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#ifndef __BAR_H
#define __BAR_H
#include <sys/mman.h>
#include <sys/auxv.h>
#include <sys/prctl.h>
#include <unistd.h>
#include <stdio.h>
// Set the allocation tag on the destination address using the STG instruction.
#define set_tag(tagged_addr) do { \
asm volatile("stg %0, [%0]" : : "r" (tagged_addr) : "memory"); \
} while (0)
int mte_enabled() {
return (getauxval(AT_HWCAP2)) & HWCAP2_MTE;
}
void *alloc_page() {
// Enable MTE with synchronous checking
if (prctl(PR_SET_TAGGED_ADDR_CTRL,
PR_TAGGED_ADDR_ENABLE | PR_MTE_TCF_SYNC | (0xfffe << PR_MTE_TAG_SHIFT),
0, 0, 0))
{
perror("prctl() failed");
}
// Using `mmap` allows us to ensure that, on systems which support MTE, the allocated
// memory is 16-byte aligned for MTE.
// This also allows us to explicitly specify whether the region should be protected by
// MTE or not.
if (mte_enabled()) {
void *ptr = mmap(NULL, sysconf(_SC_PAGESIZE),
PROT_READ | PROT_WRITE | PROT_MTE, MAP_PRIVATE | MAP_ANONYMOUS,
-1, 0);
} else {
void *ptr = mmap(NULL, sysconf(_SC_PAGESIZE),
PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS,
-1, 0);
}
}
#endif // __BAR_H
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