Revision 297f9233b53a08fd457815e19f1d6f2c3389857b authored by Jessica Yu on 09 January 2018, 23:51:24 UTC, committed by Ingo Molnar on 16 February 2018, 08:12:58 UTC
Improve error handling when disarming ftrace-based kprobes. Like with arm_kprobe_ftrace(), propagate any errors from disarm_kprobe_ftrace() so that we do not disable/unregister kprobes that are still armed. In other words, unregister_kprobe() and disable_kprobe() should not report success if the kprobe could not be disarmed. disarm_all_kprobes() keeps its current behavior and attempts to disarm all kprobes. It returns the last encountered error and gives a warning if not all probes could be disarmed. This patch is based on Petr Mladek's original patchset (patches 2 and 3) back in 2015, which improved kprobes error handling, found here: https://lkml.org/lkml/2015/2/26/452 However, further work on this had been paused since then and the patches were not upstreamed. Based-on-patches-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Jessica Yu <jeyu@kernel.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S . Miller <davem@davemloft.net> Cc: Jiri Kosina <jikos@kernel.org> Cc: Joe Lawrence <joe.lawrence@redhat.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Miroslav Benes <mbenes@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/20180109235124.30886-3-jeyu@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent 12310e3
test_udelay.c
/*
* udelay() test kernel module
*
* Test is executed by writing and reading to /sys/kernel/debug/udelay_test
* Tests are configured by writing: USECS ITERATIONS
* Tests are executed by reading from the same file.
* Specifying usecs of 0 or negative values will run multiples tests.
*
* Copyright (C) 2014 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/ktime.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#define DEFAULT_ITERATIONS 100
#define DEBUGFS_FILENAME "udelay_test"
static DEFINE_MUTEX(udelay_test_lock);
static struct dentry *udelay_test_debugfs_file;
static int udelay_test_usecs;
static int udelay_test_iterations = DEFAULT_ITERATIONS;
static int udelay_test_single(struct seq_file *s, int usecs, uint32_t iters)
{
int min = 0, max = 0, fail_count = 0;
uint64_t sum = 0;
uint64_t avg;
int i;
/* Allow udelay to be up to 0.5% fast */
int allowed_error_ns = usecs * 5;
for (i = 0; i < iters; ++i) {
s64 kt1, kt2;
int time_passed;
kt1 = ktime_get_ns();
udelay(usecs);
kt2 = ktime_get_ns();
time_passed = kt2 - kt1;
if (i == 0 || time_passed < min)
min = time_passed;
if (i == 0 || time_passed > max)
max = time_passed;
if ((time_passed + allowed_error_ns) / 1000 < usecs)
++fail_count;
WARN_ON(time_passed < 0);
sum += time_passed;
}
avg = sum;
do_div(avg, iters);
seq_printf(s, "%d usecs x %d: exp=%d allowed=%d min=%d avg=%lld max=%d",
usecs, iters, usecs * 1000,
(usecs * 1000) - allowed_error_ns, min, avg, max);
if (fail_count)
seq_printf(s, " FAIL=%d", fail_count);
seq_puts(s, "\n");
return 0;
}
static int udelay_test_show(struct seq_file *s, void *v)
{
int usecs;
int iters;
int ret = 0;
mutex_lock(&udelay_test_lock);
usecs = udelay_test_usecs;
iters = udelay_test_iterations;
mutex_unlock(&udelay_test_lock);
if (usecs > 0 && iters > 0) {
return udelay_test_single(s, usecs, iters);
} else if (usecs == 0) {
struct timespec64 ts;
ktime_get_ts64(&ts);
seq_printf(s, "udelay() test (lpj=%ld kt=%lld.%09ld)\n",
loops_per_jiffy, (s64)ts.tv_sec, ts.tv_nsec);
seq_puts(s, "usage:\n");
seq_puts(s, "echo USECS [ITERS] > " DEBUGFS_FILENAME "\n");
seq_puts(s, "cat " DEBUGFS_FILENAME "\n");
}
return ret;
}
static int udelay_test_open(struct inode *inode, struct file *file)
{
return single_open(file, udelay_test_show, inode->i_private);
}
static ssize_t udelay_test_write(struct file *file, const char __user *buf,
size_t count, loff_t *pos)
{
char lbuf[32];
int ret;
int usecs;
int iters;
if (count >= sizeof(lbuf))
return -EINVAL;
if (copy_from_user(lbuf, buf, count))
return -EFAULT;
lbuf[count] = '\0';
ret = sscanf(lbuf, "%d %d", &usecs, &iters);
if (ret < 1)
return -EINVAL;
else if (ret < 2)
iters = DEFAULT_ITERATIONS;
mutex_lock(&udelay_test_lock);
udelay_test_usecs = usecs;
udelay_test_iterations = iters;
mutex_unlock(&udelay_test_lock);
return count;
}
static const struct file_operations udelay_test_debugfs_ops = {
.owner = THIS_MODULE,
.open = udelay_test_open,
.read = seq_read,
.write = udelay_test_write,
.llseek = seq_lseek,
.release = single_release,
};
static int __init udelay_test_init(void)
{
mutex_lock(&udelay_test_lock);
udelay_test_debugfs_file = debugfs_create_file(DEBUGFS_FILENAME,
S_IRUSR, NULL, NULL, &udelay_test_debugfs_ops);
mutex_unlock(&udelay_test_lock);
return 0;
}
module_init(udelay_test_init);
static void __exit udelay_test_exit(void)
{
mutex_lock(&udelay_test_lock);
debugfs_remove(udelay_test_debugfs_file);
mutex_unlock(&udelay_test_lock);
}
module_exit(udelay_test_exit);
MODULE_AUTHOR("David Riley <davidriley@chromium.org>");
MODULE_LICENSE("GPL");
![swh spinner](/static/img/swh-spinner.gif)
Computing file changes ...