mmu_context.h

  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#include <linux/pgtable.h>
 22
 23#include <asm/vectors.h>
 24
 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
114#define init_new_context init_new_context
115static inline int init_new_context(struct task_struct *tsk,
116		struct mm_struct *mm)
117{
118	int cpu;
119	for_each_possible_cpu(cpu) {
120		mm->context.asid[cpu] = NO_CONTEXT;
121	}
122	mm->context.cpu = -1;
123	return 0;
124}
125
126static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
127			     struct task_struct *tsk)
128{
129	unsigned int cpu = smp_processor_id();
130	int migrated = next->context.cpu != cpu;
131	/* Flush the icache if we migrated to a new core. */
132	if (migrated) {
133		__invalidate_icache_all();
134		next->context.cpu = cpu;
135	}
136	if (migrated || prev != next)
137		activate_context(next, cpu);
138}
139
140/*
141 * Destroy context related info for an mm_struct that is about
142 * to be put to rest.
143 */
144#define destroy_context destroy_context
145static inline void destroy_context(struct mm_struct *mm)
146{
147	invalidate_page_directory();
148}
149
150
151#include <asm-generic/mmu_context.h>
152
153#endif /* CONFIG_MMU */
154#endif /* _XTENSA_MMU_CONTEXT_H */