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Rao" Subject: Re: [PATCH v2 11/16] objtool: Add --mnop as an option to --mcount To: Peter Zijlstra , Sathvika Vasireddy References: <20220829055223.24767-1-sv@linux.ibm.com> <20220829055223.24767-12-sv@linux.ibm.com> In-Reply-To: MIME-Version: 1.0 User-Agent: astroid/4d6b06ad (https://github.com/astroidmail/astroid) Message-Id: <1662374882.xll36f5qp9.naveen@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: -ivhpHtwgOuKksI_EqLA-PE6EGqb9quV X-Proofpoint-GUID: hQxC3vMDz6wa3zeQUJbX6AAjXuYDmZCb X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-09-05_07,2022-09-05_02,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 mlxlogscore=920 adultscore=0 clxscore=1015 mlxscore=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 spamscore=0 priorityscore=1501 bulkscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2207270000 definitions=main-2209050051 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: aik@ozlabs.ru, chenzhongjin@huawei.com, npiggin@gmail.com, linux-kernel@vger.kernel.org, mingo@redhat.com, rostedt@goodmis.org, jpoimboe@redhat.com, mbenes@suse.cz, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Peter Zijlstra wrote: > On Mon, Aug 29, 2022 at 11:22:18AM +0530, Sathvika Vasireddy wrote: >> Architectures can select HAVE_NOP_MCOUNT if they choose >> to nop out mcount call sites. If that config option is >> selected, then --mnop is passed as an option to objtool, >> along with --mcount. >>=20 >> Also, make sure that --mnop can be passed as an option >> to objtool only when --mcount is passed. >>=20 >> Signed-off-by: Sathvika Vasireddy >=20 > IIRC you want to nop the things yourself because PLT entries or > something? For two reasons: 1. We want to maintain a pointer to 'struct module' as part of the=20 ftrace rec so that we can patch ftrace sites in modules to go to module=20 stubs. 2. We depend on compiler generated long branches to support large=20 kernels. >=20 > Anyway, patch looks fine, even though the Changelog doesn't relaly > justify the change. Sure. We should add that powerpc kernel does not support nop'ed out=20 ftrace locations. >=20 > Acked-by: Peter Zijlstra (Intel) >=20 Thanks, Naveen