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