139 lines
3.8 KiB
C
139 lines
3.8 KiB
C
/* MN10300 MMU context management
|
|
*
|
|
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
|
|
* Modified by David Howells (dhowells@redhat.com)
|
|
* - Derived from include/asm-m32r/mmu_context.h
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public Licence
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the Licence, or (at your option) any later version.
|
|
*
|
|
*
|
|
* This implements an algorithm to provide TLB PID mappings to provide
|
|
* selective access to the TLB for processes, thus reducing the number of TLB
|
|
* flushes required.
|
|
*
|
|
* Note, however, that the M32R algorithm is technically broken as it does not
|
|
* handle version wrap-around, and could, theoretically, have a problem with a
|
|
* very long lived program that sleeps long enough for the version number to
|
|
* wrap all the way around so that its TLB mappings appear valid once again.
|
|
*/
|
|
#ifndef _ASM_MMU_CONTEXT_H
|
|
#define _ASM_MMU_CONTEXT_H
|
|
|
|
#include <asm/atomic.h>
|
|
#include <asm/pgalloc.h>
|
|
#include <asm/tlbflush.h>
|
|
#include <asm-generic/mm_hooks.h>
|
|
|
|
#define MMU_CONTEXT_TLBPID_MASK 0x000000ffUL
|
|
#define MMU_CONTEXT_VERSION_MASK 0xffffff00UL
|
|
#define MMU_CONTEXT_FIRST_VERSION 0x00000100UL
|
|
#define MMU_NO_CONTEXT 0x00000000UL
|
|
|
|
extern unsigned long mmu_context_cache[NR_CPUS];
|
|
#define mm_context(mm) (mm->context.tlbpid[smp_processor_id()])
|
|
|
|
#define enter_lazy_tlb(mm, tsk) do {} while (0)
|
|
|
|
#ifdef CONFIG_SMP
|
|
#define cpu_ran_vm(cpu, mm) \
|
|
cpumask_set_cpu((cpu), mm_cpumask(mm))
|
|
#define cpu_maybe_ran_vm(cpu, mm) \
|
|
cpumask_test_and_set_cpu((cpu), mm_cpumask(mm))
|
|
#else
|
|
#define cpu_ran_vm(cpu, mm) do {} while (0)
|
|
#define cpu_maybe_ran_vm(cpu, mm) true
|
|
#endif /* CONFIG_SMP */
|
|
|
|
/*
|
|
* allocate an MMU context
|
|
*/
|
|
static inline unsigned long allocate_mmu_context(struct mm_struct *mm)
|
|
{
|
|
unsigned long *pmc = &mmu_context_cache[smp_processor_id()];
|
|
unsigned long mc = ++(*pmc);
|
|
|
|
if (!(mc & MMU_CONTEXT_TLBPID_MASK)) {
|
|
/* we exhausted the TLB PIDs of this version on this CPU, so we
|
|
* flush this CPU's TLB in its entirety and start new cycle */
|
|
flush_tlb_all();
|
|
|
|
/* fix the TLB version if needed (we avoid version #0 so as to
|
|
* distingush MMU_NO_CONTEXT) */
|
|
if (!mc)
|
|
*pmc = mc = MMU_CONTEXT_FIRST_VERSION;
|
|
}
|
|
mm_context(mm) = mc;
|
|
return mc;
|
|
}
|
|
|
|
/*
|
|
* get an MMU context if one is needed
|
|
*/
|
|
static inline unsigned long get_mmu_context(struct mm_struct *mm)
|
|
{
|
|
unsigned long mc = MMU_NO_CONTEXT, cache;
|
|
|
|
if (mm) {
|
|
cache = mmu_context_cache[smp_processor_id()];
|
|
mc = mm_context(mm);
|
|
|
|
/* if we have an old version of the context, replace it */
|
|
if ((mc ^ cache) & MMU_CONTEXT_VERSION_MASK)
|
|
mc = allocate_mmu_context(mm);
|
|
}
|
|
return mc;
|
|
}
|
|
|
|
/*
|
|
* initialise the context related info for a new mm_struct instance
|
|
*/
|
|
static inline int init_new_context(struct task_struct *tsk,
|
|
struct mm_struct *mm)
|
|
{
|
|
int num_cpus = NR_CPUS, i;
|
|
|
|
for (i = 0; i < num_cpus; i++)
|
|
mm->context.tlbpid[i] = MMU_NO_CONTEXT;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* destroy context related info for an mm_struct that is about to be put to
|
|
* rest
|
|
*/
|
|
#define destroy_context(mm) do { } while (0)
|
|
|
|
/*
|
|
* after we have set current->mm to a new value, this activates the context for
|
|
* the new mm so we see the new mappings.
|
|
*/
|
|
static inline void activate_context(struct mm_struct *mm, int cpu)
|
|
{
|
|
PIDR = get_mmu_context(mm) & MMU_CONTEXT_TLBPID_MASK;
|
|
}
|
|
|
|
/*
|
|
* change between virtual memory sets
|
|
*/
|
|
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
|
|
struct task_struct *tsk)
|
|
{
|
|
int cpu = smp_processor_id();
|
|
|
|
if (prev != next) {
|
|
cpu_ran_vm(cpu, next);
|
|
activate_context(next, cpu);
|
|
PTBR = (unsigned long) next->pgd;
|
|
} else if (!cpu_maybe_ran_vm(cpu, next)) {
|
|
activate_context(next, cpu);
|
|
}
|
|
}
|
|
|
|
#define deactivate_mm(tsk, mm) do {} while (0)
|
|
#define activate_mm(prev, next) switch_mm((prev), (next), NULL)
|
|
|
|
#endif /* _ASM_MMU_CONTEXT_H */
|