1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
// SPDX-License-Identifier: GPL-2.0
/*
* Provide kernel BTF information for introspection and use by eBPF tools.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kobject.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/io.h>
#include <linux/btf.h>
/* See scripts/link-vmlinux.sh, gen_btf() func for details */
extern char __start_BTF[];
extern char __stop_BTF[];
static int btf_sysfs_mmap_check(void *data, size_t size, struct vm_area_struct *vma)
{
unsigned long pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
size_t vm_size = vma->vm_end - vma->vm_start;
if (!data || !PAGE_ALIGNED((unsigned long)data))
return -EINVAL;
if (vma->vm_pgoff)
return -EINVAL;
if (vma->vm_flags & (VM_WRITE | VM_EXEC | VM_MAYSHARE))
return -EACCES;
if ((vm_size >> PAGE_SHIFT) > pages)
return -EINVAL;
vm_flags_mod(vma, VM_DONTDUMP, VM_MAYEXEC | VM_MAYWRITE);
return 0;
}
static int btf_sysfs_mmap_image(struct file *filp, struct kobject *kobj,
const struct bin_attribute *attr,
struct vm_area_struct *vma)
{
void *data = READ_ONCE(attr->private);
phys_addr_t addr;
unsigned long pfn;
size_t vm_size = vma->vm_end - vma->vm_start;
int err;
err = btf_sysfs_mmap_check(data, attr->size, vma);
if (err)
return err;
/* Kernel image addresses can lie inside the vmalloc range on arm64. */
addr = __pa_symbol(data);
pfn = addr >> PAGE_SHIFT;
if (pfn + (PAGE_ALIGN(attr->size) >> PAGE_SHIFT) < pfn)
return -EINVAL;
return remap_pfn_range(vma, vma->vm_start, pfn, vm_size, vma->vm_page_prot);
}
static struct bin_attribute bin_attr_btf_vmlinux __ro_after_init = {
.attr = { .name = "vmlinux", .mode = 0444, },
.read = sysfs_bin_attr_simple_read,
.mmap = btf_sysfs_mmap_image,
};
struct kobject *btf_kobj;
struct btf_sysfs_entry {
struct bin_attribute attr;
char *module_name;
};
static void *btf_sysfs_lazy_data(const struct bin_attribute *attr)
{
struct btf_sysfs_entry *entry = container_of(attr, struct btf_sysfs_entry, attr);
void *data;
data = smp_load_acquire(&attr->private);
if (!data) {
request_module("%s", entry->module_name);
data = smp_load_acquire(&attr->private);
}
return data;
}
static ssize_t btf_sysfs_read_lazy(struct file *filp, struct kobject *kobj,
const struct bin_attribute *attr, char *buf,
loff_t off, size_t count)
{
void *data = btf_sysfs_lazy_data(attr);
if (!data)
return -ENODEV;
return memory_read_from_buffer(buf, count, &off, data, attr->size);
}
static int btf_sysfs_mmap_lazy(struct file *filp, struct kobject *kobj,
const struct bin_attribute *attr,
struct vm_area_struct *vma)
{
void *data = btf_sysfs_lazy_data(attr);
int err;
if (!data)
return -ENODEV;
err = btf_sysfs_mmap_check(data, attr->size, vma);
if (err)
return err;
return remap_vmalloc_range(vma, data, 0);
}
struct bin_attribute *sysfs_btf_add(const char *name, void *data, size_t data_size,
bool mmap, const char *lazy_module_name)
{
struct btf_sysfs_entry *entry;
struct bin_attribute *attr;
int err;
entry = kzalloc_obj(*entry);
if (!entry)
return ERR_PTR(-ENOMEM);
attr = &entry->attr;
sysfs_bin_attr_init(attr);
attr->attr.mode = 0444;
attr->size = data_size;
attr->private = data;
attr->read = lazy_module_name ? btf_sysfs_read_lazy : sysfs_bin_attr_simple_read;
if (mmap)
attr->mmap = lazy_module_name ? btf_sysfs_mmap_lazy : btf_sysfs_mmap_image;
attr->attr.name = kstrdup(name, GFP_KERNEL);
if (!attr->attr.name) {
err = -ENOMEM;
goto err_free;
}
if (lazy_module_name) {
entry->module_name = kstrdup(lazy_module_name, GFP_KERNEL);
if (!entry->module_name) {
err = -ENOMEM;
goto err_free;
}
}
err = sysfs_create_bin_file(btf_kobj, attr);
if (err) {
pr_warn("failed to register [%s] BTF in sysfs: %d\n", name, err);
goto err_free;
}
return attr;
err_free:
kfree(entry->module_name);
kfree(attr->attr.name);
kfree(entry);
return ERR_PTR(err);
}
bool sysfs_btf_update(struct bin_attribute *attr, void *data)
{
return attr && !cmpxchg(&attr->private, NULL, data);
}
void sysfs_btf_remove(struct bin_attribute *attr)
{
struct btf_sysfs_entry *entry = container_of(attr, struct btf_sysfs_entry, attr);
sysfs_remove_bin_file(btf_kobj, attr);
kfree(entry->module_name);
kfree(attr->attr.name);
kfree(entry);
}
static int __init btf_vmlinux_init(void)
{
bin_attr_btf_vmlinux.private = __start_BTF;
bin_attr_btf_vmlinux.size = __stop_BTF - __start_BTF;
if (bin_attr_btf_vmlinux.size == 0)
return 0;
btf_kobj = kobject_create_and_add("btf", kernel_kobj);
if (!btf_kobj)
return -ENOMEM;
return sysfs_create_bin_file(btf_kobj, &bin_attr_btf_vmlinux);
}
subsys_initcall(btf_vmlinux_init);
|
