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#define _GNU_SOURCE 1
#include <assert.h>
#include <stdlib.h>
#include <signal.h>
#include <endian.h>
unsigned long long x = 0x8877665544332211ull;
void * volatile p = (void *)&x + 1;
void sigbus(int sig, siginfo_t *info, void *uc)
{
assert(sig == SIGBUS);
assert(info->si_signo == SIGBUS);
#ifdef BUS_ADRALN
assert(info->si_code == BUS_ADRALN);
#endif
assert(info->si_addr == p);
exit(EXIT_SUCCESS);
}
int main()
{
struct sigaction sa = {
.sa_sigaction = sigbus,
.sa_flags = SA_SIGINFO
};
int allow_fail = 0;
int tmp;
tmp = sigaction(SIGBUS, &sa, NULL);
assert(tmp == 0);
/*
* Select an operation that's likely to enforce alignment.
* On many guests that support unaligned accesses by default,
* this is often an atomic operation.
*/
#if defined(__aarch64__)
asm volatile("ldxr %w0,[%1]" : "=r"(tmp) : "r"(p) : "memory");
#elif defined(__alpha__)
asm volatile("ldl_l %0,0(%1)" : "=r"(tmp) : "r"(p) : "memory");
#elif defined(__arm__)
asm volatile("ldrex %0,[%1]" : "=r"(tmp) : "r"(p) : "memory");
#elif defined(__powerpc__)
asm volatile("lwarx %0,0,%1" : "=r"(tmp) : "r"(p) : "memory");
#elif defined(__riscv_atomic)
asm volatile("lr.w %0,(%1)" : "=r"(tmp) : "r"(p) : "memory");
#else
/* No insn known to fault unaligned -- try for a straight load. */
allow_fail = 1;
tmp = *(volatile int *)p;
#endif
assert(allow_fail);
/*
* We didn't see a signal.
* We might as well validate the unaligned load worked.
*/
if (BYTE_ORDER == LITTLE_ENDIAN) {
assert(tmp == 0x55443322);
} else {
assert(tmp == 0x77665544);
}
return EXIT_SUCCESS;
}
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