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 89A32214209 for ; Thu, 6 Feb 2025 11:48:21 +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=1738842504; cv=none; b=mqie6zfXHm+sVs7MuEOzsNsFM43pvb9f42RsQ4eIMJzEvF6r5R5YCER14eIE3g9RHjRJU1dTOmIc+DDyIKQAnCYaiBo+IP3nvDmdzHImCg0sjIhvHBngadXEMlI5b81Y80IpXBf4wZwuCfCzCTMf9XYnwSpcCTiQOzKgENHf04k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738842504; c=relaxed/simple; bh=PiJ40gXy5ngnydgoQKkaQ1FuaBUx4yrq+N/7Jr5I5Rk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=PP1fyHyk0DV3QP0CeM5rp6vHoC9waDk64js7BwMjEi5DfHPTCwyKikVqfIqcusbJ2P+ya6C+om2ocMgEJool1aCP6JIX/my666whjDMPGmSIK5L/WxZkvzWxIIPYPVg6d0UmnJQYT1CSI6HeV6q8jDZx9cKT8+30PBpeSrtntKo= 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 1A47312FC; Thu, 6 Feb 2025 03:48:44 -0800 (PST) Received: from [10.163.34.115] (unknown [10.163.34.115]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0405E3F5A1; Thu, 6 Feb 2025 03:48:14 -0800 (PST) Message-ID: Date: Thu, 6 Feb 2025 17:18:12 +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 v1 06/16] arm64/mm: Refactor __set_ptes() and __ptep_get_and_clear() To: Ryan Roberts , Catalin Marinas , Will Deacon , Muchun Song , Pasha Tatashin , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Mark Rutland , Ard Biesheuvel , Dev Jain , Alexandre Ghiti , Steve Capper , Kevin Brodsky Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250205151003.88959-1-ryan.roberts@arm.com> <20250205151003.88959-7-ryan.roberts@arm.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: <20250205151003.88959-7-ryan.roberts@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/5/25 20:39, Ryan Roberts wrote: > Refactor __set_ptes(), set_pmd_at() and set_pud_at() so that they are > all a thin wrapper around a generic ___set_ptes(), which takes pgsize s/generic/common - as generic might be misleading for being generic MM. > parameter. This cleans up the code to remove the confusing > __set_pte_at() (which was only ever used for pmd/pud) and will allow us > to perform future barrier optimizations in a single place. Additionally, > it will permit the huge_pte API to efficiently batch-set pgtable entries > and take advantage of the future barrier optimizations. Makes sense. > > ___set_ptes() calls the correct page_table_check_*_set() function based > on the pgsize. This means that huge_ptes be able to get proper coverage > regardless of their size, once it's plumbed into huge_pte. Currently the > huge_pte API always uses the pte API which assumes an entry only covers > a single page. Right > > While we are at it, refactor __ptep_get_and_clear() and > pmdp_huge_get_and_clear() to use a common ___ptep_get_and_clear() which > also takes a pgsize parameter. This will provide the huge_pte API the > means to clear ptes corresponding with the way they were set. __ptep_get_and_clear() refactoring does not seem to be related to the previous __set_ptes(). Should they be separated out into two different patches instead - for better clarity and review ? Both these clean ups have enough change and can stand own their own. > > Signed-off-by: Ryan Roberts > --- > arch/arm64/include/asm/pgtable.h | 108 +++++++++++++++++++------------ > 1 file changed, 67 insertions(+), 41 deletions(-) > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index 0b2a2ad1b9e8..3b55d9a15f05 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -420,23 +420,6 @@ static inline pte_t pte_advance_pfn(pte_t pte, unsigned long nr) > return pfn_pte(pte_pfn(pte) + nr, pte_pgprot(pte)); > } > > -static inline void __set_ptes(struct mm_struct *mm, > - unsigned long __always_unused addr, > - pte_t *ptep, pte_t pte, unsigned int nr) > -{ > - page_table_check_ptes_set(mm, ptep, pte, nr); > - __sync_cache_and_tags(pte, nr); > - > - for (;;) { > - __check_safe_pte_update(mm, ptep, pte); > - __set_pte(ptep, pte); > - if (--nr == 0) > - break; > - ptep++; > - pte = pte_advance_pfn(pte, 1); > - } > -} > - > /* > * Hugetlb definitions. > */ > @@ -641,30 +624,59 @@ static inline pgprot_t pud_pgprot(pud_t pud) > return __pgprot(pud_val(pfn_pud(pfn, __pgprot(0))) ^ pud_val(pud)); > } > > -static inline void __set_pte_at(struct mm_struct *mm, > - unsigned long __always_unused addr, > - pte_t *ptep, pte_t pte, unsigned