xref: /linux/arch/um/kernel/skas/stub.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2021 Benjamin Berg <benjamin@sipsolutions.net>
4  */
5 
6 #include <sysdep/stub.h>
7 
syscall_handler(struct stub_data * d)8 static __always_inline int syscall_handler(struct stub_data *d)
9 {
10 	int i;
11 	unsigned long res;
12 
13 	for (i = 0; i < d->syscall_data_len; i++) {
14 		struct stub_syscall *sc = &d->syscall_data[i];
15 
16 		switch (sc->syscall) {
17 		case STUB_SYSCALL_MMAP:
18 			res = stub_syscall6(STUB_MMAP_NR,
19 					    sc->mem.addr, sc->mem.length,
20 					    sc->mem.prot,
21 					    MAP_SHARED | MAP_FIXED,
22 					    sc->mem.fd, sc->mem.offset);
23 			if (res != sc->mem.addr) {
24 				d->err = res;
25 				d->syscall_data_len = i;
26 				return -1;
27 			}
28 			break;
29 		case STUB_SYSCALL_MUNMAP:
30 			res = stub_syscall2(__NR_munmap,
31 					    sc->mem.addr, sc->mem.length);
32 			if (res) {
33 				d->err = res;
34 				d->syscall_data_len = i;
35 				return -1;
36 			}
37 			break;
38 		case STUB_SYSCALL_MPROTECT:
39 			res = stub_syscall3(__NR_mprotect,
40 					    sc->mem.addr, sc->mem.length,
41 					    sc->mem.prot);
42 			if (res) {
43 				d->err = res;
44 				d->syscall_data_len = i;
45 				return -1;
46 			}
47 			break;
48 		default:
49 			d->err = -95; /* EOPNOTSUPP */
50 			d->syscall_data_len = i;
51 			return -1;
52 		}
53 	}
54 
55 	d->err = 0;
56 	d->syscall_data_len = 0;
57 
58 	return 0;
59 }
60 
61 void __section(".__syscall_stub")
stub_syscall_handler(void)62 stub_syscall_handler(void)
63 {
64 	struct stub_data *d = get_stub_data();
65 
66 	syscall_handler(d);
67 
68 	trap_myself();
69 }
70