From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dl1-f73.google.com (mail-dl1-f73.google.com [74.125.82.73]) (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 29DCF3BFE34 for ; Thu, 26 Mar 2026 11:25:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774524336; cv=none; b=S7NJw2+wCZ0HXiPKe2OoGx097yHR6/OS9QE+VfItZy+639WaAW7BOYz8oapzkuVSF2ot4rtiG8PtyVLVrgUm9A6jFu9GjiIPrgzTYZsQYKiCtZFBUQgbwtw3vj7+xJOQuNGkT29p2FoM/RXQAgIUM1W7X/75rwqKPgtTEcCgvbg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774524336; c=relaxed/simple; bh=SXKjAxsdGUmKwSrMydXTRmH3TVk5HoSMhyyX86S/7tw=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=mUiUU/4hDrI9ByEIa3An/fWypg3dUTu9R6OV5lFyA/af7CrhUQoSWNLUcaZTaLAnU3rpxJPQbEf6ZfPCU1edmg5sCeakbhrKWbjUMNIcJIQtLmrRoGfVkJ+QWrLujfvgIYMgfozcF4fPPcQI7StvFX5uSB3hnHZaiXscns7hyKs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--wusamuel.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=I/J7PeCy; arc=none smtp.client-ip=74.125.82.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--wusamuel.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="I/J7PeCy" Received: by mail-dl1-f73.google.com with SMTP id a92af1059eb24-12737f276a2so743492c88.1 for ; Thu, 26 Mar 2026 04:25:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1774524334; x=1775129134; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=IJTelMffLYeUWQfdwTRKWfmopMGExMPo1dZE2xtXqZU=; b=I/J7PeCy4nXM2lBumXeUy20uA2cA9YShVMtdIaVUlBSWw2JU3JZvoSf1mHqUKgjapH ukiMS001/JMnztcY9tVFAsjsIUqZjOaiD1YeOGZBTlgreUpWjO9J8C+MMhVgYZNBjRhR vAcGlxb5cHr2py+Hqij1jvL/cvdGqugQ+je/QTWrEUo1s7CaDu1aLYFRg1j0akfDVFIg zrpD43PYiq8fAVNxH6dLu3aLJ5T+oafZwtiUM+dsDtO+V2rcbSXOfmoM2IRIgtXqipbz iN/tMw5GrrU0ke4yAAqfxaq66OwAfVKzVF7oq8283sK0G4tycKANV/49wlKkXLeEx50l Bwzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774524334; x=1775129134; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=IJTelMffLYeUWQfdwTRKWfmopMGExMPo1dZE2xtXqZU=; b=B2lrXn5XDceG3qBy8aZW/x5ng3sl9hugM3V2QfF1CjjP7zgE2AD/bScxzBiDfcjQTN Touz+jrGiesm3g/XPl/XOpmdFAjOs8UZX9benmhQ+q3AgmPKsufpbJGGzu8a32KWVNrM BLE0QO96oLBHUkbEroKajczj/YXsdK0IEYd1V6I3zJMprfTuZJaAxwZmCB96bOyFvYOG u9Ol8vDrYhrae+cRyEI+CPzXBzPiJiXH3KH3Br3GztDGFRy1xw2KS5J0KKqnom4Z+/UO ZFigl21UgcU2oaoHctd3Mx+oYAiZ/Nn1Gk0AOkUlEyCGoTxTazbRaAgw7peJcIVl0hfe 1voQ== X-Forwarded-Encrypted: i=1; AJvYcCVH8Xbvk3K4DGSWxKbqueLxIEjEWFqFHdocpJiNT8Q3Cso+7NQv3yX7XwmiPyuHipTfMafd+z7m6g==@vger.kernel.org X-Gm-Message-State: AOJu0Yw0z1D3s33xhSjGxTC/+tk066ymSn2M/0pQc0ZuPYSO6tm0sstu c/MJd+bBvojjMVlRqAQkpL+5GhSSCa/QwopNgYBh03W8XIgv/zRfk6fpGWa96VNuwyrgg4KKEJQ OrBfWgBjly2yRgw== X-Received: from dlaj3.prod.google.com ([2002:a05:701b:2803:b0:128:cff2:6560]) (user=wusamuel job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:6189:b0:128:d4be:7433 with SMTP id a92af1059eb24-12a96f0977emr3562318c88.34.1774524334043; Thu, 26 Mar 2026 04:25:34 -0700 (PDT) Date: Thu, 26 Mar 2026 04:25:19 -0700 In-Reply-To: <20260326112521.2827500-1-wusamuel@google.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260326112521.2827500-1-wusamuel@google.com> X-Mailer: git-send-email 2.53.0.1018.g2bb0e51243-goog Message-ID: <20260326112521.2827500-2-wusamuel@google.com> Subject: [PATCH v2 1/2] PM: wakeup: Add kfuncs to traverse over wakeup_sources From: Samuel Wu To: "Rafael J. Wysocki" , Len Brown , Pavel Machek , Greg Kroah-Hartman , Danilo Krummrich , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan Cc: memxor@gmail.com, Samuel Wu , kernel-team@android.