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  1/*
  2 * Copyright IBM Corporation, 2015
  3 * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
  4 *
  5 * This program is free software; you can redistribute it and/or modify it
  6 * under the terms of version 2 of the GNU Lesser General Public License
  7 * as published by the Free Software Foundation.
  8 *
  9 * This program is distributed in the hope that it would be useful, but
 10 * WITHOUT ANY WARRANTY; without even the implied warranty of
 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 12 *
 13 */
 14
 15#include <linux/mm.h>
 16#include <asm/machdep.h>
 17#include <asm/mmu.h>
 18/*
 19 * index from 0 - 15
 20 */
 21bool __rpte_sub_valid(real_pte_t rpte, unsigned long index)
 22{
 23	unsigned long g_idx;
 24	unsigned long ptev = pte_val(rpte.pte);
 25
 26	g_idx = (ptev & _PAGE_COMBO_VALID) >> _PAGE_F_GIX_SHIFT;
 27	index = index >> 2;
 28	if (g_idx & (0x1 << index))
 29		return true;
 30	else
 31		return false;
 32}
 33/*
 34 * index from 0 - 15
 35 */
 36static unsigned long mark_subptegroup_valid(unsigned long ptev, unsigned long index)
 37{
 38	unsigned long g_idx;
 39
 40	if (!(ptev & _PAGE_COMBO))
 41		return ptev;
 42	index = index >> 2;
 43	g_idx = 0x1 << index;
 44
 45	return ptev | (g_idx << _PAGE_F_GIX_SHIFT);
 46}
 47
 48int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
 49		   pte_t *ptep, unsigned long trap, unsigned long flags,
 50		   int ssize, int subpg_prot)
 51{
 52	real_pte_t rpte;
 53	unsigned long *hidxp;
 54	unsigned long hpte_group;
 55	unsigned int subpg_index;
 56	unsigned long rflags, pa, hidx;
 57	unsigned long old_pte, new_pte, subpg_pte;
 58	unsigned long vpn, hash, slot;
 59	unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
 60
 61	/*
 62	 * atomically mark the linux large page PTE busy and dirty
 63	 */
 64	do {
 65		pte_t pte = READ_ONCE(*ptep);
 66
 67		old_pte = pte_val(pte);
 68		/* If PTE busy, retry the access */
 69		if (unlikely(old_pte & _PAGE_BUSY))
 70			return 0;
 71		/* If PTE permissions don't match, take page fault */
 72		if (unlikely(access & ~old_pte))
 73			return 1;
 74		/*
 75		 * Try to lock the PTE, add ACCESSED and DIRTY if it was
 76		 * a write access. Since this is 4K insert of 64K page size
 77		 * also add _PAGE_COMBO
 78		 */
 79		new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED | _PAGE_COMBO;
 80		if (access & _PAGE_RW)
 81			new_pte |= _PAGE_DIRTY;
 82	} while (old_pte != __cmpxchg_u64((unsigned long *)ptep,
 83					  old_pte, new_pte));
 84	/*
 85	 * Handle the subpage protection bits
 86	 */
 87	subpg_pte = new_pte & ~subpg_prot;
 88	rflags = htab_convert_pte_flags(subpg_pte);
 89
 90	if (!cpu_has_feature(CPU_FTR_NOEXECUTE) &&
 91	    !cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
 92
 93		/*
 94		 * No CPU has hugepages but lacks no execute, so we
 95		 * don't need to worry about that case
 96		 */
 97		rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
 98	}
 99
100	subpg_index = (ea & (PAGE_SIZE - 1)) >> shift;
101	vpn  = hpt_vpn(ea, vsid, ssize);
102	rpte = __real_pte(__pte(old_pte), ptep);
103	/*
104	 *None of the sub 4k page is hashed
105	 */
106	if (!(old_pte & _PAGE_HASHPTE))
107		goto htab_insert_hpte;
108	/*
109	 * Check if the pte was already inserted into the hash table
110	 * as a 64k HW page, and invalidate the 64k HPTE if so.
111	 */
112	if (!(old_pte & _PAGE_COMBO)) {
113		flush_hash_page(vpn, rpte, MMU_PAGE_64K, ssize, flags);
114		/*
115		 * clear the old slot details from the old and new pte.
