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/spinlock.h>
20 #include <linux/idr.h>
21 #include <linux/export.h>
22 #include <linux/gfp.h>
23 #include <linux/slab.h>
25 #include <asm/mmu_context.h>
26 #include <asm/pgalloc.h>
28 static DEFINE_SPINLOCK(mmu_context_lock);
29 static DEFINE_IDA(mmu_context_ida);
31 static int alloc_context_id(int min_id, int max_id)
36 if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
39 spin_lock(&mmu_context_lock);
40 err = ida_get_new_above(&mmu_context_ida, min_id, &index);
41 spin_unlock(&mmu_context_lock);
49 spin_lock(&mmu_context_lock);
50 ida_remove(&mmu_context_ida, index);
51 spin_unlock(&mmu_context_lock);
58 void hash__reserve_context_id(int id)
63 if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
66 spin_lock(&mmu_context_lock);
67 rc = ida_get_new_above(&mmu_context_ida, id, &result);
68 spin_unlock(&mmu_context_lock);
69 } while (rc == -EAGAIN);
71 WARN(result != id, "mmu: Failed to reserve context id %d (rc %d)\n", id, result);
74 int hash__alloc_context_id(void)
78 if (mmu_has_feature(MMU_FTR_68_BIT_VA))
79 max = MAX_USER_CONTEXT;
81 max = MAX_USER_CONTEXT_65BIT_VA;
83 return alloc_context_id(MIN_USER_CONTEXT, max);
85 EXPORT_SYMBOL_GPL(hash__alloc_context_id);
87 static int hash__init_new_context(struct mm_struct *mm)
91 index = hash__alloc_context_id();
96 * In the case of exec, use the default limit,
97 * otherwise inherit it from the mm we are duplicating.
99 if (!mm->context.addr_limit)
100 mm->context.addr_limit = DEFAULT_MAP_WINDOW_USER64;
103 * The old code would re-promote on fork, we don't do that when using
104 * slices as it could cause problem promoting slices that have been
107 * For book3s we have MMU_NO_CONTEXT set to be ~0. Hence check
108 * explicitly against context.id == 0. This ensures that we properly
109 * initialize context slice details for newly allocated mm's (which will
110 * have id == 0) and don't alter context slice inherited via fork (which
111 * will have id != 0).
113 * We should not be calling init_new_context() on init_mm. Hence a
114 * check against 0 is OK.
116 if (mm->context.id == 0)
117 slice_set_user_psize(mm, mmu_virtual_psize);
119 subpage_prot_init_new_context(mm);
124 static int radix__init_new_context(struct mm_struct *mm)
126 unsigned long rts_field;
129 max_id = (1 << mmu_pid_bits) - 1;
130 index = alloc_context_id(mmu_base_pid, max_id);
135 * set the process table entry,
137 rts_field = radix__get_tree_size();
138 process_tb[index].prtb0 = cpu_to_be64(rts_field | __pa(mm->pgd) | RADIX_PGD_INDEX_SIZE);
141 * Order the above store with subsequent update of the PID
142 * register (at which point HW can start loading/caching
143 * the entry) and the corresponding load by the MMU from
146 asm volatile("ptesync;isync" : : : "memory");
148 mm->context.npu_context = NULL;
153 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
158 index = radix__init_new_context(mm);
160 index = hash__init_new_context(mm);
165 mm->context.id = index;
167 #ifdef CONFIG_PPC_64K_PAGES
168 mm->context.pte_frag = NULL;
170 #ifdef CONFIG_SPAPR_TCE_IOMMU
173 atomic_set(&mm->context.active_cpus, 0);
178 void __destroy_context(int context_id)
180 spin_lock(&mmu_context_lock);
181 ida_remove(&mmu_context_ida, context_id);
182 spin_unlock(&mmu_context_lock);
184 EXPORT_SYMBOL_GPL(__destroy_context);
186 #ifdef CONFIG_PPC_64K_PAGES
187 static void destroy_pagetable_page(struct mm_struct *mm)
193 pte_frag = mm->context.pte_frag;
197 page = virt_to_page(pte_frag);
198 /* drop all the pending references */
199 count = ((unsigned long)pte_frag & ~PAGE_MASK) >> PTE_FRAG_SIZE_SHIFT;
200 /* We allow PTE_FRAG_NR fragments from a PTE page */
201 if (page_ref_sub_and_test(page, PTE_FRAG_NR - count)) {
202 pgtable_page_dtor(page);
203 free_hot_cold_page(page, 0);
208 static inline void destroy_pagetable_page(struct mm_struct *mm)
214 void destroy_context(struct mm_struct *mm)
216 #ifdef CONFIG_SPAPR_TCE_IOMMU
217 WARN_ON_ONCE(!list_empty(&mm->context.iommu_group_mem_list));
219 if (radix_enabled()) {
221 * Radix doesn't have a valid bit in the process table
222 * entries. However we know that at least P9 implementation
223 * will avoid caching an entry with an invalid RTS field,
224 * and 0 is invalid. So this will do.
226 process_tb[mm->context.id].prtb0 = 0;
228 subpage_prot_free(mm);
229 destroy_pagetable_page(mm);
230 __destroy_context(mm->context.id);
231 mm->context.id = MMU_NO_CONTEXT;
234 #ifdef CONFIG_PPC_RADIX_MMU
235 void radix__switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
238 if (cpu_has_feature(CPU_FTR_POWER9_DD1)) {
240 mtspr(SPRN_PID, next->context.id);
242 asm volatile(PPC_INVALIDATE_ERAT : : :"memory");
244 mtspr(SPRN_PID, next->context.id);