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received-spf: None (protection.outlook.com: arm.com does not designate permitted sender hosts) x-microsoft-antispam-message-info: UbMSHXHZohc2rcQ3SIlUtEVNamZtoOmvC2vYqQNDWI7sDS1R9NLAhLX33yur57qov0xCWILfWl0zJiyWhOHAQXI2KEdg0U+st5EmpnifKgrkfreg92AG2cVkEBRp+fz6XXa/1lhEiN2Ajtbx3pTHTEI5A/YwlnFubH0dUrfPWf4p/okV/dMAmXCUVxVFkQb0UB5Vt/xEAsDpmBdIwO+O0RN0UPRQ0PhOzuu6Up0/tNk6h86RIVzq3De0NvC1s/oK5q8XA2iNaJwvuOGNjXSKKewJv3PdDMYSZ2c8X8P54Hbc3RqshSDjUDdhH1buurVGaCDw6ZqZg+sFPP2TDO5UaRUbXYmDSVlRQZlOGzASpEU= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-Network-Message-Id: 262c1159-abeb-43d7-0455-08d640cd3908 X-MS-Exchange-CrossTenant-originalarrivaltime: 02 Nov 2018 14:12:28.7673 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM6PR08MB2998 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > root@debian:~/coresight_test# perf buildid-list > 0242d9154c78df1d8fe1d0512c36a236d0861a18 [kernel.kallsyms] > b8c89e8ba41a2ea486c66a50c29c60d38c34a759 /root/coresight_test/main > 26b12a9d1a54ed2b0478cb0203435b76aabab3fb /usr/lib/aarch64-linux-gnu/ld- > 2.27.so > 8fca7ed524c9469b065af83bc8a529fe72858f53 [vdso] > 25829a59e21012cfde7850b30a310cd3a58f531c > /root/coresight_test/libcstest.so > 70512527439ef76c8802a7a2a546bde6a5a6e967 /usr/lib/aarch64-linux- > gnu/libc-2.27.so > root@debian:~/coresight_test# ls > ~/.debug/\[kernel.kallsyms\]/0242d9154c78df1d8fe1d0512c36a236d0861a18/ > kallsyms What's in that last file? I've seen it happen that the copy of kallsyms in ~/.debug has the symbol addresses as zeroes - possibly because it was created when you didn't have permissions. That's really a bug in perf, as cacheing a copy of this file with the addresses zeroed out is kind of pointless. Again, this happens on Intel too. Then, you can give yourself permissions - but perf's already cached the file and won't update it! If you delete it, and then rerun perf record (either as sudo or now that you've got kptr_restrict=3D0) you should see it reappear, with correct kernel addresses. Perhaps nobody spotted this on Intel because perf report goes directly to /proc/kallsyms. But it would be an issue if you ran a perf report on a perf.data from an older kernel and it had to go to ~/.debug. At that point the fact that ~/.debug/[kernel.kallsyms] had zeroes would mean you couldn't symbolicate any addresses. Al > > > Does it all work if you run perf record as sudo? Or if you do > > > > sudo sysctl kernel.kptr_restrict=3D0 > > > > before you run perf record? > > Yes, tested this on Juno board with Debian rootFS and logined in with 'ro= ot' user. > I suspected the pointer permission issue so checked with below command: > > root@debian:~/coresight_test# cat /proc/sys/kernel/kptr_restrict > 0 > > Thanks, > Leo Yan IMPORTANT NOTICE: The contents of this email and any attachments are confid= ential and may also be privileged. If you are not the intended recipient, p= lease notify the sender immediately and do not disclose the contents to any= other person, use it for any purpose, or store or copy the information in = any medium. Thank you.