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/*
* Switch an MMU context.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2013 Tensilica Inc.
*/
#ifndef _XTENSA_MMU_CONTEXT_H
#define _XTENSA_MMU_CONTEXT_H
#ifndef CONFIG_MMU
#include <asm/nommu_context.h>
#else
#include <linux/stringify.h>
#include <linux/sched.h>
#include <linux/mm_types.h>
#include <asm/vectors.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm-generic/mm_hooks.h>
#include <asm-generic/percpu.h>
#if (XCHAL_HAVE_TLBS != 1)
# error "Linux must have an MMU!"
#endif
DECLARE_PER_CPU(unsigned long, asid_cache);
#define cpu_asid_cache(cpu) per_cpu(asid_cache, cpu)
/*
* NO_CONTEXT is the invalid ASID value that we don't ever assign to
* any user or kernel context. We use the reserved values in the
* ASID_INSERT macro below.
*
* 0 invalid
* 1 kernel
* 2 reserved
* 3 reserved
* 4...255 available
*/
#define NO_CONTEXT 0
#define ASID_USER_FIRST 4
#define ASID_MASK ((1 << XCHAL_MMU_ASID_BITS) - 1)
#define ASID_INSERT(x) (0x03020001 | (((x) & ASID_MASK) << 8))
void init_mmu(void);
static inline void set_rasid_register (unsigned long val)
{
__asm__ __volatile__ (" wsr %0, rasid\n\t"
" isync\n" : : "a" (val));
}
static inline unsigned long get_rasid_register (void)
{
unsigned long tmp;
__asm__ __volatile__ (" rsr %0, rasid\n\t" : "=a" (tmp));
return tmp;
}
static inline void get_new_mmu_context(struct mm_struct *mm, unsigned int cpu)
{
unsigned long asid = cpu_asid_cache(cpu);
if ((++asid & ASID_MASK) == 0) {
/*
* Start new asid cycle; continue counting with next
* incarnation bits; skipping over 0, 1, 2, 3.
*/
local_flush_tlb_all();
asid += ASID_USER_FIRST;
}
cpu_asid_cache(cpu) = asid;
mm->context.asid[cpu] = asid;
mm->context.cpu = cpu;
}
static inline void get_mmu_context(struct mm_struct *mm, unsigned int cpu)
{
/*
* Check if our ASID is of an older version and thus invalid.
*/
if (mm) {
unsigned long asid = mm->context.asid[cpu];
if (asid == NO_CONTEXT ||
((asid ^ cpu_asid_cache(cpu)) & ~ASID_MASK))
get_new_mmu_context(mm, cpu);
}
}
static inline void activate_context(struct mm_struct *mm, unsigned int cpu)
{
get_mmu_context(mm, cpu);
set_rasid_register(ASID_INSERT(mm->context.asid[cpu]));
invalidate_page_directory();
}
/*
* Initialize the context related info for a new mm_struct
* instance. Valid cpu values are 0..(NR_CPUS-1), so initializing
* to -1 says the process has never run on any core.
*/
static inline int init_new_context(struct task_struct *tsk,
struct mm_struct *mm)
{
int cpu;
for_each_possible_cpu(cpu) {
mm->context.asid[cpu] = NO_CONTEXT;
}
mm->context.cpu = -1;
return 0;
}
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
unsigned int cpu = smp_processor_id();
int migrated = next->context.cpu != cpu;
/* Flush the icache if we migrated to a new core. */
if (migrated) {
__invalidate_icache_all();
next->context.cpu = cpu;
}
if (migrated || prev != next)
activate_context(next, cpu);
}
#define activate_mm(prev, next) switch_mm((prev), (next), NULL)
#define deactivate_mm(tsk, mm) do { } while (0)
/*
* Destroy context related info for an mm_struct that is about
* to be put to rest.
*/
static inline void destroy_context(struct mm_struct *mm)
{
invalidate_page_directory();
}
static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
/* Nothing to do. */
}
#endif /* CONFIG_MMU */
#endif /* _XTENSA_MMU_CONTEXT_H */
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