116		 * On hash insert failure we use old pte value and we don't
117		 * want slot information there if we have a insert failure.
118		 */
119		old_pte &= ~(_PAGE_HASHPTE | _PAGE_F_GIX | _PAGE_F_SECOND);
120		new_pte &= ~(_PAGE_HASHPTE | _PAGE_F_GIX | _PAGE_F_SECOND);
121		goto htab_insert_hpte;
122	}
123	/*
124	 * Check for sub page valid and update
125	 */
126	if (__rpte_sub_valid(rpte, subpg_index)) {
127		int ret;
128
129		hash = hpt_hash(vpn, shift, ssize);
130		hidx = __rpte_to_hidx(rpte, subpg_index);
131		if (hidx & _PTEIDX_SECONDARY)
132			hash = ~hash;
133		slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
134		slot += hidx & _PTEIDX_GROUP_IX;
135
136		ret = ppc_md.hpte_updatepp(slot, rflags, vpn,
137					   MMU_PAGE_4K, MMU_PAGE_4K,
138					   ssize, flags);
139		/*
140		 *if we failed because typically the HPTE wasn't really here
141		 * we try an insertion.
142		 */
143		if (ret == -1)
144			goto htab_insert_hpte;
145
146		*ptep = __pte(new_pte & ~_PAGE_BUSY);
147		return 0;
148	}
149
150htab_insert_hpte:
151	/*
152	 * handle _PAGE_4K_PFN case
153	 */
154	if (old_pte & _PAGE_4K_PFN) {
155		/*
156		 * All the sub 4k page have the same
157		 * physical address.
158		 */
159		pa = pte_pfn(__pte(old_pte)) << HW_PAGE_SHIFT;
160	} else {
161		pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
162		pa += (subpg_index << shift);
163	}
164	hash = hpt_hash(vpn, shift, ssize);
165repeat:
166	hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
167
168	/* Insert into the hash table, primary slot */
169	slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
170				  MMU_PAGE_4K, MMU_PAGE_4K, ssize);
171	/*
172	 * Primary is full, try the secondary
173	 */
174	if (unlikely(slot == -1)) {
175		hpte_group = ((~hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
176		slot = ppc_md.hpte_insert(hpte_group, vpn, pa,
177					  rflags, HPTE_V_SECONDARY,
178					  MMU_PAGE_4K, MMU_PAGE_4K, ssize);
179		if (slot == -1) {
180			if (mftb() & 0x1)
181				hpte_group = ((hash & htab_hash_mask) *
182					      HPTES_PER_GROUP) & ~0x7UL;
183			ppc_md.hpte_remove(hpte_group);
184			/*
185			 * FIXME!! Should be try the group from which we removed ?
186			 */
187			goto repeat;
188		}
189	}
190	/*
191	 * Hypervisor failure. Restore old pte and return -1
192	 * similar to __hash_page_*
193	 */
194	if (unlikely(slot == -2)) {
195		*ptep = __pte(old_pte);
196		hash_failure_debug(ea, access, vsid, trap, ssize,
197				   MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
198		return -1;
199	}
200	/*
201	 * Insert slot number & secondary bit in PTE second half,
202	 * clear _PAGE_BUSY and set appropriate HPTE slot bit
203	 * Since we have _PAGE_BUSY set on ptep, we can be sure
204	 * nobody is undating hidx.
