2 * MMU context allocation for 64-bit kernels.
4 * Copyright (C) 2004 Anton Blanchard, IBM Corp. <anton@samba.org>
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
13 #include <linux/sched.h>
14 #include <linux/kernel.h>
15 #include <linux/errno.h>
16 #include <linux/string.h>
17 #include <linux/types.h>
19 #include <linux/pkeys.h>
20 #include <linux/spinlock.h>
21 #include <linux/idr.h>
22 #include <linux/export.h>
23 #include <linux/gfp.h>
24 #include <linux/slab.h>
26 #include <asm/mmu_context.h>
27 #include <asm/pgalloc.h>
29 static DEFINE_IDA(mmu_context_ida);
31 static int alloc_context_id(int min_id, int max_id)
33 return ida_alloc_range(&mmu_context_ida, min_id, max_id, GFP_KERNEL);
36 void hash__reserve_context_id(int id)
38 int result = ida_alloc_range(&mmu_context_ida, id, id, GFP_KERNEL);
40 WARN(result != id, "mmu: Failed to reserve context id %d (rc %d)\n", id, result);
43 int hash__alloc_context_id(void)
47 if (mmu_has_feature(MMU_FTR_68_BIT_VA))
48 max = MAX_USER_CONTEXT;
50 max = MAX_USER_CONTEXT_65BIT_VA;
52 return alloc_context_id(MIN_USER_CONTEXT, max);
54 EXPORT_SYMBOL_GPL(hash__alloc_context_id);
56 void slb_setup_new_exec(void);
58 static int hash__init_new_context(struct mm_struct *mm)
62 index = hash__alloc_context_id();
67 * The old code would re-promote on fork, we don't do that when using
68 * slices as it could cause problem promoting slices that have been
71 * For book3s we have MMU_NO_CONTEXT set to be ~0. Hence check
72 * explicitly against context.id == 0. This ensures that we properly
73 * initialize context slice details for newly allocated mm's (which will
74 * have id == 0) and don't alter context slice inherited via fork (which
77 * We should not be calling init_new_context() on init_mm. Hence a
78 * check against 0 is OK.
80 if (mm->context.id == 0)
81 slice_init_new_context_exec(mm);
83 subpage_prot_init_new_context(mm);
89 void hash__setup_new_exec(void)
91 slice_setup_new_exec();
96 static int radix__init_new_context(struct mm_struct *mm)
98 unsigned long rts_field;
101 max_id = (1 << mmu_pid_bits) - 1;
102 index = alloc_context_id(mmu_base_pid, max_id);
107 * set the process table entry,
109 rts_field = radix__get_tree_size();
110 process_tb[index].prtb0 = cpu_to_be64(rts_field | __pa(mm->pgd) | RADIX_PGD_INDEX_SIZE);
113 * Order the above store with subsequent update of the PID
114 * register (at which point HW can start loading/caching
115 * the entry) and the corresponding load by the MMU from
118 asm volatile("ptesync;isync" : : : "memory");
120 mm->context.npu_context = NULL;
125 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
130 index = radix__init_new_context(mm);
132 index = hash__init_new_context(mm);
137 mm->context.id = index;
139 mm->context.pte_frag = NULL;
140 mm->context.pmd_frag = NULL;
141 #ifdef CONFIG_SPAPR_TCE_IOMMU
144 atomic_set(&mm->context.active_cpus, 0);
145 atomic_set(&mm->context.copros, 0);
150 void __destroy_context(int context_id)
152 ida_free(&mmu_context_ida, context_id);
154 EXPORT_SYMBOL_GPL(__destroy_context);
156 static void destroy_contexts(mm_context_t *ctx)
158 int index, context_id;
160 for (index = 0; index < ARRAY_SIZE(ctx->extended_id); index++) {
161 context_id = ctx->extended_id[index];
163 ida_free(&mmu_context_ida, context_id);
167 static void pte_frag_destroy(void *pte_frag)
172 page = virt_to_page(pte_frag);
173 /* drop all the pending references */
174 count = ((unsigned long)pte_frag & ~PAGE_MASK) >> PTE_FRAG_SIZE_SHIFT;
175 /* We allow PTE_FRAG_NR fragments from a PTE page */
176 if (atomic_sub_and_test(PTE_FRAG_NR - count, &page->pt_frag_refcount)) {
177 pgtable_page_dtor(page);
182 static void pmd_frag_destroy(void *pmd_frag)
187 page = virt_to_page(pmd_frag);
188 /* drop all the pending references */
189 count = ((unsigned long)pmd_frag & ~PAGE_MASK) >> PMD_FRAG_SIZE_SHIFT;
190 /* We allow PTE_FRAG_NR fragments from a PTE page */
191 if (atomic_sub_and_test(PMD_FRAG_NR - count, &page->pt_frag_refcount)) {
192 pgtable_pmd_page_dtor(page);
197 static void destroy_pagetable_cache(struct mm_struct *mm)
201 frag = mm->context.pte_frag;
203 pte_frag_destroy(frag);
205 frag = mm->context.pmd_frag;
207 pmd_frag_destroy(frag);
211 void destroy_context(struct mm_struct *mm)
213 #ifdef CONFIG_SPAPR_TCE_IOMMU
214 WARN_ON_ONCE(!list_empty(&mm->context.iommu_group_mem_list));
217 WARN_ON(process_tb[mm->context.id].prtb0 != 0);
219 subpage_prot_free(mm);
220 destroy_contexts(&mm->context);
221 mm->context.id = MMU_NO_CONTEXT;
224 void arch_exit_mmap(struct mm_struct *mm)
226 destroy_pagetable_cache(mm);
228 if (radix_enabled()) {
230 * Radix doesn't have a valid bit in the process table
231 * entries. However we know that at least P9 implementation
232 * will avoid caching an entry with an invalid RTS field,
233 * and 0 is invalid. So this will do.
235 * This runs before the "fullmm" tlb flush in exit_mmap,
236 * which does a RIC=2 tlbie to clear the process table
237 * entry. See the "fullmm" comments in tlb-radix.c.
239 * No barrier required here after the store because
240 * this process will do the invalidate, which starts with
243 process_tb[mm->context.id].prtb0 = 0;
247 #ifdef CONFIG_PPC_RADIX_MMU
248 void radix__switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
250 mtspr(SPRN_PID, next->context.id);