[PATCH 04/26] tty: kbd: reduce stack size with KASAN

Arnd Bergmann
2017-03-02T17:11:12Z

As reported by kernelci, some functions in the VT code use significant
amounts of kernel stack when local variables get inlined into the caller
multiple times:

drivers/tty/vt/keyboard.c: In function 'kbd_keycode':
drivers/tty/vt/keyboard.c:1452:1: error: the frame size of 2240 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]

Annotating those functions as noinline_for_kasan prevents the inlining
and reduces the overall stack usage in this driver.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/tty/vt/keyboard.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index 397e1509fe51..f8a183c1639f 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -300,13 +300,13 @@ int kbd_rate(struct kbd_repeat *rpt)
/*
* Helper Functions.
*/
-static void put_queue(struct vc_data *vc, int ch)
+static noinline_for_kasan void put_queue(struct vc_data *vc, int ch)
{
tty_insert_flip_char(&vc->port, ch, 0);
tty_schedule_flip(&vc->port);
}

-static void puts_queue(struct vc_data *vc, char *cp)
+static noinline_for_kasan void puts_queue(struct vc_data *vc, char *cp)
{
while (*cp) {
tty_insert_flip_char(&vc->port, *cp, 0);
@@ -554,7 +554,7 @@ static void fn_inc_console(struct vc_data *vc)
set_console(i);
}

-static void fn_send_intr(struct vc_data *vc)
+static noinline_for_kasan void fn_send_intr(struct vc_data *vc)
{
tty_insert_flip_char(&vc->port, 0, TTY_BREAK);
tty_schedule_flip(&vc->port);
--
2.9.0