From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dy1-f202.google.com (mail-dy1-f202.google.com [74.125.82.202]) (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 F274F421EFC for ; Tue, 31 Mar 2026 15:34:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774971297; cv=none; b=NtZDfZwyF2qde19YsRg2yQ5Q0XdIIfuyjAcp9nJ810OIOJewFVbAzl+MFjVZFE19fjIEXmlNlI/QYInHoqW9iIyuOi5jtWMRop0loG80F6J/BrccCW64/96QV3ba64S4xaCh95pVvTh4DsnJ7vBq6Ay8dqZpsA+9D8FPCjiwHjg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774971297; c=relaxed/simple; bh=QKH00JljZrlMfVod10pqmeNjUeUmhefNzONLwQdWIy4=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=DR7KNgu0PzfgkAnq1viIN38V7HOo3LNCChpR0eNosbGk38I41Rt92DzAV1y4lb6OuNtFExakCljYwzOn7MDAdTkfM+vNuigmfECL0aQKXZ9UTvict/cBCeg5nqA0EoRGwNSp9lj3coQ/WvFopW0e6eRvpK5Cdqm+Ky2IolGV+9Y= 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=q/UFGRcR; arc=none smtp.client-ip=74.125.82.202 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="q/UFGRcR" Received: by mail-dy1-f202.google.com with SMTP id 5a478bee46e88-2bdf75bc88fso4877563eec.0 for ; Tue, 31 Mar 2026 08:34:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1774971293; x=1775576093; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=EQA/UKYBuXcCvugMU5yRxI2SsSzVyoeHKW9NqHrZ5UA=; b=q/UFGRcR/aTRAMltCyJw+PkaGwxst0/befFbrcuUP6/HmtuM84jDDPxaugHfgmYsdL 7ZUQnhQpUeWHRa0eaI1FVf7nWqLKJ7gjpPhQjxkuD2eYZzDLgvMvYSAOW0yY0pVoAZQ1 EyrLzWy4Ym8mcT6jWrpxBLwXnPXpuaH+/HfO9gKPFVcvmtvILM5NR58ckqYQm8Td9IX3 CsNq/wD+Wk9pDjgAIV5WWDnNsxNjaxmeVc3x1lv9ZztQyrBW/t5w+Auv8MTre8PLLW9J A+DBICvV6v7mF1TEQUk1xTIcR5MmZ3y+svyJuwnb5oaW8i1xhSVonKJ0p+SKXIbkDdF6 Tpyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774971293; x=1775576093; 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=EQA/UKYBuXcCvugMU5yRxI2SsSzVyoeHKW9NqHrZ5UA=; b=Gji9mX7UrL8nWjXixOdwpZ3ODqpFg9Qr29ND50pH3Mk0niaNr0nKAzWoSjCKpxHXXE fjbBxS77KT1YoP6YvQmfmCdEnrfk+looXwS0ezgQs5pWnK5+s18n82ntbv7Zl/z6CuMS 7xSk56/ZxWEy1njoTxe3C9xR+jrtaq9cZCMARMijcCJUWNCc/1aQo1Y7t/coVC34CLIx qulz9+RjOaPxXU1L+s3DCq3ZnVUSO8u22tjQ7LAUlHLbQH1hBXqaDVux60jdUoPAW6cI nSYqFNe0tV1E/zo5h6E7cKwSPOqExkqSFxk7uOOUW9OJPqJbzphLrTU+ChRpPfEGmqm3 SWrw== X-Forwarded-Encrypted: i=1; AJvYcCVwIVjOhW5EgSsptfUwcNSkqPxKEUx3s+jJFqjvsrDaU4LgRSpiZIPElaOdgpVead1atH9Q8/00mHraFA==@lists.linux.dev X-Gm-Message-State: AOJu0Ywh/YeNzULPdQSxuJMaTSoFsvQzbZ57Q0leEh32bbXvie7OySbo M3wuWNa/7X8HujrpzgVpEZ4ZiNii2NRVjQrqcFakxnh7KlEtWUa/o6r7tXSNWCAIF1tItb7pC9V uy2sUBdCxJDp5lQ== X-Received: from dyr23.prod.google.com ([2002:a05:693c:4017:b0:2be:6911:c4f2]) (user=wusamuel job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7301:da0b:b0:2c3:b172:83c2 with SMTP id 5a478bee46e88-2c3b1728c62mr5463093eec.20.1774971292418; Tue, 31 Mar 2026 08:34:52 -0700 (PDT) Date: Tue, 31 Mar 2026 08:34:10 -0700 In-Reply-To: <20260331153413.2469218-1-wusamuel@google.com> Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260331153413.2469218-1-wusamuel@google.com> X-Mailer: git-send-email 2.53.0.1018.g2bb0e51243-goog Message-ID: <20260331153413.2469218-2-wusamuel@google.com> Subject: [PATCH v3 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 , Andrii Nakryiko , Eduard Zingerman , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa , Shuah Khan Cc: 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..8823aceeac8b 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); +void *bpf_wakeup_sources_get_head(void); +#endif diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c index b8e48a023bf0..8eda7d35d9cc 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 void *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