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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>
109 lines
2.7 KiB
C
109 lines
2.7 KiB
C
/*
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* Access to user system call parameters and results
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*
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* Copyright (C) 2008 Red Hat, Inc. All rights reserved.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU General Public License v.2.
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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_SYSCALL_H
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#define _ASM_SYSCALL_H 1
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#include <uapi/linux/audit.h>
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#include <linux/sched.h>
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#include <linux/thread_info.h>
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/* ftrace syscalls requires exporting the sys_call_table */
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extern const unsigned long sys_call_table[];
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extern const unsigned long compat_sys_call_table[];
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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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/*
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* Note that we are returning an int here. That means 0xffffffff, ie.
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* 32-bit negative 1, will be interpreted as -1 on a 64-bit kernel.
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* This is important for seccomp so that compat tasks can set r0 = -1
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* to reject the syscall.
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*/
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return TRAP(regs) == 0xc00 ? regs->gpr[0] : -1;
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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->gpr[3] = regs->orig_gpr3;
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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->gpr[3];
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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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/*
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* In the general case it's not obvious that we must deal with CCR
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* here, as the syscall exit path will also do that for us. However
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* there are some places, eg. the signal code, which check ccr to
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* decide if the value in r3 is actually an error.
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*/
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if (error) {
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regs->ccr |= 0x10000000L;
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regs->gpr[3] = error;
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} else {
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regs->ccr &= ~0x10000000L;
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regs->gpr[3] = val;
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}
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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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unsigned long val, mask = -1UL;
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unsigned int n = 6;
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#ifdef CONFIG_COMPAT
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if (test_tsk_thread_flag(task, TIF_32BIT))
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mask = 0xffffffff;
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#endif
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while (n--) {
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if (n == 0)
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val = regs->orig_gpr3;
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else
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val = regs->gpr[3 + n];
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args[n] = val & mask;
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}
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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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memcpy(®s->gpr[3 + i], args, n * sizeof(args[0]));
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/* Also copy the first argument into orig_gpr3 */
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if (i == 0 && n > 0)
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regs->orig_gpr3 = args[0];
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}
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static inline int syscall_get_arch(void)
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{
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int arch = is_32bit_task() ? AUDIT_ARCH_PPC : AUDIT_ARCH_PPC64;
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#ifdef __LITTLE_ENDIAN__
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arch |= __AUDIT_ARCH_LE;
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#endif
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return arch;
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}
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#endif /* _ASM_SYSCALL_H */
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