From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 580CFC433DF for ; Fri, 9 Oct 2020 09:38:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DEE262225A for ; Fri, 9 Oct 2020 09:37:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602236279; bh=qKDWHZKc2QllAAp0MK7WBMA0uqYrzQj6Jk2nI8Ea0pI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=0LrJ2i8b02Y+RqifiIqvfX0vUUD5JfRDwF6UIC7XloKdmjRMTlHUwCQl2t+IdNhik +ilfaIbao1HedNW8E3EOj1M9x4cP5y54lKR6WXCg+Kp8uuH2P/StWCLLcrlcvlai28 lU6h+HqrfU38n4m8DYvx0BwERu4xSBp0cB84D3C8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733122AbgJIJh6 (ORCPT ); Fri, 9 Oct 2020 05:37:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:59878 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733111AbgJIJh6 (ORCPT ); Fri, 9 Oct 2020 05:37:58 -0400 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EB15F22258; Fri, 9 Oct 2020 09:37:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602236277; bh=qKDWHZKc2QllAAp0MK7WBMA0uqYrzQj6Jk2nI8Ea0pI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YrhMPzARymQIZS5n3bb1V7YpdIkjja0LwIcZZFkdfCzI2Nio04DHrCOY0mCS1zXkv 5PvY+yhh5938AoR0j/ZaQzY03WcMv9Rg0Q6Wb/8kRVmyZf5u+B2aTP3B8zGCCCXt5l mcNbBQdWw2vhC2U+Cw+DW1JoyhnjPCkZ2OzOJDFo= Date: Fri, 9 Oct 2020 10:37:51 +0100 From: Will Deacon To: Peter Zijlstra Cc: kan.liang@linux.intel.com, mingo@redhat.com, acme@kernel.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@redhat.com, eranian@google.com, ak@linux.intel.com, dave.hansen@intel.com, kirill.shutemov@linux.intel.com, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, David Miller Subject: Re: [PATCH V9 1/4] perf/core: Add PERF_SAMPLE_DATA_PAGE_SIZE Message-ID: <20201009093750.GD29594@willie-the-truck> References: <20201001135749.2804-1-kan.liang@linux.intel.com> <20201001135749.2804-2-kan.liang@linux.intel.com> <20201009090927.GQ2611@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201009090927.GQ2611@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 09, 2020 at 11:09:27AM +0200, Peter Zijlstra wrote: > On Thu, Oct 01, 2020 at 06:57:46AM -0700, kan.liang@linux.intel.com wrote: > > +/* > > + * Return the MMU page size of a given virtual address > > + */ > > +static u64 __perf_get_page_size(struct mm_struct *mm, unsigned long addr) > > +{ > > + pgd_t *pgd; > > + p4d_t *p4d; > > + pud_t *pud; > > + pmd_t *pmd; > > + pte_t *pte; > > + > > + pgd = pgd_offset(mm, addr); > > + if (pgd_none(*pgd)) > > + return 0; > > + > > + p4d = p4d_offset(pgd, addr); > > + if (!p4d_present(*p4d)) > > + return 0; > > + > > + if (p4d_leaf(*p4d)) > > + return 1ULL << P4D_SHIFT; > > + > > + pud = pud_offset(p4d, addr); > > + if (!pud_present(*pud)) > > + return 0; > > + > > + if (pud_leaf(*pud)) > > + return 1ULL << PUD_SHIFT; > > + > > + pmd = pmd_offset(pud, addr); > > + if (!pmd_present(*pmd)) > > + return 0; > > + > > + if (pmd_leaf(*pmd)) > > + return 1ULL << PMD_SHIFT; > > + > > + pte = pte_offset_map(pmd, addr); > > + if (!pte_present(*pte)) { > > + pte_unmap(pte); > > + return 0; > > + } > > + > > + pte_unmap(pte); > > + return PAGE_SIZE; > > +} > > So this mostly works, but gets a number of hugetlb and arch specific > things wrong. > > With the first 3 patches, this is only exposed to x86 and Power. > Michael, does the above work for you? > > Looking at: > > arch/powerpc/include/asm/book3s/64/hugetlb.h:check_and_get_huge_psize() > > You seem to limit yourself to page-table sizes, however if I then look > at the same function in: > > arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h > arch/powerpc/include/asm/nohash/hugetlb-book3e.h > > it doesn't seem to constrain itself so. > > Patch 4 makes it all far worse by exposing it to pretty much everybody. > > Now, I think we can fix at least the user mappings with the below delta, > but if archs are using non-page-table MMU sizes we'll need arch helpers. > > ARM64 is in that last boat. > > Will, can you live with the below, if not, what would you like to do, > make the entire function __weak so that you can override it, or hook > into it somewhere? Hmm, so I don't think we currently have any PMUs that set 'data->addr' on arm64, in which case maybe none of this currently matters for us. However, I must admit that I couldn't figure out exactly what gets exposed to userspace when the backend drivers don't look at the sample_type or do anything with the addr field. Will