| 1 | /* |
| 2 | * Test s390x-linux-user precise self-modifying code handling. |
| 3 | * |
| 4 | * SPDX-License-Identifier: GPL-2.0-or-later |
| 5 | */ |
| 6 | #include <assert.h> |
| 7 | #include <sys/mman.h> |
| 8 | #include <stdint.h> |
| 9 | #include <stdlib.h> |
| 10 | |
| 11 | extern __uint128_t __attribute__((__aligned__(1))) smc; |
| 12 | extern __uint128_t __attribute__((__aligned__(1))) patch; |
| 13 | |
| 14 | int main(void) |
| 15 | { |
| 16 | char *aligned_smc = (char *)((uintptr_t)&smc & ~0xFFFULL); |
| 17 | char *smc_end = (char *)&smc + sizeof(smc); |
| 18 | uint64_t value = 21; |
| 19 | int err; |
| 20 | |
| 21 | err = mprotect(aligned_smc, smc_end - aligned_smc, |
| 22 | PROT_READ | PROT_WRITE | PROT_EXEC); |
| 23 | assert(err == 0); |
| 24 | |
| 25 | asm("jg 0f\n" /* start a new TB */ |
| 26 | "patch: .byte 0,0,0,0,0,0\n" /* replaces padding */ |
| 27 | ".byte 0,0,0,0,0,0\n" /* replaces vstl */ |
| 28 | "agr %[value],%[value]\n" /* replaces sgr */ |
| 29 | "smc: .org . + 6\n" /* pad patched code to 16 bytes */ |
| 30 | "0: vstl %[patch],%[idx],%[smc]\n" /* start writing before TB */ |
| 31 | "sgr %[value],%[value]" /* this becomes `agr %r0,%r0` */ |
| 32 | : [smc] "=R" (smc) |
| 33 | , [value] "+r" (value) |
| 34 | : [patch] "v" (patch) |
| 35 | , [idx] "r" (sizeof(patch) - 1) |
| 36 | : "cc"); |
| 37 | |
| 38 | return value == 42 ? EXIT_SUCCESS : EXIT_FAILURE; |
| 39 | } |