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Mon, 29 Sep 2025 19:44:59 -0700 (PDT) From: Jinchao Wang To: Andrew Morton , Masami Hiramatsu , Peter Zijlstra , Mike Rapoport , Alexander Potapenko , Randy Dunlap , Marco Elver , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Kees Cook , Alice Ryhl , Sami Tolvanen , Miguel Ojeda , Masahiro Yamada , Rong Xu , Naveen N Rao , David Kaplan , Andrii Nakryiko , Jinjie Ruan , Nam Cao , workflows@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev, Andrey Ryabinin , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , kasan-dev@googlegroups.com, "David S. Miller" , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org Cc: Jinchao Wang Subject: [PATCH v6 08/23] mm/ksw: Add atomic watchpoint management api Date: Tue, 30 Sep 2025 10:43:29 +0800 Message-ID: <20250930024402.1043776-9-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250930024402.1043776-1-wangjinchao600@gmail.com> References: <20250930024402.1043776-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 8347C120008 X-Stat-Signature: ber8pqtuf9h6dxqfwnqs9jg3nofw3ccm X-Rspam-User: X-HE-Tag: 1759200301-835504 X-HE-Meta: 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 ySL1j0al 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 --- 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