From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id E1A981A02F4 for ; Thu, 9 Apr 2015 09:11:35 +1000 (AEST) Message-ID: <1428534695.4682.18.camel@neuling.org> Subject: Re: [V6,1/9] elf: Add new powerpc specifc core note sections From: Michael Neuling To: Ulrich Weigand Date: Thu, 09 Apr 2015 09:11:35 +1000 In-Reply-To: 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> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: shuahkh@osg.samsung.com, james.hogan@imgtec.com, avagin@openvz.org, Paul.Clothier@imgtec.com, peterz@infradead.org, palves@redhat.com, linux-kernel@vger.kernel.org, Edjunior Barbosa Machado , dhowells@redhat.com, linuxppc-dev@ozlabs.org, kirjanov@gmail.com, tglx@linutronix.de, oleg@redhat.com, davej@redhat.com, akpm@linux-foundation.org, sukadev@linux.vnet.ibm.com, davem@davemloft.net, sam.bobroff@au1.ibm.com, Anshuman Khandual List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2015-04-08 at 19:50 +0200, Ulrich Weigand wrote: > Anshuman Khandual wrote on 23.03.2015 > 11:34:30: >=20 > > > 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. >=20 > I'm not sure I understand this. I thought we had the following: >=20 > - 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. >=20 > - 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. >=20 > Is this not correct? I think you're correct. We should be right. I'd forgotten about the GET/SETREGS64 interfaces. Mikey