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232 lines · 4.3 KiB

1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Privileged ADI driver for sparc64
4 *
5 * Author: Tom Hromatka <[email protected]>
6 */
7#include <linux/kernel.h>
8#include <linux/miscdevice.h>
9#include <linux/module.h>
10#include <linux/proc_fs.h>
11#include <linux/slab.h>
12#include <linux/uaccess.h>
13#include <asm/asi.h>
14
15#define MAX_BUF_SZ PAGE_SIZE
16
17static int read_mcd_tag(unsigned long addr)
18{
19 long err;
20 int ver;
21
22 __asm__ __volatile__(
23 "1: ldxa [%[addr]] %[asi], %[ver]\n"
24 " mov 0, %[err]\n"
25 "2:\n"
26 " .section .fixup,#alloc,#execinstr\n"
27 " .align 4\n"
28 "3: sethi %%hi(2b), %%g1\n"
29 " jmpl %%g1 + %%lo(2b), %%g0\n"
30 " mov %[invalid], %[err]\n"
31 " .previous\n"
32 " .section __ex_table, \"a\"\n"
33 " .align 4\n"
34 " .word 1b, 3b\n"
35 " .previous\n"
36 : [ver] "=r" (ver), [err] "=r" (err)
37 : [addr] "r" (addr), [invalid] "i" (EFAULT),
38 [asi] "i" (ASI_MCD_REAL)
39 : "memory", "g1"
40 );
41
42 if (err)
43 return -EFAULT;
44 else
45 return ver;
46}
47
48static ssize_t adi_read(struct file *file, char __user *buf,
49 size_t count, loff_t *offp)
50{
51 size_t ver_buf_sz, bytes_read = 0;
52 int ver_buf_idx = 0;
53 loff_t offset;
54 u8 *ver_buf;
55 ssize_t ret;
56
57 ver_buf_sz = min_t(size_t, count, MAX_BUF_SZ);
58 ver_buf = kmalloc(ver_buf_sz, GFP_KERNEL);
59 if (!ver_buf)
60 return -ENOMEM;
61
62 offset = (*offp) * adi_blksize();
63
64 while (bytes_read < count) {
65 ret = read_mcd_tag(offset);
66 if (ret < 0)
67 goto out;
68
69 ver_buf[ver_buf_idx] = (u8)ret;
70 ver_buf_idx++;
71 offset += adi_blksize();
72
73 if (ver_buf_idx >= ver_buf_sz) {
74 if (copy_to_user(buf + bytes_read, ver_buf,
75 ver_buf_sz)) {
76 ret = -EFAULT;
77 goto out;
78 }
79
80 bytes_read += ver_buf_sz;
81 ver_buf_idx = 0;
82
83 ver_buf_sz = min_t(size_t, count - bytes_read,
84 MAX_BUF_SZ);
85 }
86 }
87
88 (*offp) += bytes_read;
89 ret = bytes_read;
90out:
91 kfree(ver_buf);
92 return ret;
93}
94
95static int set_mcd_tag(unsigned long addr, u8 ver)
96{
97 long err;
98
99 __asm__ __volatile__(
100 "1: stxa %[ver], [%[addr]] %[asi]\n"
101 " mov 0, %[err]\n"
102 "2:\n"
103 " .section .fixup,#alloc,#execinstr\n"
104 " .align 4\n"
105 "3: sethi %%hi(2b), %%g1\n"
106 " jmpl %%g1 + %%lo(2b), %%g0\n"
107 " mov %[invalid], %[err]\n"
108 " .previous\n"
109 " .section __ex_table, \"a\"\n"
110 " .align 4\n"
111 " .word 1b, 3b\n"
112 " .previous\n"
113 : [err] "=r" (err)
114 : [ver] "r" (ver), [addr] "r" (addr),
115 [invalid] "i" (EFAULT), [asi] "i" (ASI_MCD_REAL)
116 : "memory", "g1"
117 );
118
119 if (err)
120 return -EFAULT;
121 else
122 return ver;
123}
124
125static ssize_t adi_write(struct file *file, const char __user *buf,
126 size_t count, loff_t *offp)
127{
128 size_t ver_buf_sz, bytes_written = 0;
129 loff_t offset;
130 u8 *ver_buf;
131 ssize_t ret;
132 int i;
133
134 if (count == 0)
135 return -EINVAL;
136
137 ver_buf_sz = min_t(size_t, count, MAX_BUF_SZ);
138 ver_buf = kmalloc(ver_buf_sz, GFP_KERNEL);
139 if (!ver_buf)
140 return -ENOMEM;
141
142 offset = (*offp) * adi_blksize();
143
144 do {
145 if (copy_from_user(ver_buf, &buf[bytes_written],
146 ver_buf_sz)) {
147 ret = -EFAULT;
148 goto out;
149 }
150
151 for (i = 0; i < ver_buf_sz; i++) {
152 ret = set_mcd_tag(offset, ver_buf[i]);
153 if (ret < 0)
154 goto out;
155
156 offset += adi_blksize();
157 }
158
159 bytes_written += ver_buf_sz;
160 ver_buf_sz = min_t(size_t, count - bytes_written, MAX_BUF_SZ);
161 } while (bytes_written < count);
162
163 (*offp) += bytes_written;
164 ret = bytes_written;
165out:
166 __asm__ __volatile__("membar #Sync");
167 kfree(ver_buf);
168 return ret;
169}
170
171static loff_t adi_llseek(struct file *file, loff_t offset, int whence)
172{
173 loff_t ret = -EINVAL;
174
175 switch (whence) {
176 case SEEK_END:
177 case SEEK_DATA:
178 case SEEK_HOLE:
179 /* unsupported */
180 return -EINVAL;
181 case SEEK_CUR:
182 if (offset == 0)
183 return file->f_pos;
184
185 offset += file->f_pos;
186 break;
187 case SEEK_SET:
188 break;
189 }
190
191 if (offset != file->f_pos) {
192 file->f_pos = offset;
193 ret = offset;
194 }
195
196 return ret;
197}
198
199static const struct file_operations adi_fops = {
200 .owner = THIS_MODULE,
201 .llseek = adi_llseek,
202 .read = adi_read,
203 .write = adi_write,
204 .fop_flags = FOP_UNSIGNED_OFFSET,
205};
206
207static struct miscdevice adi_miscdev = {
208 .minor = MISC_DYNAMIC_MINOR,
209 .name = KBUILD_MODNAME,
210 .fops = &adi_fops,
211};
212
213static int __init adi_init(void)
214{
215 if (!adi_capable())
216 return -EPERM;
217
218 return misc_register(&adi_miscdev);
219}
220
221static void __exit adi_exit(void)
222{
223 misc_deregister(&adi_miscdev);
224}
225
226module_init(adi_init);
227module_exit(adi_exit);
228
229MODULE_AUTHOR("Tom Hromatka <[email protected]>");
230MODULE_DESCRIPTION("Privileged interface to ADI");
231MODULE_VERSION("1.0");
232MODULE_LICENSE("GPL v2");