From b35f549df1d7520d37ba1e6d4a8d4df6bd52d136 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 7 Nov 2016 16:26:37 -0500 Subject: syscalls: Remove start and number from syscall_get_arguments() args 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 Cc: Kees Cook Cc: Andy Lutomirski Cc: Dominik Brodowski Cc: Dave Martin Cc: "Dmitry V. Levin" 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 # MIPS parts Acked-by: Max Filippov # For xtensa changes Acked-by: Will Deacon # For the arm64 bits Reviewed-by: Thomas Gleixner # for x86 Reviewed-by: Dmitry V. Levin Reported-by: Andy Lutomirski Signed-off-by: Steven Rostedt (VMware) --- include/asm-generic/syscall.h | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) (limited to 'include/asm-generic') diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h index 0c938a4354f6..269e9412ef42 100644 --- a/include/asm-generic/syscall.h +++ b/include/asm-generic/syscall.h @@ -105,21 +105,16 @@ void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs, * syscall_get_arguments - extract system call parameter values * @task: task of interest, must be blocked * @regs: task_pt_regs() of @task - * @i: argument index [0,5] - * @n: number of arguments; n+i must be [1,6]. * @args: array filled with argument values * - * Fetches @n arguments to the system call starting with the @i'th argument - * (from 0 through 5). Argument @i is stored in @args[0], and so on. - * An arch inline version is probably optimal when @i and @n are constants. + * Fetches 6 arguments to the system call. First argument is stored in +* @args[0], and so on. * * It's only valid to call this when @task is stopped for tracing on * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. - * It's invalid to call this with @i + @n > 6; we only support system calls - * taking up to 6 arguments. */ void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs, - unsigned int i, unsigned int n, unsigned long *args); + unsigned long *args); /** * syscall_set_arguments - change system call parameter value -- cgit v1.2.3