From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v2 23/31] arm64: Debugging support Date: Thu, 16 Aug 2012 12:49:34 +0000 Message-ID: <201208161249.35008.arnd@arndb.de> References: <1344966752-16102-1-git-send-email-catalin.marinas@arm.com> <201208151507.36174.arnd@arndb.de> <20120816104748.GI31784@mudshark.cambridge.arm.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from moutng.kundenserver.de ([212.227.17.9]:56431 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754872Ab2HPMtn (ORCPT ); Thu, 16 Aug 2012 08:49:43 -0400 In-Reply-To: <20120816104748.GI31784@mudshark.cambridge.arm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Will Deacon Cc: Catalin Marinas , "linux-arch@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , ulrich.weigand@linaro.rg On Thursday 16 August 2012, Will Deacon wrote: > On Wed, Aug 15, 2012 at 04:07:36PM +0100, Arnd Bergmann wrote: > > On Tuesday 14 August 2012, Catalin Marinas wrote: > > From what I can tell, there is no support for 32 bit processes debugging > > 64 bit ones. Is that something you plan to add in the future, or do you > > consider that out of scope? In either case, a comment would be helpful. > > That can't really work because the debugger won't be able to manipulate > child pointers properly without us adding a new ptrace interface (and then, > I still wonder about how feasible it really is). I can add a comment. You can already have a 32 bit gdb that is able to do remote debugging of 64 bit processes using a gdb server process. I guess it wouldn't be too strange to have a ptrace extension to allow the native case as well. I agree it's not a high priority. > > > +long arch_ptrace(struct task_struct *child, long request, > > > + unsigned long addr, unsigned long data) > > > +{ > > > + int ret; > > > + unsigned long *datap = (unsigned long __user *)data; > > > + > > > + switch (request) { > > > + case PTRACE_GET_THREAD_AREA: > > > + ret = put_user(child->thread.tp_value, datap); > > > + break; > > > + > > > +#ifdef CONFIG_HAVE_HW_BREAKPOINT > > > + case PTRACE_GETHBPREGS: > > > + ret = ptrace_gethbpregs(child, addr, datap); > > > + break; > > > + > > > + case PTRACE_SETHBPREGS: > > > + ret = ptrace_sethbpregs(child, addr, datap); > > > + break; > > > +#endif > > > + > > > + default: > > > + ret = ptrace_request(child, request, addr, data); > > > + break; > > > + } > > > + > > > + return ret; > > > +} > > > > Is there a reaons why these are not regsets but have their own ptrace > > commands? I believe new architectures should generally not add ptrace > > commands any more. > > I could probably add some regset wrappers about the hbp accessors (which we > have to keep for the compat ptrace interface). I'll have a think as it might > even make sense to have different regsets for breakpoints and watchpoints. > > As for the the tls, is it worth having a regset with only one register? Better ask the gdb folks. I'm adding Uli to Cc, maybe he has some insight. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Thu, 16 Aug 2012 12:49:34 +0000 Subject: [PATCH v2 23/31] arm64: Debugging support In-Reply-To: <20120816104748.GI31784@mudshark.cambridge.arm.com> References: <1344966752-16102-1-git-send-email-catalin.marinas@arm.com> <201208151507.36174.arnd@arndb.de> <20120816104748.GI31784@mudshark.cambridge.arm.com> Message-ID: <201208161249.35008.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thursday 16 August 2012, Will Deacon wrote: > On Wed, Aug 15, 2012 at 04:07:36PM +0100, Arnd Bergmann wrote: > > On Tuesday 14 August 2012, Catalin Marinas wrote: > > From what I can tell, there is no support for 32 bit processes debugging > > 64 bit ones. Is that something you plan to add in the future, or do you > > consider that out of scope? In either case, a comment would be helpful. > > That can't really work because the debugger won't be able to manipulate > child pointers properly without us adding a new ptrace interface (and then, > I still wonder about how feasible it really is). I can add a comment. You can already have a 32 bit gdb that is able to do remote debugging of 64 bit processes using a gdb server process. I guess it wouldn't be too strange to have a ptrace extension to allow the native case as well. I agree it's not a high priority. > > > +long arch_ptrace(struct task_struct *child, long request, > > > + unsigned long addr, unsigned long data) > > > +{ > > > + int ret; > > > + unsigned long *datap = (unsigned long __user *)data; > > > + > > > + switch (request) { > > > + case PTRACE_GET_THREAD_AREA: > > > + ret = put_user(child->thread.tp_value, datap); > > > + break; > > > + > > > +#ifdef CONFIG_HAVE_HW_BREAKPOINT > > > + case PTRACE_GETHBPREGS: > > > + ret = ptrace_gethbpregs(child, addr, datap); > > > + break; > > > + > > > + case PTRACE_SETHBPREGS: > > > + ret = ptrace_sethbpregs(child, addr, datap); > > > + break; > > > +#endif > > > + > > > + default: > > > + ret = ptrace_request(child, request, addr, data); > > > + break; > > > + } > > > + > > > + return ret; > > > +} > > > > Is there a reaons why these are not regsets but have their own ptrace > > commands? I believe new architectures should generally not add ptrace > > commands any more. > > I could probably add some regset wrappers about the hbp accessors (which we > have to keep for the compat ptrace interface). I'll have a think as it might > even make sense to have different regsets for breakpoints and watchpoints. > > As for the the tls, is it worth having a regset with only one register? Better ask the gdb folks. I'm adding Uli to Cc, maybe he has some insight. Arnd