arch/sh/mm/asids-debugfs.c

   1 /*
   2  * debugfs ops for process ASIDs
   3  *
   4  *  Copyright (C) 2000, 2001  Paolo Alberelli
   5  *  Copyright (C) 2003 - 2008  Paul Mundt
   6  *  Copyright (C) 2003, 2004  Richard Curnow
   7  *
   8  * Provides a debugfs file that lists out the ASIDs currently associated
   9  * with the processes.
  10  *
  11  * In the SH-5 case, if the DM.PC register is examined through the debug
  12  * link, this shows ASID + PC. To make use of this, the PID->ASID
  13  * relationship needs to be known. This is primarily for debugging.
  14  *
  15  * This file is subject to the terms and conditions of the GNU General Public
  16  * License.  See the file "COPYING" in the main directory of this archive
  17  * for more details.
  18  */
  19 #include <linux/init.h>
  20 #include <linux/debugfs.h>
  21 #include <linux/seq_file.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/sched/signal.h>
  24 #include <linux/sched/task.h>
  25
  26 #include <asm/processor.h>
  27 #include <asm/mmu_context.h>
  28
  29 static int asids_seq_show(struct seq_file *file, void *iter)
  30 {
  31         struct task_struct *p;
  32
  33         read_lock(&tasklist_lock);
  34
  35         for_each_process(p) {
  36                 int pid = p->pid;
  37
  38                 if (unlikely(!pid))
  39                         continue;
  40
  41                 if (p->mm)
  42                         seq_printf(file, "%5d : %04lx\n", pid,
  43                                    cpu_asid(smp_processor_id(), p->mm));
  44         }
  45
  46         read_unlock(&tasklist_lock);
  47
  48         return 0;
  49 }
  50
  51 static int asids_debugfs_open(struct inode *inode, struct file *file)
  52 {
  53         return single_open(file, asids_seq_show, inode->i_private);
  54 }
  55
  56 static const struct file_operations asids_debugfs_fops = {
  57         .owner          = THIS_MODULE,
  58         .open           = asids_debugfs_open,
  59         .read           = seq_read,
  60         .llseek         = seq_lseek,
  61         .release        = single_release,
  62 };
  63
  64 static int __init asids_debugfs_init(void)
  65 {
  66         struct dentry *asids_dentry;
  67
  68         asids_dentry = debugfs_create_file("asids", S_IRUSR, arch_debugfs_dir,
  69                                            NULL, &asids_debugfs_fops);
  70         if (!asids_dentry)
  71                 return -ENOMEM;
  72
  73         return PTR_ERR_OR_ZERO(asids_dentry);
  74 }
  75 device_initcall(asids_debugfs_init);