LXR linux/arch/um/kernel/skas/syscall.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   4 */
   5
   6#include <linux/kernel.h>
   7#include <linux/ptrace.h>
   8#include <linux/seccomp.h>
   9#include <kern_util.h>
  10#include <sysdep/ptrace.h>
  11#include <sysdep/ptrace_user.h>
  12#include <sysdep/syscalls.h>
  13#include <linux/time-internal.h>
  14#include <asm/unistd.h>
  15
  16void handle_syscall(struct uml_pt_regs *r)
  17{
  18        struct pt_regs *regs = container_of(r, struct pt_regs, regs);
  19        int syscall;
  20
  21        /*
  22         * If we have infinite CPU resources, then make every syscall also a
  23         * preemption point, since we don't have any other preemption in this
  24         * case, and kernel threads would basically never run until userspace
  25         * went to sleep, even if said userspace interacts with the kernel in
  26         * various ways.
  27         */
  28        if (time_travel_mode == TT_MODE_INFCPU ||
  29            time_travel_mode == TT_MODE_EXTERNAL)
  30                schedule();
  31
  32        /* Initialize the syscall number and default return value. */
  33        UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
  34        PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS);
  35
  36        if (syscall_trace_enter(regs))
  37                goto out;
  38
  39        /* Do the seccomp check after ptrace; failures should be fast. */
  40        if (secure_computing() == -1)
  41                goto out;
  42
  43        syscall = UPT_SYSCALL_NR(r);
  44        if (syscall >= 0 && syscall <= __NR_syscall_max)
  45                PT_REGS_SET_SYSCALL_RETURN(regs,
  46                                EXECUTE_SYSCALL(syscall, regs));
  47
  48out:
  49        syscall_trace_leave(regs);
  50}
  51