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>

Author: pmundt

arch/sh/Kconfig.debug

@@ -180,10 +180,6 @@ endmenu
 
 if SUPERH64
 
-config SH64_PROC_ASIDS
-	bool "Debug: report ASIDs through /proc/asids"
-	depends on PROC_FS && MMU
-
 config SH64_SR_WATCH
 	bool "Debug: set SR.WATCH to enable hardware watchpoints and trace"
 

arch/sh/kernel/process_64.c

@@ -23,7 +23,6 @@
 #include <linux/reboot.h>
 #include <linux/init.h>
 #include <linux/module.h>
-#include <linux/proc_fs.h>
 #include <linux/io.h>
 #include <asm/syscalls.h>
 #include <asm/uaccess.h>
@@ -590,41 +589,3 @@ unsigned long get_wchan(struct task_struct *p)
 #endif
 	return pc;
 }
-
-/* Provide a /proc/asids file that lists out the
-   ASIDs currently associated with the processes.  (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.)
-   */
-
-#if defined(CONFIG_SH64_PROC_ASIDS)
-static int
-asids_proc_info(char *buf, char **start, off_t fpos, int length, int *eof, void *data)
-{
-	int len=0;
-	struct task_struct *p;
-	read_lock(&tasklist_lock);
-	for_each_process(p) {
-		int pid = p->pid;
-
-		if (!pid)
-			continue;
-		if (p->mm)
-			len += sprintf(buf+len, "%5d : %02lx\n", pid,
-				       asid_cache(smp_processor_id()));
-		else
-			len += sprintf(buf+len, "%5d : (none)\n", pid);
-	}
-	read_unlock(&tasklist_lock);
-	*eof = 1;
-	return len;
-}
-
-static int __init register_proc_asids(void)
-{
-	create_proc_read_entry("asids", 0, NULL, asids_proc_info, NULL);
-	return 0;
-}
-__initcall(register_proc_asids);
-#endif

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

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

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");