pgalloc.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *  Page table allocation functions
  4 *
  5 *    Copyright IBM Corp. 2016
  6 *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
  7 */
  8
  9#include <linux/sysctl.h>
 10#include <linux/slab.h>
 11#include <linux/mm.h>
 12#include <asm/mmu_context.h>
 13#include <asm/page-states.h>
 14#include <asm/pgalloc.h>
 15#include <asm/tlbflush.h>
 16
 17unsigned long *crst_table_alloc_noprof(struct mm_struct *mm)
 18{
 19	gfp_t gfp = GFP_KERNEL_ACCOUNT;
 20	struct ptdesc *ptdesc;
 21	unsigned long *table;
 22
 23	if (mm == &init_mm)
 24		gfp &= ~__GFP_ACCOUNT;
 25	ptdesc = pagetable_alloc_noprof(gfp, CRST_ALLOC_ORDER);
 26	if (!ptdesc)
 27		return NULL;
 28	table = ptdesc_address(ptdesc);
 29	__arch_set_page_dat(table, 1UL << CRST_ALLOC_ORDER);
 30	return table;
 31}
 32
 33void crst_table_free(struct mm_struct *mm, unsigned long *table)
 34{
 35	if (!table)
 36		return;
 37	pagetable_free(virt_to_ptdesc(table));
 38}
 39
 40static void __crst_table_upgrade(void *arg)
 41{
 42	struct mm_struct *mm = arg;
 43	struct ctlreg asce;
 44
 45	/* change all active ASCEs to avoid the creation of new TLBs */
 46	if (current->active_mm == mm) {
 47		asce.val = mm->context.asce;
 48		get_lowcore()->user_asce = asce;
 49		local_ctl_load(7, &asce);
 50		if (!test_thread_flag(TIF_ASCE_PRIMARY))
 51			local_ctl_load(1, &asce);
 52	}
 53	__tlb_flush_local();
 54}
 55
 56int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
 57{
 58	unsigned long *pgd = NULL, *p4d = NULL, *__pgd;
 59	unsigned long asce_limit = mm->context.asce_limit;
 60
 61	mmap_assert_write_locked(mm);
 62
 63	/* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */
 64	VM_BUG_ON(asce_limit < _REGION2_SIZE);
 65
 66	if (end <= asce_limit)
 67		return 0;
 68
 69	if (asce_limit == _REGION2_SIZE) {
 70		p4d = crst_table_alloc(mm);
 71		if (unlikely(!p4d))
 72			goto err_p4d;
 73		crst_table_init(p4d, _REGION2_ENTRY_EMPTY);
 74		pagetable_p4d_ctor(virt_to_ptdesc(p4d));
 75	}
 76	if (end > _REGION1_SIZE) {
 77		pgd = crst_table_alloc(mm);
 78		if (unlikely(!pgd))
 79			goto err_pgd;
 80		crst_table_init(pgd, _REGION1_ENTRY_EMPTY);
 81		pagetable_pgd_ctor(virt_to_ptdesc(pgd));
 82	}
 83
 84	spin_lock_bh(&mm->page_table_lock);
 85
 86	if (p4d) {
 87		__pgd = (unsigned long *) mm->pgd;
 88		p4d_populate(mm, (p4d_t *) p4d, (pud_t *) __pgd);
 89		mm->pgd = (pgd_t *) p4d;
 90		mm->context.asce_limit = _REGION1_SIZE;
 91		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
 92			_ASCE_USER_BITS | _ASCE_TYPE_REGION2;
 93		mm_inc_nr_puds(mm);
 94	}
 95	if (pgd) {
 96		__pgd = (unsigned long *) mm->pgd;
 97		pgd_populate(mm, (pgd_t *) pgd, (p4d_t *) __pgd);
 98		mm->pgd = (pgd_t *) pgd;
 99		mm->context.asce_limit = TASK_SIZE_MAX;
100		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
101			_ASCE_USER_BITS | _ASCE_TYPE_REGION1;
102	}
103
104	spin_unlock_bh(&mm->page_table_lock);
105
106	on_each_cpu(__crst_table_upgrade, mm, 0);
107
108	return 0;
109
110err_pgd:
111	pagetable_dtor(virt_to_ptdesc(p4d));
112	crst_table_free(mm, p4d);
113err_p4d:
114	return -ENOMEM;
115}
116
117#ifdef CONFIG_PGSTE
118
119struct ptdesc *page_table_alloc_pgste_noprof(struct mm_struct *mm)
120{
121	struct ptdesc *ptdesc;
122	u64 *table;
123
124	ptdesc = pagetable_alloc_noprof(GFP_KERNEL_ACCOUNT, 0);
125	if (ptdesc) {
126		table = (u64 *)ptdesc_address(ptdesc);
127		__arch_set_page_dat(table, 1);
128		memset64(table, _PAGE_INVALID, PTRS_PER_PTE);
129		memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
