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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1511BCAC5B8 for ; Tue, 30 Sep 2025 23:48:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1F2288E0005; Tue, 30 Sep 2025 19:48:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 17B808E0002; Tue, 30 Sep 2025 19:48:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 043758E0005; Tue, 30 Sep 2025 19:48:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id E11438E0002 for ; Tue, 30 Sep 2025 19:48:48 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 93BDEBBF68 for ; Tue, 30 Sep 2025 23:48:48 +0000 (UTC) X-FDA: 83947559136.28.2A72E75 Received: from mail-pg1-f174.google.com (mail-pg1-f174.google.com [209.85.215.174]) by imf12.hostedemail.com (Postfix) with ESMTP id 9EFAF4000B for ; Tue, 30 Sep 2025 23:48:46 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=rivosinc.com header.s=google header.b=EYzSfdQd; spf=pass (imf12.hostedemail.com: domain of debug@rivosinc.com designates 209.85.215.174 as permitted sender) smtp.mailfrom=debug@rivosinc.com; dmarc=pass (policy=none) header.from=rivosinc.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1759276126; 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-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=4bm7dBKTe7VHUpax5O4A5sblWjBcLkrJbyIa/W7uP1A=; b=OBZ/6tFNX5Y1MHmnQSveGnVw0PEwP6ngxezD7/jl1+ydqyhWCmuqxjXW7vzPnwq8y7mk9e gS2pe/Qntnkx7+K/UAAYrl14RM+Jj/il7u/bR/t81sjKWm/KNbVSmJ2GM4J+ShFTUn4eL2 JhyBbJlE3bCaH5CL27HlrpXy3vIpZ5Y= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1759276126; a=rsa-sha256; cv=none; b=Y2S2+BZIoRMEynSMovLdFgErWdu8FLtnOYiPFyORaACMeRP1XjAbsTzAGLPbL+B/f9Cjow bVAUzlixRrC/UDehxI+gsNc5Q4IeWk/ctclHT3m/KYQ9733QF+P0umoY16rG+lnLfbMPMM OJ8Raq4AS2I3VmtP7vbt/wNCCXdNVNw= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=rivosinc.com header.s=google header.b=EYzSfdQd; spf=pass (imf12.hostedemail.com: domain of debug@rivosinc.com designates 209.85.215.174 as permitted sender) smtp.mailfrom=debug@rivosinc.com; dmarc=pass (policy=none) header.from=rivosinc.com Received: by mail-pg1-f174.google.com with SMTP id 41be03b00d2f7-b57de3f63c8so3967210a12.3 for ; Tue, 30 Sep 2025 16:48:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc.com; s=google; t=1759276125; x=1759880925; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=4bm7dBKTe7VHUpax5O4A5sblWjBcLkrJbyIa/W7uP1A=; b=EYzSfdQd5YYW8Q4puIwdBfMktQ+A2EhPHmLHu/l/kOjmaCYMxrroqt6jCW2M2oHIL0 rw5EZ5GaCtGTp/Btxdmahtzp26gqYNlH54ix8+3/2J+2wo52hJ66bJBlLXQJa5p/RznG 0shQvdj4TWztsPwv7uobj7AD77masYqesdu788eyHnaJ+R4V6RdE21Q97lTAaXN4tnA0 x1l3uFS6FtlINCp+zvU9uzgDBXH0Hld+rBLmtYQbVoJvkPG/las2JOZpGpJhmLsbDOB9 PZPXx1WA1IfNSu6CHjoc1QIsvpx+ITqKhg9ZJPJZn6SiH1ETuvS3ooXOpbkRMXnuEzx3 i31Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1759276125; x=1759880925; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=4bm7dBKTe7VHUpax5O4A5sblWjBcLkrJbyIa/W7uP1A=; b=H/2HIbjrd34jGUTIpkmoRY1xGPec1MVN8V32jkm0hVPK9Ct33XsbpqtvEJBnl0W0e6 QRLWvPM0WdZSspLT0PcdHVpPb1CovlI0jNwXNznTXaqhuiTOzL8tfEfLDAaNSjrYSs9P ZVZxwLU2rLtmOGJtzBF9EY2dIeZJs8YuZa+5wfBzHJsvsHrwqXejkPqFFlX5qjOJWxdO GelTBpCywQutDoCyblZKSq4pl77RLmk3FziDar0rEX+IxmHFgGg4GONIYKEujwSvlVdC XWCmmx+3fn1Jp5r8eixkRqxi73NPIBbor/b52Bqgn9kvZSfXy0egsAW9SNRjnzGv5aol daRw== X-Forwarded-Encrypted: i=1; AJvYcCX1cVuGMkHeRNwWnEFQn44TTpHEuUL+MVd7DaY4QnEzKZnIFYBK/1e2TnnXLHT06/vefJ5ZSAk0+Q==@kvack.org X-Gm-Message-State: AOJu0YyEaCXtGq8wKmRwNk7ovgfJogUFk/wnjH+plAkUuXsr/WRKqkj6 QAszDOhQY56EzXGd8zserpdYlj+6tXYTLf+IuVAfee6le0XFL9YMhl5HznFeF532SaQ= X-Gm-Gg: ASbGncttWXFKLfPLNEwZ6QlIKJN6vZs9Ob5mayr6aqk4O/IZPJUvUeriZz1dXlZTgz+ ndaCsaTHBjTUQV6rchgT2lJ4u75Zbianpi6t/DvyTfyZbXuhPyZblLv9/3lN9JZg6RbDSxD5TGc xpLGxWVZC9Gt4X7WKo+xYqg0ETjn3IaeRjSZe8t/H0Zimvd0Ju2jIomlYc5gJN/WPXc1q1qbUqu OXDd5NZXx6u0PYb26p5/JyRExwrce/GPHVV0B1kAkT6LMVLiWfOr1Dh8CC90zkRRi48J+cKPA48 kI/57byj/ou42Z9mk9fhrqnRtaEkAXgQvDN3iQjZkThIzMWw48K5xQwkuWxK8pgLFvmeLVI0JBx uAxe5ByWeKHBQ9vjWO+9tngPyxUSYfBR6Gc6NwLL+vpEuUbAQL47dlNyA X-Google-Smtp-Source: AGHT+IHuRRsekWNjgE7yCPLG9pq3eS/GOyyUhj/f2Q9rAEjbYAirvs/e72q2qhgNkEK8PrNvRevQ9g== X-Received: by 2002:a17:903:3d06:b0:27e:ea82:5ce8 with SMTP id d9443c01a7336-28e7f291db3mr15309515ad.14.1759276125338; Tue, 30 Sep 2025 16:48:45 -0700 (PDT) Received: from debug.