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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 AC72CC4332B for ; Tue, 24 Mar 2020 19:38:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 869CD2076E for ; Tue, 24 Mar 2020 19:38:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727088AbgCXTik (ORCPT ); Tue, 24 Mar 2020 15:38:40 -0400 Received: from mx2.suse.de ([195.135.220.15]:42494 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725835AbgCXTik (ORCPT ); Tue, 24 Mar 2020 15:38:40 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id DEFC2AAB8; Tue, 24 Mar 2020 19:38:35 +0000 (UTC) Date: Tue, 24 Mar 2020 20:38:33 +0100 From: Michal =?iso-8859-1?Q?Such=E1nek?= To: Nicholas Piggin Cc: linuxppc-dev@lists.ozlabs.org, Arnaldo Carvalho de Melo , Alexander Shishkin , Allison Randal , Andy Shevchenko , Arnd Bergmann , Thiago Jung Bauermann , Benjamin Herrenschmidt , Sebastian Andrzej Siewior , Claudio Carvalho , Christophe Leroy , "David S. Miller" , "Eric W. Biederman" , Eric Richter , Greg Kroah-Hartman , Gustavo Luiz Duarte , Hari Bathini , Jordan Niethe , Jiri Olsa , Jonathan Cameron , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Mark Rutland , Masahiro Yamada , Mauro Carvalho Chehab , Michael Neuling , Ingo Molnar , Michael Ellerman , Namhyung Kim , Nayna Jain , Paul Mackerras , Peter Zijlstra , Rob Herring , Thomas Gleixner , Valentin Schneider , Alexander Viro Subject: Re: [PATCH v11 3/8] powerpc/perf: consolidate read_user_stack_32 Message-ID: <20200324193833.GH25468@kitsune.suse.cz> References: <20200225173541.1549955-1-npiggin@gmail.com> <184347595442b4ca664613008a09e8cea7188c36.1584620202.git.msuchanek@suse.de> <1585039473.da4762n2s0.astroid@bobo.none> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1585039473.da4762n2s0.astroid@bobo.none> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 24, 2020 at 06:48:20PM +1000, Nicholas Piggin wrote: > Michal Suchanek's on March 19, 2020 10:19 pm: > > There are two almost identical copies for 32bit and 64bit. > > > > The function is used only in 32bit code which will be split out in next > > patch so consolidate to one function. > > > > Signed-off-by: Michal Suchanek > > Reviewed-by: Christophe Leroy > > --- > > v6: new patch > > v8: move the consolidated function out of the ifdef block. > > v11: rebase on top of def0bfdbd603 > > --- > > arch/powerpc/perf/callchain.c | 48 +++++++++++++++++------------------ > > 1 file changed, 24 insertions(+), 24 deletions(-) > > > > diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c > > index cbc251981209..c9a78c6e4361 100644 > > --- a/arch/powerpc/perf/callchain.c > > +++ b/arch/powerpc/perf/callchain.c > > @@ -161,18 +161,6 @@ static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret) > > return read_user_stack_slow(ptr, ret, 8); > > } > > > > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret) > > -{ > > - if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) || > > - ((unsigned long)ptr & 3)) > > - return -EFAULT; > > - > > - if (!probe_user_read(ret, ptr, sizeof(*ret))) > > - return 0; > > - > > - return read_user_stack_slow(ptr, ret, 4); > > -} > > - > > static inline int valid_user_sp(unsigned long sp, int is_64) > > { > > if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32) > > @@ -277,19 +265,9 @@ static void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry, > > } > > > > #else /* CONFIG_PPC64 */ > > -/* > > - * On 32-bit we just access the address and let hash_page create a > > - * HPTE if necessary, so there is no need to fall back to reading > > - * the page tables. Since this is called at interrupt level, > > - * do_page_fault() won't treat a DSI as a page fault. > > - */ > > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret) > > +static int read_user_stack_slow(void __user *ptr, void *buf, int nb) > > { > > - if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) || > > - ((unsigned long)ptr & 3)) > > - return -EFAULT; > > - > > - return probe_user_read(ret, ptr, sizeof(*ret)); > > + return 0; > > } > > > > static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry, > > @@ -312,6 +290,28 @@ static inline int valid_user_sp(unsigned long sp, int is_64) > > > > #endif /* CONFIG_PPC64 */ > > > > +/* > > + * On 32-bit we just access the address and let hash_page create a > > + * HPTE if necessary, so there is no need to fall back to reading > > + * the page tables. Since this is called at interrupt level, > > + * do_page_fault() won't treat a DSI as a page fault. > > + */ > > The comment is actually probably better to stay in the 32-bit > read_user_stack_slow implementation. Is that function defined > on 32-bit purely so that you can use IS_ENABLED()? In that case It documents the IS_ENABLED() and that's where it is. The 32bit definition is only a technical detail. > I would prefer to put a BUG() there which makes it self documenting. Which will cause checkpatch complaints about introducing new BUG() which is frowned on. Thanks Michal