linux-kernel - [RFC PATCH 08/13] mm/kstackwatch: Wire up watch and stack subsystems in module core

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Message-ID: <20250818122720.434981-9-wangjinchao600@gmail.com>
Date: Mon, 18 Aug 2025 20:26:13 +0800
From: Jinchao Wang <wangjinchao600@...il.com>
To: akpm@...ux-foundation.org
Cc: mhiramat@...nel.org,
	naveen@...nel.org,
	davem@...emloft.net,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	Jinchao Wang <wangjinchao600@...il.com>
Subject: [RFC PATCH 08/13] mm/kstackwatch: Wire up watch and stack subsystems in module core

Connect the watch and stack functions to complete
the kstackwatch initialization sequence with proper ordering and
error handling.

This patch integrates the previously implemented components:

Initialization sequence:
1. ksw_watch_init() - Pre-allocate HWBP on all CPUs (must be first)
2. ksw_stack_init() - Register kprobes for function entry/exit
3. Set watching_active flag to enable operation

The ordering is critical because:
- HWBP must be pre-allocated before kprobes are registered
- Kprobe handlers depend on pre-existing HWBP infrastructure

Cleanup sequence:
1. ksw_stack_exit() - Unregister kprobes (stops new activations)
2. ksw_watch_exit() - Release pre-allocated HWBP resources
3. Clear watching_active flag

This completes the functional kstackwatch implementation, enabling
real-time stack corruption detection through the proc interface
with automatic HWBP management.

Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
---
 mm/kstackwatch/kernel.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/mm/kstackwatch/kernel.c b/mm/kstackwatch/kernel.c
index 726cf3f25888..b6366808e891 100644
--- a/mm/kstackwatch/kernel.c
+++ b/mm/kstackwatch/kernel.c
@@ -26,11 +26,29 @@ MODULE_PARM_DESC(panic_on_catch,
 
 static int start_watching(void)
 {
+	int ret;
+
 	if (strlen(ksw_config->function) == 0) {
 		pr_err("KSW: No target function specified\n");
 		return -EINVAL;
 	}
 
+	/*
+	 * watch init will prealloc HWBP
+	 * so it must be before stack init
+	 */
+	ret = ksw_watch_init(ksw_config);
+	if (ret) {
+		pr_err("KSW: ksw_watch_init ret: %d\n", ret);
+		return ret;
+	}
+
+	ret = ksw_stack_init(ksw_config);
+	if (ret) {
+		pr_err("KSW: ksw_stack_init ret: %d\n", ret);
+		ksw_watch_exit();
+		return ret;
+	}
 	watching_active = true;
 
 	pr_info("KSW: start watching %s\n", ksw_config->config_str);
@@ -39,6 +57,8 @@ static int start_watching(void)
 
 static void stop_watching(void)
 {
+	ksw_stack_exit();
+	ksw_watch_exit();
 	watching_active = false;
 
 	pr_info("KSW: stop watching %s\n", ksw_config->config_str);
-- 
2.43.0