130	}
131	return ptdesc;
132}
133
134void page_table_free_pgste(struct ptdesc *ptdesc)
135{
136	pagetable_free(ptdesc);
137}
138
139#endif /* CONFIG_PGSTE */
140
141unsigned long *page_table_alloc_noprof(struct mm_struct *mm)
142{
143	gfp_t gfp = GFP_KERNEL_ACCOUNT;
144	struct ptdesc *ptdesc;
145	unsigned long *table;
146
147	if (mm == &init_mm)
148		gfp &= ~__GFP_ACCOUNT;
149	ptdesc = pagetable_alloc_noprof(gfp, 0);
150	if (!ptdesc)
151		return NULL;
152	if (!pagetable_pte_ctor(mm, ptdesc)) {
153		pagetable_free(ptdesc);
154		return NULL;
155	}
156	table = ptdesc_address(ptdesc);
157	__arch_set_page_dat(table, 1);
158	memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE);
159	memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
160	return table;
161}
162
163void page_table_free(struct mm_struct *mm, unsigned long *table)
164{
165	struct ptdesc *ptdesc = virt_to_ptdesc(table);
166
167	if (pagetable_is_reserved(ptdesc))
168		return free_reserved_ptdesc(ptdesc);
169	pagetable_dtor_free(ptdesc);
170}
171
172#ifdef CONFIG_TRANSPARENT_HUGEPAGE
173static void pte_free_now(struct rcu_head *head)
174{
175	struct ptdesc *ptdesc = container_of(head, struct ptdesc, pt_rcu_head);
176
177	pagetable_dtor_free(ptdesc);
178}
179
180void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable)
181{
182	struct ptdesc *ptdesc = virt_to_ptdesc(pgtable);
183
184	call_rcu(&ptdesc->pt_rcu_head, pte_free_now);
185}
186#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
187
188/*
189 * Base infrastructure required to generate basic asces, region, segment,
190 * and page tables that do not make use of enhanced features like EDAT1.
191 */
192
193static struct kmem_cache *base_pgt_cache;
194
195static unsigned long *base_pgt_alloc(void)
196{
197	unsigned long *table;
198
199	table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL);
200	if (table)
201		memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE);
202	return table;
203}
204
205static void base_pgt_free(unsigned long *table)
206{
207	kmem_cache_free(base_pgt_cache, table);
208}
209
210static unsigned long *base_crst_alloc(unsigned long val)
211{
212	unsigned long *table;
213	struct ptdesc *ptdesc;
214
215	ptdesc = pagetable_alloc(GFP_KERNEL, CRST_ALLOC_ORDER);
216	if (!ptdesc)
217		return NULL;
218	table = ptdesc_address(ptdesc);
219	crst_table_init(table, val);
220	return table;
221}
222
223static void base_crst_free(unsigned long *table)
224{
225	if (!table)
226		return;
227	pagetable_free(virt_to_ptdesc(table));
228}
229
230#define BASE_ADDR_END_FUNC(NAME, SIZE)					\
231static inline unsigned long base_##NAME##_addr_end(unsigned long addr,	\
232						   unsigned long end)	\
233{									\
234	unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1);		\
235									\
236	return (next - 1) < (end - 1) ? next : end;			\
237}
238
239BASE_ADDR_END_FUNC(page,    PAGE_SIZE)
240BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE)
241BASE_ADDR_END_FUNC(region3, _REGION3_SIZE)
242BASE_ADDR_END_FUNC(region2, _REGION2_SIZE)
243BASE_ADDR_END_FUNC(region1, _REGION1_SIZE)
244
245static inline unsigned long base_lra(unsigned long address)
246{
247	unsigned long real;
248
249	asm volatile(
250		"	lra	%0,0(%1)"
251		: "=d" (real) : "a" (address) : "cc");
252	return real;
253}
254
255static int base_page_walk(unsigned long *origin, unsigned long addr,
256			  unsigned long end, int alloc)
257{
258	unsigned long *pte, next;
259
260	if (!alloc)
261		return 0;
262	pte = origin;
263	pte += (addr & _PAGE_INDEX) >> PAGE_SHIFT;
