xref: /openbmc/qemu/tests/tcg/arm/commpage.c (revision 9e7f1469b9994d910fc1b185c657778bde51639c)
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