| 1 | /* |
| 2 | * Branch target identification, basic notskip cases. |
| 3 | */ |
| 4 | |
| 5 | #include <stdio.h> |
| 6 | #include <signal.h> |
| 7 | #include <string.h> |
| 8 | #include <unistd.h> |
| 9 | #include <sys/mman.h> |
| 10 | |
| 11 | #ifndef PROT_BTI |
| 12 | #define PROT_BTI 0x10 |
| 13 | #endif |
| 14 | |
| 15 | static void skip2_sigill(int sig, siginfo_t *info, void *vuc) |
| 16 | { |
| 17 | ucontext_t *uc = vuc; |
| 18 | uc->uc_mcontext.pc += 8; |
| 19 | uc->uc_mcontext.pstate = 1; |
| 20 | } |
| 21 | |
| 22 | #define NOP "nop" |
| 23 | #define BTI_N "hint #32" |
| 24 | #define BTI_C "hint #34" |
| 25 | #define BTI_J "hint #36" |
| 26 | #define BTI_JC "hint #38" |
| 27 | |
| 28 | #define BTYPE_1(DEST) \ |
| 29 | "mov x1, #1\n\t" \ |
| 30 | "adr x16, 1f\n\t" \ |
| 31 | "br x16\n" \ |
| 32 | "1: " DEST "\n\t" \ |
| 33 | "mov x1, #0" |
| 34 | |
| 35 | #define BTYPE_2(DEST) \ |
| 36 | "mov x1, #1\n\t" \ |
| 37 | "adr x16, 1f\n\t" \ |
| 38 | "blr x16\n" \ |
| 39 | "1: " DEST "\n\t" \ |
| 40 | "mov x1, #0" |
| 41 | |
| 42 | #define BTYPE_3(DEST) \ |
| 43 | "mov x1, #1\n\t" \ |
| 44 | "adr x15, 1f\n\t" \ |
| 45 | "br x15\n" \ |
| 46 | "1: " DEST "\n\t" \ |
| 47 | "mov x1, #0" |
| 48 | |
| 49 | #define TEST(WHICH, DEST, EXPECT) \ |
| 50 | WHICH(DEST) "\n" \ |
| 51 | ".if " #EXPECT "\n\t" \ |
| 52 | "eor x1, x1," #EXPECT "\n" \ |
| 53 | ".endif\n\t" \ |
| 54 | "add x0, x0, x1\n\t" |
| 55 | |
| 56 | asm("\n" |
| 57 | "test_begin:\n\t" |
| 58 | BTI_C "\n\t" |
| 59 | "mov x2, x30\n\t" |
| 60 | "mov x0, #0\n\t" |
| 61 | |
| 62 | TEST(BTYPE_1, NOP, 1) |
| 63 | TEST(BTYPE_1, BTI_N, 1) |
| 64 | TEST(BTYPE_1, BTI_C, 0) |
| 65 | TEST(BTYPE_1, BTI_J, 0) |
| 66 | TEST(BTYPE_1, BTI_JC, 0) |
| 67 | |
| 68 | TEST(BTYPE_2, NOP, 1) |
| 69 | TEST(BTYPE_2, BTI_N, 1) |
| 70 | TEST(BTYPE_2, BTI_C, 0) |
| 71 | TEST(BTYPE_2, BTI_J, 1) |
| 72 | TEST(BTYPE_2, BTI_JC, 0) |
| 73 | |
| 74 | TEST(BTYPE_3, NOP, 1) |
| 75 | TEST(BTYPE_3, BTI_N, 1) |
| 76 | TEST(BTYPE_3, BTI_C, 1) |
| 77 | TEST(BTYPE_3, BTI_J, 0) |
| 78 | TEST(BTYPE_3, BTI_JC, 0) |
| 79 | |
| 80 | "ret x2\n" |
| 81 | "test_end:" |
| 82 | ); |
| 83 | |
| 84 | int main() |
| 85 | { |
| 86 | struct sigaction sa; |
| 87 | void *tb, *te; |
| 88 | |
| 89 | void *p = mmap(0, getpagesize(), |
| 90 | PROT_EXEC | PROT_READ | PROT_WRITE | PROT_BTI, |
| 91 | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
| 92 | if (p == MAP_FAILED) { |
| 93 | perror("mmap"); |
| 94 | return 1; |
| 95 | } |
| 96 | |
| 97 | memset(&sa, 0, sizeof(sa)); |
| 98 | sa.sa_sigaction = skip2_sigill; |
| 99 | sa.sa_flags = SA_SIGINFO; |
| 100 | if (sigaction(SIGILL, &sa, NULL) < 0) { |
| 101 | perror("sigaction"); |
| 102 | return 1; |
| 103 | } |
| 104 | |
| 105 | /* |
| 106 | * ??? With "extern char test_begin[]", some compiler versions |
| 107 | * will use :got references, and some linker versions will |
| 108 | * resolve this reference to a static symbol incorrectly. |
| 109 | * Bypass this error by using a pc-relative reference directly. |
| 110 | */ |
| 111 | asm("adr %0, test_begin; adr %1, test_end" : "=r"(tb), "=r"(te)); |
| 112 | |
| 113 | memcpy(p, tb, te - tb); |
| 114 | |
| 115 | return ((int (*)(void))p)(); |
| 116 | } |