From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 5D1F339A4C4 for ; Thu, 20 Aug 2026 23:44:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787269482; cv=none; b=utvLPJbJ2Axt+WFLuRxKMPH8Ildzg2Wsz+/rcf+IcJ7T5GEDBdhqsBkwcGyKyd0BAGYOf0rEIN+i2iVzburCEb28SYKGc0gtlfb8qMFiGtWOAUYt7rNDYnkR8uNUA8Gkn2sW6n1P1PeoE9cn31d5RtoxKoGNXBTFMSt63pEWDwo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787269482; c=relaxed/simple; bh=rSHNoI1q7rB2oSTuAUarEq+dSwooRPIryXGF267OU1M=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=NOJzJR5xinSg1rXpji9h3qwHqg0rTKWPa3+c2AqO8WpTc9RmLXbPkSOa/l/fNSaKQBiEtNUGxHf/Pat/m0rTATjRNHbN8+kR/Sos7njKYE/29ZLTCUg5KdwDqor0fTOe/MEnngB2q3rVIKM84+MqDmjI/RKhMzNqsAbQh2NcHxY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Hla9xLvC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Hla9xLvC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 650D81F000E9; Thu, 20 Aug 2026 23:44:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787269481; bh=AucMdxpKqWIDptLE//Ma53AtN235JlXmNlvQ13jfyn4=; h=Date:From:To:cc:Subject:In-Reply-To:References; b=Hla9xLvC2wEukAuDp8X0tvV7s9u6TN4J3p1JDKAMYsFtgULNye+NXg77FB30PCY4o IjHcQxiQ8AixeqWvo9zDWkwIK7Z+gGpZZaKq5Wl4iQAKQ8vBkCcU5zh6tqskB75bde QO+ZnFc+/fuw+I9TPFmRcOXa8lCoAQ/L6bVydTp4zvMIaqtrL7cnABF7EH3jPXqEPd eTSyajUfsC2TiIrhgO+r5EvcwfFjLtECxMqNfF3EazKNIJa5jAROj9WEdJ+EX5ZPcQ EVCQYz6NNwMu8F1f0q4xNgVho+LJVL3Dxj59iR5smfkd2T1cr71ij8BcijvZ3pHPqK K29lq8KCFB2BQ== Date: Thu, 20 Aug 2026 17:44:37 -0600 (MDT) From: Paul Walmsley To: Samuel Holland cc: Palmer Dabbelt , linux-riscv@lists.infradead.org, Albert Ou , Alexandre Ghiti , Deepak Gupta , Paul Walmsley , Simon Schuster , Zishun Yi , Zong Li , linux-kernel@vger.kernel.org Subject: Re: [PATCH] Revert "riscv: Reset pmm when PR_TAGGED_ADDR_ENABLE is not set" In-Reply-To: <20260820014551.1979772-1-samuel.holland@sifive.com> Message-ID: <866528a0-bebb-91d3-9d9d-d5f8a15b8f1c@kernel.org> References: <20260820014551.1979772-1-samuel.holland@sifive.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Wed, 19 Aug 2026, Samuel Holland wrote: > This reverts commit 3033b2b1e3949274f33a140e2a97571b5a307298. > > The reverted patch is userspace-visible behavior change, not a bug fix. > The two variables here (pmm and pmlen) control two independent features: > pmm is the _hardware_ pointer masking mode that applies while executing > in userspace. pmlen is the shift amount that the _kernel_ uses when > untagging addresses; PMLEN_0 means no untagging occurs, so the kernel > does not accept tagged addresses in syscall arguments. > > It is valid (as documented and tested by the self test) to enable > pointer masking without enabling the tagged address ABI. This separation > is necessary to allow userspace to create an execution environment > similar to what the kernel supports on arm64 by default, where TBI is > enabled but the tagged address ABI is not. (On arm64, there is no > equivalent to PR_PMLEN_MASK because TBI is always enabled.) > > Signed-off-by: Samuel Holland Thanks, queued for v7.3-rc with a Fixes: tag and cc: stable. - Paul