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
20struct 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
27void papr_sysparm_buf_free(struct papr_sysparm_buf *buf)
28{
29 kfree(objp: buf);
30}
31
32static size_t papr_sysparm_buf_get_length(const struct papr_sysparm_buf *buf)
33{
34 return be16_to_cpu(buf->len);
35}
36
37static 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 */
50static void papr_sysparm_buf_clamp_length(struct papr_sysparm_buf *buf)
51{
52 papr_sysparm_buf_set_length(buf, length: 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 */
59static 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 */
96int 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
152int 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
205static struct papr_sysparm_buf *
206papr_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(error: -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(error: -EINVAL);
224
225 kern_spbuf = papr_sysparm_buf_alloc();
226 if (!kern_spbuf)
227 return ERR_PTR(error: -ENOMEM);
228
229 papr_sysparm_buf_set_length(buf: kern_spbuf, length: len);
230
231 if (len > 0 && copy_from_user(to: kern_spbuf->val, from: user_iob->data, n: len)) {
232 err = -EFAULT;
233 goto free_sysparm_buf;
234 }
235
236 return kern_spbuf;
237
238free_sysparm_buf:
239 papr_sysparm_buf_free(buf: kern_spbuf);
240 return ERR_PTR(error: err);
241}
242
243static 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(buf: 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(to: user_iob->data, from: kern_spbuf->val, n: PAPR_SYSPARM_MAX_OUTPUT))
255 return -EFAULT;
256
257 return 0;
258}
259
260static 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(ptr: kern_spbuf))
271 return PTR_ERR(ptr: 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
283free_sysparm_buf:
284 papr_sysparm_buf_free(buf: kern_spbuf);
285 return ret;
286}
287
288
289static 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(ptr: kern_spbuf))
300 return PTR_ERR(ptr: kern_spbuf);
301
302 ret = papr_sysparm_set(param, kern_spbuf);
303 if (ret)
304 goto free_sysparm_buf;
305
306 ret = 0;
307
308free_sysparm_buf:
309 papr_sysparm_buf_free(buf: kern_spbuf);
310 return ret;
311}
312
313static 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(user_iob: argp);
321 break;
322 case PAPR_SYSPARM_IOC_SET:
323 if (filp->f_mode & FMODE_WRITE)
324 ret = papr_sysparm_ioctl_set(user_iob: argp);
325 else
326 ret = -EBADF;
327 break;
328 default:
329 ret = -ENOIOCTLCMD;
330 break;
331 }
332 return ret;
333}
334
335static const struct file_operations papr_sysparm_ops = {
336 .unlocked_ioctl = papr_sysparm_ioctl,
337};
338
339static struct miscdevice papr_sysparm_dev = {
340 .minor = MISC_DYNAMIC_MINOR,
341 .name = "papr-sysparm",
342 .fops = &papr_sysparm_ops,
343};
344
345static __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(misc: &papr_sysparm_dev);
351}
352machine_device_initcall(pseries, papr_sysparm_init);
353

source code of linux/arch/powerpc/platforms/pseries/papr-sysparm.c