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 D622B2DF717 for ; Wed, 7 Jan 2026 09:07:56 +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=1767776879; cv=none; b=Q9siMvEYuZfv0muBwVwAIXsQYMm3czZlmhqw801XbyvDS7q1V1/XXpvt2ICRrjQN/SJHiLjo0VPHkQ3oURHwifB0eXh/ywR3qfV8d8F6+8FLBDDBYVx7OSLFb9jfXb45KKcyJrjLW57Jg5C52iiUpNTmVn+IwpuubWsVQ3FqgAE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767776879; c=relaxed/simple; bh=cGh+k3qM6POM8UbygxGFV4EGhOS/pl0d65PI4qPwHdU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=NVFfoDG226YwCMqT/NxlcnDPWC8oVeOrI7oTma+Td22OEBVEi8XT+3hSSq9RFePKaQIZ977/c5ln/r3mk+p3W9F/ZKxInY6cnfaCZ6ybRK6f/l+NGKPNoPxS1yCePIrGrF2nQoGBSGk7kV+5efzp//zLObti2Rj+77nKDa11cqg= 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 56567497; Wed, 7 Jan 2026 01:07:49 -0800 (PST) Received: from [10.164.18.63] (unknown [10.164.18.63]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 692013F5A1; Wed, 7 Jan 2026 01:07:54 -0800 (PST) Message-ID: <32030401-06d3-40ad-a0b6-fbd366092f2b@arm.com> Date: Wed, 7 Jan 2026 14:37:51 +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: Assert NR_BM_PUD_TABLES for bm_pud[] To: Ryan Roberts , linux-arm-kernel@lists.infradead.org Cc: mark.rutland@arm.com, Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org References: <20260107061606.3160088-1-anshuman.khandual@arm.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 07/01/26 2:03 PM, Ryan Roberts wrote: > On 07/01/2026 06:16, Anshuman Khandual wrote: >> There is an implicit assumption about bm_pud[] being single entry PUD table >> just like bp_pmd[] which is a single entry PMD table. Though only the later >> gets asserted via NR_BM_PMD_TABLES. Hence let's add a similar check for PUD >> table as well. >> >> Cc: Catalin Marinas >> Cc: Will Deacon >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Signed-off-by: Anshuman Khandual >> --- >> arch/arm64/mm/fixmap.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/arch/arm64/mm/fixmap.c b/arch/arm64/mm/fixmap.c >> index c5c5425791da..e02594be8b8e 100644 >> --- a/arch/arm64/mm/fixmap.c >> +++ b/arch/arm64/mm/fixmap.c >> @@ -23,8 +23,11 @@ static_assert(FIXADDR_TOT_START > PCI_IO_END); >> SPAN_NR_ENTRIES(FIXADDR_TOT_START, FIXADDR_TOP, PMD_SHIFT) >> #define NR_BM_PMD_TABLES \ >> SPAN_NR_ENTRIES(FIXADDR_TOT_START, FIXADDR_TOP, PUD_SHIFT) >> +#define NR_BM_PUD_TABLES \ >> + SPAN_NR_ENTRIES(FIXADDR_TOT_START, FIXADDR_TOP, P4D_SHIFT) >> >> static_assert(NR_BM_PMD_TABLES == 1); >> +static_assert(NR_BM_PUD_TABLES == 1); > > But if there is only one PMD table, there must only be one PUD table (and one > P4D table, and one PGD table) by definition. So I don't think this is checking > anything that the existing PMD table check is not. Agreed but should not this check help tighten this code up given that bm_pud[] array gets used for possible PUD entries ? > > Thanks, > Ryan > >> >> #define __BM_TABLE_IDX(addr, shift) \ >> (((addr) >> (shift)) - (FIXADDR_TOT_START >> (shift))) >