/*
 * data_breakpoint.c - Sample HW Breakpoint file to watch kernel data address
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * usage: insmod data_breakpoint.ko ksym=<ksym_name>
 *
 * This file is a kernel module that places a breakpoint over ksym_name kernel
 * variable using Hardware Breakpoint register. The corresponding handler which
 * prints a backtrace is invoked every time a write operation is performed on
 * that variable.
 *
 * Copyright (C) IBM Corporation, 2009
 *
 * Author: K.Prasad <prasad@linux.vnet.ibm.com>
 */
#include <linux/module.h>	/* Needed by all modules */
#include <linux/kernel.h>	/* Needed for KERN_INFO */
#include <linux/init.h>		/* Needed for the macros */
#include <linux/kallsyms.h>

#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>

struct perf_event * __percpu *sample_hbp;

static char ksym_name[KSYM_NAME_LEN] = "pid_max";
module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any"
			" write operations on the kernel symbol");

static void sample_hbp_handler(struct perf_event *bp,
			       struct perf_sample_data *data,
			       struct pt_regs *regs)
{
	printk(KERN_INFO "%s value is changed\n", ksym_name);
	dump_stack();
	printk(KERN_INFO "Dump stack from sample_hbp_handler\n");
}

static int __init hw_break_module_init(void)
{
	int ret;
	struct perf_event_attr attr;

	hw_breakpoint_init(&attr);
	attr.bp_addr = kallsyms_lookup_name(ksym_name);
	attr.bp_len = HW_BREAKPOINT_LEN_4;
	attr.bp_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;

	sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler, NULL);
	if (IS_ERR((void __force *)sample_hbp)) {
		ret = PTR_ERR((void __force *)sample_hbp);
		goto fail;
	}

	printk(KERN_INFO "HW Breakpoint for %s write installed\n", ksym_name);

	return 0;

fail:
	printk(KERN_INFO "Breakpoint registration failed\n");

	return ret;
}

static void __exit hw_break_module_exit(void)
{
	unregister_wide_hw_breakpoint(sample_hbp);
	printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name);
}

module_init(hw_break_module_init);
module_exit(hw_break_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("K.Prasad");
MODULE_DESCRIPTION("ksym breakpoint");
cgi/linux/net-next.git/commit/net?h=nds-private-remove&amp;id=4205e4786d0b9fc3b4fec7b1910cf645a0468307'>net</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net/nfc?h=nds-private-remove&amp;id=4205e4786d0b9fc3b4fec7b1910cf645a0468307'>nfc</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='h' value='nds-private-remove'/><input type='hidden' name='id' value='4205e4786d0b9fc3b4fec7b1910cf645a0468307'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Thomas Gleixner &lt;tglx@linutronix.de&gt;</td><td class='right'>2017-01-10 14:01:05 +0100</td></tr>
<tr><th>committer</th><td>Thomas Gleixner &lt;tglx@linutronix.de&gt;</td><td class='right'>2017-01-16 13:20:05 +0100</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/nfc?h=nds-private-remove&amp;id=4205e4786d0b9fc3b4fec7b1910cf645a0468307'>4205e4786d0b9fc3b4fec7b1910cf645a0468307</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/nfc?id=4205e4786d0b9fc3b4fec7b1910cf645a0468307'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=4205e4786d0b9fc3b4fec7b1910cf645a0468307'>685ccb486409197b936c785eb9d173c3edff45a1</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/nfc?h=nds-private-remove&amp;id=4205e4786d0b9fc3b4fec7b1910cf645a0468307'>net/nfc</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/nfc?h=nds-private-remove&amp;id=7e164ce4e8ecd7e9a58a83750bd3ee03125df154'>7e164ce4e8ecd7e9a58a83750bd3ee03125df154</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/nfc?h=nds-private-remove&amp;id=4205e4786d0b9fc3b4fec7b1910cf645a0468307&amp;id2=7e164ce4e8ecd7e9a58a83750bd3ee03125df154'>diff</a>)</td></tr></table>
<div class='commit-subject'>cpu/hotplug: Provide dynamic range for prepare stage</div><div class='commit-msg'>Mathieu reported that the LTTNG modules are broken as of 4.10-rc1 due to
the removal of the cpu hotplug notifiers.

Usually I don't care much about out of tree modules, but LTTNG is widely
used in distros. There are two ways to solve that:

1) Reserve a hotplug state for LTTNG

2) Add a dynamic range for the prepare states.

While #1 is the simplest solution, #2 is the proper one as we can convert
in tree users, which do not care about ordering, to the dynamic range as
well.

Add a dynamic range which allows LTTNG to request states in the prepare
stage.

Reported-and-tested-by: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Sebastian Sewior &lt;bigeasy@linutronix.de&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1701101353010.3401@nanos
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;

</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=4205e4786d0b9fc3b4fec7b1910cf645a0468307'>Diffstat</a> (limited to 'net/nfc')</div><table summary='diffstat' class='diffstat'>