205	 */
206	hidxp = (unsigned long *)(ptep + PTRS_PER_PTE);
207	rpte.hidx &= ~(0xfUL << (subpg_index << 2));
208	*hidxp = rpte.hidx  | (slot << (subpg_index << 2));
209	new_pte = mark_subptegroup_valid(new_pte, subpg_index);
210	new_pte |=  _PAGE_HASHPTE;
211	/*
212	 * check __real_pte for details on matching smp_rmb()
213	 */
214	smp_wmb();
215	*ptep = __pte(new_pte & ~_PAGE_BUSY);
216	return 0;
217}
218
219int __hash_page_64K(unsigned long ea, unsigned long access,
220		    unsigned long vsid, pte_t *ptep, unsigned long trap,
221		    unsigned long flags, int ssize)
222{
223
224	unsigned long hpte_group;
225	unsigned long rflags, pa;
226	unsigned long old_pte, new_pte;
227	unsigned long vpn, hash, slot;
228	unsigned long shift = mmu_psize_defs[MMU_PAGE_64K].shift;
229
230	/*
231	 * atomically mark the linux large page PTE busy and dirty
232	 */
233	do {
234		pte_t pte = READ_ONCE(*ptep);
235
236		old_pte = pte_val(pte);
237		/* If PTE busy, retry the access */
238		if (unlikely(old_pte & _PAGE_BUSY))
239			return 0;
240		/* If PTE permissions don't match, take page fault */
241		if (unlikely(access & ~old_pte))
242			return 1;
243		/*
244		 * Check if PTE has the cache-inhibit bit set
245		 * If so, bail out and refault as a 4k page
246		 */
247		if (!mmu_has_feature(MMU_FTR_CI_LARGE_PAGE) &&
248		    unlikely(old_pte & _PAGE_NO_CACHE))
249			return 0;
250		/*
251		 * Try to lock the PTE, add ACCESSED and DIRTY if it was
252		 * a write access.
253		 */
254		new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED;
255		if (access & _PAGE_RW)
256			new_pte |= _PAGE_DIRTY;
257	} while (old_pte != __cmpxchg_u64((unsigned long *)ptep,
258					  old_pte, new_pte));
259
260	rflags = htab_convert_pte_flags(new_pte);
261
262	if (!cpu_has_feature(CPU_FTR_NOEXECUTE) &&
263	    !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
264		rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
265
266	vpn  = hpt_vpn(ea, vsid, ssize);
267	if (unlikely(old_pte & _PAGE_HASHPTE)) {
268		/*
269		 * There MIGHT be an HPTE for this pte
270		 */
271		hash = hpt_hash(vpn, shift, ssize);
272		if (old_pte & _PAGE_F_SECOND)
273			hash = ~hash;
274		slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
275		slot += (old_pte & _PAGE_F_GIX) >> _PAGE_F_GIX_SHIFT;
276
277		if (ppc_md.hpte_updatepp(slot, rflags, vpn, MMU_PAGE_64K,
278					 MMU_PAGE_64K, ssize, flags) == -1)
279			old_pte &= ~_PAGE_HPTEFLAGS;
280	}
281
282	if (likely(!(old_pte & _PAGE_HASHPTE))) {
283
284		pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
285		hash = hpt_hash(vpn, shift, ssize);
286
287repeat:
288		hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
289
290		/* Insert into the hash table, primary slot */
291		slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
292				  MMU_PAGE_64K, MMU_PAGE_64K, ssize);
293		/*
294		 * Primary is full, try the secondary
295		 */
296		if (unlikely(slot == -1)) {
297			hpte_group = ((~hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
298			slot = ppc_md.hpte_insert(hpte_group, vpn, pa,
299						  rflags, HPTE_V_SECONDARY,
300						  MMU_PAGE_64K, MMU_PAGE_64K, ssize);
301			if (slot == -1) {
302				if (mftb() & 0x1)
303					hpte_group = ((hash & htab_hash_mask) *
304						      HPTES_PER_GROUP) & ~0x7UL;
305				ppc_md.hpte_remove(hpte_group);
306				/*
307				 * FIXME!! Should be try the group from which we removed ?
308				 */
309				goto repeat;
310			}
311		}
312		/*
313		 * Hypervisor failure. Restore old pte and return -1
314		 * similar to __hash_page_*
315		 */
316		if (unlikely(slot == -2)) {
317			*ptep = __pte(old_pte);
318			hash_failure_debug(ea, access, vsid, trap, ssize,
319					   MMU_PAGE_64K, MMU_PAGE_64K, old_pte);
320			return -1;
321		}
322		new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | _PAGE_HASHPTE;
323		new_pte |= (slot << _PAGE_F_GIX_SHIFT) & (_PAGE_F_SECOND | _PAGE_F_GIX);
324	}
325	*ptep = __pte(new_pte & ~_PAGE_BUSY);
326	return 0;
327}