From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752963AbdKIAGz (ORCPT ); Wed, 8 Nov 2017 19:06:55 -0500 Received: from shards.monkeyblade.net ([184.105.139.130]:52984 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751168AbdKIAGy (ORCPT ); Wed, 8 Nov 2017 19:06:54 -0500 Date: Thu, 09 Nov 2017 09:06:47 +0900 (KST) Message-Id: <20171109.090647.824552877953564084.davem@davemloft.net> To: yhs@fb.com Cc: mingo@kernel.org, tglx@linutronix.de, oleg@redhat.com, peterz@infradead.org, linux-kernel@vger.kernel.org, x86@kernel.org, netdev@vger.kernel.org, ast@fb.com, kernel-team@fb.com Subject: Re: [PATCH x86/urgent] bpf: emulate push insns for uprobe on x86 From: David Miller In-Reply-To: <20171108213712.1232793-1-yhs@fb.com> References: <20171108213712.1232793-1-yhs@fb.com> X-Mailer: Mew version 6.7 on Emacs 25.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Wed, 08 Nov 2017 16:06:53 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yonghong Song Date: Wed, 8 Nov 2017 13:37:12 -0800 > Uprobe is a tracing mechanism for userspace programs. > Typical uprobe will incur overhead of two traps. > First trap is caused by replaced trap insn, and > the second trap is to execute the original displaced > insn in user space. ... I don't understand how this is bpf related, and if it is you don't explain it well in the commit message. Thank you.