From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 094A114532B for ; Fri, 14 Jun 2024 02:24:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718331901; cv=none; b=IQB5HzFnz5rohIDPm40uC007D/zF++fw2WpY56hLxvxcEkc1DLkai+KPVwZxFloclcwUixdaW/5zENDUU3cWddXTn1vxWk4G6W6OOlvmu1+KpaZRr4Gh3CQXpEWbGR42kGCe7lMHAKwtRUMerbBTnQZN9baorD1qkXrVdZ16eyI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718331901; c=relaxed/simple; bh=/Xs1YwUSUUPtBTM3JJOUhEixbPf3wiUKxyU+gNVx/Uw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=lnI58idG483xn/U2tSzcqdU6o7VAFVnUNAVVCzukclQmPzHb2sXn64JEuamfZC9mAUJE+qpUmW5bP3ujAQ/kA+Y3SaVi4rFe9Oa2Uz8wayIRnzCE4HcLx5htBTWcDLW0QuXfaPVu2Zjcmdcgqm6GGmMCnhxq/C+WxzjFP0cr9Ks= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9DB4DFEC; Thu, 13 Jun 2024 19:25:22 -0700 (PDT) Received: from [10.162.16.42] (a077893.blr.arm.com [10.162.16.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0FFCA3F73B; Thu, 13 Jun 2024 19:24:55 -0700 (PDT) Message-ID: Date: Fri, 14 Jun 2024 07:54:53 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] arm64/mm: Drop ESR_ELx_FSC_TYPE Content-Language: en-US To: Marc Zyngier Cc: linux-arm-kernel@lists.infradead.org, mark.rutland@arm.com, ryan.roberts@arm.com, Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org References: <20240613094538.3263536-1-anshuman.khandual@arm.com> <86y179jdbx.wl-maz@kernel.org> From: Anshuman Khandual In-Reply-To: <86y179jdbx.wl-maz@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/13/24 16:53, Marc Zyngier wrote: > On Thu, 13 Jun 2024 10:45:38 +0100, > Anshuman Khandual wrote: >> >> Fault status codes at page table level 0, 1, 2 and 3 for access, permission >> and translation faults are architecturally organized in a way, that masking >> out ESR_ELx_FSC_TYPE, fetches Level 0 status code for the respective fault. >> >> Helpers like esr_fsc_is_[translation|permission|access_flag]_fault() mask >> out ESR_ELx_FSC_TYPE before comparing against corresponding Level 0 status >> code as the kernel does not yet care about the page table level, the fault >> really occurred previously. >> >> This scheme is starting to crumble after FEAT_LPA2 when level -1 got added. >> Fault status code for translation fault at level -1 is 0x2B which does not >> follow ESR_ELx_FSC_TYPE, requiring esr_fsc_is_translation_fault() changes. >> >> This changes above helpers to compare against individual fault status code >> values for each page table level and drop ESR_ELx_FSC_TYPE which is losing >> its value as a common mask. > > I'd rather we do not drop the existing #defines, for a very > self-serving reason: > > NV requires an implementation to synthesise fault syndromes, and these > definition are extensively used to compose the syndrome information > (see the NV MMU series at [1]). This is also heavily use to emulate > the AT instructions (fault reporting in PAR_EL1.FST). > > Having additional helpers is fine. Dropping the base definitions > isn't, and I'd like to avoid reintroducing them. You would like to just leave behind all the existing level 0 syndrome macro definitions in place ? #define ESR_ELx_FSC_ACCESS (0x08) #define ESR_ELx_FSC_FAULT (0x04) #define ESR_ELx_FSC_PERM (0x0C) Or which are rather #define ESR_ELx_FSC_ACCESS ESR_ELx_FSC_ACCESS_L0 #define ESR_ELx_FSC_FAULT ESR_ELx_FSC_FAULT_L0 #define ESR_ELx_FSC_PERM ESR_ELx_FSC_PERM_L0 But just wondering why cannot ESR_ELx_FSC_[ACCESS|FAULT|PERM]_L0 definitions be used directly in new use cases ? > > Thanks, > > M. > > [1] http://lore.kernel.org/r/20240529145628.3272630-1-maz@kernel.org >