xref: /openbmc/qemu/tests/tcg/arm/commpage.c (revision 5acc270a)
1 /*
2  * Verify the COMMPAGE emulation
3  *
4  * The ARM commpage is a set of user space helper functions provided
5  * by the kernel in an effort to ease portability of user space code
6  * between different CPUs with potentially different capabilities. It
7  * is a 32 bit invention and similar to the vdso segment in many ways.
8  *
9  * The ABI is documented in the Linux kernel:
10  *     Documentation/arm/kernel_userspace_helpers.rst
11  *
12  * Copyright (c) 2020 Linaro Ltd
13  *
14  * SPDX-License-Identifier: GPL-2.0-or-later
15  */
16 
17 #include <stdlib.h>
18 #include <stdio.h>
19 #include <stdint.h>
20 
21 #define ARM_COMMPAGE      (0xffff0f00u)
22 #define ARM_KUSER_VERSION (*(int32_t *)(ARM_COMMPAGE + 0xfc))
23 typedef void * (get_tls_fn)(void);
24 #define ARM_KUSER_GET_TLS (*(get_tls_fn *)(ARM_COMMPAGE + 0xe0))
25 typedef int (cmpxchg_fn)(int oldval, int newval, volatile int *ptr);
26 #define ARM_KUSER_CMPXCHG (*(cmpxchg_fn *)(ARM_COMMPAGE + 0xc0))
27 typedef void (dmb_fn)(void);
28 #define ARM_KUSER_DMB (*(dmb_fn *)(ARM_COMMPAGE + 0xa0))
29 typedef int (cmpxchg64_fn)(const int64_t *oldval,
30                            const int64_t *newval,
31                            volatile int64_t *ptr);
32 #define ARM_KUSER_CMPXCHG64 (*(cmpxchg64_fn *)(ARM_COMMPAGE + 0x60))
33 
34 #define fail_unless(x)                                                  \
35     do {                                                                \
36         if (!(x)) {                                                     \
37             fprintf(stderr, "FAILED at %s:%d\n", __FILE__, __LINE__);   \
38             exit(EXIT_FAILURE);                                         \
39         }                                                               \
40     } while (0)
41 
42 
main(int argc,char * argv[argc])43 int main(int argc, char *argv[argc])
44 {
45     void *kuser_tls;
46     int val = 1;
47     const int64_t oldval = 1, newval = 2;
48     int64_t val64 = 1;
49 
50     fail_unless(ARM_KUSER_VERSION == 0x5);
51     kuser_tls = ARM_KUSER_GET_TLS();
52     printf("TLS = %p\n", kuser_tls);
53     fail_unless(kuser_tls != 0);
54     fail_unless(ARM_KUSER_CMPXCHG(1, 2, &val) == 0);
55     printf("val = %d\n", val);
56     /* this is a crash test, not checking an actual barrier occurs */
57     ARM_KUSER_DMB();
58     fail_unless(ARM_KUSER_CMPXCHG64(&oldval, &newval, &val64) == 0);
59     printf("val64 = %lld\n", val64);
60     return 0;
61 }
62