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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 745A4C35641 for ; Sat, 22 Feb 2020 00:42:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4510620722 for ; Sat, 22 Feb 2020 00:42:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727497AbgBVAmA (ORCPT ); Fri, 21 Feb 2020 19:42:00 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:34010 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726697AbgBVAmA (ORCPT ); Fri, 21 Feb 2020 19:42:00 -0500 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j5Irl-00Gerj-Gl; Sat, 22 Feb 2020 00:41:57 +0000 Date: Sat, 22 Feb 2020 00:41:57 +0000 From: Al Viro To: David Miller Cc: torvalds@linux-foundation.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, arnd@arndb.de Subject: Re: [RFC] regset ->get() API Message-ID: <20200222004157.GX23230@ZenIV.linux.org.uk> References: <20200221033016.GV23230@ZenIV.linux.org.uk> <20200221185903.GA3929948@ZenIV.linux.org.uk> <20200221.112244.1426580944977593272.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200221.112244.1426580944977593272.davem@davemloft.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 21, 2020 at 11:22:44AM -0800, David Miller wrote: > From: Al Viro > Date: Fri, 21 Feb 2020 18:59:03 +0000 > > > Again, a couple of copy_regset_to_user(), but there's an additional > > twist - GETREGSET of 32bit task on sparc64 will use access_process_vm() > > when trying to fetch L0..L7/I0..I7 of other task, using copy_from_user() > > only when the target is equal to current. For sparc32 this is not > > true - it's always copy_from_user() there, so the values it reports > > for those registers have nothing to do with the target process. That > > part smells like a bug; by the time GETREGSET had been introduced > > sparc32 was not getting much attention, GETREGS worked just fine > > (not reporting L*/I* anyway) and for coredump it was accessing the > > caller's memory. Not sure if anyone cares at that point... > > That's definitely a bug and sparc64 is doing it correctly. OK... What does the comment in case PTRACE_GETREGS64: ret = copy_regset_to_user(child, view, REGSET_GENERAL, 1 * sizeof(u64), 15 * sizeof(u64), &pregs->u_regs[0]); if (!ret) { /* XXX doesn't handle 'y' register correctly XXX */ ret = copy_regset_to_user(child, view, REGSET_GENERAL, 32 * sizeof(u64), 4 * sizeof(u64), &pregs->tstate); } break; refer to? The fact that you end up with 0 in pregs->y and Y in pregs->magic? In that case it's probably too late to do anything about that... Or is that something different?