• Steven Rostedt (Red Hat)'s avatar
    syscalls: Remove start and number from syscall_get_arguments() args · b35f549d
    Steven Rostedt (Red Hat) authored
    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: default avatarDmitry V. Levin <ldv@altlinux.org>
    Reported-by: default avatarAndy Lutomirski <luto@amacapital.net>
    Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
    b35f549d
syscall.h 1.24 KB