2 * Switch a MMU context.
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
8 * Copyright (C) 1996, 1997, 1998, 1999 by Ralf Baechle
9 * Copyright (C) 1999 Silicon Graphics, Inc.
11 #ifndef _ASM_MMU_CONTEXT_H
12 #define _ASM_MMU_CONTEXT_H
14 #include <linux/config.h>
15 #include <linux/errno.h>
16 #include <linux/sched.h>
17 #include <linux/slab.h>
18 #include <asm/cacheflush.h>
19 #include <asm/tlbflush.h>
22 * For the fast tlb miss handlers, we currently keep a per cpu array
23 * of pointers to the current pgd for each processor. Also, the proc.
24 * id is stuffed into the context register. This should be changed to
25 * use the processor id via current->processor, where current is stored
26 * in watchhi/lo. The context register should be used to contiguously
27 * map the page tables.
29 #define TLBMISS_HANDLER_SETUP_PGD(pgd) \
30 pgd_current[smp_processor_id()] = (unsigned long)(pgd)
32 #define TLBMISS_HANDLER_SETUP() \
33 write_c0_context((unsigned long) smp_processor_id() << 23); \
34 TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
37 #define TLBMISS_HANDLER_SETUP() \
38 write_c0_context((unsigned long) &pgd_current[smp_processor_id()] << 23); \
39 TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
41 extern unsigned long pgd_current[];
43 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
46 #define ASID_MASK 0xfc0
48 #elif defined(CONFIG_CPU_RM9000)
51 #define ASID_MASK 0xfff
53 #else /* FIXME: not correct for R6000, R8000 */
56 #define ASID_MASK 0xff
60 #define cpu_context(cpu, mm) ((mm)->context[cpu])
61 #define cpu_asid(cpu, mm) (cpu_context((cpu), (mm)) & ASID_MASK)
62 #define asid_cache(cpu) (cpu_data[cpu].asid_cache)
64 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
69 * All unused by hardware upper bits will be considered
70 * as a software asid extension.
72 #define ASID_VERSION_MASK ((unsigned long)~(ASID_MASK|(ASID_MASK-1)))
73 #define ASID_FIRST_VERSION ((unsigned long)(~ASID_VERSION_MASK) + 1)
76 get_new_mmu_context(struct mm_struct *mm, unsigned long cpu)
78 unsigned long asid = asid_cache(cpu);
80 if (! ((asid += ASID_INC) & ASID_MASK) ) {
81 #ifdef CONFIG_VTAG_ICACHE
84 local_flush_tlb_all(); /* start new asid cycle */
85 if (!asid) /* fix version if needed */
86 asid = ASID_FIRST_VERSION;
88 cpu_context(cpu, mm) = asid_cache(cpu) = asid;
92 * Initialize the context related info for a new mm_struct
96 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
100 for (i = 0; i < num_online_cpus(); i++)
101 cpu_context(i, mm) = 0;
106 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
107 struct task_struct *tsk)
109 unsigned int cpu = smp_processor_id();
112 local_irq_save(flags);
114 /* Check if our ASID is of an older version and thus invalid */
115 if ((cpu_context(cpu, next) ^ asid_cache(cpu)) & ASID_VERSION_MASK)
116 get_new_mmu_context(next, cpu);
118 write_c0_entryhi(cpu_context(cpu, next));
119 TLBMISS_HANDLER_SETUP_PGD(next->pgd);
122 * Mark current->active_mm as not "active" anymore.
123 * We don't want to mislead possible IPI tlb flush routines.
125 clear_bit(cpu, &prev->cpu_vm_mask);
126 set_bit(cpu, &next->cpu_vm_mask);
128 local_irq_restore(flags);
132 * Destroy context related info for an mm_struct that is about
135 static inline void destroy_context(struct mm_struct *mm)
139 #define deactivate_mm(tsk,mm) do { } while (0)
142 * After we have set current->mm to a new value, this activates
143 * the context for the new mm so we see the new mappings.
146 activate_mm(struct mm_struct *prev, struct mm_struct *next)
149 int cpu = smp_processor_id();
151 local_irq_save(flags);
153 /* Unconditionally get a new ASID. */
154 get_new_mmu_context(next, cpu);
156 write_c0_entryhi(cpu_context(cpu, next));
157 TLBMISS_HANDLER_SETUP_PGD(next->pgd);
159 /* mark mmu ownership change */
160 clear_bit(cpu, &prev->cpu_vm_mask);
161 set_bit(cpu, &next->cpu_vm_mask);
163 local_irq_restore(flags);
167 * If mm is currently active_mm, we can't really drop it. Instead,
168 * we will get a new one for it.
171 drop_mmu_context(struct mm_struct *mm, unsigned cpu)
175 local_irq_save(flags);
177 if (test_bit(cpu, &mm->cpu_vm_mask)) {
178 get_new_mmu_context(mm, cpu);
179 write_c0_entryhi(cpu_asid(cpu, mm));
181 /* will get a new context next time */
182 cpu_context(cpu, mm) = 0;
185 local_irq_restore(flags);
188 #endif /* _ASM_MMU_CONTEXT_H */