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 DEDA4CD5BD1 for ; Mon, 1 Jun 2026 20:59:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 01C526B04C8; Mon, 1 Jun 2026 16:59:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F0F6F6B04C9; Mon, 1 Jun 2026 16:59:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E24F06B04CA; Mon, 1 Jun 2026 16:59:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id D3A576B04C8 for ; Mon, 1 Jun 2026 16:59:09 -0400 (EDT) Received: from smtpin06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 686F9162972 for ; Mon, 1 Jun 2026 20:59:09 +0000 (UTC) X-FDA: 84832558818.06.CD59F59 Received: from mail-out.m-online.net (mail-out.m-online.net [212.18.0.9]) by imf01.hostedemail.com (Postfix) with ESMTP id 1671B40013 for ; Mon, 1 Jun 2026 20:59:06 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; spf=pass (imf01.hostedemail.com: domain of whitebox@nefkom.net designates 212.18.0.9 as permitted sender) smtp.mailfrom=whitebox@nefkom.net ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1780347547; 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; bh=Lf8royKGKY/88tWjnvDeTQ3D1s3N+bR+jt5KeXdcXGU=; b=zUvGyR2hqze8JT/YPOTVd7Bjs8canIndcurZ9SIXdszwb03Qat+ozu4YcnLfCjN+bmyBzN Kl2jb2PHXdtpPb+EUYFnqrTdWNGmb9m3eLvoWWMxwEAkAGMg0KR3TNvkJvq0UZwJ3tZ7f+ rBzakrLqh/eB5hevf1QnRA1sWhAu0w4= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=none; spf=pass (imf01.hostedemail.com: domain of whitebox@nefkom.net designates 212.18.0.9 as permitted sender) smtp.mailfrom=whitebox@nefkom.net; dmarc=none ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1780347547; b=JPLIZSB+ICzgaBZWLvY9XSYt5KOLbIIUpJ0Hi5UoajibqKWrFmSrXe1Vljseb2Enjb5Leq DJVp1VLfMH5MPWdKTPSoC1JBgzeEEfnPShpULyV8/7Ev0c+rhLjpHvZ6ehDTjtcZtjwpls 4wdRiottqc5jGyyqWMaiHNl6zLW9RX0= Received: from mail-out.m-online.net (mail-out.m-online.net [212.18.0.9]) by mail-out.m-online.net (Postfix) with ESMTP id 4gTmXn29XPz1r5Sh; Mon, 1 Jun 2026 22:59:05 +0200 (CEST) Received: from frontend03.mail.m-online.net (unknown [192.168.6.182]) by mail-out.m-online.net (Postfix) with ESMTP id 4gTmXb1NBBz1r5Sf; Mon, 1 Jun 2026 22:58:55 +0200 (CEST) Received: from localhost (dynscan3.mnet-online.de [192.168.6.87]) by mail.m-online.net (Postfix) with ESMTP id 4gTmXZ2s9rz1qqlS; Mon, 1 Jun 2026 22:58:54 +0200 (CEST) X-Virus-Scanned: amavis at mnet-online.de Received: from mail.mnet-online.de ([192.168.6.182]) by localhost (dynscan3.mail.m-online.net [192.168.6.87]) (amavis, port 10024) with ESMTP id StDKLQCMjWpS; Mon, 1 Jun 2026 22:58:52 +0200 (CEST) X-Auth-Info: FqnxIDPc+CejjKHAe9u56JUkf8btEszKYhyFrkdtC5LkcdNUzyTOWALY7FYpYrLU Received: from igel.home (aftr-82-135-83-133.dynamic.mnet-online.de [82.135.83.133]) (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 mail.mnet-online.de (Postfix) with ESMTPSA; Mon, 1 Jun 2026 22:58:52 +0200 (CEST) Received: by igel.home (Postfix, from userid 1000) id 6F0742C16DB; Mon, 1 Jun 2026 22:58:52 +0200 (CEST) From: Andreas Schwab To: Deepak Gupta Cc: Deepak Gupta via B4 Relay , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , Paul Walmsley , Palmer Dabbelt , Albert Ou , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Arnd Bergmann , Christian Brauner , Peter Zijlstra , Oleg Nesterov , Eric Biederman , Kees Cook , Jonathan Corbet , Shuah Khan , Jann Horn , Conor Dooley , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6?= =?utf-8?Q?rn?= Roy Baron , Andreas Hindborg , Alice Ryhl , Trevor Gross , Benno Lossin , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, alistair.francis@wdc.com, richard.henderson@linaro.org, jim.shu@sifive.com, andybnac@gmail.com, kito.cheng@sifive.com, charlie@rivosinc.com, atishp@rivosinc.com, evan@rivosinc.com, cleger@rivosinc.com, alexghiti@rivosinc.com, samitolvanen@google.com, broonie@kernel.org, rick.p.edgecombe@intel.com, rust-for-linux@vger.kernel.org, Zong Li Subject: Re: [PATCH v23 06/28] riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE In-Reply-To: (Deepak Gupta's message of "Mon, 1 Jun 2026 10:57:41 -0700") References: <20251112-v5_user_cfi_series-v23-0-b55691eacf4f@rivosinc.com> <20251112-v5_user_cfi_series-v23-6-b55691eacf4f@rivosinc.com> <87jyslndo4.fsf@igel.home> <875x44o9hj.fsf@igel.home> <871peqgp9v.fsf@igel.home> Date: Mon, 01 Jun 2026 22:58:52 +0200 Message-ID: <87wlwif04z.fsf@igel.home> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1671B40013 X-Stat-Signature: apr8j7fw5a7neyrcxojmm9iwoawyc1i4 X-Rspam-User: X-HE-Tag: 1780347546-58127 X-HE-Meta: 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 gWxaLbxw 5BfjLYQJvvUatj9JKY3LejOvTB/y7K+HFml3lzh/YkuUoD9+IkzjbWuPpHcOzvsNeYEFwYeMq5iv4l/nGyplqnCCiIKRpdk6/2L9zlukiyeW78LJPvCKqpQKbHZXf6vN+xq7nlbHFc23hcTXtcGr46yjnaQ6UuO50p5ZSwTgnivYf4R8HK722kQw4cqQfcxPpxsW1hJ93s3do+hYmXgjNLooT7Xdf9TSukHJ/cCh4N+GsqB2XogfOBDc81AW2NKXqYwSm3/YFKBERzMVF9x1V+dxBt7GH1Kw0kzo4R7uaRgnApkpwXH46jLXmApyptMysLjZuoINxmFtz5eHZrfuoVdX9mFLNmjQBoYgPOKga6GXJ3d97jUIqmOpC7bOtfkZwvMzyq0UKuB4yZyKVTZ7qu9/KlChkGmRbv3FNRe3Rmj6E2v5wPrr/vtFh/yfFObyUM7lm Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Jun 01 2026, Deepak Gupta wrote: > riscv uses `VM_SHADOW_STACK`. It's just very simple to use `protection_map` > with just `VM_WRITE`. On RISC-V, `-W-` is a shadow stack mapping. It's not same > on x86 or arm64. So `protection_map[VM_WRITE]` simply picks shadow stack > encoding. We just ensure that PROT_WRITE is converted to > "VM_READ | VM_WRITE" at vma level. That does not explain _why_ you need to make that user visible change, when others can get away without it. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 "And now for something completely different."