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, driver-core@lists.linux.dev, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Iterating through wakeup sources via sysfs or debugfs can be inefficient or restricted. Introduce BPF kfuncs to allow high-performance and safe in-kernel traversal of the wakeup_sources list. The new kfuncs include: - bpf_wakeup_sources_get_head() to obtain the list head. - bpf_wakeup_sources_read_lock/unlock() to manage the SRCU lock. For verifier safety, the underlying SRCU index is wrapped in an opaque 'struct bpf_ws_lock' pointer. This enables the use of KF_ACQUIRE and KF_RELEASE flags, allowing the BPF verifier to strictly enforce paired lock/unlock cycles and prevent resource leaks. Signed-off-by: Samuel Wu --- drivers/base/power/power.h | 7 ++++ drivers/base/power/wakeup.c | 72 +++++++++++++++++++++++++++++++++++-- 2 files changed, 77 insertions(+), 2 deletions(-) diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h index 922ed457db19..ced563286ac5 100644 --- a/drivers/base/power/power.h +++ b/drivers/base/power/power.h @@ -168,3 +168,10 @@ static inline void device_pm_init(struct device *dev) device_pm_sleep_init(dev); pm_runtime_init(dev); } + +#ifdef CONFIG_BPF_SYSCALL +struct bpf_ws_lock { }; +struct bpf_ws_lock *bpf_wakeup_sources_read_lock(void); +void bpf_wakeup_sources_read_unlock(struct bpf_ws_lock *lock); +struct list_head *bpf_wakeup_sources_get_head(void); +#endif diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c index b8e48a023bf0..27a26a30b6ee 100644 --- a/drivers/base/power/wakeup.c +++ b/drivers/base/power/wakeup.c @@ -1168,11 +1168,79 @@ static const struct file_operations wakeup_sources_stats_fops = { .release = seq_release_private, }; -static int __init wakeup_sources_debugfs_init(void) +#ifdef CONFIG_BPF_SYSCALL +#include + +__bpf_kfunc_start_defs(); + +/** + * bpf_wakeup_sources_read_lock - Acquire the SRCU lock for wakeup sources + * + * The underlying SRCU lock returns an integer index. However, the BPF verifier + * requires a pointer (PTR_TO_BTF_ID) to strictly track the state of acquired + * resources using KF_ACQUIRE and KF_RELEASE semantics. We use an opaque + * structure pointer (struct bpf_ws_lock *) to satisfy the verifier while + * safely encoding the integer index within the pointer address itself. + * + * Return: An opaque pointer encoding the SRCU lock index + 1 (to avoid NULL). + */ +__bpf_kfunc struct bpf_ws_lock *bpf_wakeup_sources_read_lock(void) +{ + return (struct bpf_ws_lock *)(long)(wakeup_sources_read_lock() + 1); +} + +/** + * bpf_wakeup_sources_read_unlock - Release the SRCU lock for wakeup sources + * @lock: The opaque pointer returned by bpf_wakeup_sources_read_lock() + * + * The BPF verifier guarantees that @lock is a valid, unreleased pointer from + * the acquire function. We decode the pointer back into the integer SRCU index + * by subtracting 1 and release the lock. + */ +__bpf_kfunc void bpf_wakeup_sources_read_unlock(struct bpf_ws_lock *lock) +{ + wakeup_sources_read_unlock((int)(long)lock - 1); +} + +/** + * bpf_wakeup_sources_get_head - Get the head of the wakeup sources list + * + * Return: The head of the wakeup sources list. + */ +__bpf_kfunc struct list_head *bpf_wakeup_sources_get_head(void) +{ + return &wakeup_sources; +} + +__bpf_kfunc_end_defs(); + +BTF_KFUNCS_START(wakeup_source_kfunc_ids) +BTF_ID_FLAGS(func, bpf_wakeup_sources_read_lock, KF_ACQUIRE) +BTF_ID_FLAGS(func, bpf_wakeup_sources_read_unlock, KF_RELEASE) +BTF_ID_FLAGS(func, bpf_wakeup_sources_get_head) +BTF_KFUNCS_END(wakeup_source_kfunc_ids) + +static const struct btf_kfunc_id_set wakeup_source_kfunc_set = { + .owner = THIS_MODULE, + .set = &wakeup_source_kfunc_ids, +}; + +static void __init wakeup_sources_bpf_init(void) +{ + if (register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &wakeup_source_kfunc_set)) + pm_pr_dbg("Wakeup: failed to register BTF kfuncs\n"); +} +#else +static inline void wakeup_sources_bpf_init(void) {} +#endif /* CONFIG_BPF_SYSCALL */ + +static int __init wakeup_sources_init(void) { debugfs_create_file("wakeup_sources", 0444, NULL, NULL, &wakeup_sources_stats_fops); + wakeup_sources_bpf_init(); + return 0; } -postcore_initcall(wakeup_sources_debugfs_init); +postcore_initcall(wakeup_sources_init); -- 2.53.0.1018.g2bb0e51243-goog