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Sourcecode: linux-2.6 version File versions  Download package

context.c

/*
 *  linux/arch/arm/mm/context.c
 *
 *  Copyright (C) 2002-2003 Deep Blue Solutions Ltd, all rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/mm.h>

#include <asm/mmu_context.h>
#include <asm/tlbflush.h>

static DEFINE_SPINLOCK(cpu_asid_lock);
unsigned int cpu_last_asid = ASID_FIRST_VERSION;

/*
 * We fork()ed a process, and we need a new context for the child
 * to run in.  We reserve version 0 for initial tasks so we will
 * always allocate an ASID. The ASID 0 is reserved for the TTBR
 * register changing sequence.
 */
void __init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
      mm->context.id = 0;
}

void __new_context(struct mm_struct *mm)
{
      unsigned int asid;

      spin_lock(&cpu_asid_lock);
      asid = ++cpu_last_asid;
      if (asid == 0)
            asid = cpu_last_asid = ASID_FIRST_VERSION;

      /*
       * If we've used up all our ASIDs, we need
       * to start a new version and flush the TLB.
       */
      if (unlikely((asid & ~ASID_MASK) == 0)) {
            asid = ++cpu_last_asid;
            /* set the reserved ASID before flushing the TLB */
            asm("mcr    p15, 0, %0, c13, c0, 1  @ set reserved context ID\n"
                :
                : "r" (0));
            isb();
            flush_tlb_all();
            if (icache_is_vivt_asid_tagged()) {
                  asm("mcr    p15, 0, %0, c7, c5, 0   @ invalidate I-cache\n"
                      "mcr    p15, 0, %0, c7, c5, 6   @ flush BTAC/BTB\n"
                      :
                      : "r" (0));
                  dsb();
            }
      }
      spin_unlock(&cpu_asid_lock);

      mm->cpu_vm_mask = cpumask_of_cpu(smp_processor_id());
      mm->context.id = asid;
}

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