xref: /openbmc/linux/arch/sh/mm/asids-debugfs.c (revision 8c0b9ee8)
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/module.h>
21 #include <linux/debugfs.h>
22 #include <linux/seq_file.h>
23 #include <linux/spinlock.h>
24 #include <asm/processor.h>
25 #include <asm/mmu_context.h>
26 
27 static int asids_seq_show(struct seq_file *file, void *iter)
28 {
29 	struct task_struct *p;
30 
31 	read_lock(&tasklist_lock);
32 
33 	for_each_process(p) {
34 		int pid = p->pid;
35 
36 		if (unlikely(!pid))
37 			continue;
38 
39 		if (p->mm)
40 			seq_printf(file, "%5d : %04lx\n", pid,
41 				   cpu_asid(smp_processor_id(), p->mm));
42 	}
43 
44 	read_unlock(&tasklist_lock);
45 
46 	return 0;
47 }
48 
49 static int asids_debugfs_open(struct inode *inode, struct file *file)
50 {
51 	return single_open(file, asids_seq_show, inode->i_private);
52 }
53 
54 static const struct file_operations asids_debugfs_fops = {
55 	.owner		= THIS_MODULE,
56 	.open		= asids_debugfs_open,
57 	.read		= seq_read,
58 	.llseek		= seq_lseek,
59 	.release	= single_release,
60 };
61 
62 static int __init asids_debugfs_init(void)
63 {
64 	struct dentry *asids_dentry;
65 
66 	asids_dentry = debugfs_create_file("asids", S_IRUSR, arch_debugfs_dir,
67 					   NULL, &asids_debugfs_fops);
68 	if (!asids_dentry)
69 		return -ENOMEM;
70 
71 	return PTR_ERR_OR_ZERO(asids_dentry);
72 }
73 module_init(asids_debugfs_init);
74 
75 MODULE_LICENSE("GPL v2");
76