b35f549df1
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. Link: http://lkml.kernel.org/r/20161107213233.754809394@goodmis.org Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <keescook@chromium.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Dominik Brodowski <linux@dominikbrodowski.net> Cc: Dave Martin <dave.martin@arm.com> Cc: "Dmitry V. Levin" <ldv@altlinux.org> Cc: x86@kernel.org Cc: linux-snps-arc@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-c6x-dev@linux-c6x.org Cc: uclinux-h8-devel@lists.sourceforge.jp Cc: linux-hexagon@vger.kernel.org Cc: linux-ia64@vger.kernel.org Cc: linux-mips@vger.kernel.org Cc: nios2-dev@lists.rocketboards.org Cc: openrisc@lists.librecores.org Cc: linux-parisc@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-riscv@lists.infradead.org Cc: linux-s390@vger.kernel.org Cc: linux-sh@vger.kernel.org Cc: sparclinux@vger.kernel.org Cc: linux-um@lists.infradead.org Cc: linux-xtensa@linux-xtensa.org Cc: linux-arch@vger.kernel.org Acked-by: Paul Burton <paul.burton@mips.com> # MIPS parts Acked-by: Max Filippov <jcmvbkbc@gmail.com> # For xtensa changes Acked-by: Will Deacon <will.deacon@arm.com> # For the arm64 bits Reviewed-by: Thomas Gleixner <tglx@linutronix.de> # for x86 Reviewed-by: Dmitry V. Levin <ldv@altlinux.org> Reported-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> |
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