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 15 void handle_syscall(struct uml_pt_regs *r) 16 { 17 struct pt_regs *regs = container_of(r, struct pt_regs, regs); 18 int syscall; 19 20 /* 21 * If we have infinite CPU resources, then make every syscall also a 22 * preemption point, since we don't have any other preemption in this 23 * case, and kernel threads would basically never run until userspace 24 * went to sleep, even if said userspace interacts with the kernel in 25 * various ways. 26 */ 27 if (time_travel_mode == TT_MODE_INFCPU || 28 time_travel_mode == TT_MODE_EXTERNAL) 29 schedule(); 30 31 /* Initialize the syscall number and default return value. */ 32 UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp); 33 PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS); 34 35 if (syscall_trace_enter(regs)) 36 goto out; 37 38 /* Do the seccomp check after ptrace; failures should be fast. */ 39 if (secure_computing() == -1) 40 goto out; 41 42 syscall = UPT_SYSCALL_NR(r); 43 if (syscall >= 0 && syscall <= __NR_syscall_max) 44 PT_REGS_SET_SYSCALL_RETURN(regs, 45 EXECUTE_SYSCALL(syscall, regs)); 46 47 out: 48 syscall_trace_leave(regs); 49 } 50