1 // SPDX-License-Identifier: GPL-2.0-only
2
3 #define pr_fmt(fmt) "papr-sysparm: " fmt
4
5 #include <linux/anon_inodes.h>
6 #include <linux/bug.h>
7 #include <linux/file.h>
8 #include <linux/fs.h>
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/miscdevice.h>
12 #include <linux/printk.h>
13 #include <linux/slab.h>
14 #include <linux/uaccess.h>
15 #include <asm/machdep.h>
16 #include <asm/papr-sysparm.h>
17 #include <asm/rtas-work-area.h>
18 #include <asm/rtas.h>
19
20 struct papr_sysparm_buf *papr_sysparm_buf_alloc(void)
21 {
22 struct papr_sysparm_buf *buf = kzalloc(sizeof(*buf), GFP_KERNEL);
23
24 return buf;
25 }
26
27 void papr_sysparm_buf_free(struct papr_sysparm_buf *buf)
28 {
29 kfree(buf);
30 }
31
32 static size_t papr_sysparm_buf_get_length(const struct papr_sysparm_buf *buf)
33 {
34 return be16_to_cpu(buf->len);
35 }
36
37 static void papr_sysparm_buf_set_length(struct papr_sysparm_buf *buf, size_t length)
38 {
39 WARN_ONCE(length > sizeof(buf->val),
40 "bogus length %zu, clamping to safe value", length);
41 length = min(sizeof(buf->val), length);
42 buf->len = cpu_to_be16(length);
43 }
44
45 /*
46 * For use on buffers returned from ibm,get-system-parameter before
47 * returning them to callers. Ensures the encoded length of valid data
48 * cannot overrun buf->val[].
49 */
50 static void papr_sysparm_buf_clamp_length(struct papr_sysparm_buf *buf)
51 {
52 papr_sysparm_buf_set_length(buf, papr_sysparm_buf_get_length(buf));
53 }
54
55 /*
56 * Perform some basic diligence on the system parameter buffer before
57 * submitting it to RTAS.
58 */
59 static bool papr_sysparm_buf_can_submit(const struct papr_sysparm_buf *buf)
60 {
61 /*
62 * Firmware ought to reject buffer lengths that exceed the
63 * maximum specified in PAPR, but there's no reason for the
64 * kernel to allow them either.
65 */
66 if (papr_sysparm_buf_get_length(buf) > sizeof(buf->val))
67 return false;
68
69 return true;
70 }
71
72 /**
73 * papr_sysparm_get() - Retrieve the value of a PAPR system parameter.
74 * @param: PAPR system parameter token as described in
75 * 7.3.16 "System Parameters Option".
76 * @buf: A &struct papr_sysparm_buf as returned from papr_sysparm_buf_alloc().
77 *
78 * Place the result of querying the specified parameter, if available,
79 * in @buf. The result includes a be16 length header followed by the
80 * value, which may be a string or binary data. See &struct papr_sysparm_buf.
81 *
82 * Since there is at least one parameter (60, OS Service Entitlement
83 * Status) where the results depend on the incoming contents of the
84 * work area, the caller-supplied buffer is copied unmodified into the
85 * work area before calling ibm,get-system-parameter.
86 *
87 * A defined parameter may not be implemented on a given system, and
88 * some implemented parameters may not be available to all partitions
89 * on a system. A parameter's disposition may change at any time due
90 * to system configuration changes or partition migration.
91 *
92 * Context: This function may sleep.
93 *
94 * Return: 0 on success, -errno otherwise. @buf is unmodified on error.
