arch/powerpc/mm/icswx_pid.c

   1 /*
   2  *  ICSWX and ACOP/PID Management
   3  *
   4  *  Copyright (C) 2011 Anton Blanchard, IBM Corp. <anton@samba.org>
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  */
  12
  13 #include <linux/sched.h>
  14 #include <linux/kernel.h>
  15 #include <linux/errno.h>
  16 #include <linux/types.h>
  17 #include <linux/mm.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/idr.h>
  20 #include <linux/module.h>
  21 #include "icswx.h"
  22
  23 #define COP_PID_MIN (COP_PID_NONE + 1)
  24 #define COP_PID_MAX (0xFFFF)
  25
  26 static DEFINE_SPINLOCK(mmu_context_acop_lock);
  27 static DEFINE_IDA(cop_ida);
  28
  29 static int new_cop_pid(struct ida *ida, int min_id, int max_id,
  30                        spinlock_t *lock)
  31 {
  32         int index;
  33         int err;
  34
  35 again:
  36         if (!ida_pre_get(ida, GFP_KERNEL))
  37                 return -ENOMEM;
  38
  39         spin_lock(lock);
  40         err = ida_get_new_above(ida, min_id, &index);
  41         spin_unlock(lock);
  42
  43         if (err == -EAGAIN)
  44                 goto again;
  45         else if (err)
  46                 return err;
  47
  48         if (index > max_id) {
  49                 spin_lock(lock);
  50                 ida_remove(ida, index);
  51                 spin_unlock(lock);
  52                 return -ENOMEM;
  53         }
  54
  55         return index;
  56 }
  57
  58 int get_cop_pid(struct mm_struct *mm)
  59 {
  60         int pid;
  61
  62         if (mm->context.cop_pid == COP_PID_NONE) {
  63                 pid = new_cop_pid(&cop_ida, COP_PID_MIN, COP_PID_MAX,
  64                                   &mmu_context_acop_lock);
  65                 if (pid >= 0)
  66                         mm->context.cop_pid = pid;
  67         }
  68         return mm->context.cop_pid;
  69 }
  70
  71 int disable_cop_pid(struct mm_struct *mm)
  72 {
  73         int free_pid = COP_PID_NONE;
  74
  75         if ((!mm->context.acop) && (mm->context.cop_pid != COP_PID_NONE)) {
  76                 free_pid = mm->context.cop_pid;
  77                 mm->context.cop_pid = COP_PID_NONE;
  78         }
  79         return free_pid;
  80 }
  81
  82 void free_cop_pid(int free_pid)
  83 {
  84         spin_lock(&mmu_context_acop_lock);
  85         ida_remove(&cop_ida, free_pid);
  86         spin_unlock(&mmu_context_acop_lock);
  87 }