| 1 | #include <assert.h> |
| 2 | #include <stdint.h> |
| 3 | #include <signal.h> |
| 4 | #include <sys/user.h> |
| 5 | |
| 6 | #define XER_SO (1 << 31) |
| 7 | #define XER_OV (1 << 30) |
| 8 | #define XER_CA (1 << 29) |
| 9 | #define XER_OV32 (1 << 19) |
| 10 | #define XER_CA32 (1 << 18) |
| 11 | |
| 12 | uint64_t saved; |
| 13 | |
| 14 | void sigtrap_handler(int sig, siginfo_t *si, void *ucontext) |
| 15 | { |
| 16 | ucontext_t *uc = ucontext; |
| 17 | uc->uc_mcontext.regs->nip += 4; |
| 18 | saved = uc->uc_mcontext.regs->xer; |
| 19 | uc->uc_mcontext.regs->xer |= XER_OV | XER_OV32; |
| 20 | } |
| 21 | |
| 22 | int main(void) |
| 23 | { |
| 24 | uint64_t initial = XER_CA | XER_CA32, restored; |
| 25 | struct sigaction sa = { |
| 26 | .sa_sigaction = sigtrap_handler, |
| 27 | .sa_flags = SA_SIGINFO |
| 28 | }; |
| 29 | |
| 30 | sigaction(SIGTRAP, &sa, NULL); |
| 31 | |
| 32 | asm("mtspr 1, %1\n\t" |
| 33 | "trap\n\t" |
| 34 | "mfspr %0, 1\n\t" |
| 35 | : "=r" (restored) |
| 36 | : "r" (initial)); |
| 37 | |
| 38 | assert(saved == initial); |
| 39 | assert(restored == (XER_OV | XER_OV32 | XER_CA | XER_CA32)); |
| 40 | |
| 41 | return 0; |
| 42 | } |