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We would get wrong results in compiler recomputed old_pmd. Avoid that by using ACCESS_ONCE CC: <stable@vger.kernel.org> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
246 lines
6.7 KiB
C
246 lines
6.7 KiB
C
/*
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* Copyright IBM Corporation, 2013
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* Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of version 2.1 of the GNU Lesser General Public License
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*
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*/
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/*
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* PPC64 THP Support for hash based MMUs
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*/
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#include <linux/mm.h>
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#include <asm/machdep.h>
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static void invalidate_old_hpte(unsigned long vsid, unsigned long addr,
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pmd_t *pmdp, unsigned int psize, int ssize)
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{
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int i, max_hpte_count, valid;
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unsigned long s_addr;
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unsigned char *hpte_slot_array;
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unsigned long hidx, shift, vpn, hash, slot;
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s_addr = addr & HPAGE_PMD_MASK;
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hpte_slot_array = get_hpte_slot_array(pmdp);
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/*
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* IF we try to do a HUGE PTE update after a withdraw is done.
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* we will find the below NULL. This happens when we do
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* split_huge_page_pmd
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*/
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if (!hpte_slot_array)
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return;
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if (ppc_md.hugepage_invalidate)
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return ppc_md.hugepage_invalidate(vsid, s_addr, hpte_slot_array,
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psize, ssize);
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/*
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* No bluk hpte removal support, invalidate each entry
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*/
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shift = mmu_psize_defs[psize].shift;
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max_hpte_count = HPAGE_PMD_SIZE >> shift;
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for (i = 0; i < max_hpte_count; i++) {
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/*
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* 8 bits per each hpte entries
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* 000| [ secondary group (one bit) | hidx (3 bits) | valid bit]
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*/
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valid = hpte_valid(hpte_slot_array, i);
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if (!valid)
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continue;
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hidx = hpte_hash_index(hpte_slot_array, i);
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/* get the vpn */
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addr = s_addr + (i * (1ul << shift));
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vpn = hpt_vpn(addr, vsid, ssize);
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hash = hpt_hash(vpn, shift, ssize);
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if (hidx & _PTEIDX_SECONDARY)
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hash = ~hash;
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slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
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slot += hidx & _PTEIDX_GROUP_IX;
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ppc_md.hpte_invalidate(slot, vpn, psize,
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MMU_PAGE_16M, ssize, 0);
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}
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}
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int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
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pmd_t *pmdp, unsigned long trap, int local, int ssize,
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unsigned int psize)
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{
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unsigned int index, valid;
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unsigned char *hpte_slot_array;
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unsigned long rflags, pa, hidx;
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unsigned long old_pmd, new_pmd;
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int ret, lpsize = MMU_PAGE_16M;
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unsigned long vpn, hash, shift, slot;
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/*
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* atomically mark the linux large page PMD busy and dirty
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*/
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do {
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pmd_t pmd = ACCESS_ONCE(*pmdp);
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old_pmd = pmd_val(pmd);
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/* If PMD busy, retry the access */
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if (unlikely(old_pmd & _PAGE_BUSY))
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return 0;
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/* If PMD is trans splitting retry the access */
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if (unlikely(old_pmd & _PAGE_SPLITTING))
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return 0;
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/* If PMD permissions don't match, take page fault */
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if (unlikely(access & ~old_pmd))
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return 1;
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/*
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* Try to lock the PTE, add ACCESSED and DIRTY if it was
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* a write access
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*/
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new_pmd = old_pmd | _PAGE_BUSY | _PAGE_ACCESSED;
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if (access & _PAGE_RW)
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new_pmd |= _PAGE_DIRTY;
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} while (old_pmd != __cmpxchg_u64((unsigned long *)pmdp,
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old_pmd, new_pmd));
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/*
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* PP bits. _PAGE_USER is already PP bit 0x2, so we only
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* need to add in 0x1 if it's a read-only user page
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*/
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rflags = new_pmd & _PAGE_USER;
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if ((new_pmd & _PAGE_USER) && !((new_pmd & _PAGE_RW) &&
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(new_pmd & _PAGE_DIRTY)))
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rflags |= 0x1;
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/*
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* _PAGE_EXEC -> HW_NO_EXEC since it's inverted
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*/
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rflags |= ((new_pmd & _PAGE_EXEC) ? 0 : HPTE_R_N);
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#if 0
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if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
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/*
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* No CPU has hugepages but lacks no execute, so we
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* don't need to worry about that case
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*/
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rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
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}
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#endif
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/*
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* Find the slot index details for this ea, using base page size.
