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