powerpc/mm: Convert 4k hash insert to C

Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 202 insertions, 0 deletions

diff --git a/arch/powerpc/mm/hash64_64k.c b/arch/powerpc/mm/hash64_64k.c
new file mode 100644
index 000000000000..9ffeae2cbb57
--- /dev/null
+++ b/arch/powerpc/mm/hash64_64k.c
@@ -0,0 +1,202 @@
+/*
+ * Copyright IBM Corporation, 2015
+ * 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 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.
+ *
+ */
+
+#include <linux/mm.h>
+#include <asm/machdep.h>
+#include <asm/mmu.h>
+
+int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
+		   pte_t *ptep, unsigned long trap, unsigned long flags,
+		   int ssize, int subpg_prot)
+{
+	real_pte_t rpte;
+	unsigned long *hidxp;
+	unsigned long hpte_group;
+	unsigned int subpg_index;
+	unsigned long rflags, pa, hidx;
+	unsigned long old_pte, new_pte, subpg_pte;
+	unsigned long vpn, hash, slot;
+	unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
+
+	/*
+	 * atomically mark the linux large page PTE busy and dirty
+	 */
+	do {
+		pte_t pte = READ_ONCE(*ptep);
+
+		old_pte = pte_val(pte);
+		/* If PTE busy, retry the access */
+		if (unlikely(old_pte & _PAGE_BUSY))
+			return 0;
+		/* If PTE permissions don't match, take page fault */
+		if (unlikely(access & ~old_pte))
+			return 1;
+		/*
+		 * Try to lock the PTE, add ACCESSED and DIRTY if it was
+		 * a write access. Since this is 4K insert of 64K page size
+		 * also add _PAGE_COMBO
+		 */
+		new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED | _PAGE_COMBO;
+		if (access & _PAGE_RW)
+			new_pte |= _PAGE_DIRTY;
+	} while (old_pte != __cmpxchg_u64((unsigned long *)ptep,
+					  old_pte, new_pte));
+	/*
+	 * Handle the subpage protection bits
+	 */
+	subpg_pte = new_pte & ~subpg_prot;
+	/*
+	 * 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 = subpg_pte & _PAGE_USER;
+	if ((subpg_pte & _PAGE_USER) && !((subpg_pte & _PAGE_RW) &&
+					(subpg_pte & _PAGE_DIRTY)))
+		rflags |= 0x1;
+	/*
+	 * _PAGE_EXEC -> HW_NO_EXEC since it's inverted
+	 */
+	rflags |= ((subpg_pte & _PAGE_EXEC) ? 0 : HPTE_R_N);
+	/*
+	 * Always add C and Memory coherence bit
+	 */
+	rflags |= HPTE_R_C | HPTE_R_M;
+	/*
+	 * Add in WIMG bits
+	 */
+	rflags |= (subpg_pte & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
+				_PAGE_COHERENT | _PAGE_GUARDED));
+
+	if (!cpu_has_feature(CPU_FTR_NOEXECUTE) &&
+	    !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);
+	}
+
+	subpg_index = (ea & (PAGE_SIZE - 1)) >> shift;
+	vpn  = hpt_vpn(ea, vsid, ssize);
+	rpte = __real_pte(__pte(old_pte), ptep);
+	/*
+	 *None of the sub 4k page is hashed
+	 */
+	if (!(old_pte & _PAGE_HASHPTE))
+		goto htab_insert_hpte;
+	/*
+	 * Check if the pte was already inserted into the hash table
+	 * as a 64k HW page, and invalidate the 64k HPTE if so.
+	 */
+	if (!(old_pte & _PAGE_COMBO)) {
+		flush_hash_page(vpn, rpte, MMU_PAGE_64K, ssize, flags);
+		old_pte &= ~_PAGE_HPTE_SUB;
+		goto htab_insert_hpte;
+	}
+	/*
+	 * Check for sub page valid and update
+	 */
+	if (__rpte_sub_valid(rpte, subpg_index)) {
+		int ret;
+
+		hash = hpt_hash(vpn, shift, ssize);
+		hidx = __rpte_to_hidx(rpte, subpg_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,
+					   MMU_PAGE_4K, MMU_PAGE_4K,
+					   ssize, flags);
+		/*
+		 *if we failed because typically the HPTE wasn't really here
+		 * we try an insertion.
+		 */
+		if (ret == -1)
+			goto htab_insert_hpte;
+
+		*ptep = __pte(new_pte & ~_PAGE_BUSY);
+		return 0;
+	}
+
+htab_insert_hpte:
+	/*
+	 * handle _PAGE_4K_PFN case
+	 */
+	if (old_pte & _PAGE_4K_PFN) {
+		/*
+		 * All the sub 4k page have the same
+		 * physical address.
+		 */
+		pa = pte_pfn(__pte(old_pte)) << HW_PAGE_SHIFT;
+	} else {
+		pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
+		pa += (subpg_index << shift);
+	}
+	hash = hpt_hash(vpn, shift, ssize);
+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,
+				  MMU_PAGE_4K, MMU_PAGE_4K, 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,
+					  MMU_PAGE_4K, MMU_PAGE_4K, ssize);
+		if (slot == -1) {
+			if (mftb() & 0x1)
+				hpte_group = ((hash & htab_hash_mask) *
+					      HPTES_PER_GROUP) & ~0x7UL;
+			ppc_md.hpte_remove(hpte_group);
+			/*
+			 * FIXME!! Should be try the group from which we removed ?
+			 */
+			goto repeat;
+		}
+	}
+	/*
+	 * Hypervisor failure. Restore old pmd and return -1
+	 * similar to __hash_page_*
+	 */
+	if (unlikely(slot == -2)) {
+		*ptep = __pte(old_pte);
+		hash_failure_debug(ea, access, vsid, trap, ssize,
+				   MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
+		return -1;
+	}
+	/*
+	 * Insert slot number & secondary bit in PTE second half,
+	 * clear _PAGE_BUSY and set appropriate HPTE slot bit
+	 * Since we have _PAGE_BUSY set on ptep, we can be sure
+	 * nobody is undating hidx.
+	 */
+	hidxp = (unsigned long *)(ptep + PTRS_PER_PTE);
+	/* __real_pte use pte_val() any idea why ? FIXME!! */
+	rpte.hidx &= ~(0xfUL << (subpg_index << 2));
+	*hidxp = rpte.hidx  | (slot << (subpg_index << 2));
+	new_pte |= (_PAGE_HPTE_SUB0 >> subpg_index);
+	/*
+	 * check __real_pte for details on matching smp_rmb()
+	 */
+	smp_wmb();
+	*ptep = __pte(new_pte & ~_PAGE_BUSY);
+	return 0;
+}