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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>
113 lines
2.6 KiB
C
113 lines
2.6 KiB
C
/*
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* Copyright (C) 2012 ARM Ltd.
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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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* 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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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __ASM_SYSCALL_H
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#define __ASM_SYSCALL_H
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#include <uapi/linux/audit.h>
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#include <linux/compat.h>
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#include <linux/err.h>
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typedef long (*syscall_fn_t)(struct pt_regs *regs);
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extern const syscall_fn_t sys_call_table[];
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#ifdef CONFIG_COMPAT
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extern const syscall_fn_t compat_sys_call_table[];
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#endif
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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->syscallno;
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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->regs[0] = regs->orig_x0;
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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->regs[0];
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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->regs[0];
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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->regs[0] = (long) error ? error : val;
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}
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#define SYSCALL_MAX_ARGS 6
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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_x0;
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args++;
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memcpy(args, ®s->regs[1], 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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if (n == 0)
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return;
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if (i + n > SYSCALL_MAX_ARGS) {
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pr_warning("%s called with max args %d, handling only %d\n",
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__func__, i + n, SYSCALL_MAX_ARGS);
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n = SYSCALL_MAX_ARGS - i;
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}
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if (i == 0) {
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regs->orig_x0 = args[0];
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args++;
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i++;
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n--;
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}
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memcpy(®s->regs[i], args, n * sizeof(args[0]));
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}
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/*
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* We don't care about endianness (__AUDIT_ARCH_LE bit) here because
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* AArch64 has the same system calls both on little- and big- endian.
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*/
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static inline int syscall_get_arch(void)
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{
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if (is_compat_task())
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return AUDIT_ARCH_ARM;
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return AUDIT_ARCH_AARCH64;
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}
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#endif /* __ASM_SYSCALL_H */
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