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 if (!start_pte) 243 goto out; 244 for (pte = start_pte; pte < start_pte + PTRS_PER_PTE; pte++) { 245 unsigned long pteval = pte_val(*pte); 246 if (pteval & H_PAGE_HASHPTE) 247 hpte_need_flush(mm, addr, pte, pteval, 0); 248 addr += PAGE_SIZE; 249 } 250 pte_unmap(start_pte); 251 out: 252 arch_leave_lazy_mmu_mode(); 253 local_irq_restore(flags); 254 } 255