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Diffstat (limited to 'drivers/misc/lkdtm/bugs.c')
-rw-r--r--drivers/misc/lkdtm/bugs.c23
1 files changed, 17 insertions, 6 deletions
diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index 7eebbdfbcacd..17f839dee976 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -32,12 +32,20 @@ static int recur_count = REC_NUM_DEFAULT;
static DEFINE_SPINLOCK(lock_me_up);
-static int recursive_loop(int remaining)
+/*
+ * Make sure compiler does not optimize this function or stack frame away:
+ * - function marked noinline
+ * - stack variables are marked volatile
+ * - stack variables are written (memset()) and read (pr_info())
+ * - function has external effects (pr_info())
+ * */
+static int noinline recursive_loop(int remaining)
{
- char buf[REC_STACK_SIZE];
+ volatile char buf[REC_STACK_SIZE];
- /* Make sure compiler does not optimize this away. */
- memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE);
+ memset((void *)buf, remaining & 0xFF, sizeof(buf));
+ pr_info("loop %d/%d ...\n", (int)buf[remaining % sizeof(buf)],
+ recur_count);
if (!remaining)
return 0;
else
@@ -81,9 +89,12 @@ void lkdtm_LOOP(void)
;
}
-void lkdtm_OVERFLOW(void)
+void lkdtm_EXHAUST_STACK(void)
{
- (void) recursive_loop(recur_count);
+ pr_info("Calling function with %d frame size to depth %d ...\n",
+ REC_STACK_SIZE, recur_count);
+ recursive_loop(recur_count);
+ pr_info("FAIL: survived without exhausting stack?!\n");
}
static noinline void __lkdtm_CORRUPT_STACK(void *stack)