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dkim=none (message not signed) header.d=none;vger.kernel.org; dmarc=none action=none header.from=windriver.com; Received: from BY5PR11MB4241.namprd11.prod.outlook.com (2603:10b6:a03:1ca::13) by BY5PR11MB4103.namprd11.prod.outlook.com (2603:10b6:a03:18c::29) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4195.21; Wed, 2 Jun 2021 11:26:13 +0000 Received: from BY5PR11MB4241.namprd11.prod.outlook.com ([fe80::34b3:17c2:b1ad:286c]) by BY5PR11MB4241.namprd11.prod.outlook.com ([fe80::34b3:17c2:b1ad:286c%5]) with mapi id 15.20.4173.030; Wed, 2 Jun 2021 11:26:13 +0000 Subject: Re: [PATCH 1/1] bpf: avoid unnecessary IPI in bpf_flush_icache To: Will Deacon , Daniel Borkmann Cc: ast@kernel.org, zlim.lnx@gmail.com, catalin.marinas@arm.com, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20210601150625.37419-1-yanfei.xu@windriver.com> <20210601150625.37419-2-yanfei.xu@windriver.com> <56cc1e25-25c3-a3da-64e3-8a1c539d685b@iogearbox.net> <20210601174114.GA29130@willie-the-truck> From: "Xu, Yanfei" Message-ID: <7637dcdf-12b4-2861-3c76-f8a8e240a05e@windriver.com> Date: Wed, 2 Jun 2021 19:26:03 +0800 User-Agent: Mozilla/5.0 (X11; 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You need to show how the executing thread ends up going through a > context synchronizing operation before jumping to the generated code if > the IPI here is removed. This patch came out with I looked through ftrace codes. Ftrace modify the text code and don't send IPI in aarch64_insn_patch_text_nosync(). I mistakenly thought the bpf is same with ftrace. But now I'm still not sure why the ftrace don't need the IPI to go through context synchronizing, maybe the worst situation is omit a tracing event? Thanks, Yanfei > > Will >