From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 119174 invoked by alias); 24 Feb 2016 18:20:06 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 119158 invoked by uid 89); 24 Feb 2016 18:20:05 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=coupling, solely X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Wed, 24 Feb 2016 18:20:01 +0000 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (Postfix) with ESMTPS id 66B22C057EC2; Wed, 24 Feb 2016 18:20:00 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u1OIJxHs021461; Wed, 24 Feb 2016 13:19:59 -0500 Message-ID: <56CDF44E.5050204@redhat.com> Date: Wed, 24 Feb 2016 18:20:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Antoine Tremblay CC: gdb-patches@sourceware.org, qiyaoltc@gmail.com Subject: Re: [PATCH v3] Enable tracing of pseudo-registers on ARM References: <1455910116-13237-1-git-send-email-antoine.tremblay@ericsson.com> <56C7796B.3030504@redhat.com> In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2016-02/txt/msg00741.txt.bz2 On 02/23/2016 07:34 PM, Antoine Tremblay wrote: > > Pedro Alves writes: > >>> + >>> + return double_regnum; >>> +} >>> + >>> +/* Implementation of the ax_pseudo_register_collect gdbarch function. */ >>> + >>> +static int >>> +arm_ax_pseudo_register_collect (struct gdbarch *gdbarch, >>> + struct agent_expr *ax, int reg) >>> +{ >>> + int rawnum = arm_pseudo_register_to_register (gdbarch, reg); >>> + >>> + /* Error. */ >>> + if (rawnum < 0) >>> + return 1; >>> + >>> + ax_reg_mask (ax, rawnum); >> >> Hmm, seems to me that gdb raw -> target raw mapping should be >> either here, or perhaps even in ax_reg / ax_reg_mask? >> > > After more investigation, this can't be in ax_reg / ax_reg_mask for > pseudo registers as this function is solely reponsible to encode the > right number here. I don't follow. ax_reg / ax_reg_mask today obviously work with gdb numbers: /* Add register REG to the register mask for expression AX. */ void ax_reg_mask (struct agent_expr *ax, int reg) { if (reg >= gdbarch_num_regs (ax->gdbarch)) { /* This is a pseudo-register. */ if (!gdbarch_ax_pseudo_register_collect_p (ax->gdbarch)) error (_("'%s' is a pseudo-register; " "GDB cannot yet trace its contents."), user_reg_map_regnum_to_name (ax->gdbarch, reg)); if (gdbarch_ax_pseudo_register_collect (ax->gdbarch, ax, reg)) error (_("Trace '%s' failed."), user_reg_map_regnum_to_name (ax->gdbarch, reg)); } else ... This is comparing gdb-side num_regs, and calling gdbarch_ax_pseudo_register_collect, whose implementations expect gdb register numbers. And it calls user_reg_map_regnum_to_name, which works with gdb register numbers. Etc. So it seems to me that we need to make ax_reg and ax_reg_mask convert gdb -> remote numbers in their else branches. > >> Consider the case of an expression requiring the collection of >> a _raw_ register, thus not even reaching here. Looking at >> ax-gdb.c/ax-general.c I don't see where is anything mapping gdb raw numbers >> to remote/tdesc numbers? So how does _that_ work? Are the register masks that gdb >> is computing actually wrong for the target, and things just happen >> to work because gdbserver ignores them and always collects all registers? > > However yes it should be in ax_reg/ax_reg_mask for non-pseudo registers, > but this is not the objective of this patch, I suggest that such a > change be the subject of another patch Sure, but in that case, drop the gdb -> remote conversion entirely. If with that things don't work for arm, let's fix ax_reg/ax_reg_mask _first_. > maybe coupled with better gdbserver handling of the R action. I think this coupling would be a mistake. This can be handled independently, if at all. > > I will send a v5 with the ax_pseudo_register_collect inside the > arm_ax_pseudo_register_collect/arm_ax_pseudo_register_push stack function. Thanks, Pedro Alves