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To: Michael Ellerman , Paul Murphy , pmenzel@molgen.mpg.de References: <3661999754da1a5e5c810fa669654cc7db95b059.camel@kernel.crashing.org> <4f037af0-5066-ebb9-53a6-733b3bd8eeac@molgen.mpg.de> <878s1q1udj.fsf@mpe.ellerman.id.au> <87czqwl67h.fsf@mpe.ellerman.id.au> From: Lynn Boger Message-ID: <4c031287-9632-c77b-e5d6-222ca761fab6@linux.vnet.ibm.com> Date: Mon, 2 Aug 2021 13:14:15 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <87czqwl67h.fsf@mpe.ellerman.id.au> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: szjwlszLeoG2xfb-8pMHWwVkruHoACZW X-Proofpoint-GUID: IZOuJOLNQGrU95TB3mcGTsXX_7TEu5Ov X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.790 definitions=2021-08-02_07:2021-08-02, 2021-08-02 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 mlxlogscore=999 lowpriorityscore=0 clxscore=1011 priorityscore=1501 mlxscore=0 malwarescore=0 phishscore=0 bulkscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108020117 X-Mailman-Approved-At: Tue, 03 Aug 2021 09:38:00 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: parkerderek86@gmail.com, xaionaro@gmail.com, paulus@samba.org, murphyp@linux.ibm.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Fixes will be in Go 1.16.7 and 1.15.15. Backports are no longer being done for Go 1.14. On 8/2/21 1:18 AM, Michael Ellerman wrote: > "Paul Murphy" writes: >> >> (My apologies for however IBM's email client munges this) >> >>> I heard it is going to be in Go 1.16.7, but I do not know much about Go. >>> Maybe the folks in Cc can chime in. >> >> >> We have backports primed and ready for the next point release. They >> are waiting on the release manager to cherrypick them. > OK good, that is still the correct fix in the long run. > >> I think we were aware that our VDSO usage may have exploited some >> peculiarities in how the ppc64 version was constructed (i.e hand >> written assembly which just didn't happen to clobber R30). > Yeah I was "somewhat surprised" that Go thought it could use r30 like > that across a VDSO call :D > > But to be fair the ABI of the VDSO has always been a little fishy, > because the entry points pretend to be a transparent wrapper around > system calls, but then in a case like this are not. > >> Go up to this point has only used the vdso function __kernel_clock_gettime; it >> is the only entry point which would need to explicitly avoid R30 for >> Go's sake. > I thought about limiting the workaround to just that code, but it seemed > silly and likely to come back to bite us. Once the compilers decides to > spill a non-volatile there are plenty of other ones to choose from. > > cheers