1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * MMU context allocation for 64-bit kernels.
5 * Copyright (C) 2004 Anton Blanchard, IBM Corp. <anton@samba.org>
8 #include <linux/sched.h>
9 #include <linux/kernel.h>
10 #include <linux/errno.h>
11 #include <linux/string.h>
12 #include <linux/types.h>
14 #include <linux/pkeys.h>
15 #include <linux/spinlock.h>
16 #include <linux/idr.h>
17 #include <linux/export.h>
18 #include <linux/gfp.h>
19 #include <linux/slab.h>
21 #include <asm/mmu_context.h>
22 #include <asm/pgalloc.h>
24 static DEFINE_IDA(mmu_context_ida);
26 static int alloc_context_id(int min_id, int max_id)
28 return ida_alloc_range(&mmu_context_ida, min_id, max_id, GFP_KERNEL);
31 void hash__reserve_context_id(int id)
33 int result = ida_alloc_range(&mmu_context_ida, id, id, GFP_KERNEL);
35 WARN(result != id, "mmu: Failed to reserve context id %d (rc %d)\n", id, result);
38 int hash__alloc_context_id(void)
42 if (mmu_has_feature(MMU_FTR_68_BIT_VA))
43 max = MAX_USER_CONTEXT;
45 max = MAX_USER_CONTEXT_65BIT_VA;
47 return alloc_context_id(MIN_USER_CONTEXT, max);
49 EXPORT_SYMBOL_GPL(hash__alloc_context_id);
51 void slb_setup_new_exec(void);
53 static int hash__init_new_context(struct mm_struct *mm)
57 index = hash__alloc_context_id();
61 mm->context.hash_context = kmalloc(sizeof(struct hash_mm_context),
63 if (!mm->context.hash_context) {
64 ida_free(&mmu_context_ida, index);
69 * The old code would re-promote on fork, we don't do that when using
70 * slices as it could cause problem promoting slices that have been
73 * For book3s we have MMU_NO_CONTEXT set to be ~0. Hence check
74 * explicitly against context.id == 0. This ensures that we properly
75 * initialize context slice details for newly allocated mm's (which will
76 * have id == 0) and don't alter context slice inherited via fork (which
79 * We should not be calling init_new_context() on init_mm. Hence a
80 * check against 0 is OK.
82 if (mm->context.id == 0) {
83 memset(mm->context.hash_context, 0, sizeof(struct hash_mm_context));
84 slice_init_new_context_exec(mm);
86 /* This is fork. Copy hash_context details from current->mm */
87 memcpy(mm->context.hash_context, current->mm->context.hash_context, sizeof(struct hash_mm_context));
88 #ifdef CONFIG_PPC_SUBPAGE_PROT
89 /* inherit subpage prot detalis if we have one. */
90 if (current->mm->context.hash_context->spt) {
91 mm->context.hash_context->spt = kmalloc(sizeof(struct subpage_prot_table),
93 if (!mm->context.hash_context->spt) {
94 ida_free(&mmu_context_ida, index);
95 kfree(mm->context.hash_context);
107 void hash__setup_new_exec(void)
109 slice_setup_new_exec();
111 slb_setup_new_exec();
114 static int radix__init_new_context(struct mm_struct *mm)
116 unsigned long rts_field;
119 max_id = (1 << mmu_pid_bits) - 1;
120 index = alloc_context_id(mmu_base_pid, max_id);
125 * set the process table entry,
127 rts_field = radix__get_tree_size();
128 process_tb[index].prtb0 = cpu_to_be64(rts_field | __pa(mm->pgd) | RADIX_PGD_INDEX_SIZE);
131 * Order the above store with subsequent update of the PID
132 * register (at which point HW can start loading/caching
133 * the entry) and the corresponding load by the MMU from
136 asm volatile("ptesync;isync" : : : "memory");
138 mm->context.npu_context = NULL;
139 mm->context.hash_context = NULL;
144 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
149 index = radix__init_new_context(mm);
151 index = hash__init_new_context(mm);
156 mm->context.id = index;
158 mm->context.pte_frag = NULL;
159 mm->context.pmd_frag = NULL;
160 #ifdef CONFIG_SPAPR_TCE_IOMMU
163 atomic_set(&mm->context.active_cpus, 0);
164 atomic_set(&mm->context.copros, 0);
169 void __destroy_context(int context_id)
171 ida_free(&mmu_context_ida, context_id);
173 EXPORT_SYMBOL_GPL(__destroy_context);
175 static void destroy_contexts(mm_context_t *ctx)
177 int index, context_id;
179 for (index = 0; index < ARRAY_SIZE(ctx->extended_id); index++) {
180 context_id = ctx->extended_id[index];
182 ida_free(&mmu_context_ida, context_id);
184 kfree(ctx->hash_context);
187 static void pmd_frag_destroy(void *pmd_frag)
192 page = virt_to_page(pmd_frag);
193 /* drop all the pending references */
194 count = ((unsigned long)pmd_frag & ~PAGE_MASK) >> PMD_FRAG_SIZE_SHIFT;
195 /* We allow PTE_FRAG_NR fragments from a PTE page */
196 if (atomic_sub_and_test(PMD_FRAG_NR - count, &page->pt_frag_refcount)) {
197 pgtable_pmd_page_dtor(page);
202 static void destroy_pagetable_cache(struct mm_struct *mm)
206 frag = mm->context.pte_frag;
208 pte_frag_destroy(frag);
210 frag = mm->context.pmd_frag;
212 pmd_frag_destroy(frag);
216 void destroy_context(struct mm_struct *mm)
218 #ifdef CONFIG_SPAPR_TCE_IOMMU
219 WARN_ON_ONCE(!list_empty(&mm->context.iommu_group_mem_list));
222 WARN_ON(process_tb[mm->context.id].prtb0 != 0);
224 subpage_prot_free(mm);
225 destroy_contexts(&mm->context);
226 mm->context.id = MMU_NO_CONTEXT;
229 void arch_exit_mmap(struct mm_struct *mm)
231 destroy_pagetable_cache(mm);
233 if (radix_enabled()) {
235 * Radix doesn't have a valid bit in the process table
236 * entries. However we know that at least P9 implementation
237 * will avoid caching an entry with an invalid RTS field,
238 * and 0 is invalid. So this will do.
240 * This runs before the "fullmm" tlb flush in exit_mmap,
241 * which does a RIC=2 tlbie to clear the process table
242 * entry. See the "fullmm" comments in tlb-radix.c.
244 * No barrier required here after the store because
245 * this process will do the invalidate, which starts with
248 process_tb[mm->context.id].prtb0 = 0;
252 #ifdef CONFIG_PPC_RADIX_MMU
253 void radix__switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
255 mtspr(SPRN_PID, next->context.id);