From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8C3E3337B9F for ; Fri, 14 Nov 2025 15:03:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763132629; cv=none; b=k2wtBQA9WBIY+82Uvfyo/A9BJwZhysFbUbN9+IkEUrRYMYzqAYqTur01avsQqVxjuytJG8Ph8E1W1gcFmGx7wtnG5y5/aSlifFuYxgQhFrcYVg391XOujTBuvqj3/HPUzqIJh8kh9jy4KGE1kN/7d2qW+pFRFBvB8IGfbTxW+XQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763132629; c=relaxed/simple; bh=tUCxDYx2/0NN5QR1DEvZrfPrIv3zYWsV4oVjHSBsnzs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AyFsV9+VQIV1nArRAKMzVsVwuuNa89jnw6fbM6ae7f/jKEvyjTD9M5LNo5mgqaAxE3S1cKveme0g8GwG9uQUU6etBU5otxld7h80SOuxkNqRMEExLFOpeAHwc8jur3t/QJheAo05r8B6y1G1eIGEvQM6QhlxnHxUKSrByjBd7RQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=bJdmXue4; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bJdmXue4" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1763132626; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ypuA88VHIrtZCycTQvLRbp4fTjYOiPnVr/lgVBnkLI0=; b=bJdmXue46LUUj5lVHeBctcJkAeqd+RjkpvICP48lJZjFx0H64TP4Eyv62tZReU3ZRJq/rZ whj4VTPMX0GqQOYBGooFcK4vrINofyvVYY/QHjmIdt/Q0o5A/3EPbQu8f+5wDJ4KZpQJSK ugIBCWlelZdvRQ+GFrP0RkE2lGrcjjU= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-504-SKUOVx5hNtSa3DHoze9ZYQ-1; Fri, 14 Nov 2025 10:03:40 -0500 X-MC-Unique: SKUOVx5hNtSa3DHoze9ZYQ-1 X-Mimecast-MFC-AGG-ID: SKUOVx5hNtSa3DHoze9ZYQ_1763132615 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E500A18D95C7; Fri, 14 Nov 2025 15:03:34 +0000 (UTC) Received: from vschneid-thinkpadt14sgen2i.remote.csb (unknown [10.45.226.10]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id DA7DF1956046; Fri, 14 Nov 2025 15:03:20 +0000 (UTC) From: Valentin Schneider To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, rcu@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org, linux-arch@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Josh Poimboeuf , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Arnaldo Carvalho de Melo , Paolo Bonzini , Arnd Bergmann , Frederic Weisbecker , "Paul E. McKenney" , Jason Baron , Steven Rostedt , Ard Biesheuvel , Sami Tolvanen , "David S. Miller" , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Mathieu Desnoyers , Mel Gorman , Andrew Morton , Masahiro Yamada , Han Shen , Rik van Riel , Jann Horn , Dan Carpenter , Oleg Nesterov , Juri Lelli , Clark Williams , Yair Podemsky , Marcelo Tosatti , Daniel Wagner , Petr Tesarik , Shrikanth Hegde Subject: [PATCH v7 05/31] jump_label: Add annotations for validating noinstr usage Date: Fri, 14 Nov 2025 16:01:07 +0100 Message-ID: <20251114150133.1056710-6-vschneid@redhat.com> In-Reply-To: <20251114150133.1056710-1-vschneid@redhat.com> References: <20251114150133.1056710-1-vschneid@redhat.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 From: Josh Poimboeuf Deferring a code patching IPI is unsafe if the patched code is in a noinstr region. In that case the text poke code must trigger an immediate IPI to all CPUs, which can rudely interrupt an isolated NO_HZ CPU running in userspace. Some noinstr static branches may really need to be patched at runtime, despite the resulting disruption. Add DEFINE_STATIC_KEY_*_NOINSTR() variants for those. They don't do anything special yet; that will come later. Signed-off-by: Josh Poimboeuf --- include/linux/jump_label.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index fdb79dd1ebd8c..c4f6240ff4d95 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -388,6 +388,23 @@ struct static_key_false { #define DEFINE_STATIC_KEY_FALSE_RO(name) \ struct static_key_false name __ro_after_init = STATIC_KEY_FALSE_INIT +/* + * The _NOINSTR variants are used to tell objtool the static key is allowed to + * be used in noinstr code. + * + * They should almost never be used, as they prevent code patching IPIs from + * being deferred, which can be problematic for isolated NOHZ_FULL CPUs running + * in pure userspace. + * + * If using one of these _NOINSTR variants, please add a comment above the + * definition with the rationale. + */ +#define DEFINE_STATIC_KEY_TRUE_NOINSTR(name) \ + DEFINE_STATIC_KEY_TRUE(name) + +#define DEFINE_STATIC_KEY_FALSE_NOINSTR(name) \ + DEFINE_STATIC_KEY_FALSE(name) + #define DECLARE_STATIC_KEY_FALSE(name) \ extern struct static_key_false name -- 2.51.0