xref: /linux/arch/sparc/mm/tlb.c (revision 44f57d78) 
1 // SPDX-License-Identifier: GPL-2.0
2 /* arch/sparc64/mm/tlb.c
3  *
4  * Copyright (C) 2004 David S. Miller <davem@redhat.com>
5  */
6 
7 #include <linux/kernel.h>
8 #include <linux/percpu.h>
9 #include <linux/mm.h>
10 #include <linux/swap.h>
11 #include <linux/preempt.h>
12 
13 #include <asm/pgtable.h>
14 #include <asm/pgalloc.h>
15 #include <asm/tlbflush.h>
16 #include <asm/cacheflush.h>
17 #include <asm/mmu_context.h>
18 #include <asm/tlb.h>
19 
20 /* Heavily inspired by the ppc64 code.  */
21 
22 static DEFINE_PER_CPU(struct tlb_batch, tlb_batch);
23 
24 void flush_tlb_pending(void)
25 {
26 	struct tlb_batch *tb = &get_cpu_var(tlb_batch);
27 	struct mm_struct *mm = tb->mm;
28 
29 	if (!tb->tlb_nr)
30 		goto out;
31 
32 	flush_tsb_user(tb);
33 
34 	if (CTX_VALID(mm->context)) {
35 		if (tb->tlb_nr == 1) {
36 			global_flush_tlb_page(mm, tb->vaddrs[0]);
37 		} else {
38 #ifdef CONFIG_SMP
39 			smp_flush_tlb_pending(tb->mm, tb->tlb_nr,
40 					      &tb->vaddrs[0]);
41 #else
42 			__flush_tlb_pending(CTX_HWBITS(tb->mm->context),
43 					    tb->tlb_nr, &tb->vaddrs[0]);
44 #endif
45 		}
46 	}
47 
48 	tb->tlb_nr = 0;
49 
50 out:
51 	put_cpu_var(tlb_batch);
52 }
53 
54 void arch_enter_lazy_mmu_mode(void)
55 {
56 	struct tlb_batch *tb = this_cpu_ptr(&tlb_batch);
57 
58 	tb->active = 1;
59 }
60 
61 void arch_leave_lazy_mmu_mode(void)
62 {
63 	struct tlb_batch *tb = this_cpu_ptr(&tlb_batch);
64 
65 	if (tb->tlb_nr)
66 		flush_tlb_pending();
67 	tb->active = 0;
68 }
69 
70 static void tlb_batch_add_one(struct mm_struct *mm, unsigned long vaddr,
71 			      bool exec, unsigned int hugepage_shift)
72 {
73 	struct tlb_batch *tb = &get_cpu_var(tlb_batch);
74 	unsigned long nr;
75 
76 	vaddr &= PAGE_MASK;
77 	if (exec)
78 		vaddr |= 0x1UL;
79 
80 	nr = tb->tlb_nr;
81 
82 	if (unlikely(nr != 0 && mm != tb->mm)) {
83 		flush_tlb_pending();
84 		nr = 0;
85 	}
86 
87 	if (!tb->active) {
88 		flush_tsb_user_page(mm, vaddr, hugepage_shift);
89 		global_flush_tlb_page(mm, vaddr);
90 		goto out;
91 	}
92 
93 	if (nr == 0) {
94 		tb->mm = mm;
95 		tb->hugepage_shift = hugepage_shift;
96 	}
97 
98 	if (tb->hugepage_shift != hugepage_shift) {
99 		flush_tlb_pending();
100 		tb->hugepage_shift = hugepage_shift;
101 		nr = 0;
102 	}
103 
104 	tb->vaddrs[nr] = vaddr;
105 	tb->tlb_nr = ++nr;
106 	if (nr >= TLB_BATCH_NR)
107 		flush_tlb_pending();
108 
109 out:
110 	put_cpu_var(tlb_batch);
111 }
112 
113 void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr,
114 		   pte_t *ptep, pte_t orig, int fullmm,
115 		   unsigned int hugepage_shift)
116 {
117 	if (tlb_type != hypervisor &&
118 	    pte_dirty(orig)) {
119 		unsigned long paddr, pfn = pte_pfn(orig);
120 		struct address_space *mapping;
121 		struct page *page;
122 
123 		if (!pfn_valid(pfn))
124 			goto no_cache_flush;
125 
126 		page = pfn_to_page(pfn);
127 		if (PageReserved(page))
128 			goto no_cache_flush;
129 
130 		/* A real file page? */
131 		mapping = page_mapping_file(page);
132 		if (!mapping)
133 			goto no_cache_flush;
134 
135 		paddr = (unsigned long) page_address(page);
136 		if ((paddr ^ vaddr) & (1 << 13))
137 			flush_dcache_page_all(mm, page);
138 	}
139 
140 no_cache_flush:
141 	if (!fullmm)
142 		tlb_batch_add_one(mm, vaddr, pte_exec(orig), hugepage_shift);
143 }
144 
145 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
146 static void tlb_batch_pmd_scan(struct mm_struct *mm, unsigned long vaddr,
147 			       pmd_t pmd)
148 {
149 	unsigned long end;
150 	pte_t *pte;
151 
152 	pte = pte_offset_map(&pmd, vaddr);
153 	end = vaddr + HPAGE_SIZE;
154 	while (vaddr < end) {
155 		if (pte_val(*pte) & _PAGE_VALID) {
156 			bool exec = pte_exec(*pte);
157 
158 			tlb_batch_add_one(mm, vaddr, exec, PAGE_SHIFT);
159 		}
160 		pte++;
161 		vaddr += PAGE_SIZE;
162 	}
163 	pte_unmap(pte);
164 }
165 
166 
167 static void __set_pmd_acct(struct mm_struct *mm, unsigned long addr,
168 			   pmd_t orig, pmd_t pmd)
169 {
170 	if (mm == &init_mm)
171 		return;
172 
173 	if ((pmd_val(pmd) ^ pmd_val(orig)) & _PAGE_PMD_HUGE) {
174 		/*
175 		 * Note that this routine only sets pmds for THP pages.
