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>
71 lines
1.5 KiB
C
71 lines
1.5 KiB
C
/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef _ASM_ARC_SYSCALL_H
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#define _ASM_ARC_SYSCALL_H 1
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#include <linux/err.h>
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#include <linux/sched.h>
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#include <asm/unistd.h>
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#include <asm/ptrace.h> /* in_syscall() */
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static inline long
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syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
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{
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if (user_mode(regs) && in_syscall(regs))
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return regs->r8;
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else
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return -1;
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}
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static inline void
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syscall_rollback(struct task_struct *task, struct pt_regs *regs)
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{
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regs->r0 = regs->orig_r0;
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}
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static inline long
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syscall_get_error(struct task_struct *task, struct pt_regs *regs)
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{
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/* 0 if syscall succeeded, otherwise -Errorcode */
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return IS_ERR_VALUE(regs->r0) ? regs->r0 : 0;
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}
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static inline long
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syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
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{
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return regs->r0;
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}
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static inline void
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syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
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int error, long val)
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{
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regs->r0 = (long) error ?: val;
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}
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/*
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* @i: argument index [0,5]
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* @n: number of arguments; n+i must be [1,6].
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*/
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static inline void
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syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
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unsigned long *args)
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{
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unsigned long *inside_ptregs = &(regs->r0);
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unsigned int n = 6;
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unsigned int i = 0;
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while (n--) {
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args[i++] = (*inside_ptregs);
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inside_ptregs--;
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}
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}
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#endif
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