1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0+ 2*4882a593Smuzhiyun /* This testcase operates with the test_fpu kernel driver. 3*4882a593Smuzhiyun * It modifies the FPU control register in user mode and calls the kernel 4*4882a593Smuzhiyun * module to perform floating point operations in the kernel. The control 5*4882a593Smuzhiyun * register value should be independent between kernel and user mode. 6*4882a593Smuzhiyun */ 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun #define _GNU_SOURCE 9*4882a593Smuzhiyun #include <stdio.h> 10*4882a593Smuzhiyun #include <errno.h> 11*4882a593Smuzhiyun #include <string.h> 12*4882a593Smuzhiyun #include <fenv.h> 13*4882a593Smuzhiyun #include <unistd.h> 14*4882a593Smuzhiyun #include <fcntl.h> 15*4882a593Smuzhiyun 16*4882a593Smuzhiyun const char *test_fpu_path = "/sys/kernel/debug/selftest_helpers/test_fpu"; 17*4882a593Smuzhiyun main(void)18*4882a593Smuzhiyunint main(void) 19*4882a593Smuzhiyun { 20*4882a593Smuzhiyun char dummy[1]; 21*4882a593Smuzhiyun int fd = open(test_fpu_path, O_RDONLY); 22*4882a593Smuzhiyun 23*4882a593Smuzhiyun if (fd < 0) { 24*4882a593Smuzhiyun printf("[SKIP]\tcan't access %s: %s\n", 25*4882a593Smuzhiyun test_fpu_path, strerror(errno)); 26*4882a593Smuzhiyun return 0; 27*4882a593Smuzhiyun } 28*4882a593Smuzhiyun 29*4882a593Smuzhiyun if (read(fd, dummy, 1) < 0) { 30*4882a593Smuzhiyun printf("[FAIL]\taccess with default rounding mode failed\n"); 31*4882a593Smuzhiyun return 1; 32*4882a593Smuzhiyun } 33*4882a593Smuzhiyun 34*4882a593Smuzhiyun fesetround(FE_DOWNWARD); 35*4882a593Smuzhiyun if (read(fd, dummy, 1) < 0) { 36*4882a593Smuzhiyun printf("[FAIL]\taccess with downward rounding mode failed\n"); 37*4882a593Smuzhiyun return 2; 38*4882a593Smuzhiyun } 39*4882a593Smuzhiyun if (fegetround() != FE_DOWNWARD) { 40*4882a593Smuzhiyun printf("[FAIL]\tusermode rounding mode clobbered\n"); 41*4882a593Smuzhiyun return 3; 42*4882a593Smuzhiyun } 43*4882a593Smuzhiyun 44*4882a593Smuzhiyun /* Note: the tests up to this point are quite safe and will only return 45*4882a593Smuzhiyun * an error. But the exception mask setting can cause misbehaving kernel 46*4882a593Smuzhiyun * to crash. 47*4882a593Smuzhiyun */ 48*4882a593Smuzhiyun feclearexcept(FE_ALL_EXCEPT); 49*4882a593Smuzhiyun feenableexcept(FE_ALL_EXCEPT); 50*4882a593Smuzhiyun if (read(fd, dummy, 1) < 0) { 51*4882a593Smuzhiyun printf("[FAIL]\taccess with fpu exceptions unmasked failed\n"); 52*4882a593Smuzhiyun return 4; 53*4882a593Smuzhiyun } 54*4882a593Smuzhiyun if (fegetexcept() != FE_ALL_EXCEPT) { 55*4882a593Smuzhiyun printf("[FAIL]\tusermode fpu exception mask clobbered\n"); 56*4882a593Smuzhiyun return 5; 57*4882a593Smuzhiyun } 58*4882a593Smuzhiyun 59*4882a593Smuzhiyun printf("[OK]\ttest_fpu\n"); 60*4882a593Smuzhiyun return 0; 61*4882a593Smuzhiyun } 62