From patchwork Tue Jan 14 17:51:32 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Valentin Schneider X-Patchwork-Id: 13939212 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D16EFE77188 for ; Tue, 14 Jan 2025 18:01:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6686B280011; Tue, 14 Jan 2025 13:01:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6202728000C; Tue, 14 Jan 2025 13:01:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 49096280011; Tue, 14 Jan 2025 13:01:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 2B2B428000C for ; Tue, 14 Jan 2025 13:01:08 -0500 (EST) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id E02DF120C17 for ; Tue, 14 Jan 2025 18:01:07 +0000 (UTC) X-FDA: 83006823774.29.46E07A5 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf18.hostedemail.com (Postfix) with ESMTP id 928351C0018 for ; Tue, 14 Jan 2025 18:01:05 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=e4NdWv9X; spf=pass (imf18.hostedemail.com: domain of vschneid@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=vschneid@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1736877665; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=GQSPZLQ3FmvxIu57q6qI2psmX9IZ2horrf+PeQlNWuI=; b=Ag8ta76CLpjGy8hM5smk3dQG6GGRY/A4y2fRJdKvEk3MxxMj0jE1TdB6t45GT2QpwA86gl /dlBE7k7DPXPRcXvAoyHRoxIlmgxHEu33vBGIJUAETHJMyb9kPktJ5IG4fTPhKKcSxGSWM zh8adNOn9q290gJ/7sUHamhFBw2Nv/s= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=e4NdWv9X; spf=pass (imf18.hostedemail.com: domain of vschneid@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=vschneid@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1736877665; a=rsa-sha256; cv=none; b=AV0dVQ00Sk9rQR6i4bmzC+PGY6TUb5HUrdvoMFzyX3Mfl8I3WiTTgf9qHhTysfl61QQWFx RjK13Xz3qirTVY9jg8d6roSb9l/IttpaHOzGT40YqYwRc/iZmuyQuXVnXDiUvKAHQjZ7iy qDax9sfsSorradklA8+rXae9UoYCPV0= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736877664; 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=GQSPZLQ3FmvxIu57q6qI2psmX9IZ2horrf+PeQlNWuI=; b=e4NdWv9XiX5E0gif/3A0cDammbayQb384yeK+jDqJX7Fm+iR5mIfU4oNXGh751kYrGN/6G +RlFzgLqLw+7sA8EHiFYoZI6cGtBbtB4SZxLfdacgEmt8o2lFKeZ2J48Ik7k9X22YdZ5H5 SZgeUlKHzROY7cppUQUC0vkfTuXZOKU= Received: from mx-prod-mc-05.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-180-l9crDhjEN0CU5mOOpfPM-A-1; Tue, 14 Jan 2025 13:01:02 -0500 X-MC-Unique: l9crDhjEN0CU5mOOpfPM-A-1 X-Mimecast-MFC-AGG-ID: l9crDhjEN0CU5mOOpfPM-A Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 734481954190; Tue, 14 Jan 2025 18:00:56 +0000 (UTC) Received: from vschneid-thinkpadt14sgen2i.remote.csb (unknown [10.39.192.55]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id F38CE195608A; Tue, 14 Jan 2025 18:00:33 +0000 (UTC) From: Valentin Schneider To: linux-kernel@vger.kernel.org, x86@kernel.org, virtualization@lists.linux.dev, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org, linux-perf-users@vger.kernel.org, xen-devel@lists.xenproject.org, kvm@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org, linux-hardening@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, bpf@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com Cc: Josh Poimboeuf , Juergen Gross , Ajay Kaher , Alexey Makhalov , Russell King , Catalin Marinas , Will Deacon , Huacai Chen , WANG Xuerui , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Peter Zijlstra , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , Boris Ostrovsky , Pawan Gupta , Sean Christopherson , Paolo Bonzini , Andy Lutomirski , Arnd Bergmann , Frederic Weisbecker , "Paul E. McKenney" , Jason Baron , Steven Rostedt , Ard Biesheuvel , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Juri Lelli , Clark Williams , Yair Podemsky , Tomas Glozar , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Kees Cook , Andrew Morton , Christoph Hellwig , Shuah Khan , Sami Tolvanen , Miguel Ojeda , Alice Ryhl , "Mike Rapoport (Microsoft)" , Samuel Holland , Rong Xu , Nicolas Saenz Julienne , Geert Uytterhoeven , Yosry Ahmed , "Kirill A. Shutemov" , "Masami Hiramatsu (Google)" , Jinghao Jia , Luis Chamberlain , Randy Dunlap , Tiezhu Yang Subject: [PATCH v4 19/30] stackleack: Mark stack_erasing_bypass key as allowed in .noinstr Date: Tue, 14 Jan 2025 18:51:32 +0100 Message-ID: <20250114175143.81438-20-vschneid@redhat.com> In-Reply-To: <20250114175143.81438-1-vschneid@redhat.com> References: <20250114175143.81438-1-vschneid@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-Rspamd-Queue-Id: 928351C0018 X-Rspamd-Server: rspam12 X-Stat-Signature: zyp8rhacs1esa76n5bqm97531xry6883 X-Rspam-User: X-HE-Tag: 1736877665-659324 X-HE-Meta: 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 tLM0tFrT cWqSf/Qsbsj7LQI5e60zzwZ8auI9Kk5KQSm27MBdLSgtoZq0en+giodxAZxx6u9EoZbxyc6ky+vRlZ6c3h60TDgQSBsCI5vQPgBHCFZQ//RIeeCzl4FiydvNlRIQE13IcOcUOrJperfnMTLWDfom+bWXywpwQDwy7u6qgtgxARB6CYWuOXSHgndX7+Y17pfv4LCL8ZeMdXt/y1JBdO7okdwXdiCLJecPv8WzVT49lZ/TIQjNIh/T6yW+hgDgb/x+ae0RgtjI0f+VFW8YNtSdPmresUUu0pVnzQ3JHIVatZZ8PbHEi+XPlw5bzEumhNILgiz8QKHmnmx7JDmIDZeENdMt9ueTYgMHseygS3/4wPwELeh26oQV59iMdkVig2/g1eEl/cNTgyNRNNk4B94ooX7RVQfLqCCBobj61TXs/TPHRyPp6ND2a6zv1JwTLo57nAaimes+si9M81pcUnu8nEMcwbjQmtdj2KEVQjXs8E1K5nOU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Later commits will cause objtool to warn about static keys being used in .noinstr sections in order to safely defer instruction patching IPIs targeted at NOHZ_FULL CPUs. stack_erasing_bypass is used in .noinstr code, and can be modified at runtime (proc/sys/kernel/stack_erasing write). However it is not expected that it will be flipped during latency-sensitive operations, and thus shouldn't be a source of interference wrt the text patching IPI. Mark it to let objtool know not to warn about it. Reported-by: Josh Poimboeuf Signed-off-by: Valentin Schneider --- kernel/stackleak.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/stackleak.c b/kernel/stackleak.c index 39fd620a7db6f..a4f07fbc13f61 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -18,7 +18,11 @@ #include #include -static DEFINE_STATIC_KEY_FALSE(stack_erasing_bypass); +/* + * This static key can only be modified via its sysctl interface. It is + * expected it will remain stable during latency-senstive operations. + */ +static DEFINE_STATIC_KEY_FALSE_NOINSTR(stack_erasing_bypass); #ifdef CONFIG_SYSCTL static int stack_erasing_sysctl(const struct ctl_table *table, int write,