176 		 * Hugetlb pages are handled elsewhere.  We need to check
177 		 * for huge zero page.  Huge zero pages are like hugetlb
178 		 * pages in that there is no RSS, but there is the need
179 		 * for TSB entries.  So, huge zero page counts go into
180 		 * hugetlb_pte_count.
181 		 */
182 		if (pmd_val(pmd) & _PAGE_PMD_HUGE) {
183 			if (is_huge_zero_page(pmd_page(pmd)))
184 				mm->context.hugetlb_pte_count++;
185 			else
186 				mm->context.thp_pte_count++;
187 		} else {
188 			if (is_huge_zero_page(pmd_page(orig)))
189 				mm->context.hugetlb_pte_count--;
190 			else
191 				mm->context.thp_pte_count--;
192 		}
193 
194 		/* Do not try to allocate the TSB hash table if we
195 		 * don't have one already.  We have various locks held
196 		 * and thus we'll end up doing a GFP_KERNEL allocation
197 		 * in an atomic context.
198 		 *
199 		 * Instead, we let the first TLB miss on a hugepage
200 		 * take care of this.
201 		 */
202 	}
203 
204 	if (!pmd_none(orig)) {
205 		addr &= HPAGE_MASK;
206 		if (pmd_trans_huge(orig)) {
207 			pte_t orig_pte = __pte(pmd_val(orig));
208 			bool exec = pte_exec(orig_pte);
209 
210 			tlb_batch_add_one(mm, addr, exec, REAL_HPAGE_SHIFT);
211 			tlb_batch_add_one(mm, addr + REAL_HPAGE_SIZE, exec,
212 					  REAL_HPAGE_SHIFT);
213 		} else {
214 			tlb_batch_pmd_scan(mm, addr, orig);
215 		}
216 	}
217 }
218 
219 void set_pmd_at(struct mm_struct *mm, unsigned long addr,
220 		pmd_t *pmdp, pmd_t pmd)
221 {
222 	pmd_t orig = *pmdp;
223 
224 	*pmdp = pmd;
225 	__set_pmd_acct(mm, addr, orig, pmd);
226 }
227 
228 static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
229 		unsigned long address, pmd_t *pmdp, pmd_t pmd)
230 {
231 	pmd_t old;
232 
233 	do {
234 		old = *pmdp;
235 	} while (cmpxchg64(&pmdp->pmd, old.pmd, pmd.pmd) != old.pmd);
236 	__set_pmd_acct(vma->vm_mm, address, old, pmd);
237 
238 	return old;
239 }
240 
241 /*
242  * This routine is only called when splitting a THP
243  */
244 pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
245 		     pmd_t *pmdp)
246 {
247 	pmd_t old, entry;
248 
249 	entry = __pmd(pmd_val(*pmdp) & ~_PAGE_VALID);
250 	old = pmdp_establish(vma, address, pmdp, entry);
251 	flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
252 
253 	/*
254 	 * set_pmd_at() will not be called in a way to decrement
255 	 * thp_pte_count when splitting a THP, so do it now.
256 	 * Sanity check pmd before doing the actual decrement.
257 	 */
258 	if ((pmd_val(entry) & _PAGE_PMD_HUGE) &&
259 	    !is_huge_zero_page(pmd_page(entry)))
260 		(vma->vm_mm)->context.thp_pte_count--;
261 
262 	return old;
263 }
264 
265 void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
266 				pgtable_t pgtable)
267 {
268 	struct list_head *lh = (struct list_head *) pgtable;
269 
270 	assert_spin_locked(&mm->page_table_lock);
271 
272 	/* FIFO */
273 	if (!pmd_huge_pte(mm, pmdp))
274 		INIT_LIST_HEAD(lh);
275 	else
276 		list_add(lh, (struct list_head *) pmd_huge_pte(mm, pmdp));
277 	pmd_huge_pte(mm, pmdp) = pgtable;
278 }
279 
280 pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
281 {
282 	struct list_head *lh;
283 	pgtable_t pgtable;
284 
285 	assert_spin_locked(&mm->page_table_lock);
286 
287 	/* FIFO */
288 	pgtable = pmd_huge_pte(mm, pmdp);
289 	lh = (struct list_head *) pgtable;
290 	if (list_empty(lh))
291 		pmd_huge_pte(mm, pmdp) = NULL;
292 	else {
293 		pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
294 		list_del(lh);
295 	}
296 	pte_val(pgtable[0]) = 0;
297 	pte_val(pgtable[1]) = 0;
298 
299 	return pgtable;
300 }
301 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
302