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-27ed6882133sm171972415ad.89.2025.09.30.16.48.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Sep 2025 16:48:44 -0700 (PDT) Date: Tue, 30 Sep 2025 16:48:41 -0700 From: Deepak Gupta To: Florian Weimer Cc: Charles Mirabile , pjw@kernel.org, Liam.Howlett@oracle.com, a.hindborg@kernel.org, akpm@linux-foundation.org, alex.gaynor@gmail.com, alexghiti@rivosinc.com, aliceryhl@google.com, alistair.francis@wdc.com, andybnac@gmail.com, aou@eecs.berkeley.edu, arnd@arndb.de, atishp@rivosinc.com, bjorn3_gh@protonmail.com, boqun.feng@gmail.com, bp@alien8.de, brauner@kernel.org, broonie@kernel.org, charlie@rivosinc.com, cleger@rivosinc.com, conor+dt@kernel.org, conor@kernel.org, corbet@lwn.net, dave.hansen@linux.intel.com, david@redhat.com, devicetree@vger.kernel.org, ebiederm@xmission.com, evan@rivosinc.com, gary@garyguo.net, hpa@zytor.com, jannh@google.com, jim.shu@sifive.com, kees@kernel.org, kito.cheng@sifive.com, krzk+dt@kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, lorenzo.stoakes@oracle.com, lossin@kernel.org, mingo@redhat.com, ojeda@kernel.org, oleg@redhat.com, palmer@dabbelt.com, paul.walmsley@sifive.com, peterz@infradead.org, richard.henderson@linaro.org, rick.p.edgecombe@intel.com, robh@kernel.org, rust-for-linux@vger.kernel.org, samitolvanen@google.com, shuah@kernel.org, tglx@linutronix.de, tmgross@umich.edu, vbabka@suse.cz, x86@kernel.org, zong.li@sifive.com Subject: Re: [PATCH v19 00/27] riscv control-flow integrity for usermode Message-ID: References: <20250926192919.349578-1-cmirabil@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 9EFAF4000B X-Stat-Signature: 8xz4hbkwxyg1e7gipstre7wuba6qngai X-Rspam-User: X-HE-Tag: 1759276126-134630 X-HE-Meta: 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 ClV9va+a FbFKduGUofhjpACsyIuzci4jS/gkjwsf+MrmRYB42lK328jTC8/ieGitXdwSSIAZYAOHIw8UCumXapSK28PxtRfoFM+crMxRLJ91hJMGIw/Ih99bFh/i1335yUT0P3spGMuooRfujtlcFxh1ckbt0bO3rmexK2I/hU3wCF9To3i5KMUUiaTx3Bv/fbsMV6zbMyRZvePv8St65lMqy9vXTr9GPxzSEpt0YUTw4RiY7+sUuXNPGgNGaQRTGRDK+rVsgRlg2yWETzREmynz6IRBk9x/jByGvKg0AaILkHHVKJlAUAm8kYiFk5pn0ksbwxalTQsNk6VahegtFmk0DcLJtH/7UBaR6+vECJDpYZ+Cu/a2O8AnWpvEp/0H2BJ3qNzqtBDNsvOwSRVB4j/U= 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: On Tue, Sep 30, 2025 at 11:20:32AM +0200, Florian Weimer wrote: >* Deepak Gupta: > >> In case of shadow stack, it similar situation. If enabled compiler >> decides to insert sspush and sspopchk. They necessarily won't be >> prologue or epilogue but somewhere in function body as deemed fit by >> compiler, thus increasing the complexity of runtime patching. >> >> More so, here are wishing for kernel to do this patching for usermode >> vDSO when there is no guarantee of such of rest of usermode (which if >> was compiled with shadow stack would have faulted before vDSO's >> sspush/sspopchk if ran on pre-zimop hardware) > >I think this capability is desirable so that you can use a distribution >kernel during CFI userspace bringup. I didn't get it, can you elaborate more. Why having kernel carry two vDSO (one with shadow stack and one without) would be required to for CFI userspace bringup? If Distro is compiling for RVA23 CONFIG_RISCV_USERCFI has to be selected yes, kernel can have vDSO with shadow stack. Distro can light this option only when its compiling entire distro for RVA23. If distro is not compiling for RVA23, then anyways CONFIG_RISCV_USERCFI is by default "N". This would simply build vDSO without shadow stack. > >Thanks, >Florian >