1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright IBM Corp. 2020 4 * 5 * This test attempts to cause a FP denormal exception on POWER8 CPUs. Unfortunately 6 * if the denormal handler is not configured or working properly, this can cause a bad 7 * crash in kernel mode when the kernel tries to save FP registers when the process 8 * exits. 9 */ 10 11 #include <stdio.h> 12 #include <string.h> 13 14 #include "utils.h" 15 16 static int test_denormal_fpu(void) 17 { 18 unsigned int m32; 19 unsigned long m64; 20 volatile float f; 21 volatile double d; 22 23 /* try to induce lfs <denormal> ; stfd */ 24 25 m32 = 0x00715fcf; /* random denormal */ 26 memcpy((float *)&f, &m32, sizeof(f)); 27 d = f; 28 memcpy(&m64, (double *)&d, sizeof(d)); 29 30 FAIL_IF((long)(m64 != 0x380c57f3c0000000)); /* renormalised value */ 31 32 return 0; 33 } 34 35 int main(int argc, char *argv[]) 36 { 37 return test_harness(test_denormal_fpu, "fpu_denormal"); 38 } 39