From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752431AbaENFsM (ORCPT ); Wed, 14 May 2014 01:48:12 -0400 Received: from e23smtp08.au.ibm.com ([202.81.31.141]:48339 "EHLO e23smtp08.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750926AbaENFsJ (ORCPT ); Wed, 14 May 2014 01:48:09 -0400 Message-ID: <53730326.6000400@linux.vnet.ibm.com> Date: Wed, 14 May 2014 11:16:14 +0530 From: Anshuman Khandual User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Pedro Alves CC: linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, michael@ellerman.id.au, mikey@neuling.org, avagin@openvz.org, oleg@redhat.com Subject: Re: [PATCH V2 2/3] powerpc, ptrace: Enable support for transactional memory register sets References: <1399276469-13541-1-git-send-email-khandual@linux.vnet.ibm.com> <1399276469-13541-3-git-send-email-khandual@linux.vnet.ibm.com> <537252C0.6090005@redhat.com> In-Reply-To: <537252C0.6090005@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14051405-5140-0000-0000-0000051D2862 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/13/2014 10:43 PM, Pedro Alves wrote: > On 05/05/14 08:54, Anshuman Khandual wrote: >> This patch enables get and set of transactional memory related register >> sets through PTRACE_GETREGSET/PTRACE_SETREGSET interface by implementing >> four new powerpc specific register sets i.e REGSET_TM_SPR, REGSET_TM_CGPR, >> REGSET_TM_CFPR, REGSET_CVMX support corresponding to these following new >> ELF core note types added previously in this regard. >> >> (1) NT_PPC_TM_SPR >> (2) NT_PPC_TM_CGPR >> (3) NT_PPC_TM_CFPR >> (4) NT_PPC_TM_CVMX > > Sorry that I couldn't tell this from the code, but, what does the > kernel return when the ptracer requests these registers and the > program is not in a transaction? Specifically I'm wondering whether > this follows the same semantics as the s390 port. > Right now, it still returns the saved state of the registers from thread struct. I had assumed that the user must know the state of the transaction before initiating the ptrace request. I guess its better to check for the transaction status before processing the request. In case if TM is not active on that thread, we should return -EINVAL. I am not familiar with the s390 side of code. But if we look at the s390_tdb_get function it checks for (regs->int_code & 0x200) before processing the request. Not sure what 0x200 signifies though.