[PATCH v2 5/5] mm: ptdump: add check_wx_pages debugfs attribute

[Christophe Leroy <christophe.leroy@xxxxxxxxxx>]

Add a readable attribute in debugfs to trigger a
W^X pages check at any time.

To trigger the test, just read /sys/kernel/debug/check_wx_pages
It will report FAILED if the test failed, SUCCESS otherwise.

Detailed result is provided into dmesg.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
v2: Make it a read attribute which reports SUCCESS/FAILED instead of only relying on kernel message log.
---
 mm/ptdump.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/mm/ptdump.c b/mm/ptdump.c
index 03c1bdae4a43..106e1d66e9f9 100644
--- a/mm/ptdump.c
+++ b/mm/ptdump.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include <linux/pagewalk.h>
+#include <linux/debugfs.h>
 #include <linux/ptdump.h>
 #include <linux/kasan.h>
 
@@ -163,3 +164,24 @@ void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)
 	/* Flush out the last page */
 	st->note_page(st, 0, -1, 0);
 }
+
+static int check_wx_show(struct seq_file *m, void *v)
+{
+	if (ptdump_check_wx())
+		seq_puts(m, "SUCCESS\n");
+	else
+		seq_puts(m, "FAILED\n");
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(check_wx);
+
+static int ptdump_debugfs_init(void)
+{
+	debugfs_create_file("check_wx_pages", 0400, NULL, NULL, &check_wx_fops);
+
+	return 0;
+}
+
+device_initcall(ptdump_debugfs_init);
-- 
2.43.0