1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | |
3 | #define pr_fmt(fmt) "papr-vpd: " fmt |
4 | |
5 | #include <linux/anon_inodes.h> |
6 | #include <linux/build_bug.h> |
7 | #include <linux/file.h> |
8 | #include <linux/fs.h> |
9 | #include <linux/init.h> |
10 | #include <linux/lockdep.h> |
11 | #include <linux/kernel.h> |
12 | #include <linux/miscdevice.h> |
13 | #include <linux/signal.h> |
14 | #include <linux/slab.h> |
15 | #include <linux/string.h> |
16 | #include <linux/string_helpers.h> |
17 | #include <linux/uaccess.h> |
18 | #include <asm/machdep.h> |
19 | #include <asm/papr-vpd.h> |
20 | #include <asm/rtas-work-area.h> |
21 | #include <asm/rtas.h> |
22 | #include <uapi/asm/papr-vpd.h> |
23 | |
24 | /* |
25 | * Function-specific return values for ibm,get-vpd, derived from PAPR+ |
26 | * v2.13 7.3.20 "ibm,get-vpd RTAS Call". |
27 | */ |
28 | #define RTAS_IBM_GET_VPD_COMPLETE 0 /* All VPD has been retrieved. */ |
29 | #define RTAS_IBM_GET_VPD_MORE_DATA 1 /* More VPD is available. */ |
30 | #define RTAS_IBM_GET_VPD_START_OVER -4 /* VPD changed, restart call sequence. */ |
31 | |
32 | /** |
33 | * struct rtas_ibm_get_vpd_params - Parameters (in and out) for ibm,get-vpd. |
34 | * @loc_code: In: Caller-provided location code buffer. Must be RTAS-addressable. |
35 | * @work_area: In: Caller-provided work area buffer for results. |
36 | * @sequence: In: Sequence number. Out: Next sequence number. |
37 | * @written: Out: Bytes written by ibm,get-vpd to @work_area. |
38 | * @status: Out: RTAS call status. |
39 | */ |
40 | struct rtas_ibm_get_vpd_params { |
41 | const struct papr_location_code *loc_code; |
42 | struct rtas_work_area *work_area; |
43 | u32 sequence; |
44 | u32 written; |
45 | s32 status; |
46 | }; |
47 | |
48 | /** |
49 | * rtas_ibm_get_vpd() - Call ibm,get-vpd to fill a work area buffer. |
50 | * @params: See &struct rtas_ibm_get_vpd_params. |
51 | * |
52 | * Calls ibm,get-vpd until it errors or successfully deposits data |
53 | * into the supplied work area. Handles RTAS retry statuses. Maps RTAS |
54 | * error statuses to reasonable errno values. |
55 | * |
56 | * The caller is expected to invoke rtas_ibm_get_vpd() multiple times |
57 | * to retrieve all the VPD for the provided location code. Only one |
58 | * sequence should be in progress at any time; starting a new sequence |
59 | * will disrupt any sequence already in progress. Serialization of VPD |
60 | * retrieval sequences is the responsibility of the caller. |
61 | * |
62 | * The caller should inspect @params.status to determine whether more |
63 | * calls are needed to complete the sequence. |
64 | * |
65 | * