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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>
108 lines
2.6 KiB
C
108 lines
2.6 KiB
C
/*
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* Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.
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* Copyright 2010 Tilera Corporation. All Rights Reserved.
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* Copyright 2015 Regents of the University of California, Berkeley
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* See asm-generic/syscall.h for descriptions of what we must do here.
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*/
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#ifndef _ASM_RISCV_SYSCALL_H
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#define _ASM_RISCV_SYSCALL_H
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#include <uapi/linux/audit.h>
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#include <linux/sched.h>
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#include <linux/err.h>
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/* The array of function pointers for syscalls. */
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extern void *sys_call_table[];
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/*
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* Only the low 32 bits of orig_r0 are meaningful, so we return int.
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* This importantly ignores the high bits on 64-bit, so comparisons
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* sign-extend the low 32 bits.
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*/
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static inline int syscall_get_nr(struct task_struct *task,
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struct pt_regs *regs)
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{
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return regs->a7;
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}
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static inline void syscall_set_nr(struct task_struct *task,
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struct pt_regs *regs,
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int sysno)
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{
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regs->a7 = sysno;
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}
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static inline void syscall_rollback(struct task_struct *task,
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struct pt_regs *regs)
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{
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regs->a0 = regs->orig_a0;
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}
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static inline long syscall_get_error(struct task_struct *task,
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struct pt_regs *regs)
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{
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unsigned long error = regs->a0;
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return IS_ERR_VALUE(error) ? error : 0;
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}
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static inline long syscall_get_return_value(struct task_struct *task,
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struct pt_regs *regs)
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{
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return regs->a0;
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}
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static inline void syscall_set_return_value(struct task_struct *task,
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struct pt_regs *regs,
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int error, long val)
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{
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regs->a0 = (long) error ?: val;
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}
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static inline void syscall_get_arguments(struct task_struct *task,
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struct pt_regs *regs,
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unsigned long *args)
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{
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args[0] = regs->orig_a0;
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args++;
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memcpy(args, ®s->a1, 5 * sizeof(args[0]));
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}
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static inline void syscall_set_arguments(struct task_struct *task,
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struct pt_regs *regs,
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unsigned int i, unsigned int n,
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const unsigned long *args)
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{
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BUG_ON(i + n > 6);
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if (i == 0) {
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regs->orig_a0 = args[0];
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args++;
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n--;
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} else {
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i--;
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}
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memcpy(®s->a1 + i, args, n * sizeof(regs->a1));
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}
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static inline int syscall_get_arch(void)
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{
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#ifdef CONFIG_64BIT
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return AUDIT_ARCH_RISCV64;
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#else
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return AUDIT_ARCH_RISCV32;
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#endif
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}
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#endif /* _ASM_RISCV_SYSCALL_H */
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