95 */
96 int papr_sysparm_get(papr_sysparm_t param, struct papr_sysparm_buf *buf)
97 {
98 const s32 token = rtas_function_token(RTAS_FN_IBM_GET_SYSTEM_PARAMETER);
99 struct rtas_work_area *work_area;
100 s32 fwrc;
101 int ret;
102
103 might_sleep();
104
105 if (WARN_ON(!buf))
106 return -EFAULT;
107
108 if (token == RTAS_UNKNOWN_SERVICE)
109 return -ENOENT;
110
111 if (!papr_sysparm_buf_can_submit(buf))
112 return -EINVAL;
113
114 work_area = rtas_work_area_alloc(sizeof(*buf));
115
116 memcpy(rtas_work_area_raw_buf(work_area), buf, sizeof(*buf));
117
118 do {
119 fwrc = rtas_call(token, 3, 1, NULL, param.token,
120 rtas_work_area_phys(work_area),
121 rtas_work_area_size(work_area));
122 } while (rtas_busy_delay(fwrc));
123
124 switch (fwrc) {
125 case 0:
126 ret = 0;
127 memcpy(buf, rtas_work_area_raw_buf(work_area), sizeof(*buf));
128 papr_sysparm_buf_clamp_length(buf);
129 break;
130 case -3: /* parameter not implemented */
131 ret = -EOPNOTSUPP;
132 break;
133 case -9002: /* this partition not authorized to retrieve this parameter */
134 ret = -EPERM;
135 break;
136 case -9999: /* "parameter error" e.g. the buffer is too small */
137 ret = -EINVAL;
138 break;
139 default:
140 pr_err("unexpected ibm,get-system-parameter result %d\n", fwrc);
141 fallthrough;
142 case -1: /* Hardware/platform error */
143 ret = -EIO;
144 break;
145 }
146
147 rtas_work_area_free(work_area);
148
149 return ret;
150 }
151
152 int papr_sysparm_set(papr_sysparm_t param, const struct papr_sysparm_buf *buf)
153 {
154 const s32 token = rtas_function_token(RTAS_FN_IBM_SET_SYSTEM_PARAMETER);
155 struct rtas_work_area *work_area;
156 s32 fwrc;
157 int ret;
158
159 might_sleep();
160
161 if (WARN_ON(!buf))
162 return -EFAULT;
163
164 if (token == RTAS_UNKNOWN_SERVICE)
165 return -ENOENT;
166
167 if (!papr_sysparm_buf_can_submit(buf))
168 return -EINVAL;
169
170 work_area = rtas_work_area_alloc(sizeof(*buf));
171
172 memcpy(rtas_work_area_raw_buf(work_area), buf, sizeof(*buf));
173
174 do {
175 fwrc = rtas_call(token, 2, 1, NULL, param.token,
176 rtas_work_area_phys(work_area));
177 } while (rtas_busy_delay(fwrc));
178
179 switch (fwrc) {
180 case 0:
181 ret = 0;
182 break;
183 case -3: /* parameter not supported */
184 ret = -EOPNOTSUPP;
185 break;
186 case -9002: /* this partition not authorized to modify this parameter */
187 ret = -EPERM;
188 break;
189 case -9999: /* "parameter error" e.g. invalid input data */
190 ret = -EINVAL;
191 break;
192 default:
193 pr_err("unexpected ibm,set-system-parameter result %d\n", fwrc);
194 fallthrough;
195 case -1: /* Hardware/platform error */
196 ret = -EIO;
197 break;
198 }
199
200 rtas_work_area_free(work_area);
201
202 return ret;
203 }
204
205 static struct papr_sysparm_buf *
206 papr_sysparm_buf_from_user(const struct papr_sysparm_io_block __user *user_iob)
207 {
208 struct papr_sysparm_buf *kern_spbuf;
209 long err;
210 u16 len;
211
212 /*
213 * The length of valid data that userspace claims to be in
214 * user_iob->data[].
