| 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
| 2 | |
| 3 | #include "gcs.h" |
| 4 | |
| 5 | /* |
| 6 | * A single garbage store to the gcs stack. |
| 7 | * The asm inside must be unique, so disallow inlining. |
| 8 | */ |
| 9 | void __attribute__((noinline)) |
| 10 | test_gcsstr(void) |
| 11 | { |
| 12 | register uint64_t *ptr __asm__("x0") = gcspr(); |
| 13 | /* GCSSTR x1, x0 */ |
| 14 | __asm__("inst_gcsstr: .inst 0xd91f1c01" : : "r"(--ptr)); |
| 15 | } |
| 16 | |
| 17 | static void test_sigsegv(int sig, siginfo_t *info, void *vuc) |
| 18 | { |
| 19 | ucontext_t *uc = vuc; |
| 20 | uint64_t inst_gcsstr; |
| 21 | |
| 22 | __asm__("adr %0, inst_gcsstr" : "=r"(inst_gcsstr)); |
| 23 | assert(uc->uc_mcontext.pc == inst_gcsstr); |
| 24 | assert(info->si_code == SEGV_CPERR); |
| 25 | /* TODO: Dig for ESR and verify syndrome. */ |
| 26 | exit(0); |
| 27 | } |
| 28 | |
| 29 | int main() |
| 30 | { |
| 31 | struct sigaction sa = { |
| 32 | .sa_sigaction = test_sigsegv, |
| 33 | .sa_flags = SA_SIGINFO, |
| 34 | }; |
| 35 | |
| 36 | /* Enable GCSSTR and test the store succeeds. */ |
| 37 | enable_gcs(PR_SHADOW_STACK_WRITE); |
| 38 | test_gcsstr(); |
| 39 | |
| 40 | /* Disable GCSSTR and test the resulting sigsegv. */ |
| 41 | enable_gcs(0); |
| 42 | if (sigaction(SIGSEGV, &sa, NULL) < 0) { |
| 43 | perror("sigaction"); |
| 44 | exit(1); |
| 45 | } |
| 46 | test_gcsstr(); |
| 47 | abort(); |
| 48 | } |