int nr) > +static inline void ___set_ptes(struct mm_struct *mm, pte_t *ptep, pte_t pte, > + unsigned int nr, unsigned long pgsize) So address got dropped and page size got added as an argument. s/___set_ptes/___set_pxds ? to be more generic for all levels. > { > - __sync_cache_and_tags(pte, nr); > - __check_safe_pte_update(mm, ptep, pte); > - __set_pte(ptep, pte); > + unsigned long stride = pgsize >> PAGE_SHIFT; > + > + switch (pgsize) { > + case PAGE_SIZE: > + page_table_check_ptes_set(mm, ptep, pte, nr); > + break; > + case PMD_SIZE: > + page_table_check_pmds_set(mm, (pmd_t *)ptep, pte_pmd(pte), nr); > + break; > + case PUD_SIZE: > + page_table_check_puds_set(mm, (pud_t *)ptep, pte_pud(pte), nr); > + break; This is where the new page table check APIs get used for batch testing. > + default: > + VM_WARN_ON(1); > + } > + > + __sync_cache_and_tags(pte, nr * stride); > + > + for (;;) { > + __check_safe_pte_update(mm, ptep, pte); > + __set_pte(ptep, pte); > + if (--nr == 0) > + break; > + ptep++; > + pte = pte_advance_pfn(pte, stride); > + } > } LGTM > > -static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr, > - pmd_t *pmdp, pmd_t pmd) > +static inline void __set_ptes(struct mm_struct *mm, > + unsigned long __always_unused addr, > + pte_t *ptep, pte_t pte, unsigned int nr) > { > - page_table_check_pmd_set(mm, pmdp, pmd); > - return __set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd), > - PMD_SIZE >> PAGE_SHIFT); > + ___set_ptes(mm, ptep, pte, nr, PAGE_SIZE); > } > > -static inline void set_pud_at(struct mm_struct *mm, unsigned long addr, > - pud_t *pudp, pud_t pud) > +static inline void __set_pmds(struct mm_struct *mm, > + unsigned long __always_unused addr, > + pmd_t *pmdp, pmd_t pmd, unsigned int nr) > +{ > + ___set_ptes(mm, (pte_t *)pmdp, pmd_pte(pmd), nr, PMD_SIZE); > +} > +#define set_pmd_at(mm, addr, pmdp, pmd) __set_pmds(mm, addr, pmdp, pmd, 1) > + > +static inline void __set_puds(struct mm_struct *mm, > + unsigned long __always_unused addr, > + pud_t *pudp, pud_t pud, unsigned int nr) > { > - page_table_check_pud_set(mm, pudp, pud); > - return __set_pte_at(mm, addr, (pte_t *)pudp, pud_pte(pud), > - PUD_SIZE >> PAGE_SHIFT); > + ___set_ptes(mm, (pte_t *)pudp, pud_pte(pud), nr, PUD_SIZE); > } > +#define set_pud_at(mm, addr, pudp, pud) __set_puds(mm, addr, pudp, pud, 1) LGTM > > #define __p4d_to_phys(p4d) __pte_to_phys(p4d_pte(p4d)) > #define __phys_to_p4d_val(phys) __phys_to_pte_val(phys) > @@ -1276,16 +1288,34 @@ static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma, > } > #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG */ > > -static inline pte_t __ptep_get_and_clear(struct mm_struct *mm, > - unsigned long address, pte_t *ptep) > +static inline pte_t ___ptep_get_and_clear(struct mm_struct *mm, pte_t *ptep, > + unsigned long pgsize) So address got dropped and page size got added as an argument. > { > pte_t pte = __pte(xchg_relaxed(&pte_val(*ptep), 0)); > > - page_table_check_pte_clear(mm, pte); > + switch (pgsize) { > + case PAGE_SIZE: > + page_table_check_pte_clear(mm, pte); > + break; > + case PMD_SIZE: > + page_table_check_pmd_clear(mm, pte_pmd(pte)); > + break; > + case PUD_SIZE: > + page_table_check_pud_clear(mm, pte_pud(pte)); > + break; > + default: > + VM_WARN_ON(1); > + } > > return pte; > } > > +static inline pte_t __ptep_get_and_clear(struct mm_struct *mm, > + unsigned long address, pte_t *ptep) > +{ > + return ___ptep_get_and_clear(mm, ptep, PAGE_SIZE); > +} > + > static inline void __clear_full_ptes(struct mm_struct *mm, unsigned long addr, > pte_t *ptep, unsigned int nr, int full) > { > @@ -1322,11 +1352,7 @@ static inline pte_t __get_and_clear_full_ptes(struct mm_struct *mm, > static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm, > unsigned long address, pmd_t *pmdp) > { > - pmd_t pmd = __pmd(xchg_relaxed(&pmd_val(*pmdp), 0)); > - > - page_table_check_pmd_clear(mm, pmd); > - > - return pmd; > + return pte_pmd(___ptep_get_and_clear(mm, (pte_t *)pmdp, PMD_SIZE)); > } > #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ > Although currently there is no pudp_huge_get_and_clear() helper on arm64 reworked ___ptep_get_and_clear() will be able to support that as well if and when required as it now supports PUD_SIZE page size.