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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>
162 lines
3.6 KiB
C
162 lines
3.6 KiB
C
/*
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* Access to user system call parameters and results
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* 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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* Copyright (C) 2012 Ralf Baechle <ralf@linux-mips.org>
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*/
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#ifndef __ASM_MIPS_SYSCALL_H
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#define __ASM_MIPS_SYSCALL_H
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#include <linux/compiler.h>
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#include <uapi/linux/audit.h>
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#include <linux/elf-em.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/uaccess.h>
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#include <asm/ptrace.h>
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#include <asm/unistd.h>
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#ifndef __NR_syscall /* Only defined if _MIPS_SIM == _MIPS_SIM_ABI32 */
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#define __NR_syscall 4000
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#endif
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static inline bool mips_syscall_is_indirect(struct task_struct *task,
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struct pt_regs *regs)
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{
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/* O32 ABI syscall() - Either 64-bit with O32 or 32-bit */
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return (IS_ENABLED(CONFIG_32BIT) ||
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test_tsk_thread_flag(task, TIF_32BIT_REGS)) &&
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(regs->regs[2] == __NR_syscall);
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}
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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 current_thread_info()->syscall;
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}
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static inline void mips_syscall_update_nr(struct task_struct *task,
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struct pt_regs *regs)
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{
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/*
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* v0 is the system call number, except for O32 ABI syscall(), where it
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* ends up in a0.
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*/
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if (mips_syscall_is_indirect(task, regs))
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task_thread_info(task)->syscall = regs->regs[4];
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else
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task_thread_info(task)->syscall = regs->regs[2];
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}
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static inline unsigned long mips_get_syscall_arg(unsigned long *arg,
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struct task_struct *task, struct pt_regs *regs, unsigned int n)
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{
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unsigned long usp __maybe_unused = regs->regs[29];
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switch (n) {
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case 0: case 1: case 2: case 3:
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*arg = regs->regs[4 + n];
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return 0;
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#ifdef CONFIG_32BIT
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case 4: case 5: case 6: case 7:
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return get_user(*arg, (int *)usp + n);
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#endif
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#ifdef CONFIG_64BIT
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case 4: case 5: case 6: case 7:
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#ifdef CONFIG_MIPS32_O32
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if (test_tsk_thread_flag(task, TIF_32BIT_REGS))
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return get_user(*arg, (int *)usp + n);
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else
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#endif
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*arg = regs->regs[4 + n];
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return 0;
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#endif
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default:
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BUG();
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}
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unreachable();
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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[2];
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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 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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if (error) {
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regs->regs[2] = -error;
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regs->regs[7] = 1;
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} else {
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regs->regs[2] = val;
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regs->regs[7] = 0;
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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 int i = 0;
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unsigned int n = 6;
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int ret;
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/* O32 ABI syscall() */
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if (mips_syscall_is_indirect(task, regs))
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i++;
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while (n--)
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ret |= mips_get_syscall_arg(args++, task, regs, i++);
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/*
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* No way to communicate an error because this is a void function.
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*/
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#if 0
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return ret;
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#endif
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}
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extern const unsigned long sys_call_table[];
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extern const unsigned long sys32_call_table[];
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extern const unsigned long sysn32_call_table[];
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static inline int syscall_get_arch(void)
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{
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int arch = AUDIT_ARCH_MIPS;
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#ifdef CONFIG_64BIT
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if (!test_thread_flag(TIF_32BIT_REGS)) {
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arch |= __AUDIT_ARCH_64BIT;
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/* N32 sets only TIF_32BIT_ADDR */
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if (test_thread_flag(TIF_32BIT_ADDR))
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arch |= __AUDIT_ARCH_CONVENTION_MIPS64_N32;
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}
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#endif
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#if defined(__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_MIPS_SYSCALL_H */
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