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Message-ID: <20250924115124.194940-9-wangjinchao600@gmail.com>
Date: Wed, 24 Sep 2025 19:50:51 +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 08/23] mm/ksw: Add atomic watchpoint management api
Add three functions for atomic lifecycle management of watchpoints:
- ksw_watch_get(): Acquires a watchpoint from a llist.
- ksw_watch_on(): Enables the watchpoint on all online CPUs.
- ksw_watch_off(): Disables the watchpoint and returns it to the llist.
For cross-CPU synchronization, updates are propagated using direct
modification on the local CPU and asynchronous IPIs for remote CPUs.
Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
---
mm/kstackwatch/kstackwatch.h | 4 ++
mm/kstackwatch/watch.c | 85 +++++++++++++++++++++++++++++++++++-
2 files changed, 88 insertions(+), 1 deletion(-)
diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h
index 4eac1be3b325..850fc2b18a9c 100644
--- a/mm/kstackwatch/kstackwatch.h
+++ b/mm/kstackwatch/kstackwatch.h
@@ -38,11 +38,15 @@ const struct ksw_config *ksw_get_config(void);
/* watch management */
struct ksw_watchpoint {
struct perf_event *__percpu *event;
+ call_single_data_t __percpu *csd;
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);
+int ksw_watch_get(struct ksw_watchpoint **out_wp);
+int ksw_watch_on(struct ksw_watchpoint *wp, ulong watch_addr, u16 watch_len);
+int ksw_watch_off(struct ksw_watchpoint *wp);
#endif /* _KSTACKWATCH_H */
diff --git a/mm/kstackwatch/watch.c b/mm/kstackwatch/watch.c
index 1d8e24fede54..887cc13292dc 100644
--- a/mm/kstackwatch/watch.c
+++ b/mm/kstackwatch/watch.c
@@ -31,11 +31,83 @@ static void ksw_watch_handler(struct perf_event *bp,
panic("Stack corruption detected");
}
+static void ksw_watch_on_local_cpu(void *info)
+{
+ struct ksw_watchpoint *wp = info;
+ struct perf_event *bp;
+ ulong flags;
+ int cpu;
+ int ret;
+
+ local_irq_save(flags);
+ cpu = raw_smp_processor_id();
+ bp = per_cpu(*wp->event, cpu);
+ if (!bp) {
+ local_irq_restore(flags);
+ return;
+ }
+
+ ret = modify_wide_hw_breakpoint_local(bp, &wp->attr);
+ local_irq_restore(flags);
+ WARN(ret, "fail to reinstall HWBP on CPU%d ret %d", cpu, ret);
+}
+
+static void ksw_watch_update(struct ksw_watchpoint *wp, ulong addr, u16 len)
+{
+ call_single_data_t *csd;
+ int cur_cpu;
+ int cpu;
+
+ wp->attr.bp_addr = addr;
+ wp->attr.bp_len = len;
+
+ cur_cpu = raw_smp_processor_id();
+ for_each_online_cpu(cpu) {
+ /* remote cpu first */
+ if (cpu == cur_cpu)
+ continue;
+ csd = per_cpu_ptr(wp->csd, cpu);
+ smp_call_function_single_async(cpu, csd);
+ }
+ ksw_watch_on_local_cpu(wp);
+}
+
+int ksw_watch_get(struct ksw_watchpoint **out_wp)
+{
+ struct ksw_watchpoint *wp;
+ struct llist_node *node;
+
+ node = llist_del_first(&free_wp_list);
+ if (!node)
+ return -EBUSY;
+
+ wp = llist_entry(node, struct ksw_watchpoint, node);
+ WARN_ON_ONCE(wp->attr.bp_addr != (u64)&holder);
+
+ *out_wp = wp;
+ return 0;
+}
+int ksw_watch_on(struct ksw_watchpoint *wp, ulong watch_addr, u16 watch_len)
+{
+ ksw_watch_update(wp, watch_addr, watch_len);
+ return 0;
+}
+
+int ksw_watch_off(struct ksw_watchpoint *wp)
+{
+ WARN_ON_ONCE(wp->attr.bp_addr == (u64)&holder);
+ ksw_watch_update(wp, (ulong)&holder, sizeof(ulong));
+ llist_add(&wp->node, &free_wp_list);
+ return 0;
+}
+
static int ksw_watch_alloc(void)
{
int max_watch = ksw_get_config()->max_watch;
struct ksw_watchpoint *wp;
+ call_single_data_t *csd;
int success = 0;
+ int cpu;
int ret;
init_llist_head(&free_wp_list);
@@ -45,6 +117,16 @@ static int ksw_watch_alloc(void)
wp = kzalloc(sizeof(*wp), GFP_KERNEL);
if (!wp)
return success > 0 ? success : -EINVAL;
+ wp->csd = alloc_percpu(call_single_data_t);
+ if (!wp->csd) {
+ kfree(wp);
+ return success > 0 ? success : -EINVAL;
+ }
+
+ for_each_possible_cpu(cpu) {
+ csd = per_cpu_ptr(wp->csd, cpu);
+ INIT_CSD(csd, ksw_watch_on_local_cpu, wp);
+ }
hw_breakpoint_init(&wp->attr);
wp->attr.bp_addr = (ulong)&holder;
@@ -54,6 +136,7 @@ static int ksw_watch_alloc(void)
ksw_watch_handler, wp);
if (IS_ERR((void *)wp->event)) {
ret = PTR_ERR((void *)wp->event);
+ free_percpu(wp->csd);
kfree(wp);
return success > 0 ? success : ret;
}
@@ -75,6 +158,7 @@ static void ksw_watch_free(void)
list_for_each_entry_safe(wp, tmp, &all_wp_list, list) {
list_del(&wp->list);
unregister_wide_hw_breakpoint(wp->event);
+ free_percpu(wp->csd);
kfree(wp);
}
mutex_unlock(&all_wp_mutex);
@@ -88,7 +172,6 @@ int ksw_watch_init(void)
if (ret <= 0)
return -EBUSY;
-
return 0;
}
--
2.43.0
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