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// SPDX-License-Identifier: GPL-2.0+
/* This testcase operates with the test_fpu kernel driver.
* It modifies the FPU control register in user mode and calls the kernel
* module to perform floating point operations in the kernel. The control
* register value should be independent between kernel and user mode.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <fenv.h>
#include <unistd.h>
#include <fcntl.h>
const char *test_fpu_path = "/sys/kernel/debug/selftest_helpers/test_fpu";
int main(void)
{
char dummy[1];
int fd = open(test_fpu_path, O_RDONLY);
if (fd < 0) {
printf("[SKIP]\tcan't access %s: %s\n",
test_fpu_path, strerror(errno));
return 0;
}
if (read(fd, dummy, 1) < 0) {
printf("[FAIL]\taccess with default rounding mode failed\n");
return 1;
}
fesetround(FE_DOWNWARD);
if (read(fd, dummy, 1) < 0) {
printf("[FAIL]\taccess with downward rounding mode failed\n");
return 2;
}
if (fegetround() != FE_DOWNWARD) {
printf("[FAIL]\tusermode rounding mode clobbered\n");
return 3;
}
/* Note: the tests up to this point are quite safe and will only return
* an error. But the exception mask setting can cause misbehaving kernel
* to crash.
*/
feclearexcept(FE_ALL_EXCEPT);
feenableexcept(FE_ALL_EXCEPT);
if (read(fd, dummy, 1) < 0) {
printf("[FAIL]\taccess with fpu exceptions unmasked failed\n");
return 4;
}
if (fegetexcept() != FE_ALL_EXCEPT) {
printf("[FAIL]\tusermode fpu exception mask clobbered\n");
return 5;
}
printf("[OK]\ttest_fpu\n");
return 0;
}
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