context.c 1.3 KB

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  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. #include <asm/mmu_context.h>
  14. #include <asm/tlbflush.h>
  15. unsigned int cpu_last_asid = { 1 << ASID_BITS };
  16. /*
  17. * We fork()ed a process, and we need a new context for the child
  18. * to run in. We reserve version 0 for initial tasks so we will
  19. * always allocate an ASID. The ASID 0 is reserved for the TTBR
  20. * register changing sequence.
  21. */
  22. void __init_new_context(struct task_struct *tsk, struct mm_struct *mm)
  23. {
  24. mm->context.id = 0;
  25. }
  26. void __new_context(struct mm_struct *mm)
  27. {
  28. unsigned int asid;
  29. asid = ++cpu_last_asid;
  30. if (asid == 0)
  31. asid = cpu_last_asid = 1 << ASID_BITS;
  32. /*
  33. * If we've used up all our ASIDs, we need
  34. * to start a new version and flush the TLB.
  35. */
  36. if ((asid & ~ASID_MASK) == 0) {
  37. asid = ++cpu_last_asid;
  38. /* set the reserved ASID before flushing the TLB */
  39. asm("mcr p15, 0, %0, c13, c0, 1 @ set reserved context ID\n"
  40. :
  41. : "r" (0));
  42. isb();
  43. flush_tlb_all();
  44. }
  45. mm->context.id = asid;
  46. }