xref: /linux/arch/um/kernel/skas/syscall.c (revision c0e297dc61f8d4453e07afbea1fa8d0e67cd4a34)
1 /*
2  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3  * Licensed under the GPL
4  */
5 
6 #include <linux/kernel.h>
7 #include <linux/ptrace.h>
8 #include <kern_util.h>
9 #include <sysdep/ptrace.h>
10 #include <sysdep/syscalls.h>
11 
12 extern int syscall_table_size;
13 #define NR_SYSCALLS (syscall_table_size / sizeof(void *))
14 
15 void handle_syscall(struct uml_pt_regs *r)
16 {
17 	struct pt_regs *regs = container_of(r, struct pt_regs, regs);
18 	long result;
19 	int syscall;
20 
21 	if (syscall_trace_enter(regs)) {
22 		result = -ENOSYS;
23 		goto out;
24 	}
25 
26 	/*
27 	 * This should go in the declaration of syscall, but when I do that,
28 	 * strace -f -c bash -c 'ls ; ls' breaks, sometimes not tracing
29 	 * children at all, sometimes hanging when bash doesn't see the first
30 	 * ls exit.
31 	 * The assembly looks functionally the same to me.  This is
32 	 *     gcc version 4.0.1 20050727 (Red Hat 4.0.1-5)
33 	 * in case it's a compiler bug.
34 	 */
35 	syscall = UPT_SYSCALL_NR(r);
36 	if ((syscall >= NR_SYSCALLS) || (syscall < 0))
37 		result = -ENOSYS;
38 	else result = EXECUTE_SYSCALL(syscall, regs);
39 
40 out:
41 	PT_REGS_SET_SYSCALL_RETURN(regs, result);
42 
43 	syscall_trace_leave(regs);
44 }
45