arch/arm/mm/context.c

   1 /*
   2  *  linux/arch/arm/mm/context.c
   3  *
   4  *  Copyright (C) 2002-2003 Deep Blue Solutions Ltd, all rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/init.h>
  11 #include <linux/sched.h>
  12 #include <linux/mm.h>
  13
  14 #include <asm/mmu_context.h>
  15 #include <asm/tlbflush.h>
  16
  17 static DEFINE_SPINLOCK(cpu_asid_lock);
  18 unsigned int cpu_last_asid = ASID_FIRST_VERSION;
  19
  20 /*
  21  * We fork()ed a process, and we need a new context for the child
  22  * to run in.  We reserve version 0 for initial tasks so we will
  23  * always allocate an ASID. The ASID 0 is reserved for the TTBR
  24  * register changing sequence.
  25  */
  26 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm)
  27 {
  28         mm->context.id = 0;
  29 }
  30
  31 void __new_context(struct mm_struct *mm)
  32 {
  33         unsigned int asid;
  34
  35         spin_lock(&cpu_asid_lock);
  36         asid = ++cpu_last_asid;
  37         if (asid == 0)
  38                 asid = cpu_last_asid = ASID_FIRST_VERSION;
  39
  40         /*
  41          * If we've used up all our ASIDs, we need
  42          * to start a new version and flush the TLB.
  43          */
  44         if (unlikely((asid & ~ASID_MASK) == 0)) {
  45                 asid = ++cpu_last_asid;
  46                 /* set the reserved ASID before flushing the TLB */
  47                 asm("mcr        p15, 0, %0, c13, c0, 1  @ set reserved context ID\n"
  48                     :
  49                     : "r" (0));
  50                 isb();
  51                 flush_tlb_all();
  52                 if (icache_is_vivt_asid_tagged()) {
  53                         asm("mcr        p15, 0, %0, c7, c5, 0   @ invalidate I-cache\n"
  54                             "mcr        p15, 0, %0, c7, c5, 6   @ flush BTAC/BTB\n"
  55                             :
  56                             : "r" (0));
  57                         dsb();
  58                 }
  59         }
  60         spin_unlock(&cpu_asid_lock);
  61
  62         mm->cpu_vm_mask = cpumask_of_cpu(smp_processor_id());
  63         mm->context.id = asid;
  64 }