From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AB609CCD185 for ; Fri, 10 Oct 2025 15:44:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=fSiRQxA5I7cbtbKutRpvTlGvB/h9JsDFAWOVN0dt9w8=; b=s1rEK4ObQ1cxSoA30S8HVCtv0S d9BnTJksxSOKtWRx1/y1kstNuYIEOB1lfAs9HBL+zhXSgyiZAGovMhBlouehBnqK/ldZyciI1UjLQ lss6ex3Oxv2k4N1Cgph52HVaubJ2EX8rUQQ2cb/g2UpWJET+bO21efWjartTZE1U6KiGdASDrliiR PomouQJKo+KUM+jRWs7H20UOHCrZzlFW7LP40aoYsDC0y8uFYaOnO+mrCSlhsvmQMd0absHOyDrPJ TUfWUzZFqO5MQOWyKHF9oFL0nyBnnEDOM8pzTjL0H2vpieIuVC7rIlBkzOLpbUU2WJbl6vMeXnjV8 pXTxRGew==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v7FHn-00000008rVC-2gQq; Fri, 10 Oct 2025 15:44:03 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v7FHm-00000008rUI-3oTZ for linux-arm-kernel@bombadil.infradead.org; Fri, 10 Oct 2025 15:44:03 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:MIME-Version :References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=fSiRQxA5I7cbtbKutRpvTlGvB/h9JsDFAWOVN0dt9w8=; b=Qafws0cd8ukBiwg8XFxXjXFPK4 K48N7ke/D92mVCCOM32EvZaBUoYimcF7Y7+5Rpe5C6DCTax1pNugGD85PTNbw59IyM3ADcYeNKh9M mq87Tt1kFN9ruoE0CBvcEMCRdlxAo6UrJxa8HUwhK0PATH8hTHo7YTsHURyMGTKEDzqSoro8rEcFa XpVXizc5j/OSr6XFlJY4tmpMWq978MTUXnXQtLYAi2DAKW27Zr0tBNTjqIqZeDZ7LXOvN941HInsB bNPFEBtWMm1HxDgm7o/MZggiZ2IXX4lSWbNXrtCRlq5vfOAm+QeD37MPG3ty4nVWlZVTJId7rltQE ecgIzd1Q==; Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by desiato.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v7FHi-00000002EhZ-3YO9 for linux-arm-kernel@lists.infradead.org; Fri, 10 Oct 2025 15:44:01 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760111037; 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=fSiRQxA5I7cbtbKutRpvTlGvB/h9JsDFAWOVN0dt9w8=; b=L/XalY/LiGpFKjrVVb5QsVXHxgv0zCKWbNfRVJg5YyxyUMcNcbNVOykDad03B87Exy/FzU PRKghj+wdmNaJAbQaPxjnc3kLn2Ia27s3b5GREro6lBtXaH9a3NoJK/YCVtGISEqbnq6Ox nYcNy9R6W9NIQGtjWPzrxge0kqjTmDg= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760111037; 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=fSiRQxA5I7cbtbKutRpvTlGvB/h9JsDFAWOVN0dt9w8=; b=L/XalY/LiGpFKjrVVb5QsVXHxgv0zCKWbNfRVJg5YyxyUMcNcbNVOykDad03B87Exy/FzU PRKghj+wdmNaJAbQaPxjnc3kLn2Ia27s3b5GREro6lBtXaH9a3NoJK/YCVtGISEqbnq6Ox nYcNy9R6W9NIQGtjWPzrxge0kqjTmDg= Received: from mx-prod-mc-04.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-442-qAxCNEYFMJiMSx-SkrmWlQ-1; Fri, 10 Oct 2025 11:42:31 -0400 X-MC-Unique: qAxCNEYFMJiMSx-SkrmWlQ-1 X-Mimecast-MFC-AGG-ID: qAxCNEYFMJiMSx-SkrmWlQ_1760110945 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id AFAEC19560B1; Fri, 10 Oct 2025 15:42:19 +0000 (UTC) Received: from vschneid-thinkpadt14sgen2i.remote.csb (unknown [10.45.224.29]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D815818004D8; Fri, 10 Oct 2025 15:42:03 +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 Subject: [PATCH v6 06/29] static_call: Add read-only-after-init static calls Date: Fri, 10 Oct 2025 17:38:16 +0200 Message-ID: <20251010153839.151763-7-vschneid@redhat.com> In-Reply-To: <20251010153839.151763-1-vschneid@redhat.com> References: <20251010153839.151763-1-vschneid@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251010_164359_114271_BD02AC27 X-CRM114-Status: GOOD ( 15.28 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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. If a noinstr static call only needs to be patched during boot, its key can be made ro-after-init to ensure it will never be patched at runtime. Signed-off-by: Josh Poimboeuf --- include/linux/static_call.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/include/linux/static_call.h b/include/linux/static_call.h index 78a77a4ae0ea8..ea6ca57e2a829 100644 --- a/include/linux/static_call.h +++ b/include/linux/static_call.h @@ -192,6 +192,14 @@ extern long __static_call_return0(void); }; \ ARCH_DEFINE_STATIC_CALL_TRAMP(name, _func) +#define DEFINE_STATIC_CALL_RO(name, _func) \ + DECLARE_STATIC_CALL(name, _func); \ + struct static_call_key __ro_after_init STATIC_CALL_KEY(name) = {\ + .func = _func, \ + .type = 1, \ + }; \ + ARCH_DEFINE_STATIC_CALL_TRAMP(name, _func) + #define DEFINE_STATIC_CALL_NULL(name, _func) \ DECLARE_STATIC_CALL(name, _func); \ struct static_call_key STATIC_CALL_KEY(name) = { \ @@ -200,6 +208,14 @@ extern long __static_call_return0(void); }; \ ARCH_DEFINE_STATIC_CALL_NULL_TRAMP(name) +#define DEFINE_STATIC_CALL_NULL_RO(name, _func) \ + DECLARE_STATIC_CALL(name, _func); \ + struct static_call_key __ro_after_init STATIC_CALL_KEY(name) = {\ + .func = NULL, \ + .type = 1, \ + }; \ + ARCH_DEFINE_STATIC_CALL_NULL_TRAMP(name) + #define DEFINE_STATIC_CALL_RET0(name, _func) \ DECLARE_STATIC_CALL(name, _func); \ struct static_call_key STATIC_CALL_KEY(name) = { \ -- 2.51.0