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 #include <asm/delay.h>
16
handle_syscall(struct uml_pt_regs * r)17 void handle_syscall(struct uml_pt_regs *r)
18 {
19 struct pt_regs *regs = container_of(r, struct pt_regs, regs);
20 int syscall;
21
22 /* Initialize the syscall number and default return value. */
23 UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
24 PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS);
25
26 if (syscall_trace_enter(regs))
27 goto out;
28
29 /* Do the seccomp check after ptrace; failures should be fast. */
30 if (secure_computing() == -1)
31 goto out;
32
33 syscall = UPT_SYSCALL_NR(r);
34
35 /*
36 * If no time passes, then sched_yield may not actually yield, causing
37 * broken spinlock implementations in userspace (ASAN) to hang for long
38 * periods of time.
39 */
40 if ((time_travel_mode == TT_MODE_INFCPU ||
41 time_travel_mode == TT_MODE_EXTERNAL) &&
42 syscall == __NR_sched_yield)
43 tt_extra_sched_jiffies += 1;
44
45 if (syscall >= 0 && syscall < __NR_syscalls) {
46 unsigned long ret = EXECUTE_SYSCALL(syscall, regs);
47
48 PT_REGS_SET_SYSCALL_RETURN(regs, ret);
49
50 /*
51 * An error value here can be some form of -ERESTARTSYS
52 * and then we'd just loop. Make any error syscalls take
53 * some time, so that it won't just loop if something is
54 * not ready, and hopefully other things will make some
55 * progress.
56 */
57 if (IS_ERR_VALUE(ret) &&
58 (time_travel_mode == TT_MODE_INFCPU ||
59 time_travel_mode == TT_MODE_EXTERNAL)) {
60 um_udelay(1);
61 schedule();
62 }
63 }
64
65 out:
66 syscall_trace_leave(regs);
67 }
68