sh: Convert sh64 /proc/asids to debugfs and generic sh.

This converts the sh64 /proc/asids entry to debugfs and enables it for
all SH parts that have debugfs enabled.

On MMU systems this can be used to determine which processes are using
which ASIDs which in turn can be used for finer grained cache tag
analysis.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

3 files changed, 81 insertions, 0 deletions

diff --git a/arch/sh/mm/Makefile_32 b/arch/sh/mm/Makefile_32
index f066e76da204..cb2f3f299591 100644
--- a/arch/sh/mm/Makefile_32
+++ b/arch/sh/mm/Makefile_32
@@ -18,6 +18,7 @@ mmu-y			:= tlb-nommu.o pg-nommu.o
 mmu-$(CONFIG_MMU)	:= fault_32.o tlbflush_32.o ioremap_32.o
 
 obj-y			+= $(mmu-y)
+obj-$(CONFIG_DEBUG_FS)	+= asids-debugfs.o
 
 ifdef CONFIG_DEBUG_FS
 obj-$(CONFIG_CPU_SH4)	+= cache-debugfs.o
diff --git a/arch/sh/mm/Makefile_64 b/arch/sh/mm/Makefile_64
index 9481d0f54efd..2863ffb7006d 100644
--- a/arch/sh/mm/Makefile_64
+++ b/arch/sh/mm/Makefile_64
@@ -13,6 +13,7 @@ obj-y			+= cache-sh5.o
 endif
 
 obj-y			+= $(mmu-y)
+obj-$(CONFIG_DEBUG_FS)	+= asids-debugfs.o
 
 obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
 obj-$(CONFIG_NUMA)		+= numa.o
diff --git a/arch/sh/mm/asids-debugfs.c b/arch/sh/mm/asids-debugfs.c
new file mode 100644
index 000000000000..0678a1044a9a
--- /dev/null
+++ b/arch/sh/mm/asids-debugfs.c
@@ -0,0 +1,79 @@
+/*
+ * debugfs ops for process ASIDs
+ *
+ *  Copyright (C) 2000, 2001  Paolo Alberelli
+ *  Copyright (C) 2003 - 2008  Paul Mundt
+ *  Copyright (C) 2003, 2004  Richard Curnow
+ *
+ * Provides a debugfs file that lists out the ASIDs currently associated
+ * with the processes.
+ *
+ * In the SH-5 case, if the DM.PC register is examined through the debug
+ * link, this shows ASID + PC. To make use of this, the PID->ASID
+ * relationship needs to be known. This is primarily for debugging.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <asm/processor.h>
+#include <asm/mmu_context.h>
+
+static int asids_seq_show(struct seq_file *file, void *iter)
+{
+	struct task_struct *p;
+
+	read_lock(&tasklist_lock);
+
+	for_each_process(p) {
+		int pid = p->pid;
+
+		if (unlikely(!pid))
+			continue;
+
+		if (p->mm)
+			seq_printf(file, "%5d : %02x\n", pid,
+				   cpu_asid(smp_processor_id(), p->mm));
+		else
+			seq_printf(file, "%5d : (none)\n", pid);
+	}
+
+	read_unlock(&tasklist_lock);
+
+	return 0;
+}
+
+static int asids_debugfs_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, asids_seq_show, inode->i_private);
+}
+
+static const struct file_operations asids_debugfs_fops = {
+	.owner		= THIS_MODULE,
+	.open		= asids_debugfs_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init asids_debugfs_init(void)
+{
+	struct dentry *asids_dentry;
+
+	asids_dentry = debugfs_create_file("asids", S_IRUSR, sh_debugfs_root,
+					   NULL, &asids_debugfs_fops);
+	if (!asids_dentry)
+		return -ENOMEM;
+	if (IS_ERR(asids_dentry))
+		return PTR_ERR(asids_dentry);
+
+	return 0;
+}
+module_init(asids_debugfs_init);
+
+MODULE_LICENSE("GPL v2");