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Date: Thu, 09 Apr 2015 09:11:35 +1000 From: Michael Neuling <mikey@...ling.org> To: Ulrich Weigand <Ulrich.Weigand@...ibm.com> Cc: Anshuman Khandual <khandual@...ux.vnet.ibm.com>, akpm@...ux-foundation.org, avagin@...nvz.org, davej@...hat.com, davem@...emloft.net, dhowells@...hat.com, Edjunior Barbosa Machado <emachado@...ux.vnet.ibm.com>, james.hogan@...tec.com, kirjanov@...il.com, linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org, oleg@...hat.com, palves@...hat.com, Paul.Clothier@...tec.com, peterz@...radead.org, sam.bobroff@....ibm.com, shuahkh@....samsung.com, sukadev@...ux.vnet.ibm.com, tglx@...utronix.de Subject: Re: [V6,1/9] elf: Add new powerpc specifc core note sections On Wed, 2015-04-08 at 19:50 +0200, Ulrich Weigand wrote: > Anshuman Khandual <khandual@...ux.vnet.ibm.com> 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? I think you're correct. We should be right. I'd forgotten about the GET/SETREGS64 interfaces. Mikey -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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