From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f172.google.com (mail-pf1-f172.google.com [209.85.210.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F0A6231A053 for ; Mon, 10 Nov 2025 16:37:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762792661; cv=none; b=GvMwyF2Nw+uIIQPq7IZpALRG+6sRqQqHaCX2g5Y03VrWJ7Yg1G905QiumaMT1iP16ffTXTqszOv44Rf5Xns4d6DCC+ns4atsDl/TSPM0Hv7MuyEf+OUeTBFsjzTwvwfWz6MNKRRxBLuzFIZmZVH5PK8I3TeQ/xZFwz/BHNnWuTg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762792661; c=relaxed/simple; bh=xxEQ3A3gLYi43VcM4txNyA5nH16DvxbSfWTaDMVtF+U=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bR4Kj7f0QQtGMGEnhWqhFMDdCxvkXxbmHxOUOtK/oArvAcFng+/LTa+vhXaLWY3glsX+xdteU/nbgp4TtH/Z+c2H7nqbI2pcS1MKqxr1T9t3ce53RheiEbKIFbI2UZuWEJjpPoCnVzv1jBauXkiwXnTawRY5pGHzMGzdm4nqSgE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=KuPlXl+q; arc=none smtp.client-ip=209.85.210.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="KuPlXl+q" Received: by mail-pf1-f172.google.com with SMTP id d2e1a72fcca58-7aa9be9f03aso2824899b3a.2 for ; Mon, 10 Nov 2025 08:37:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1762792659; x=1763397459; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:from:to:cc:subject:date:message-id :reply-to; bh=qY+qINpaOz0cBrftmlOPWeh/tDbDV+8hjCudsDUPv3w=; b=KuPlXl+qZQSyNBuOAXuQO4DRHm7J492d13z6AiLgqUOlc8hHq489IyM+p6zboLWI1s oj0ve+yu+Sj8ohA+TjPxqmmpS3+9eSIzzgNFqAvL72AMmOcz8GVyl1jf1tKn0HD4zOtc Z9cjjKHdMHPQoFSxGeapBSH5iEetnGTdYVk8njOc34pX5TaZ56Q9egMCaJ4IhZSbbucT MCneCHQstUg6l03SD3K50IkpgDNDbDhpRRq3MXqBfCq2fFxQn0+TXk5bca3vo6p66TpD h5CDZrrAGmnmWUUe1OQPx6eJLLkzMpA/F2kAUls2mIkKLkNeao2GGUbr2KlUDlOM8X4L Y+TQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762792659; x=1763397459; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:x-gm-gg:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=qY+qINpaOz0cBrftmlOPWeh/tDbDV+8hjCudsDUPv3w=; b=TT9NM1Ck0gJD3Z4uUflgRGdo5DGmZc2H9Hk3coXNPLFaGB3SUKkWLZuZVGgUpMyAyb YdC6sCdnGOUhbaOWXtqN0z5iXBuGxm8mKN3YKg9XlpZ3/uA3Sp0qdSnxFes95RgzBmy4 b1fUIO/F2oyO91/avpvDYJaN16v+mUE52g0fW+M7YHknzkA9AloTpf+/Dy4ruY7aewjw bMI0zaZI0+NxgNNzunPSIzi+AslUULQZiVl1MK7J/ZvUy0j+4TVk2CtEEIoMNNRodSNo gVA4ousDoioqOgTk2pVsuiqbFKiELTeR/WwsqhFQdclCYPqfBdHbULkbhYP9EIGsFMF0 o8nQ== X-Forwarded-Encrypted: i=1; AJvYcCWgwOclbpsGPuqT7MXyE6XMboj8XcBI3xPa0mRuyp3PA2jbFMwIZKry6Y6jsk14N9LxPbJQJUwVEFXNhVCtgqs6@vger.kernel.org X-Gm-Message-State: AOJu0YygPonXPRIVjzrY6GW99WrMkSaHIZC6qjVsJVoMQiELZAKRlso8 nsAmBYGrphRqP6q8WAW4naVQwtQGXRxncPw8us7AV9Ek9gqHjKMQlt1R X-Gm-Gg: ASbGncsb5SzsxRE7AaOn+z8F1UX1LoNA4QUY+PTs716A/U5GYrzqIYJIK1pDzWvlqU7 K7m2IERvce7vGYKy1U2gxE0Df2aUZCL/La/CSpXapdigKwxR83z8yEbQ8/lDh3Qmvp2KMKSwcz7 KzMVo596J3cuBB08Tk/DuJ9Ue/xy41SM+TT3lOzzt6d1S7iTD0t1xvT5+iHZ/SLnynfV41yjWXf J+Tcu5o/v/VYMjJM3VGArqpUfJIGaGAAx9SRRtuZTLOWxX1U5jrJW5nHKjZVjq6gKbiWtUwp2A7 JVpq+o000b0SxJUtkH3euaHSlLWCF5djS3FNjaKbGJ1VdEyOT4YCz7WtqG8+NJ+7df7k4rNSSoO Vom10ghKQtQ7FXNki3UxIZwD6+KY2s0rJ2chmrFjEbTyTQBFe9j7olT3xVlAPXOpCtrHGyY5r9J thdXYMsaqi24V+70FJ/UUVRg== X-Google-Smtp-Source: AGHT+IH2fkExOiw2xx23499QoJR+0QVGEltJ2Kq069nEQ8OMBF3QJ74WPA0vkc5LrwSnkN3SgQQOIA== X-Received: by 2002:a05:6a21:6d97:b0:334:8d0b:6640 with SMTP id adf61e73a8af0-353a13aaf66mr12767757637.8.1762792659125; Mon, 10 Nov 2025 08:37:39 -0800 (PST) Received: from localhost ([103.88.46.62]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-ba8f8e750c1sm13193534a12.1.2025.11.10.08.37.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Nov 2025 08:37:38 -0800 (PST) From: Jinchao Wang To: Andrew Morton , "Masami Hiramatsu (Google)" , Peter Zijlstra , Randy Dunlap , Marco Elver , Mike Rapoport , Alexander Potapenko , Adrian Hunter , Alexander Shishkin , Alice Ryhl , Andrey Konovalov , Andrey Ryabinin , Andrii Nakryiko , Ard Biesheuvel , Arnaldo Carvalho de Melo , Ben Segall , Bill Wendling , Borislav Petkov , Catalin Marinas , Dave Hansen , David Hildenbrand , David Kaplan , "David S. Miller" , Dietmar Eggemann , Dmitry Vyukov , "H. Peter Anvin" , Ian Rogers , Ingo Molnar , James