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// SPDX-License-Identifier: GPL-2.0
/*
* PPC64 Huge TLB Page Support for hash based MMUs (POWER4 and later)
*
* Copyright (C) 2003 David Gibson, IBM Corporation.
*
* Based on the IA-32 version:
* Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
*/
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/cacheflush.h>
#include <asm/machdep.h>
extern long hpte_insert_repeating(unsigned long hash, unsigned long vpn,
unsigned long pa, unsigned long rlags,
unsigned long vflags, int psize, int ssize);
int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
pte_t *ptep, unsigned long trap, unsigned long flags,
int ssize, unsigned int shift, unsigned int mmu_psize)
{
real_pte_t rpte;
unsigned long vpn;
unsigned long old_pte, new_pte;
unsigned long rflags, pa;
long slot, offset;
BUG_ON(shift != mmu_psize_defs[mmu_psize].shift);
/* Search the Linux page table for a match with va */
vpn = hpt_vpn(ea, vsid, ssize);
/* At this point, we have a pte (old_pte) which can be used to build
* or update an HPTE. There are 2 cases:
*
* 1. There is a valid (present) pte with no associated HPTE (this is
* the most common case)
* 2. There is a valid (present) pte with an associated HPTE. The
* current values of the pp bits in the HPTE prevent access
* because we are doing software DIRTY bit management and the
* page is currently not DIRTY.
*/
do {
old_pte = pte_val(*ptep);
/* If PTE busy, retry the access */
if (unlikely(old_pte & H_PAGE_BUSY))
return 0;
/* If PTE permissions don't match, take page fault */
if (unlikely(!check_pte_access(access, old_pte)))
return 1;
/* Try to lock the PTE, add ACCESSED and DIRTY if it was
* a write access */
new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
if (access & _PAGE_WRITE)
new_pte |= _PAGE_DIRTY;
} while(!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
/* Make sure this is a hugetlb entry */
if (old_pte & (H_PAGE_THP_HUGE | _PAGE_DEVMAP))
return 0;
rflags = htab_convert_pte_flags(new_pte);
if (unlikely(mmu_psize == MMU_PAGE_16G))
offset = PTRS_PER_PUD;
else
offset = PTRS_PER_PMD;
rpte = __real_pte(__pte(old_pte), ptep, offset);
if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
/* No CPU has hugepages but lacks no execute, so we
* don't need to worry about that case */
rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
/* Check if pte already has an hpte (case 2) */
if (unlikely(old_pte & H_PAGE_HASHPTE)) {
/* There MIGHT be an HPTE for this pte */
unsigned long gslot;
gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0);
if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, mmu_psize,
mmu_psize, ssize, flags) == -1)
old_pte &= ~_PAGE_HPTEFLAGS;
}
if (likely(!(old_pte & H_PAGE_HASHPTE))) {
unsigned long hash = hpt_hash(vpn, shift, ssize);
pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
/* clear HPTE slot informations in new PTE */
new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
slot = hpte_insert_repeating(hash, vpn, pa, rflags, 0,
mmu_psize, ssize);
/*
* Hypervisor failure. Restore old pte and return -1
* similar to __hash_page_*
*/
if (unlikely(slot == -2)) {
*ptep = __pte(old_pte);
hash_failure_debug(ea, access, vsid, trap, ssize,
mmu_psize, mmu_psize, old_pte);
return -1;
}
new_pte |= pte_set_hidx(ptep, rpte, 0, slot, offset);
}
/*
* No need to use ldarx/stdcx here
*/
*ptep = __pte(new_pte & ~H_PAGE_BUSY);
return 0;
}
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