From mboxrd@z Thu Jan 1 00:00:00 1970 From: Max Filippov Date: Thu, 04 Apr 2019 18:56:23 +0000 Subject: Re: [PATCH 5/6 v3] syscalls: Remove start and number from syscall_get_arguments() args Message-Id: List-Id: References: <20190401134104.676620247@goodmis.org> <20190401134421.278590567@goodmis.org> In-Reply-To: <20190401134421.278590567@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Steven Rostedt Cc: LKML , Linus Torvalds , Ingo Molnar , Andrew Morton , Andy Lutomirski , Roland McGrath , Oleg Nesterov , Linux-Arch , Peter Zijlstra , Thomas Gleixner , "Gustavo A. R. Silva" , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , "maintainer:X86 ARCHITECTURE..." , Dominik Brodowski , Andy Lutomirski , Kees Cook , "Eric W. Biederman" , Dm On Mon, Apr 1, 2019 at 6:45 AM Steven Rostedt wrote: > > From: "Steven Rostedt (Red Hat)" > > At Linux Plumbers, Andy Lutomirski approached me and pointed out that the > function call syscall_get_arguments() implemented in x86 was horribly > written and not optimized for the standard case of passing in 0 and 6 for > the starting index and the number of system calls to get. When looking at > all the users of this function, I discovered that all instances pass in only > 0 and 6 for these arguments. Instead of having this function handle > different cases that are never used, simply rewrite it to return the first 6 > arguments of a system call. > > This should help out the performance of tracing system calls by ptrace, > ftrace and perf. [...] > arch/xtensa/include/asm/syscall.h | 16 ++---- For xtensa changes: Acked-by: Max Filippov -- Thanks. -- Max