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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>
97 lines
2.3 KiB
C
97 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Access to user system call parameters and results
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*
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* Copyright IBM Corp. 2008
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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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/err.h>
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#include <asm/ptrace.h>
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/*
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* The syscall table always contains 32 bit pointers since we know that the
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* address of the function to be called is (way) below 4GB. So the "int"
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* type here is what we want [need] for both 32 bit and 64 bit systems.
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*/
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extern const unsigned int sys_call_table[];
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extern const unsigned int sys_call_table_emu[];
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static inline long syscall_get_nr(struct task_struct *task,
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struct pt_regs *regs)
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{
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return test_pt_regs_flag(regs, PIF_SYSCALL) ?
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(regs->int_code & 0xffff) : -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->gprs[2] = regs->orig_gpr2;
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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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return IS_ERR_VALUE(regs->gprs[2]) ? regs->gprs[2] : 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->gprs[2];
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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->gprs[2] = error ? 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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unsigned long 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_31BIT))
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mask = 0xffffffff;
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#endif
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while (n-- > 0)
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if (n > 0)
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args[n] = regs->gprs[2 + n] & mask;
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args[0] = regs->orig_gpr2 & mask;
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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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while (n-- > 0)
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if (i + n > 0)
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regs->gprs[2 + i + n] = args[n];
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if (i == 0)
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regs->orig_gpr2 = 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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#ifdef CONFIG_COMPAT
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if (test_tsk_thread_flag(current, TIF_31BIT))
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return AUDIT_ARCH_S390;
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#endif
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return AUDIT_ARCH_S390X;
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}
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#endif /* _ASM_SYSCALL_H */
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