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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>
112 lines
2.4 KiB
C
112 lines
2.4 KiB
C
/*
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* Access to user system call parameters and results
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*
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* See asm-generic/syscall.h for function descriptions.
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*
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* Copyright (C) 2015 Mickaël Salaün <mic@digikod.net>
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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 __UM_SYSCALL_GENERIC_H
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#define __UM_SYSCALL_GENERIC_H
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#include <asm/ptrace.h>
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#include <linux/err.h>
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#include <linux/sched.h>
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#include <sysdep/ptrace.h>
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static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
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{
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return PT_REGS_SYSCALL_NR(regs);
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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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/* do nothing */
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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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const long error = regs_return_value(regs);
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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_return_value(regs);
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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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PT_REGS_SET_SYSCALL_RETURN(regs, (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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const struct uml_pt_regs *r = ®s->regs;
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*args++ = UPT_SYSCALL_ARG1(r);
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*args++ = UPT_SYSCALL_ARG2(r);
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*args++ = UPT_SYSCALL_ARG3(r);
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*args++ = UPT_SYSCALL_ARG4(r);
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*args++ = UPT_SYSCALL_ARG5(r);
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*args = UPT_SYSCALL_ARG6(r);
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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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struct uml_pt_regs *r = ®s->regs;
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switch (i) {
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case 0:
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if (!n--)
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break;
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UPT_SYSCALL_ARG1(r) = *args++;
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case 1:
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if (!n--)
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break;
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UPT_SYSCALL_ARG2(r) = *args++;
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case 2:
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if (!n--)
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break;
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UPT_SYSCALL_ARG3(r) = *args++;
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case 3:
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if (!n--)
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break;
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UPT_SYSCALL_ARG4(r) = *args++;
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case 4:
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if (!n--)
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break;
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UPT_SYSCALL_ARG5(r) = *args++;
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case 5:
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if (!n--)
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break;
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UPT_SYSCALL_ARG6(r) = *args++;
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case 6:
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if (!n--)
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break;
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default:
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BUG();
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break;
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}
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}
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/* See arch/x86/um/asm/syscall.h for syscall_get_arch() definition. */
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#endif /* __UM_SYSCALL_GENERIC_H */
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