LXR linux/arch/powerpc/mm/hugetlbpage-hash64.c

   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
  18extern 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
  22int __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}
 120