1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * This file contains the routines for flushing entries from the
4  * TLB and MMU hash table.
5  *
6  *  Derived from arch/ppc64/mm/init.c:
7  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
8  *
9  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
10  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
11  *    Copyright (C) 1996 Paul Mackerras
12  *
13  *  Derived from "arch/i386/mm/init.c"
14  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
15  *
16  *  Dave Engebretsen <engebret@us.ibm.com>
17  *      Rework for PPC64 port.
18  */
19 
20 #include <linux/kernel.h>
21 #include <linux/mm.h>
22 #include <linux/percpu.h>
23 #include <linux/hardirq.h>
24 #include <asm/tlbflush.h>
25 #include <asm/tlb.h>
26 #include <asm/bug.h>
27 #include <asm/pte-walk.h>
28 
29 
30 #include <trace/events/thp.h>
31 
32 DEFINE_PER_CPU(struct ppc64_tlb_batch, ppc64_tlb_batch);
33 
34 /*
35  * A linux PTE was changed and the corresponding hash table entry
36  * neesd to be flushed. This function will either perform the flush
37  * immediately or will batch it up if the current CPU has an active
38  * batch on it.
39  */
40 void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
41 		     pte_t *ptep, unsigned long pte, int huge)
42 {
43 	unsigned long vpn;
44 	struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
45 	unsigned long vsid;
46 	unsigned int psize;
47 	int ssize;
48 	real_pte_t rpte;
49 	int i, offset;
50 
51 	i = batch->index;
52 
53 	/*
54 	 * Get page size (maybe move back to caller).
55 	 *
56 	 * NOTE: when using special 64K mappings in 4K environment like
57 	 * for SPEs, we obtain the page size from the slice, which thus
58 	 * must still exist (and thus the VMA not reused) at the time
59 	 * of this call
60 	 */
61 	if (huge) {
62 #ifdef CONFIG_HUGETLB_PAGE
63 		psize = get_slice_psize(mm, addr);
64 		/* Mask the address for the correct page size */
65 		addr &= ~((1UL << mmu_psize_defs[psize].shift) - 1);
66 		if (unlikely(psize == MMU_PAGE_16G))
67 			offset = PTRS_PER_PUD;
68 		else
69 			offset = PTRS_PER_PMD;
70 #else
71 		BUG();
72 		psize = pte_pagesize_index(mm, addr, pte); /* shutup gcc */
73 #endif
74 	} else {
75 		psize = pte_pagesize_index(mm, addr, pte);
76 		/*
77 		 * Mask the address for the standard page size.  If we
78 		 * have a 64k page kernel, but the hardware does not
79 		 * support 64k pages, this might be different from the
80 		 * hardware page size encoded in the slice table.
81 		 */
82 		addr &= PAGE_MASK;
83 		offset = PTRS_PER_PTE;
84 	}
85 
86 
87 	/* Build full vaddr */
88 	if (!is_kernel_addr(addr)) {
89 		ssize = user_segment_size(addr);
90 		vsid = get_user_vsid(&mm->context, addr, ssize);
91 	} else {
92 		vsid = get_kernel_vsid(addr, mmu_kernel_ssize);
93 		ssize = mmu_kernel_ssize;
94 	}
95 	WARN_ON(vsid == 0);
96 	vpn = hpt_vpn(addr, vsid, ssize);
97 	rpte = __real_pte(__pte(pte), ptep, offset);
98 
99 	/*
100 	 * Check if we have an active batch on this CPU. If not, just
101 	 * flush now and return.
102 	 */
103 	if (!batch->active) {
104 		flush_hash_page(vpn, rpte, psize, ssize, mm_is_thread_local(mm));
105 		put_cpu_var(ppc64_tlb_batch);
106 		return;
107 	}
108 
109 	/*
110 	 * This can happen when we are in the middle of a TLB batch and
111 	 * we encounter memory pressure (eg copy_page_range when it tries
112 	 * to allocate a new pte). If we have to reclaim memory and end
113 	 * up scanning and resetting referenced bits then our batch context
114 	 * will change mid stream.
115 	 *
116 	 * We also need to ensure only one page size is present in a given
117 	 * batch
118 	 */
119 	if (i != 0 && (mm != batch->mm || batch->psize != psize ||
120 		       batch->ssize != ssize)) {
121 		__flush_tlb_pending(batch);
122 		i = 0;
123 	}
124 	if (i == 0) {
125 		batch->mm = mm;
126 		batch->psize = psize;
127 		batch->ssize = ssize;
128 	}
129 	batch->pte[i] = rpte;
130 	batch->vpn[i] = vpn;
131 	batch->index = ++i;
132 	if (i >= PPC64_TLB_BATCH_NR)
133 		__flush_tlb_pending(batch);
134 	put_cpu_var(ppc64_tlb_batch);
135 }
136 
137 /*
138  * This function is called when terminating an mmu batch or when a batch
139  * is full. It will perform the flush of all the entries currently stored
140  * in a batch.
