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kmod/patch: export patched functions information via sysfs

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This feature is implemented as:
```
[root@localhost kpatch]# insmod ./kpatch-meminfo.ko
[root@localhost kpatch]# ls /sys/kernel/kpatch/patches/kpatch_meminfo/functions/meminfo_proc_show/
new_addr  old_addr
[root@localhost kpatch]# cat /sys/kernel/kpatch/patches/kpatch_meminfo/functions/meminfo_proc_show/new_addr
0xffffffffa05211e0
[root@localhost kpatch]# cat /sys/kernel/kpatch/patches/kpatch_meminfo/functions/meminfo_proc_show/old_addr
0xffffffff8125d0e0
```

The patch module init function will allocate and init kpatch_func_obj with
customized kobj_type func_ktype. The attribute new_addr and old_addr of
kpatch_func_obj is attached to this func_ktype, so that these files could
be created by kobject_add automatically.

Signed-off-by: Jincheng Miao <jincheng.miao@gmail.com>
This commit is contained in:
Jincheng Miao 2014-05-25 01:09:28 +08:00
parent 54111376c0
commit 827a143caf
1 changed files with 128 additions and 1 deletions
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129
kmod/patch/kpatch-patch-hook.c
View File

@ -22,6 +22,7 @@
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/kallsyms.h>
#include "kpatch.h"
static bool replace;
@ -33,6 +34,15 @@ extern char __kpatch_dynrelas, __kpatch_dynrelas_end;
static struct kpatch_module kpmod;
static struct kobject *patch_kobj;
static struct kobject *functions_kobj;
struct kpatch_func_obj {
struct kobject kobj;
struct kpatch_patch *patch;
char name[KSYM_NAME_LEN];
};
static struct kpatch_func_obj **funcs = NULL;
static ssize_t patch_enabled_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
@ -67,12 +77,83 @@ static ssize_t patch_enabled_store(struct kobject *kobj,
return count;
}
static struct kobj_attribute patch_enabled_attr =
__ATTR(enabled, 0644, patch_enabled_show, patch_enabled_store);
static ssize_t func_old_addr_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct kpatch_func_obj *func =
container_of(kobj, struct kpatch_func_obj, kobj);
return sprintf(buf, "0x%lx\n", func->patch->old_addr);
}
static ssize_t func_new_addr_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct kpatch_func_obj *func =
container_of(kobj, struct kpatch_func_obj, kobj);
return sprintf(buf, "0x%lx\n", func->patch->new_addr);
}
static struct kobj_attribute old_addr_attr =
__ATTR(old_addr, S_IRUGO, func_old_addr_show, NULL);
static struct kobj_attribute new_addr_attr =
__ATTR(new_addr, S_IRUGO, func_new_addr_show, NULL);
static void func_kobj_free(struct kobject *kobj)
{
struct kpatch_func_obj *func =
container_of(kobj, struct kpatch_func_obj, kobj);
kfree(func);
}
static struct attribute *func_kobj_attrs[] = {
&old_addr_attr.attr,
&new_addr_attr.attr,
NULL,
};
static ssize_t func_kobj_show(struct kobject *kobj,
struct attribute *attr, char *buf)
{
struct kobj_attribute *func_attr =
container_of(attr, struct kobj_attribute, attr);
return func_attr->show(kobj, func_attr, buf);
}
static const struct sysfs_ops func_sysfs_ops = {
.show = func_kobj_show,
};
static struct kobj_type func_ktype = {
.release = func_kobj_free,
.sysfs_ops = &func_sysfs_ops,
.default_attrs = func_kobj_attrs,
};
static struct kpatch_func_obj *func_kobj_alloc(void)
{
struct kpatch_func_obj *func;
func = kzalloc(sizeof(*func), GFP_KERNEL);
if (!func)
return NULL;
kobject_init(&func->kobj, &func_ktype);
return func;
}
static int __init patch_init(void)
{
int ret;
int i = 0;
struct kpatch_func_obj *func = NULL;
kpmod.mod = THIS_MODULE;
kpmod.patches = (struct kpatch_patch *)&__kpatch_patches;
@ -82,6 +163,13 @@ static int __init patch_init(void)
kpmod.dynrelas_nr = (&__kpatch_dynrelas_end - &__kpatch_dynrelas) /
sizeof(*kpmod.dynrelas);
funcs = kzalloc(kpmod.patches_nr * sizeof(struct kpatch_func_obj*),
GFP_KERNEL);
if (!funcs) {
ret = -ENOMEM;
goto err_ret;
}
patch_kobj = kobject_create_and_add(THIS_MODULE->name,
kpatch_patches_kobj);
if (!patch_kobj) {
@ -93,23 +181,62 @@ static int __init patch_init(void)
if (ret)
goto err_put;
functions_kobj = kobject_create_and_add("functions", patch_kobj);
if (!functions_kobj) {
ret = -ENOMEM;
goto err_sysfs;
}
for (i = 0; i < kpmod.patches_nr; i++) {
func = func_kobj_alloc();
if (!func) {
ret = -ENOMEM;
goto err_sysfs2;
}
funcs[i] = func;
sprint_symbol_no_offset(func->name, kpmod.patches[i].old_addr);
ret = kobject_add(&func->kobj, functions_kobj,
"%s", func->name);
if (ret)
goto err_sysfs2;
func->patch = &kpmod.patches[i];
}
ret = kpatch_register(&kpmod, replace);
if (ret)
goto err_sysfs;
goto err_sysfs2;
return 0;
err_sysfs2:
for (i = 0; i < kpmod.patches_nr; i++) {
if (funcs[i] != NULL)
kobject_put(&funcs[i]->kobj);
}
kobject_put(functions_kobj);
err_sysfs:
sysfs_remove_file(patch_kobj, &patch_enabled_attr.attr);
err_put:
kobject_put(patch_kobj);
err_free:
kfree(funcs);
err_ret:
return ret;
}
static void __exit patch_exit(void)
{
int i;
WARN_ON(kpmod.enabled);
for (i = 0; i < kpmod.patches_nr; i++) {
kobject_put(&funcs[i]->kobj);
}
kfree(funcs);
kobject_put(functions_kobj);
sysfs_remove_file(patch_kobj, &patch_enabled_attr.attr);
kobject_put(patch_kobj);
}