x86/mm/dump_pagetables: Add page table directory to the debugfs VFS hierarchy

suryasaimadhu · Ingo Molnar · commit 75298aa179d5 · 2017-12-23T21:13:01.000+01:00
The upcoming support for dumping the kernel and the user space page tables
of the current process would create more random files in the top level
debugfs directory.

Add a page table directory and move the existing file to it.

Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Boris Ostrovsky &lt;boris.ostrovsky@oracle.com&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Brian Gerst &lt;brgerst@gmail.com&gt;
Cc: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Cc: David Laight &lt;David.Laight@aculab.com&gt;
Cc: Denys Vlasenko &lt;dvlasenk@redhat.com&gt;
Cc: Eduardo Valentin &lt;eduval@amazon.com&gt;
Cc: Greg KH &lt;gregkh@linuxfoundation.org&gt;
Cc: H. Peter Anvin &lt;hpa@zytor.com&gt;
Cc: Josh Poimboeuf &lt;jpoimboe@redhat.com&gt;
Cc: Juergen Gross &lt;jgross@suse.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Will Deacon &lt;will.deacon@arm.com&gt;
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
diff --git a/arch/x86/mm/debug_pagetables.c b/arch/x86/mm/debug_pagetables.c
@@ -22,21 +22,26 @@ static const struct file_operations ptdump_fops = {
 	.release	= single_release,
 };
 
-static struct dentry *pe;
+static struct dentry *dir, *pe;
 
 static int __init pt_dump_debug_init(void)
 {
-	pe = debugfs_create_file("kernel_page_tables", S_IRUSR, NULL, NULL,
-				 &ptdump_fops);
-	if (!pe)
+	dir = debugfs_create_dir("page_tables", NULL);
+	if (!dir)
 		return -ENOMEM;
 
+	pe = debugfs_create_file("kernel", 0400, dir, NULL, &ptdump_fops);
+	if (!pe)
+		goto err;
 	return 0;
+err:
+	debugfs_remove_recursive(dir);
+	return -ENOMEM;
 }
 
 static void __exit pt_dump_debug_exit(void)
 {
-	debugfs_remove_recursive(pe);
+	debugfs_remove_recursive(dir);
 }
 
 module_init(pt_dump_debug_init);
