From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752786AbeDRSRh (ORCPT ); Wed, 18 Apr 2018 14:17:37 -0400 Received: from isilmar-4.linta.de ([136.243.71.142]:42138 "EHLO isilmar-4.linta.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752707AbeDRSRf (ORCPT ); Wed, 18 Apr 2018 14:17:35 -0400 Date: Wed, 18 Apr 2018 20:17:29 +0200 From: Dominik Brodowski To: Steven Rostedt Cc: LKML , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Arnaldo Carvalho de Melo , x86@kernel.org Subject: Re: [PATCH v3] tracing/x86: Update syscall trace events to handle new prefixed syscall func names Message-ID: <20180418181729.GA4816@light.dominikbrodowski.net> References: <20180418114509.5a76847d@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180418114509.5a76847d@gandalf.local.home> User-Agent: Mutt/1.9.5 (2018-04-13) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 18, 2018 at 11:45:09AM -0400, Steven Rostedt wrote: > From: "Steven Rostedt (VMware)" > > Arnaldo noticed that the latest kernel is missing the syscall event system > directory in x86. I bisected it down to d5a00528b58c ("syscalls/core, > syscalls/x86: Rename struct pt_regs-based sys_*() to __x64_sys_*()"). > > The system call trace events are special, as there is only one trace event > for all system calls (the raw_syscalls). But a macro that wraps the system > calls creates meta data for them that copies the name to find the system > call that maps to the system call table (the number). At boot up, it does a > kallsyms lookup of the system call table to find the function that maps to > the meta data of the system call. If it does not find a function, then that > system call is ignored. > > Because the x86 system calls had "__x64_", or "__ia32_" prefixed to the > "sys" for the names, they do not match the default compare algorithm. As > this was a problem for power pc, the algorithm can be overwritten by the > architecture. The solution is to have x86 have its own algorithm to do the > compare and this brings back the system call trace events. > > Link: http://lkml.kernel.org/r/20180417174128.0f3457f0@gandalf.local.home > > Reported-by: Arnaldo Carvalho de Melo > Tested-by: Arnaldo Carvalho de Melo > Fixes: d5a00528b58c ("syscalls/core, syscalls/x86: Rename struct pt_regs-based sys_*() to __x64_sys_*()") > Signed-off-by: Steven Rostedt (VMware) Acked-by: Dominik Brodowski