| 1 | /* |
| 2 | * To be compiled with -march=armv8.5-a+memtag |
| 3 | * |
| 4 | * This test is adapted from a Linux test. Please see: |
| 5 | * |
| 6 | * https://www.kernel.org/doc/html/next/arch/arm64/memory-tagging-extension.html#example-of-correct-usage |
| 7 | */ |
| 8 | #include <errno.h> |
| 9 | #include <stdint.h> |
| 10 | #include <stdio.h> |
| 11 | #include <stdlib.h> |
| 12 | #include <unistd.h> |
| 13 | #include <sys/auxv.h> |
| 14 | #include <sys/mman.h> |
| 15 | #include <sys/prctl.h> |
| 16 | #include <string.h> |
| 17 | /* |
| 18 | * From arch/arm64/include/uapi/asm/hwcap.h |
| 19 | */ |
| 20 | #define HWCAP2_MTE (1 << 18) |
| 21 | |
| 22 | /* |
| 23 | * From arch/arm64/include/uapi/asm/mman.h |
| 24 | */ |
| 25 | #define PROT_MTE 0x20 |
| 26 | |
| 27 | /* |
| 28 | * Insert a random logical tag into the given pointer. |
| 29 | */ |
| 30 | #define insert_random_tag(ptr) ({ \ |
| 31 | uint64_t __val; \ |
| 32 | asm("irg %0, %1" : "=r" (__val) : "r" (ptr)); \ |
| 33 | __val; \ |
| 34 | }) |
| 35 | |
| 36 | /* |
| 37 | * Set the allocation tag on the destination address. |
| 38 | */ |
| 39 | #define set_tag(tagged_addr) do { \ |
| 40 | asm volatile("stg %0, [%0]" : : "r" (tagged_addr) : "memory"); \ |
| 41 | } while (0) |
| 42 | |
| 43 | |
| 44 | int main(int argc, char *argv[]) |
| 45 | { |
| 46 | unsigned char *a; |
| 47 | unsigned long page_sz = sysconf(_SC_PAGESIZE); |
| 48 | unsigned long hwcap2 = getauxval(AT_HWCAP2); |
| 49 | |
| 50 | /* check if MTE is present */ |
| 51 | if (!(hwcap2 & HWCAP2_MTE)) { |
| 52 | return EXIT_FAILURE; |
| 53 | } |
| 54 | |
| 55 | /* |
| 56 | * Enable the tagged address ABI, synchronous or asynchronous MTE |
| 57 | * tag check faults (based on per-CPU preference) and allow all |
| 58 | * non-zero tags in the randomly generated set. |
| 59 | */ |
| 60 | if (prctl(PR_SET_TAGGED_ADDR_CTRL, |
| 61 | PR_TAGGED_ADDR_ENABLE | PR_MTE_TCF_SYNC | PR_MTE_TCF_ASYNC | |
| 62 | (0xfffe << PR_MTE_TAG_SHIFT), |
| 63 | 0, 0, 0)) { |
| 64 | perror("prctl() failed"); |
| 65 | return EXIT_FAILURE; |
| 66 | } |
| 67 | |
| 68 | a = mmap(0, page_sz, PROT_READ | PROT_WRITE, |
| 69 | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
| 70 | if (a == MAP_FAILED) { |
| 71 | perror("mmap() failed"); |
| 72 | return EXIT_FAILURE; |
| 73 | } |
| 74 | |
| 75 | printf("a[] address is %p\n", a); |
| 76 | |
| 77 | /* |
| 78 | * Enable MTE on the above anonymous mmap. The flag could be passed |
| 79 | * directly to mmap() and skip this step. |
| 80 | */ |
| 81 | if (mprotect(a, page_sz, PROT_READ | PROT_WRITE | PROT_MTE)) { |
| 82 | perror("mprotect() failed"); |
| 83 | return EXIT_FAILURE; |
| 84 | } |
| 85 | |
| 86 | /* access with the default tag (0) */ |
| 87 | a[0] = 1; |
| 88 | a[1] = 2; |
| 89 | |
| 90 | printf("a[0] = %hhu a[1] = %hhu\n", a[0], a[1]); |
| 91 | |
| 92 | /* set the logical and allocation tags */ |
| 93 | a = (unsigned char *)insert_random_tag(a); |
| 94 | set_tag(a); |
| 95 | |
| 96 | printf("%p\n", a); |
| 97 | |
| 98 | return 0; |
| 99 | } |