141  *
142  * Must be called from within some kind of spinlock/non-preempt region...
143  */
144 void __flush_tlb_pending(struct ppc64_tlb_batch *batch)
145 {
146 	int i, local;
147 
148 	i = batch->index;
149 	local = mm_is_thread_local(batch->mm);
150 	if (i == 1)
151 		flush_hash_page(batch->vpn[0], batch->pte[0],
152 				batch->psize, batch->ssize, local);
153 	else
154 		flush_hash_range(i, local);
155 	batch->index = 0;
156 }
157 
158 void hash__tlb_flush(struct mmu_gather *tlb)
159 {
160 	struct ppc64_tlb_batch *tlbbatch = &get_cpu_var(ppc64_tlb_batch);
161 
162 	/*
163 	 * If there's a TLB batch pending, then we must flush it because the
164 	 * pages are going to be freed and we really don't want to have a CPU
165 	 * access a freed page because it has a stale TLB
166 	 */
167 	if (tlbbatch->index)
168 		__flush_tlb_pending(tlbbatch);
169 
170 	put_cpu_var(ppc64_tlb_batch);
171 }
172 
173 /**
174  * __flush_hash_table_range - Flush all HPTEs for a given address range
175  *                            from the hash table (and the TLB). But keeps
176  *                            the linux PTEs intact.
177  *
178  * @start	: starting address
179  * @end         : ending address (not included in the flush)
180  *
181  * This function is mostly to be used by some IO hotplug code in order
182  * to remove all hash entries from a given address range used to map IO
183  * space on a removed PCI-PCI bidge without tearing down the full mapping
184  * since 64K pages may overlap with other bridges when using 64K pages
185  * with 4K HW pages on IO space.
186  *
187  * Because of that usage pattern, it is implemented for small size rather
188  * than speed.
189  */
190 void __flush_hash_table_range(unsigned long start, unsigned long end)
191 {
192 	int hugepage_shift;
193 	unsigned long flags;
194 
195 	start = ALIGN_DOWN(start, PAGE_SIZE);
196 	end = ALIGN(end, PAGE_SIZE);
197 
198 
199 	/*
200 	 * Note: Normally, we should only ever use a batch within a
201 	 * PTE locked section. This violates the rule, but will work
202 	 * since we don't actually modify the PTEs, we just flush the
203 	 * hash while leaving the PTEs intact (including their reference
204 	 * to being hashed). This is not the most performance oriented
205 	 * way to do things but is fine for our needs here.
206 	 */
207 	local_irq_save(flags);
208 	arch_enter_lazy_mmu_mode();
209 	for (; start < end; start += PAGE_SIZE) {
210 		pte_t *ptep = find_init_mm_pte(start, &hugepage_shift);
211 		unsigned long pte;
212 
213 		if (ptep == NULL)
214 			continue;
215 		pte = pte_val(*ptep);
216 		if (!(pte & H_PAGE_HASHPTE))
217 			continue;
218 		hpte_need_flush(&init_mm, start, ptep, pte, hugepage_shift);
219 	}
220 	arch_leave_lazy_mmu_mode();
221 	local_irq_restore(flags);
222 }
223 
224 void flush_hash_table_pmd_range(struct mm_struct *mm, pmd_t *pmd, unsigned long addr)
225 {
226 	pte_t *pte;
227 	pte_t *start_pte;
228 	unsigned long flags;
229 
230 	addr = ALIGN_DOWN(addr, PMD_SIZE);
231 	/*
232 	 * Note: Normally, we should only ever use a batch within a
233 	 * PTE locked section. This violates the rule, but will work
234 	 * since we don't actually modify the PTEs, we just flush the
235 	 * hash while leaving the PTEs intact (including their reference
236 	 * to being hashed). This is not the most performance oriented
237 	 * way to do things but is fine for our needs here.
238 	 */
239 	local_irq_save(flags);
240 	arch_enter_lazy_mmu_mode();
241 	start_pte = pte_offset_map(pmd, addr);
242 	for (pte = start_pte; pte < start_pte + PTRS_PER_PTE; pte++) {
243 		unsigned long pteval = pte_val(*pte);
244 		if (pteval & H_PAGE_HASHPTE)
245 			hpte_need_flush(mm, addr, pte, pteval, 0);
246 		addr += PAGE_SIZE;
247 	}
248 	arch_leave_lazy_mmu_mode();
249 	local_irq_restore(flags);
250 }
251