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/slab.h>
16 #include <asm/pgalloc.h>
17 #include <asm/pgtable.h>
20 * For the fast tlb miss handlers, we currently keep a per cpu array
21 * of pointers to the current pgd for each processor. Also, the proc.
22 * id is stuffed into the context register. This should be changed to
23 * use the processor id via current->processor, where current is stored
24 * in watchhi/lo. The context register should be used to contiguously
25 * map the page tables.
27 #define TLBMISS_HANDLER_SETUP_PGD(pgd) \
28 pgd_current[smp_processor_id()] = (unsigned long)(pgd)
29 #define TLBMISS_HANDLER_SETUP() \
30 set_context(((long)(&pgd_current[smp_processor_id()])) << 23); \
31 TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
32 extern unsigned long pgd_current[];
35 #define CPU_CONTEXT(cpu, mm) (mm)->context
37 #define CPU_CONTEXT(cpu, mm) (*((unsigned long *)((mm)->context) + cpu))
39 #define ASID_CACHE(cpu) cpu_data[cpu].asid_cache
42 #define ASID_MASK 0xff
44 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk, unsigned cpu)
49 * All unused by hardware upper bits will be considered
50 * as a software asid extension.
52 #define ASID_VERSION_MASK ((unsigned long)~(ASID_MASK|(ASID_MASK-1)))
53 #define ASID_FIRST_VERSION ((unsigned long)(~ASID_VERSION_MASK) + 1)
56 get_new_mmu_context(struct mm_struct *mm, unsigned long cpu)
58 unsigned long asid = ASID_CACHE(cpu);
60 if (! ((asid += ASID_INC) & ASID_MASK) ) {
62 local_flush_tlb_all(); /* start new asid cycle */
63 if (!asid) /* fix version if needed */
64 asid = ASID_FIRST_VERSION;
66 CPU_CONTEXT(cpu, mm) = ASID_CACHE(cpu) = asid;
70 * Initialize the context related info for a new mm_struct
74 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
79 mm->context = (unsigned long)kmalloc(smp_num_cpus *
80 sizeof(unsigned long), GFP_KERNEL);
82 * Init the "context" values so that a tlbpid allocation
83 * happens on the first switch.
87 memset((void *)mm->context, 0, smp_num_cpus * sizeof(unsigned long));
92 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
93 struct task_struct *tsk, unsigned cpu)
95 /* Check if our ASID is of an older version and thus invalid */
96 if ((CPU_CONTEXT(cpu, next) ^ ASID_CACHE(cpu)) & ASID_VERSION_MASK)
97 get_new_mmu_context(next, cpu);
99 set_entryhi(CPU_CONTEXT(cpu, next));
100 TLBMISS_HANDLER_SETUP_PGD(next->pgd);
104 * Destroy context related info for an mm_struct that is about
107 static inline void destroy_context(struct mm_struct *mm)
111 kfree((void *)mm->context);
116 * After we have set current->mm to a new value, this activates
117 * the context for the new mm so we see the new mappings.
120 activate_mm(struct mm_struct *prev, struct mm_struct *next)
122 /* Unconditionally get a new ASID. */
123 get_new_mmu_context(next, smp_processor_id());
125 set_entryhi(CPU_CONTEXT(smp_processor_id(), next));
126 TLBMISS_HANDLER_SETUP_PGD(next->pgd);
129 #endif /* _ASM_MMU_CONTEXT_H */