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

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Message-ID: <20250910053147.1152253-5-wangjinchao600@gmail.com>
Date: Wed, 10 Sep 2025 13:31:11 +0800
From: Jinchao Wang <wangjinchao600@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Mike Rapoport <rppt@...nel.org>,
	"Naveen N . Rao" <naveen@...nel.org>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Alexander Potapenko <glider@...gle.com>,
	Andrey Konovalov <andreyknvl@...il.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Vincenzo Frascino <vincenzo.frascino@....com>,
	kasan-dev@...glegroups.com,
	"David S. Miller" <davem@...emloft.net>,
	Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	linux-mm@...ck.org,
	linux-trace-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Jinchao Wang <wangjinchao600@...il.com>
Subject: [PATCH v3 13/19] mm/ksw: add self-debug helpers

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@...il.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