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*/
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shift = mmu_psize_defs[psize].shift;
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index = (ea & ~HPAGE_PMD_MASK) >> shift;
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BUG_ON(index >= 4096);
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vpn = hpt_vpn(ea, vsid, ssize);
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hash = hpt_hash(vpn, shift, ssize);
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hpte_slot_array = get_hpte_slot_array(pmdp);
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if (psize == MMU_PAGE_4K) {
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/*
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* invalidate the old hpte entry if we have that mapped via 64K
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* base page size. This is because demote_segment won't flush
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* hash page table entries.
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*/
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if ((old_pmd & _PAGE_HASHPTE) && !(old_pmd & _PAGE_COMBO))
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invalidate_old_hpte(vsid, ea, pmdp, MMU_PAGE_64K, ssize);
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}
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valid = hpte_valid(hpte_slot_array, index);
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if (valid) {
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/* update the hpte bits */
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hidx = hpte_hash_index(hpte_slot_array, index);
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if (hidx & _PTEIDX_SECONDARY)
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hash = ~hash;
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slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
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slot += hidx & _PTEIDX_GROUP_IX;
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ret = ppc_md.hpte_updatepp(slot, rflags, vpn,
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psize, lpsize, ssize, local);
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/*
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* We failed to update, try to insert a new entry.
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*/
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if (ret == -1) {
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/*
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* large pte is marked busy, so we can be sure
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* nobody is looking at hpte_slot_array. hence we can
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* safely update this here.
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*/
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valid = 0;
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hpte_slot_array[index] = 0;
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}
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}
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if (!valid) {
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unsigned long hpte_group;
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/* insert new entry */
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pa = pmd_pfn(__pmd(old_pmd)) << PAGE_SHIFT;
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new_pmd |= _PAGE_HASHPTE;
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/* Add in WIMG bits */
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rflags |= (new_pmd & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
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_PAGE_GUARDED));
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/*
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* enable the memory coherence always
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*/
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rflags |= HPTE_R_M;
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repeat:
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hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
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/* Insert into the hash table, primary slot */
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slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
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psize, lpsize, ssize);
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/*
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* Primary is full, try the secondary
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*/
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if (unlikely(slot == -1)) {
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hpte_group = ((~hash & htab_hash_mask) *
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HPTES_PER_GROUP) & ~0x7UL;
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slot = ppc_md.hpte_insert(hpte_group, vpn, pa,
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rflags, HPTE_V_SECONDARY,
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psize, lpsize, ssize);
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if (slot == -1) {
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if (mftb() & 0x1)
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hpte_group = ((hash & htab_hash_mask) *
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HPTES_PER_GROUP) & ~0x7UL;
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ppc_md.hpte_remove(hpte_group);
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goto repeat;
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}
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}
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/*
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* Hypervisor failure. Restore old pmd and return -1
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* similar to __hash_page_*
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*/
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if (unlikely(slot == -2)) {
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*pmdp = __pmd(old_pmd);
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hash_failure_debug(ea, access, vsid, trap, ssize,
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psize, lpsize, old_pmd);
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return -1;
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}
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/*
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* large pte is marked busy, so we can be sure
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* nobody is looking at hpte_slot_array. hence we can
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* safely update this here.
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*/
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mark_hpte_slot_valid(hpte_slot_array, index, slot);
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}
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/*
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* Mark the pte with _PAGE_COMBO, if we are trying to hash it with
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* base page size 4k.
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*/
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if (psize == MMU_PAGE_4K)
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new_pmd |= _PAGE_COMBO;
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/*
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* The hpte valid is stored in the pgtable whose address is in the
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* second half of the PMD. Order this against clearing of the busy bit in
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* huge pmd.
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*/
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smp_wmb();
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*pmdp = __pmd(new_pmd & ~_PAGE_BUSY);
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return 0;
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}
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