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) --- arch/s390/include/asm/syscall.h | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-) (limited to 'arch/s390') diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h index 96f9a9151fde..ee0b1f6aa36d 100644 --- a/arch/s390/include/asm/syscall.h +++ b/arch/s390/include/asm/syscall.h @@ -56,27 +56,20 @@ static inline void syscall_set_return_value(struct task_struct *task, static inline void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs, - unsigned int i, unsigned int n, unsigned long *args) { unsigned long mask = -1UL; + unsigned int n = 6; - /* - * No arguments for this syscall, there's nothing to do. - */ - if (!n) - return; - - BUG_ON(i + n > 6); #ifdef CONFIG_COMPAT if (test_tsk_thread_flag(task, TIF_31BIT)) mask = 0xffffffff; #endif while (n-- > 0) - if (i + n > 0) - args[n] = regs->gprs[2 + i + n] & mask; - if (i == 0) - args[0] = regs->orig_gpr2 & mask; + if (n > 0) + args[n] = regs->gprs[2 + n] & mask; + + args[0] = regs->orig_gpr2 & mask; } static inline void syscall_set_arguments(struct task_struct *task, -- cgit v1.2.3