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 38B2B14F9D5 for ; Mon, 14 Oct 2024 08:59:49 +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=1728896392; cv=none; b=Z5kG9Z0WRvFn6inltUiJjHOIbotsVxxYWObd36WV8w33stkDciXglWeL45lSKdaIyozFyX7tg/IHdhv/1KnDwD0NlbKwaRXNIpGyfkR8dyvMrORjT9rdqFoJKtGV0GQQmrzo195dM+LHi8uPdNjL3Yhqvrn7fAVFzH0IxsUsX5E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728896392; c=relaxed/simple; bh=jRUrqrcUQ/cfKT11cpnjzllP2EcHwRhCubyxVYmFnyY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=NW++cksATXM4cGFeuyBVrx1DDPx8jt48hlkMSip5AicVgsSXYVoHGbbGTfxOr/yEiyLYggEnF4C3UCnZFINN/dTo3Nig7oqyfkkyUsca2TFWc/PldzNxbqOTA3f3apovho4xa2X4FcFDw5dPHR5xosACmW5uqzaD3GksvxEAh6A= 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 2C0DF1424; Mon, 14 Oct 2024 02:00:19 -0700 (PDT) Received: from [10.163.38.184] (unknown [10.163.38.184]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 40EEA3F71E; Mon, 14 Oct 2024 01:59:46 -0700 (PDT) Message-ID: Date: Mon, 14 Oct 2024 14:29:49 +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 1/5] arm64/mm: Drop pte_mkhuge() To: Ryan Roberts , linux-arm-kernel@lists.infradead.org Cc: Marc Zyngier , Oliver Upton , James Morse , Catalin Marinas , Will Deacon , Ard Biesheuvel , Mark Rutland , kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org References: <20241005123824.1366397-1-anshuman.khandual@arm.com> <20241005123824.1366397-2-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 10/9/24 18:50, Ryan Roberts wrote: > On 05/10/2024 13:38, Anshuman Khandual wrote: >> Core HugeTLB defines arch_make_huge_pte() fallback definition, which calls >> platform provided pte_mkhuge(). But if any platform already provides custom >> arch_make_huge_pte(), then it does not need to provide pte_mkhuge(). arm64 >> defines arch_make_huge_pte(), but then also calls pte_mkhuge() internally. >> This creates confusion as if both of these callbacks are being used in core >> HugeTLB and required to be defined in the platform. >> >> This changes arch_make_huge_pte() to create block mapping directly and also >> drops off now redundant helper pte_mkhuge(), making things clear. Also this >> changes HugeTLB page creation from just clearing the PTE_TABLE_BIT (bit[1]) >> to actually setting bits[1:0] via PTE_TYPE_[MASK|SECT] instead. >> >> Cc: Catalin Marinas >> Cc: Will Deacon >> Cc: Ard Biesheuvel >> Cc: Ryan Roberts >> Cc: Mark Rutland >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Signed-off-by: Anshuman Khandual >> --- >> arch/arm64/include/asm/pgtable-hwdef.h | 1 + >> arch/arm64/include/asm/pgtable.h | 5 ----- >> arch/arm64/mm/hugetlbpage.c | 2 +- >> 3 files changed, 2 insertions(+), 6 deletions(-) >> >> diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h >> index fd330c1db289..956a702cb532 100644 >> --- a/arch/arm64/include/asm/pgtable-hwdef.h >> +++ b/arch/arm64/include/asm/pgtable-hwdef.h >> @@ -158,6 +158,7 @@ >> #define PTE_VALID (_AT(pteval_t, 1) << 0) >> #define PTE_TYPE_MASK (_AT(pteval_t, 3) << 0) >> #define PTE_TYPE_PAGE (_AT(pteval_t, 3) << 0) >> +#define PTE_TYPE_SECT (_AT(pteval_t, 1) << 0) >> #define PTE_TABLE_BIT (_AT(pteval_t, 1) << 1) >> #define PTE_USER (_AT(pteval_t, 1) << 6) /* AP[1] */ >> #define PTE_RDONLY (_AT(pteval_t, 1) << 7) /* AP[2] */ >> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h >> index c329ea061dc9..fa4c32a9f572 100644 >> --- a/arch/arm64/include/asm/pgtable.h >> +++ b/arch/arm64/include/asm/pgtable.h >> @@ -438,11 +438,6 @@ static inline void __set_ptes(struct mm_struct *mm, >> } >> } >> >> -/* >> - * Huge pte definitions. >> - */ >> -#define pte_mkhuge(pte) (__pte(pte_val(pte) & ~PTE_TABLE_BIT)) >> - >> /* >> * Hugetlb definitions. >> */ >> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c >> index 5f1e2103888b..5922c95630ad 100644 >> --- a/arch/arm64/mm/hugetlbpage.c >> +++ b/arch/arm64/mm/hugetlbpage.c >> @@ -361,7 +361,7 @@ pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags) >> { >> size_t pagesize = 1UL << shift; >> >> - entry = pte_mkhuge(entry); >> + entry = __pte((pte_val(entry) & ~PTE_TYPE_MASK) | PTE_TYPE_SECT); > > I think there may be an existing bug here; if pagesize == CONT_PTE_SIZE, then > entry will be placed in the level 3 table. In this case, shouldn't bit 1 remain > set, because at level 3, a page mapping is denoted by bits[1:0] = 3 ? Currently > its being unconditionally cleared. That's not a problem, pte_mkcont() brings back both the bits via PTE_TYPE_PAGE along with PTE_CONT. if (pagesize == CONT_PTE_SIZE) { entry = pte_mkcont(entry); } else if (pagesize == CONT_PMD_SIZE) { entry = pmd_pte(pmd_mkcont(pte_pmd(entry))); } else if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) { pr_warn("%s: unrecognized huge page size 0x%lx\n", __func__, pagesize); } static inline pte_t pte_mkcont(pte_t pte) { pte = set_pte_bit(pte, __pgprot(PTE_CONT)); return set_pte_bit(pte, __pgprot(PTE_TYPE_PAGE)); } Although the same is not required for CONT_PMD_SIZE size huge pages where only PTE_CONT is enough. static inline pmd_t pmd_mkcont(pmd_t pmd) { return __pmd(pmd_val(pmd) | PMD_SECT_CONT); } >> if (pagesize == CONT_PTE_SIZE) { >> entry = pte_mkcont(entry); >> } else if (pagesize == CONT_PMD_SIZE) { >