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[217.140.101.70]) by mx.google.com with ESMTP id e13si30531eds.130.2019.02.18.05.45.24 for ; Mon, 18 Feb 2019 05:45:26 -0800 (PST) Received-SPF: pass (google.com: domain of mark.rutland@arm.com designates 217.140.101.70 as permitted sender) client-ip=217.140.101.70; Authentication-Results: mx.google.com; spf=pass (google.com: domain of mark.rutland@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=mark.rutland@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 290FCA78; Mon, 18 Feb 2019 05:45:21 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2FF3B3F720; Mon, 18 Feb 2019 05:45:13 -0800 (PST) Date: Mon, 18 Feb 2019 13:45:07 +0000 From: Mark Rutland To: Peter Zijlstra Cc: Steven Price , linux-mm@kvack.org, Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Dave Hansen , Ingo Molnar , James Morse , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Thomas Gleixner , Will Deacon , x86@kernel.org, "H. Peter Anvin" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 01/13] arm64: mm: Add p?d_large() definitions Message-ID: <20190218134507.GA9603@lakrids.cambridge.arm.com> References: <20190215170235.23360-1-steven.price@arm.com> <20190215170235.23360-2-steven.price@arm.com> <20190218112922.GT32477@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190218112922.GT32477@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Feb 18, 2019 at 12:29:22PM +0100, Peter Zijlstra wrote: > On Fri, Feb 15, 2019 at 05:02:22PM +0000, Steven Price wrote: > > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > > index de70c1eabf33..09d308921625 100644 > > --- a/arch/arm64/include/asm/pgtable.h > > +++ b/arch/arm64/include/asm/pgtable.h > > @@ -428,6 +428,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, > > PMD_TYPE_TABLE) > > #define pmd_sect(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \ > > PMD_TYPE_SECT) > > +#define pmd_large(x) pmd_sect(x) > > > > #if defined(CONFIG_ARM64_64K_PAGES) || CONFIG_PGTABLE_LEVELS < 3 > > #define pud_sect(pud) (0) > > @@ -435,6 +436,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, > > #else > > #define pud_sect(pud) ((pud_val(pud) & PUD_TYPE_MASK) == \ > > PUD_TYPE_SECT) > > +#define pud_large(x) pud_sect(x) > > #define pud_table(pud) ((pud_val(pud) & PUD_TYPE_MASK) == \ > > PUD_TYPE_TABLE) > > #endif > > So on x86 p*d_large() also matches p*d_huge() and thp, But it is not > clear to me this p*d_sect() thing does so, given your definitions. > > See here why I care: > > http://lkml.kernel.org/r/20190201124741.GE31552@hirez.programming.kicks-ass.net I believe it does not. IIUC our p?d_huge() helpers implicitly handle contiguous entries. That's where you have $N entries in the current level of table that the TLB can cache together as one. Our p?d_sect() helpers only match section entries. That's where we map an entire next-level-table's worth of VA space with a single entry at the current level. Thanks, Mark.