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
test_denormal_fpu(void)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
main(int argc,char * argv[])35 int main(int argc, char *argv[])
36 {
37 return test_harness(test_denormal_fpu, "fpu_denormal");
38 }
39