Clark , Jinchao Wang , Jinjie Ruan , Jiri Olsa , Jonathan Corbet , Juri Lelli , Justin Stitt , kasan-dev@googlegroups.com, Kees Cook , "Liam R. Howlett" , "Liang Kan" , Linus Walleij , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org, llvm@lists.linux.dev, Lorenzo Stoakes , Mark Rutland , Masahiro Yamada , Mathieu Desnoyers , Mel Gorman , Michal Hocko , Miguel Ojeda , Nam Cao , Namhyung Kim , Nathan Chancellor , Naveen N Rao , Nick Desaulniers , Rong Xu , Sami Tolvanen , Steven Rostedt , Suren Baghdasaryan , Thomas Gleixner , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , Valentin Schneider , Vincent Guittot , Vincenzo Frascino , Vlastimil Babka , Will Deacon , workflows@vger.kernel.org, x86@kernel.org Subject: [PATCH v8 13/27] mm/ksw: add per-task ctx tracking Date: Tue, 11 Nov 2025 00:36:08 +0800 Message-ID: <20251110163634.3686676-14-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251110163634.3686676-1-wangjinchao600@gmail.com> References: <20251110163634.3686676-1-wangjinchao600@gmail.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Each task tracks its depth, stack pointer, and generation. A watchpoint is enabled only when the configured depth is reached, and disabled on function exit. The context is reset when probes are disabled, generation changes, or exit depth becomes inconsistent. Duplicate arming on the same frame is skipped. Signed-off-by: Jinchao Wang --- mm/kstackwatch/stack.c | 67 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) diff --git a/mm/kstackwatch/stack.c b/mm/kstackwatch/stack.c index 3aa02f8370af..96014eb4cb12 100644 --- a/mm/kstackwatch/stack.c +++ b/mm/kstackwatch/stack.c @@ -11,6 +11,53 @@ static struct kprobe entry_probe; static struct fprobe exit_probe; +static bool probe_enable; +static u16 probe_generation; + +static void ksw_reset_ctx(void) +{ + struct ksw_ctx *ctx = ¤t->ksw_ctx; + + if (ctx->wp) + ksw_watch_off(ctx->wp); + + ctx->wp = NULL; + ctx->sp = 0; + ctx->depth = 0; + ctx->generation = READ_ONCE(probe_generation); +} + +static bool ksw_stack_check_ctx(bool entry) +{ + struct ksw_ctx *ctx = ¤t->ksw_ctx; + u16 cur_enable = READ_ONCE(probe_enable); + u16 cur_generation = READ_ONCE(probe_generation); + u16 cur_depth, target_depth = ksw_get_config()->depth; + + if (!cur_enable) { + ksw_reset_ctx(); + return false; + } + + if (ctx->generation != cur_generation) + ksw_reset_ctx(); + + if (!entry && !ctx->depth) { + ksw_reset_ctx(); + return false; + } + + if (entry) + cur_depth = ctx->depth++; + else + cur_depth = --ctx->depth; + + if (cur_depth == target_depth) + return true; + else + return false; +} + static int ksw_stack_prepare_watch(struct pt_regs *regs, const struct ksw_config *config, ulong *watch_addr, u16 *watch_len) @@ -25,10 +72,22 @@ static void ksw_stack_entry_handler(struct kprobe *p, struct pt_regs *regs, unsigned long flags) { struct ksw_ctx *ctx = ¤t->ksw_ctx; + ulong stack_pointer; ulong watch_addr; u16 watch_len; int ret; + stack_pointer = kernel_stack_pointer(regs); + + /* + * triggered more than once, may be in a loop + */ + if (ctx->wp && ctx->sp == stack_pointer) + return; + + if (!ksw_stack_check_ctx(true)) + return; + ret = ksw_watch_get(&ctx->wp); if (ret) return; @@ -49,6 +108,7 @@ static void ksw_stack_entry_handler(struct kprobe *p, struct pt_regs *regs, return; } + ctx->sp = stack_pointer; } static void ksw_stack_exit_handler(struct fprobe *fp, unsigned long ip, @@ -57,6 +117,8 @@ static void ksw_stack_exit_handler(struct fprobe *fp, unsigned long ip, { struct ksw_ctx *ctx = ¤t->ksw_ctx; + if (!ksw_stack_check_ctx(false)) + return; if (ctx->wp) { ksw_watch_off(ctx->wp); @@ -91,11 +153,16 @@ int ksw_stack_init(void) return ret; } + WRITE_ONCE(probe_generation, READ_ONCE(probe_generation) + 1); + WRITE_ONCE(probe_enable, true); + return 0; } void ksw_stack_exit(void) { + WRITE_ONCE(probe_enable, false); + WRITE_ONCE(probe_generation, READ_ONCE(probe_generation) + 1); unregister_fprobe(&exit_probe); unregister_kprobe(&entry_probe); } -- 2.43.0