LXR linux/arch/xtensa/include/asm/mmu

   1/*
   2 * Switch an MMU context.
   3 *
   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
   6 * for more details.
   7 *
   8 * Copyright (C) 2001 - 2013 Tensilica Inc.
   9 */
  10
  11#ifndef _XTENSA_MMU_CONTEXT_H
  12#define _XTENSA_MMU_CONTEXT_H
  13
  14#ifndef CONFIG_MMU
  15#include <asm/nommu_context.h>
  16#else
  17
  18#include <linux/stringify.h>
  19#include <linux/sched.h>
  20#include <linux/mm_types.h>
  21
  22#include <asm/vectors.h>
  23
  24#include <asm/pgtable.h>
  25#include <asm/cacheflush.h>
  26#include <asm/tlbflush.h>
  27#include <asm-generic/mm_hooks.h>
  28#include <asm-generic/percpu.h>
  29
  30#if (XCHAL_HAVE_TLBS != 1)
  31# error "Linux must have an MMU!"
  32#endif
  33
  34DECLARE_PER_CPU(unsigned long, asid_cache);
  35#define cpu_asid_cache(cpu) per_cpu(asid_cache, cpu)
  36
  37/*
  38 * NO_CONTEXT is the invalid ASID value that we don't ever assign to
  39 * any user or kernel context.  We use the reserved values in the
  40 * ASID_INSERT macro below.
  41 *
  42 * 0 invalid
  43 * 1 kernel
  44 * 2 reserved
  45 * 3 reserved
  46 * 4...255 available
  47 */
  48
  49#define NO_CONTEXT      0
  50#define ASID_USER_FIRST 4
  51#define ASID_MASK       ((1 << XCHAL_MMU_ASID_BITS) - 1)
  52#define ASID_INSERT(x)  (0x03020001 | (((x) & ASID_MASK) << 8))
  53
  54void init_mmu(void);
  55void init_kio(void);
  56
  57static inline void set_rasid_register (unsigned long val)
  58{
  59        __asm__ __volatile__ (" wsr %0, rasid\n\t"
  60                              " isync\n" : : "a" (val));
  61}
  62
  63static inline unsigned long get_rasid_register (void)
  64{
  65        unsigned long tmp;
  66        __asm__ __volatile__ (" rsr %0, rasid\n\t" : "=a" (tmp));
  67        return tmp;
  68}
  69
  70static inline void get_new_mmu_context(struct mm_struct *mm, unsigned int cpu)
  71{
  72        unsigned long asid = cpu_asid_cache(cpu);
  73        if ((++asid & ASID_MASK) == 0) {
  74                /*
  75                 * Start new asid cycle; continue counting with next
  76                 * incarnation bits; skipping over 0, 1, 2, 3.
  77                 */
  78                local_flush_tlb_all();
  79                asid += ASID_USER_FIRST;
  80        }
  81        cpu_asid_cache(cpu) = asid;
  82        mm->context.asid[cpu] = asid;
  83        mm->context.cpu = cpu;
  84}
  85
  86static inline void get_mmu_context(struct mm_struct *mm, unsigned int cpu)
  87{
  88        /*
  89         * Check if our ASID is of an older version and thus invalid.
  90         */
  91
  92        if (mm) {
  93                unsigned long asid = mm->context.asid[cpu];
  94
  95                if (asid == NO_CONTEXT ||
  96                                ((asid ^ cpu_asid_cache(cpu)) & ~ASID_MASK))
  97                        get_new_mmu_context(mm, cpu);
  98        }
  99}
 100
 101static inline void activate_context(struct mm_struct *mm, unsigned int cpu)
 102{
 103        get_mmu_context(mm, cpu);
 104        set_rasid_register(ASID_INSERT(mm->context.asid[cpu]));
 105        invalidate_page_directory();
 106}
 107
 108/*
 109 * Initialize the context related info for a new mm_struct
 110 * instance.  Valid cpu values are 0..(NR_CPUS-1), so initializing
 111 * to -1 says the process has never run on any core.
 112 */
 113
 114static inline int init_new_context(struct task_struct *tsk,
 115                struct mm_struct *mm)
 116{
 117        int cpu;
 118        for_each_possible_cpu(cpu) {
 119                mm->context.asid[cpu] = NO_CONTEXT;
 120        }
 121        mm->context.cpu = -1;
 122        return 0;
 123}
 124
 125static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 126                             struct task_struct *tsk)
 127{
 128        unsigned int cpu = smp_processor_id();
 129        int migrated = next->context.cpu != cpu;
 130        /* Flush the icache if we migrated to a new core. */
 131        if (migrated) {
 132                __invalidate_icache_all();
 133                next->context.cpu = cpu;
 134        }
 135        if (migrated || prev != next)
 136                activate_context(next, cpu);
 137}
 138
 139#define activate_mm(prev, next) switch_mm((prev), (next), NULL)
 140#define deactivate_mm(tsk, mm)  do { } while (0)
 141
 142/*
 143 * Destroy context related info for an mm_struct that is about
 144 * to be put to rest.
 145 */
 146static inline void destroy_context(struct mm_struct *mm)
 147{
 148        invalidate_page_directory();
 149}
 150
 151
 152static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 153{
 154        /* Nothing to do. */
 155
 156}
 157
 158#endif /* CONFIG_MMU */
 159#endif /* _XTENSA_MMU_CONTEXT_H */
 160