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
handle_syscall(struct uml_pt_regs * r)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_syscall_max)
45 PT_REGS_SET_SYSCALL_RETURN(regs,
46 EXECUTE_SYSCALL(syscall, regs));
47
48 out:
49 syscall_trace_leave(regs);
50 }
51
