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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/powerpc/mm/hugepage-hash64.c
Initial import
Diffstat (limited to 'arch/powerpc/mm/hugepage-hash64.c')
-rw-r--r--arch/powerpc/mm/hugepage-hash64.c195
1 files changed, 195 insertions, 0 deletions
diff --git a/arch/powerpc/mm/hugepage-hash64.c b/arch/powerpc/mm/hugepage-hash64.c
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+++ b/arch/powerpc/mm/hugepage-hash64.c
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+/*
+ * Copyright IBM Corporation, 2013
+ * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ */
+
+/*
+ * PPC64 THP Support for hash based MMUs
+ */
+#include <linux/mm.h>
+#include <asm/machdep.h>
+
+int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
+ pmd_t *pmdp, unsigned long trap, unsigned long flags,
+ int ssize, unsigned int psize)
+{
+ unsigned int index, valid;
+ unsigned char *hpte_slot_array;
+ unsigned long rflags, pa, hidx;
+ unsigned long old_pmd, new_pmd;
+ int ret, lpsize = MMU_PAGE_16M;
+ unsigned long vpn, hash, shift, slot;
+
+ /*
+ * atomically mark the linux large page PMD busy and dirty
+ */
+ do {
+ pmd_t pmd = READ_ONCE(*pmdp);
+
+ old_pmd = pmd_val(pmd);
+ /* If PMD busy, retry the access */
+ if (unlikely(old_pmd & _PAGE_BUSY))
+ return 0;
+ /* If PMD is trans splitting retry the access */
+ if (unlikely(old_pmd & _PAGE_SPLITTING))
+ return 0;
+ /* If PMD permissions don't match, take page fault */
+ if (unlikely(access & ~old_pmd))
+ return 1;
+ /*
+ * Try to lock the PTE, add ACCESSED and DIRTY if it was
+ * a write access
+ */
+ new_pmd = old_pmd | _PAGE_BUSY | _PAGE_ACCESSED;
+ if (access & _PAGE_RW)
+ new_pmd |= _PAGE_DIRTY;
+ } while (old_pmd != __cmpxchg_u64((unsigned long *)pmdp,
+ old_pmd, new_pmd));
+ /*
+ * PP bits. _PAGE_USER is already PP bit 0x2, so we only
+ * need to add in 0x1 if it's a read-only user page
+ */
+ rflags = new_pmd & _PAGE_USER;
+ if ((new_pmd & _PAGE_USER) && !((new_pmd & _PAGE_RW) &&
+ (new_pmd & _PAGE_DIRTY)))
+ rflags |= 0x1;
+ /*
+ * _PAGE_EXEC -> HW_NO_EXEC since it's inverted
+ */
+ rflags |= ((new_pmd & _PAGE_EXEC) ? 0 : HPTE_R_N);
+
+#if 0
+ 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);
+ }
+#endif
+ /*
+ * Find the slot index details for this ea, using base page size.
+ */
+ shift = mmu_psize_defs[psize].shift;
+ index = (ea & ~HPAGE_PMD_MASK) >> shift;
+ BUG_ON(index >= 4096);
+
+ vpn = hpt_vpn(ea, vsid, ssize);
+ hash = hpt_hash(vpn, shift, ssize);
+ hpte_slot_array = get_hpte_slot_array(pmdp);
+ if (psize == MMU_PAGE_4K) {
+ /*
+ * invalidate the old hpte entry if we have that mapped via 64K
+ * base page size. This is because demote_segment won't flush
+ * hash page table entries.
+ */
+ if ((old_pmd & _PAGE_HASHPTE) && !(old_pmd & _PAGE_COMBO))
+ flush_hash_hugepage(vsid, ea, pmdp, MMU_PAGE_64K,
+ ssize, flags);
+ }
+
+ valid = hpte_valid(hpte_slot_array, index);
+ if (valid) {
+ /* update the hpte bits */
+ hidx = hpte_hash_index(hpte_slot_array, index);
+ if (hidx & _PTEIDX_SECONDARY)
+ hash = ~hash;
+ slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
+ slot += hidx & _PTEIDX_GROUP_IX;
+
+ ret = ppc_md.hpte_updatepp(slot, rflags, vpn,
+ psize, lpsize, ssize, flags);
+ /*
+ * We failed to update, try to insert a new entry.
+ */
+ if (ret == -1) {
+ /*
+ * large pte is marked busy, so we can be sure
+ * nobody is looking at hpte_slot_array. hence we can
+ * safely update this here.
+ */
+ valid = 0;
+ hpte_slot_array[index] = 0;
+ }
+ }
+
+ if (!valid) {
+ unsigned long hpte_group;
+
+ /* insert new entry */
+ pa = pmd_pfn(__pmd(old_pmd)) << PAGE_SHIFT;
+ new_pmd |= _PAGE_HASHPTE;
+
+ /* Add in WIMG bits */
+ rflags |= (new_pmd & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
+ _PAGE_GUARDED));
+ /*
+ * enable the memory coherence always
+ */
+ rflags |= HPTE_R_M;
+repeat:
+ hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
+
+ /* Insert into the hash table, primary slot */
+ slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
+ psize, lpsize, ssize);
+ /*
+ * Primary is full, try the secondary
+ */
+ if (unlikely(slot == -1)) {
+ hpte_group = ((~hash & htab_hash_mask) *
+ HPTES_PER_GROUP) & ~0x7UL;
+ slot = ppc_md.hpte_insert(hpte_group, vpn, pa,
+ rflags, HPTE_V_SECONDARY,
+ psize, lpsize, ssize);
+ if (slot == -1) {
+ if (mftb() & 0x1)
+ hpte_group = ((hash & htab_hash_mask) *
+ HPTES_PER_GROUP) & ~0x7UL;
+
+ ppc_md.hpte_remove(hpte_group);
+ goto repeat;
+ }
+ }
+ /*
+ * Hypervisor failure. Restore old pmd and return -1
+ * similar to __hash_page_*
+ */
+ if (unlikely(slot == -2)) {
+ *pmdp = __pmd(old_pmd);
+ hash_failure_debug(ea, access, vsid, trap, ssize,
+ psize, lpsize, old_pmd);
+ return -1;
+ }
+ /*
+ * large pte is marked busy, so we can be sure
+ * nobody is looking at hpte_slot_array. hence we can
+ * safely update this here.
+ */
+ mark_hpte_slot_valid(hpte_slot_array, index, slot);
+ }
+ /*
+ * Mark the pte with _PAGE_COMBO, if we are trying to hash it with
+ * base page size 4k.
+ */
+ if (psize == MMU_PAGE_4K)
+ new_pmd |= _PAGE_COMBO;
+ /*
+ * The hpte valid is stored in the pgtable whose address is in the
+ * second half of the PMD. Order this against clearing of the busy bit in
+ * huge pmd.
+ */
+ smp_wmb();
+ *pmdp = __pmd(new_pmd & ~_PAGE_BUSY);
+ return 0;
+}