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 16 void 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_syscalls) 45 PT_REGS_SET_SYSCALL_RETURN(regs, 46 EXECUTE_SYSCALL(syscall, regs)); 47 48 out: 49 syscall_trace_leave(regs); 50 } 51