linux/samples/livepatch/livepatch-shadow-fix2.c
Thomas Gleixner 1ccea77e2a treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13
Based on 2 normalized pattern(s):

  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 see http www gnu org licenses

  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 [based]
  [from] [clk] [highbank] [c] you should have received a copy of the
  gnu general public license along with this program if not see http
  www gnu org licenses

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 355 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21 11:28:45 +02:00

133 lines
2.9 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
*/
/*
* livepatch-shadow-fix2.c - Shadow variables, livepatch demo
*
* Purpose
* -------
*
* Adds functionality to livepatch-shadow-mod's in-flight data
* structures through a shadow variable. The livepatch patches a
* routine that periodically inspects data structures, incrementing a
* per-data-structure counter, creating the counter if needed.
*
*
* Usage
* -----
*
* This module is not intended to be standalone. See the "Usage"
* section of livepatch-shadow-mod.c.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/livepatch.h>
#include <linux/slab.h>
/* Shadow variable enums */
#define SV_LEAK 1
#define SV_COUNTER 2
struct dummy {
struct list_head list;
unsigned long jiffies_expire;
};
static bool livepatch_fix2_dummy_check(struct dummy *d, unsigned long jiffies)
{
int *shadow_count;
/*
* Patch: handle in-flight dummy structures, if they do not
* already have a SV_COUNTER shadow variable, then attach a
* new one.
*/
shadow_count = klp_shadow_get_or_alloc(d, SV_COUNTER,
sizeof(*shadow_count), GFP_NOWAIT,
NULL, NULL);
if (shadow_count)
*shadow_count += 1;
return time_after(jiffies, d->jiffies_expire);
}
static void livepatch_fix2_dummy_leak_dtor(void *obj, void *shadow_data)
{
void *d = obj;
void **shadow_leak = shadow_data;
kfree(*shadow_leak);
pr_info("%s: dummy @ %p, prevented leak @ %p\n",
__func__, d, *shadow_leak);
}
static void livepatch_fix2_dummy_free(struct dummy *d)
{
void **shadow_leak;
int *shadow_count;
/* Patch: copy the memory leak patch from the fix1 module. */
shadow_leak = klp_shadow_get(d, SV_LEAK);
if (shadow_leak)
klp_shadow_free(d, SV_LEAK, livepatch_fix2_dummy_leak_dtor);
else
pr_info("%s: dummy @ %p leaked!\n", __func__, d);
/*
* Patch: fetch the SV_COUNTER shadow variable and display
* the final count. Detach the shadow variable.
*/
shadow_count = klp_shadow_get(d, SV_COUNTER);
if (shadow_count) {
pr_info("%s: dummy @ %p, check counter = %d\n",
__func__, d, *shadow_count);
klp_shadow_free(d, SV_COUNTER, NULL);
}
kfree(d);
}
static struct klp_func funcs[] = {
{
.old_name = "dummy_check",
.new_func = livepatch_fix2_dummy_check,
},
{
.old_name = "dummy_free",
.new_func = livepatch_fix2_dummy_free,
}, { }
};
static struct klp_object objs[] = {
{
.name = "livepatch_shadow_mod",
.funcs = funcs,
}, { }
};
static struct klp_patch patch = {
.mod = THIS_MODULE,
.objs = objs,
};
static int livepatch_shadow_fix2_init(void)
{
return klp_enable_patch(&patch);
}
static void livepatch_shadow_fix2_exit(void)
{
/* Cleanup any existing SV_COUNTER shadow variables */
klp_shadow_free_all(SV_COUNTER, NULL);
}
module_init(livepatch_shadow_fix2_init);
module_exit(livepatch_shadow_fix2_exit);
MODULE_LICENSE("GPL");
MODULE_INFO(livepatch, "Y");