linux/lib/test_fpu_glue.c
Yang Ruibin 38676d9e33 lib: fix the NULL vs IS_ERR() bug for debugfs_create_dir()
debugfs_create_dir() returns error pointers.  It never returns NULL.  So
use IS_ERR() to check it.

Link: https://lkml.kernel.org/r/20240821073441.9701-1-11162571@vivo.com
Signed-off-by: Yang Ruibin <11162571@vivo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-01 20:43:40 -07:00

64 lines
1.6 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Test cases for using floating point operations inside a kernel module.
*
* This tests kernel_fpu_begin() and kernel_fpu_end() functions, especially
* when userland has modified the floating point control registers. The kernel
* state might depend on the state set by the userland thread that was active
* before a syscall.
*
* To facilitate the test, this module registers file
* /sys/kernel/debug/selftest_helpers/test_fpu, which when read causes a
* sequence of floating point operations. If the operations fail, either the
* read returns error status or the kernel crashes.
* If the operations succeed, the read returns "1\n".
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/debugfs.h>
#include <linux/fpu.h>
#include "test_fpu.h"
static int test_fpu_get(void *data, u64 *val)
{
int status = -EINVAL;
kernel_fpu_begin();
status = test_fpu();
kernel_fpu_end();
*val = 1;
return status;
}
DEFINE_DEBUGFS_ATTRIBUTE(test_fpu_fops, test_fpu_get, NULL, "%lld\n");
static struct dentry *selftest_dir;
static int __init test_fpu_init(void)
{
if (!kernel_fpu_available())
return -EINVAL;
selftest_dir = debugfs_create_dir("selftest_helpers", NULL);
if (IS_ERR(selftest_dir))
return -ENOMEM;
debugfs_create_file_unsafe("test_fpu", 0444, selftest_dir, NULL,
&test_fpu_fops);
return 0;
}
static void __exit test_fpu_exit(void)
{
debugfs_remove(selftest_dir);
}
module_init(test_fpu_init);
module_exit(test_fpu_exit);
MODULE_DESCRIPTION("Test cases for floating point operations");
MODULE_LICENSE("GPL");