Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754774AbbDHRvP (ORCPT ); Wed, 8 Apr 2015 13:51:15 -0400 Received: from e06smtp13.uk.ibm.com ([195.75.94.109]:43237 "EHLO e06smtp13.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753496AbbDHRvN (ORCPT ); Wed, 8 Apr 2015 13:51:13 -0400 In-Reply-To: <550FEC36.8080803@linux.vnet.ibm.com> References: <20141203052204.9DA8F1400DD@ozlabs.org> <547EB253.5050307@linux.vnet.ibm.com> <548578A8.5020901@linux.vnet.ibm.com> <54947C64.4030206@linux.vnet.ibm.com> <54A50094.5070902@linux.vnet.ibm.com> <1421883597.30744.3.camel@neuling.org> <1421963049.30744.23.camel@neuling.org> <1422419289.9646.20.camel@neuling.org> <1424667110.16027.6.camel@neuling.org> <1426718702.4866.2.camel@neuling.org> <1426719027.4866.4.camel@neuling.org> <550FEC36.8080803@linux.vnet.ibm.com> Subject: Re: [V6,1/9] elf: Add new powerpc specifc core note sections X-KeepSent: 91038A37:65C405E5-C1257E21:0061938F; type=4; name=$KeepSent To: Anshuman Khandual Cc: akpm@linux-foundation.org, avagin@openvz.org, davej@redhat.com, davem@davemloft.net, dhowells@redhat.com, Edjunior Barbosa Machado , james.hogan@imgtec.com, kirjanov@gmail.com, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Michael Neuling , oleg@redhat.com, palves@redhat.com, Paul.Clothier@imgtec.com, peterz@infradead.org, sam.bobroff@au1.ibm.com, shuahkh@osg.samsung.com, sukadev@linux.vnet.ibm.com, tglx@linutronix.de X-Mailer: IBM Notes Release 9.0.1FP2 August 03, 2014 Message-ID: From: Ulrich Weigand Date: Wed, 8 Apr 2015 19:50:50 +0200 X-MIMETrack: Serialize by Router on D06ML032/06/M/IBM(Release 9.0.1FP3|January 12, 2015) at 08/04/2015 19:51:05 MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15040817-0013-0000-0000-000003944ECE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1611 Lines: 38 Anshuman Khandual wrote on 23.03.2015 11:34:30: > > With that in mind, do we have a way to set the top 32bits of the MSR > > (which contain the TM bits) when ptracing 32 bit processes? I can't > > find anything like that in this patch set. > > No, we dont have that yet. When ptracing in 32-bit mode the MSR value > which can be viewed or set from the user space through PTRACE_GETREGS > PTRACE_SETREGS call is it's lower 32 bits only. Either we can club > the upper 32 bits of MSR as part of one of the ELF core notes we are > adding in the patch series or we can create one more separate ELF core > note for that purpose. Let me know your opinion on this. I'm not sure I understand this. I thought we had the following: - If the process calling ptrace is itself 64-bit (which is how GDB is built on all current Linux distributions), then PTRACE_GETREGS etc. will *always* operate on 64-bit register sets, even if the target process is 32-bit. - If the process calling ptrace is 32-bit, then PTRACE_GETREGS will operate on 32-bit register sets. However, there is a separate PTRACE_GETREGS64 / PTRACE_SETREGS64 call that will also provide the opportunity to operate on the full 64-bit register set. Both apply independently of whether the target process is 32-bit or 64-bit. Is this not correct? Bye, Ulrich -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/