215 */
216 if (get_user(len, &user_iob->length))
217 return ERR_PTR(-EFAULT);
218
219 static_assert(sizeof(user_iob->data) >= PAPR_SYSPARM_MAX_INPUT);
220 static_assert(sizeof(kern_spbuf->val) >= PAPR_SYSPARM_MAX_INPUT);
221
222 if (len > PAPR_SYSPARM_MAX_INPUT)
223 return ERR_PTR(-EINVAL);
224
225 kern_spbuf = papr_sysparm_buf_alloc();
226 if (!kern_spbuf)
227 return ERR_PTR(-ENOMEM);
228
229 papr_sysparm_buf_set_length(kern_spbuf, len);
230
231 if (len > 0 && copy_from_user(kern_spbuf->val, user_iob->data, len)) {
232 err = -EFAULT;
233 goto free_sysparm_buf;
234 }
235
236 return kern_spbuf;
237
238 free_sysparm_buf:
239 papr_sysparm_buf_free(kern_spbuf);
240 return ERR_PTR(err);
241 }
242
243 static int papr_sysparm_buf_to_user(const struct papr_sysparm_buf *kern_spbuf,
244 struct papr_sysparm_io_block __user *user_iob)
245 {
246 u16 len_out = papr_sysparm_buf_get_length(kern_spbuf);
247
248 if (put_user(len_out, &user_iob->length))
249 return -EFAULT;
250
251 static_assert(sizeof(user_iob->data) >= PAPR_SYSPARM_MAX_OUTPUT);
252 static_assert(sizeof(kern_spbuf->val) >= PAPR_SYSPARM_MAX_OUTPUT);
253
254 if (copy_to_user(user_iob->data, kern_spbuf->val, PAPR_SYSPARM_MAX_OUTPUT))
255 return -EFAULT;
256
257 return 0;
258 }
259
260 static long papr_sysparm_ioctl_get(struct papr_sysparm_io_block __user *user_iob)
261 {
262 struct papr_sysparm_buf *kern_spbuf;
263 papr_sysparm_t param;
264 long ret;
265
266 if (get_user(param.token, &user_iob->parameter))
267 return -EFAULT;
268
269 kern_spbuf = papr_sysparm_buf_from_user(user_iob);
270 if (IS_ERR(kern_spbuf))
271 return PTR_ERR(kern_spbuf);
272
273 ret = papr_sysparm_get(param, kern_spbuf);
274 if (ret)
275 goto free_sysparm_buf;
276
277 ret = papr_sysparm_buf_to_user(kern_spbuf, user_iob);
278 if (ret)
279 goto free_sysparm_buf;
280
281 ret = 0;
282
283 free_sysparm_buf:
284 papr_sysparm_buf_free(kern_spbuf);
285 return ret;
286 }
287
288
289 static long papr_sysparm_ioctl_set(struct papr_sysparm_io_block __user *user_iob)
290 {
291 struct papr_sysparm_buf *kern_spbuf;
292 papr_sysparm_t param;
293 long ret;
294
295 if (get_user(param.token, &user_iob->parameter))
296 return -EFAULT;
297
298 kern_spbuf = papr_sysparm_buf_from_user(user_iob);
299 if (IS_ERR(kern_spbuf))
300 return PTR_ERR(kern_spbuf);
301
302 ret = papr_sysparm_set(param, kern_spbuf);
303 if (ret)
304 goto free_sysparm_buf;
305
306 ret = 0;
307
308 free_sysparm_buf:
309 papr_sysparm_buf_free(kern_spbuf);
310 return ret;
311 }
312
313 static long papr_sysparm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
314 {
315 void __user *argp = (__force void __user *)arg;
316 long ret;
317
318 switch (ioctl) {
319 case PAPR_SYSPARM_IOC_GET:
320 ret = papr_sysparm_ioctl_get(argp);
321 break;
322 case PAPR_SYSPARM_IOC_SET:
323 if (filp->f_mode & FMODE_WRITE)
324 ret = papr_sysparm_ioctl_set(argp);
325 else
326 ret = -EBADF;
327 break;
328 default:
329 ret = -ENOIOCTLCMD;
330 break;
331 }
332 return ret;
333 }
334
335 static const struct file_operations papr_sysparm_ops = {
336 .unlocked_ioctl = papr_sysparm_ioctl,
337 };
338
339 static struct miscdevice papr_sysparm_dev = {
340 .minor = MISC_DYNAMIC_MINOR,
341 .name = "papr-sysparm",
342 .fops = &papr_sysparm_ops,
343 };
344
345 static __init int papr_sysparm_init(void)
346 {
347 if (!rtas_function_implemented(RTAS_FN_IBM_GET_SYSTEM_PARAMETER))
348 return -ENODEV;
349
350 return misc_register(&papr_sysparm_dev);
351 }
352 machine_device_initcall(pseries, papr_sysparm_init);
353
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