpte_insert_repeating(hash, vpn, pa, rflags, 0,
97 * Hypervisor failure. Restore old pte and return -1
98 * similar to __hash_page_*
100 if (unlikely(slot == -2)) {
101 *ptep = __pte(old_pte);
102 hash_failure_debug(ea, access, vsid, trap, ssize,
103 mmu_psize, mmu_psize, old_pte);
107 new_pte |= pte_set_hidx(ptep, rpte, 0, slot);
111 * No need to use ldarx/stdcx here
113 *ptep = __pte(new_pte & ~H_PAGE_BUSY);