[PATCH v2 12/18] mm/ksw: add self-debug functions for kstackwatch watch

[Jinchao Wang]

Introduce ksw_watch_show() and ksw_watch_fire() for runtime debugging of
kstackwatch's watch mechanism:

 - ksw_watch_show(): prints the currently armed watch address and length
 - ksw_watch_fire(): forcibly triggers the watch by writing to the watched
   address

These functions help validate the dynamic watch behavior and facilitate
testing without requiring real events.

Signed-off-by: Jinchao Wang <wangjinchao...@gmail.com>
---
 mm/kstackwatch/kstackwatch.h |  2 ++
 mm/kstackwatch/watch.c       | 17 ++++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h
index bc8664af4fa6..d1bb5ae75aae 100644
--- a/mm/kstackwatch/kstackwatch.h
+++ b/mm/kstackwatch/kstackwatch.h
@@ -47,5 +47,7 @@ int ksw_watch_init(struct ksw_config *config);
 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 c563f8d17829..8f3f6cb9f17a 100644
--- a/mm/kstackwatch/watch.c
+++ b/mm/kstackwatch/watch.c
@@ -116,7 +116,6 @@ int ksw_watch_on(u64 watch_addr, u64 watch_len)
                        ksw_watch_on_local_cpu(&watch_info);
                } else {
                        call_single_data_t *csd = &per_cpu(watch_csd, cpu);
-
                        smp_call_function_single_async(cpu, csd);
                }
        }
@@ -158,3 +157,19 @@ void ksw_watch_exit(void)
 
        pr_info("KSW: watch exited\n");
 }
+
+/* self debug function */
+void ksw_watch_show(void)
+{
+       pr_info("KSW: watch target bp_addr: 0x%llx len:%llu\n",
+               watch_info.addr, watch_info.len);
+}
+
+/* self debug function */
+void ksw_watch_fire(void)
+{
+       char *ptr = (char *)watch_info.addr;
+
+       pr_warn("KSW: watch triggered immediately\n");
+       *ptr = 0x42; // This should trigger immediately
+}
-- 
2.43.0