[PATCH v3 13/19] mm/ksw: add self-debug helpers

[Jinchao Wang <wangjinchao600@gmail.com>]

Provide two debug helpers:

- ksw_watch_show(): print the current watch target address and length.
- ksw_watch_fire(): intentionally trigger the watchpoint immediately
  by writing to the watched address, useful for testing HWBP behavior.

Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
---
 mm/kstackwatch/kstackwatch.h |  2 ++
 mm/kstackwatch/watch.c       | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h
index 79ca40e69268..8632b43b6a33 100644
--- a/mm/kstackwatch/kstackwatch.h
+++ b/mm/kstackwatch/kstackwatch.h
@@ -47,5 +47,7 @@ int ksw_watch_init(void);
 void ksw_watch_exit(void);
 int ksw_watch_on(u64 watch_addr, u64 watch_len);
 void ksw_watch_off(void);
+void ksw_watch_show(void);
+void ksw_watch_fire(void);
 
 #endif /* _KSTACKWATCH_H */
diff --git a/mm/kstackwatch/watch.c b/mm/kstackwatch/watch.c
index d95efefdffe9..87bbe54bb5d3 100644
--- a/mm/kstackwatch/watch.c
+++ b/mm/kstackwatch/watch.c
@@ -185,3 +185,21 @@ void ksw_watch_exit(void)
 	unregister_wide_hw_breakpoint(watch_events);
 	watch_events = NULL;
 }
+
+/* self debug function */
+void ksw_watch_show(void)
+{
+	pr_info("watch target bp_addr: 0x%llx len:%llu\n", watch_attr.bp_addr,
+		watch_attr.bp_len);
+}
+EXPORT_SYMBOL_GPL(ksw_watch_show);
+
+/* self debug function */
+void ksw_watch_fire(void)
+{
+	char *ptr = (char *)watch_attr.bp_addr;
+
+	pr_warn("watch triggered immediately\n");
+	*ptr = 0x42; // This should trigger immediately for any bp_len
+}
+EXPORT_SYMBOL_GPL(ksw_watch_fire);
-- 
2.43.0