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/*
* Verify the COMMPAGE emulation
*
* The ARM commpage is a set of user space helper functions provided
* by the kernel in an effort to ease portability of user space code
* between different CPUs with potentially different capabilities. It
* is a 32 bit invention and similar to the vdso segment in many ways.
*
* The ABI is documented in the Linux kernel:
* Documentation/arm/kernel_userspace_helpers.rst
*
* Copyright (c) 2020 Linaro Ltd
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#define ARM_COMMPAGE (0xffff0f00u)
#define ARM_KUSER_VERSION (*(int32_t *)(ARM_COMMPAGE + 0xfc))
typedef void * (get_tls_fn)(void);
#define ARM_KUSER_GET_TLS (*(get_tls_fn *)(ARM_COMMPAGE + 0xe0))
typedef int (cmpxchg_fn)(int oldval, int newval, volatile int *ptr);
#define ARM_KUSER_CMPXCHG (*(cmpxchg_fn *)(ARM_COMMPAGE + 0xc0))
typedef void (dmb_fn)(void);
#define ARM_KUSER_DMB (*(dmb_fn *)(ARM_COMMPAGE + 0xa0))
typedef int (cmpxchg64_fn)(const int64_t *oldval,
const int64_t *newval,
volatile int64_t *ptr);
#define ARM_KUSER_CMPXCHG64 (*(cmpxchg64_fn *)(ARM_COMMPAGE + 0x60))
#define fail_unless(x) \
do { \
if (!(x)) { \
fprintf(stderr, "FAILED at %s:%d\n", __FILE__, __LINE__); \
exit(EXIT_FAILURE); \
} \
} while (0)
int main(int argc, char *argv[argc])
{
void *kuser_tls;
int val = 1;
const int64_t oldval = 1, newval = 2;
int64_t val64 = 1;
fail_unless(ARM_KUSER_VERSION == 0x5);
kuser_tls = ARM_KUSER_GET_TLS();
printf("TLS = %p\n", kuser_tls);
fail_unless(kuser_tls != 0);
fail_unless(ARM_KUSER_CMPXCHG(1, 2, &val) == 0);
printf("val = %d\n", val);
/* this is a crash test, not checking an actual barrier occurs */
ARM_KUSER_DMB();
fail_unless(ARM_KUSER_CMPXCHG64(&oldval, &newval, &val64) == 0);
printf("val64 = %lld\n", val64);
return 0;
}
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