linux-kernel - [PATCH v3 06/19] mm/ksw: add HWBP pre-allocation

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Message-ID: <20250910052335.1151048-7-wangjinchao600@gmail.com>
Date: Wed, 10 Sep 2025 13:23:15 +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 06/19] mm/ksw: add HWBP pre-allocation

Pre-allocate per-CPU hardware breakpoints at init with a dummy address,
which will be retargeted dynamically in kprobe handler.
This avoids allocation in atomic contexts.

Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
---
 mm/kstackwatch/kstackwatch.h |  4 +++
 mm/kstackwatch/watch.c       | 55 ++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h
index 277b192f80fa..3ea191370970 100644
--- a/mm/kstackwatch/kstackwatch.h
+++ b/mm/kstackwatch/kstackwatch.h
@@ -38,4 +38,8 @@ struct ksw_config {
 // singleton, only modified in kernel.c
 const struct ksw_config *ksw_get_config(void);
 
+/* watch management */
+int ksw_watch_init(void);
+void ksw_watch_exit(void);
+
 #endif /* _KSTACKWATCH_H */
diff --git a/mm/kstackwatch/watch.c b/mm/kstackwatch/watch.c
index cec594032515..d3399ac840b2 100644
--- a/mm/kstackwatch/watch.c
+++ b/mm/kstackwatch/watch.c
@@ -1 +1,56 @@
 // SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/hw_breakpoint.h>
+#include <linux/perf_event.h>
+#include <linux/printk.h>
+
+#include "kstackwatch.h"
+
+static struct perf_event *__percpu *watch_events;
+
+static unsigned long watch_holder;
+
+static struct perf_event_attr watch_attr;
+
+bool panic_on_catch;
+module_param(panic_on_catch, bool, 0644);
+MODULE_PARM_DESC(panic_on_catch, "panic immediately on corruption catch");
+static void ksw_watch_handler(struct perf_event *bp,
+			      struct perf_sample_data *data,
+			      struct pt_regs *regs)
+{
+	pr_err("========== KStackWatch: Caught stack corruption =======\n");
+	pr_err("config %s\n", ksw_get_config()->config_str);
+	dump_stack();
+	pr_err("=================== KStackWatch End ===================\n");
+
+	if (panic_on_catch)
+		panic("Stack corruption detected");
+}
+
+int ksw_watch_init(void)
+{
+	int ret;
+
+	hw_breakpoint_init(&watch_attr);
+	watch_attr.bp_addr = (unsigned long)&watch_holder;
+	watch_attr.bp_len = sizeof(watch_holder);
+	watch_attr.bp_type = HW_BREAKPOINT_W;
+	watch_events = register_wide_hw_breakpoint(&watch_attr,
+						   ksw_watch_handler,
+						   NULL);
+	if (IS_ERR(watch_events)) {
+		ret = PTR_ERR(watch_events);
+		pr_err("failed to register wide hw breakpoint: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+void ksw_watch_exit(void)
+{
+	unregister_wide_hw_breakpoint(watch_events);
+	watch_events = NULL;
+}
-- 
2.43.0