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Message-ID: <20250924122448.9101-1-wangjinchao600@gmail.com>
Date: Wed, 24 Sep 2025 20:24:40 +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>,
Alexander Potapenko <glider@...gle.com>,
Randy Dunlap <rdunlap@...radead.org>,
Jonathan Corbet <corbet@....net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>,
Mel Gorman <mgorman@...e.de>,
Valentin Schneider <vschneid@...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>,
David Hildenbrand <david@...hat.com>,
Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Vlastimil Babka <vbabka@...e.cz>,
Suren Baghdasaryan <surenb@...gle.com>,
Michal Hocko <mhocko@...e.com>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
Bill Wendling <morbo@...gle.com>,
Justin Stitt <justinstitt@...gle.com>,
Kees Cook <kees@...nel.org>,
Alice Ryhl <aliceryhl@...gle.com>,
Sami Tolvanen <samitolvanen@...gle.com>,
Miguel Ojeda <ojeda@...nel.org>,
Masahiro Yamada <masahiroy@...nel.org>,
Rong Xu <xur@...gle.com>,
Naveen N Rao <naveen@...nel.org>,
David Kaplan <david.kaplan@....com>,
Andrii Nakryiko <andrii@...nel.org>,
Jinjie Ruan <ruanjinjie@...wei.com>,
Nam Cao <namcao@...utronix.de>,
workflows@...r.kernel.org,
linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org,
linux-mm@...ck.org,
llvm@...ts.linux.dev,
Andrey Ryabinin <ryabinin.a.a@...il.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>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
linux-trace-kernel@...r.kernel.org
Cc: Jinchao Wang <wangjinchao600@...il.com>
Subject: [PATCH v5 07/23] mm/ksw: add HWBP pre-allocation
Pre-allocate per-CPU hardware breakpoints at init with a place holder
address, which will be retargeted dynamically in kprobe handler.
This avoids allocation in atomic context.
At most max_watch breakpoints are allocated (0 means no limit).
Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
---
mm/kstackwatch/kstackwatch.h | 13 +++++
mm/kstackwatch/watch.c | 97 ++++++++++++++++++++++++++++++++++++
2 files changed, 110 insertions(+)
diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h
index 983125d5cf18..4eac1be3b325 100644
--- a/mm/kstackwatch/kstackwatch.h
+++ b/mm/kstackwatch/kstackwatch.h
@@ -2,6 +2,9 @@
#ifndef _KSTACKWATCH_H
#define _KSTACKWATCH_H
+#include <linux/llist.h>
+#include <linux/percpu.h>
+#include <linux/perf_event.h>
#include <linux/types.h>
#define MAX_CONFIG_STR_LEN 128
@@ -32,4 +35,14 @@ struct ksw_config {
// singleton, only modified in kernel.c
const struct ksw_config *ksw_get_config(void);
+/* watch management */
+struct ksw_watchpoint {
+ struct perf_event *__percpu *event;
+ struct perf_event_attr attr;
+ struct llist_node node; // for atomic watch_on and off
+ struct list_head list; // for cpu online and offline
+};
+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..1d8e24fede54 100644
--- a/mm/kstackwatch/watch.c
+++ b/mm/kstackwatch/watch.c
@@ -1 +1,98 @@
// SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cpuhotplug.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/irqflags.h>
+#include <linux/mutex.h>
+#include <linux/printk.h>
+
+#include "kstackwatch.h"
+
+static LLIST_HEAD(free_wp_list);
+static LIST_HEAD(all_wp_list);
+static DEFINE_MUTEX(all_wp_mutex);
+
+static ulong holder;
+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()->user_input);
+ dump_stack();
+ pr_err("=================== KStackWatch End ===================\n");
+
+ if (panic_on_catch)
+ panic("Stack corruption detected");
+}
+
+static int ksw_watch_alloc(void)
+{
+ int max_watch = ksw_get_config()->max_watch;
+ struct ksw_watchpoint *wp;
+ int success = 0;
+ int ret;
+
+ init_llist_head(&free_wp_list);
+
+ //max_watch=0 means at most
+ while (!max_watch || success < max_watch) {
+ wp = kzalloc(sizeof(*wp), GFP_KERNEL);
+ if (!wp)
+ return success > 0 ? success : -EINVAL;
+
+ hw_breakpoint_init(&wp->attr);
+ wp->attr.bp_addr = (ulong)&holder;
+ wp->attr.bp_len = sizeof(ulong);
+ wp->attr.bp_type = HW_BREAKPOINT_W;
+ wp->event = register_wide_hw_breakpoint(&wp->attr,
+ ksw_watch_handler, wp);
+ if (IS_ERR((void *)wp->event)) {
+ ret = PTR_ERR((void *)wp->event);
+ kfree(wp);
+ return success > 0 ? success : ret;
+ }
+ llist_add(&wp->node, &free_wp_list);
+ mutex_lock(&all_wp_mutex);
+ list_add(&wp->list, &all_wp_list);
+ mutex_unlock(&all_wp_mutex);
+ success++;
+ }
+
+ return success;
+}
+
+static void ksw_watch_free(void)
+{
+ struct ksw_watchpoint *wp, *tmp;
+
+ mutex_lock(&all_wp_mutex);
+ list_for_each_entry_safe(wp, tmp, &all_wp_list, list) {
+ list_del(&wp->list);
+ unregister_wide_hw_breakpoint(wp->event);
+ kfree(wp);
+ }
+ mutex_unlock(&all_wp_mutex);
+}
+
+int ksw_watch_init(void)
+{
+ int ret;
+
+ ret = ksw_watch_alloc();
+ if (ret <= 0)
+ return -EBUSY;
+
+
+ return 0;
+}
+
+void ksw_watch_exit(void)
+{
+ ksw_watch_free();
+}
--
2.43.0
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