[PATCH v2 11/13] lkdtm: Fix lkdtm_EXEC_RODATA()

[Christophe Leroy]

Behind its location, lkdtm_EXEC_RODATA() executes
lkdtm_rodata_do_nothing() which is a real function,
not a copy of do_nothing().

So executes it directly instead of using execute_location().

This is necessary because following patch will fix execute_location()
to use a copy of the function descriptor of do_nothing() and
function descriptor of lkdtm_rodata_do_nothing() might be different.

And fix displayed addresses by dereferencing the function descriptors.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
 drivers/misc/lkdtm/perms.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c
index 035fcca441f0..5266dc28df6e 100644
--- a/drivers/misc/lkdtm/perms.c
+++ b/drivers/misc/lkdtm/perms.c
@@ -153,7 +153,14 @@ void lkdtm_EXEC_VMALLOC(void)
 
 void lkdtm_EXEC_RODATA(void)
 {
-	execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS);
+	pr_info("attempting ok execution at %px\n",
+		dereference_function_descriptor(do_nothing));
+	do_nothing();
+
+	pr_info("attempting bad execution at %px\n",
+		dereference_function_descriptor(lkdtm_rodata_do_nothing));
+	lkdtm_rodata_do_nothing();
+	pr_err("FAIL: func returned\n");
 }
 
 void lkdtm_EXEC_USERSPACE(void)
-- 
2.31.1