264	do {
265		next = base_page_addr_end(addr, end);
266		*pte = base_lra(addr);
267	} while (pte++, addr = next, addr < end);
268	return 0;
269}
270
271static int base_segment_walk(unsigned long *origin, unsigned long addr,
272			     unsigned long end, int alloc)
273{
274	unsigned long *ste, next, *table;
275	int rc;
276
277	ste = origin;
278	ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
279	do {
280		next = base_segment_addr_end(addr, end);
281		if (*ste & _SEGMENT_ENTRY_INVALID) {
282			if (!alloc)
283				continue;
284			table = base_pgt_alloc();
285			if (!table)
286				return -ENOMEM;
287			*ste = __pa(table) | _SEGMENT_ENTRY;
288		}
289		table = __va(*ste & _SEGMENT_ENTRY_ORIGIN);
290		rc = base_page_walk(table, addr, next, alloc);
291		if (rc)
292			return rc;
293		if (!alloc)
294			base_pgt_free(table);
295		cond_resched();
296	} while (ste++, addr = next, addr < end);
297	return 0;
298}
299
300static int base_region3_walk(unsigned long *origin, unsigned long addr,
301			     unsigned long end, int alloc)
302{
303	unsigned long *rtte, next, *table;
304	int rc;
305
306	rtte = origin;
307	rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT;
308	do {
309		next = base_region3_addr_end(addr, end);
310		if (*rtte & _REGION_ENTRY_INVALID) {
311			if (!alloc)
312				continue;
313			table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY);
314			if (!table)
315				return -ENOMEM;
316			*rtte = __pa(table) | _REGION3_ENTRY;
317		}
318		table = __va(*rtte & _REGION_ENTRY_ORIGIN);
319		rc = base_segment_walk(table, addr, next, alloc);
320		if (rc)
321			return rc;
322		if (!alloc)
323			base_crst_free(table);
324	} while (rtte++, addr = next, addr < end);
325	return 0;
326}
327
328static int base_region2_walk(unsigned long *origin, unsigned long addr,
329			     unsigned long end, int alloc)
330{
331	unsigned long *rste, next, *table;
332	int rc;
333
334	rste = origin;
335	rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT;
336	do {
337		next = base_region2_addr_end(addr, end);
338		if (*rste & _REGION_ENTRY_INVALID) {
339			if (!alloc)
340				continue;
341			table = base_crst_alloc(_REGION3_ENTRY_EMPTY);
342			if (!table)
343				return -ENOMEM;
344			*rste = __pa(table) | _REGION2_ENTRY;
345		}
346		table = __va(*rste & _REGION_ENTRY_ORIGIN);
347		rc = base_region3_walk(table, addr, next, alloc);
348		if (rc)
349			return rc;
350		if (!alloc)
351			base_crst_free(table);
352	} while (rste++, addr = next, addr < end);
353	return 0;
354}
355
356static int base_region1_walk(unsigned long *origin, unsigned long addr,
357			     unsigned long end, int alloc)
358{
359	unsigned long *rfte, next, *table;
360	int rc;
361
362	rfte = origin;
363	rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT;
364	do {
365		next = base_region1_addr_end(addr, end);
366		if (*rfte & _REGION_ENTRY_INVALID) {
367			if (!alloc)
368				continue;
369			table = base_crst_alloc(_REGION2_ENTRY_EMPTY);
370			if (!table)
371				return -ENOMEM;
372			*rfte = __pa(table) | _REGION1_ENTRY;
373		}
374		table = __va(*rfte & _REGION_ENTRY_ORIGIN);
375		rc = base_region2_walk(table, addr, next, alloc);
376		if (rc)
377			return rc;
378		if (!alloc)
379			base_crst_free(table);
380	} while (rfte++, addr = next, addr < end);
381	return 0;
382}
383
384/**
385 * base_asce_free - free asce and tables returned from base_asce_alloc()
386 * @asce: asce to be freed
387 *
388 * Frees all region, segment, and page tables that were allocated with a
389 * corresponding base_asce_alloc() call.
