LXR qemu/tests/tcg/arm/commpage.c

   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))
  23typedef void * (get_tls_fn)(void);
  24#define ARM_KUSER_GET_TLS (*(get_tls_fn *)(ARM_COMMPAGE + 0xe0))
  25typedef int (cmpxchg_fn)(int oldval, int newval, volatile int *ptr);
  26#define ARM_KUSER_CMPXCHG (*(cmpxchg_fn *)(ARM_COMMPAGE + 0xc0))
  27typedef void (dmb_fn)(void);
  28#define ARM_KUSER_DMB (*(dmb_fn *)(ARM_COMMPAGE + 0xa0))
  29typedef 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
  43int 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