| 1 | #include <stdlib.h> |
| 2 | #include <stdint.h> |
| 3 | #include <assert.h> |
| 4 | #include <signal.h> |
| 5 | #include <sys/prctl.h> |
| 6 | |
| 7 | #define MTFSF(FLM, FRB) asm volatile ("mtfsf %0, %1" :: "i" (FLM), "f" (FRB)) |
| 8 | #define MFFS(FRT) asm("mffs %0" : "=f" (FRT)) |
| 9 | |
| 10 | #define FPSCR_VE 7 /* Floating-point invalid operation exception enable */ |
| 11 | #define FPSCR_VXSOFT 10 /* Floating-point invalid operation exception (soft) */ |
| 12 | #define FPSCR_FI 17 /* Floating-point fraction inexact */ |
| 13 | |
| 14 | #define FP_VE (1ull << FPSCR_VE) |
| 15 | #define FP_VXSOFT (1ull << FPSCR_VXSOFT) |
| 16 | #define FP_FI (1ull << FPSCR_FI) |
| 17 | |
| 18 | void sigfpe_handler(int sig, siginfo_t *si, void *ucontext) |
| 19 | { |
| 20 | if (si->si_code == FPE_FLTINV) { |
| 21 | exit(0); |
| 22 | } |
| 23 | exit(1); |
| 24 | } |
| 25 | |
| 26 | int main(void) |
| 27 | { |
| 28 | uint64_t fpscr; |
| 29 | |
| 30 | struct sigaction sa = { |
| 31 | .sa_sigaction = sigfpe_handler, |
| 32 | .sa_flags = SA_SIGINFO |
| 33 | }; |
| 34 | |
| 35 | /* |
| 36 | * Enable the MSR bits F0 and F1 to enable exceptions. |
| 37 | * This shouldn't be needed in linux-user as these bits are enabled by |
| 38 | * default, but this allows to execute either in a VM or a real machine |
| 39 | * to compare the behaviors. |
| 40 | */ |
| 41 | prctl(PR_SET_FPEXC, PR_FP_EXC_PRECISE); |
| 42 | |
| 43 | /* First test if the FI bit is being set correctly */ |
| 44 | MTFSF(0b11111111, FP_FI); |
| 45 | MFFS(fpscr); |
| 46 | assert((fpscr & FP_FI) != 0); |
| 47 | |
| 48 | /* Then test if the deferred exception is being called correctly */ |
| 49 | sigaction(SIGFPE, &sa, NULL); |
| 50 | |
| 51 | /* |
| 52 | * Although the VXSOFT exception has been chosen, based on test in a Power9 |
| 53 | * any combination of exception bit + its enabling bit should work. |
| 54 | * But if a different exception is chosen si_code check should |
| 55 | * change accordingly. |
| 56 | */ |
| 57 | MTFSF(0b11111111, FP_VE | FP_VXSOFT); |
| 58 | |
| 59 | return 1; |
| 60 | } |