390 */
391void base_asce_free(unsigned long asce)
392{
393	unsigned long *table = __va(asce & _ASCE_ORIGIN);
394
395	if (!asce)
396		return;
397	switch (asce & _ASCE_TYPE_MASK) {
398	case _ASCE_TYPE_SEGMENT:
399		base_segment_walk(table, 0, _REGION3_SIZE, 0);
400		break;
401	case _ASCE_TYPE_REGION3:
402		base_region3_walk(table, 0, _REGION2_SIZE, 0);
403		break;
404	case _ASCE_TYPE_REGION2:
405		base_region2_walk(table, 0, _REGION1_SIZE, 0);
406		break;
407	case _ASCE_TYPE_REGION1:
408		base_region1_walk(table, 0, TASK_SIZE_MAX, 0);
409		break;
410	}
411	base_crst_free(table);
412}
413
414static int base_pgt_cache_init(void)
415{
416	static DEFINE_MUTEX(base_pgt_cache_mutex);
417	unsigned long sz = _PAGE_TABLE_SIZE;
418
419	if (base_pgt_cache)
420		return 0;
421	mutex_lock(&base_pgt_cache_mutex);
422	if (!base_pgt_cache)
423		base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL);
424	mutex_unlock(&base_pgt_cache_mutex);
425	return base_pgt_cache ? 0 : -ENOMEM;
426}
427
428/**
429 * base_asce_alloc - create kernel mapping without enhanced DAT features
430 * @addr: virtual start address of kernel mapping
431 * @num_pages: number of consecutive pages
432 *
433 * Generate an asce, including all required region, segment and page tables,
434 * that can be used to access the virtual kernel mapping. The difference is
435 * that the returned asce does not make use of any enhanced DAT features like
436 * e.g. large pages. This is required for some I/O functions that pass an
437 * asce, like e.g. some service call requests.
438 *
439 * Note: the returned asce may NEVER be attached to any cpu. It may only be
440 *	 used for I/O requests. tlb entries that might result because the
441 *	 asce was attached to a cpu won't be cleared.
442 */
443unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages)
444{
445	unsigned long asce, *table, end;
446	int rc;
447
448	if (base_pgt_cache_init())
449		return 0;
450	end = addr + num_pages * PAGE_SIZE;
451	if (end <= _REGION3_SIZE) {
452		table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY);
453		if (!table)
454			return 0;
455		rc = base_segment_walk(table, addr, end, 1);
456		asce = __pa(table) | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH;
457	} else if (end <= _REGION2_SIZE) {
458		table = base_crst_alloc(_REGION3_ENTRY_EMPTY);
459		if (!table)
460			return 0;
461		rc = base_region3_walk(table, addr, end, 1);
462		asce = __pa(table) | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH;
463	} else if (end <= _REGION1_SIZE) {
464		table = base_crst_alloc(_REGION2_ENTRY_EMPTY);
465		if (!table)
466			return 0;
467		rc = base_region2_walk(table, addr, end, 1);
468		asce = __pa(table) | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH;
469	} else {
470		table = base_crst_alloc(_REGION1_ENTRY_EMPTY);
471		if (!table)
472			return 0;
473		rc = base_region1_walk(table, addr, end, 1);
474		asce = __pa(table) | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH;
475	}
476	if (rc) {
477		base_asce_free(asce);
478		asce = 0;
479	}
480	return asce;
481}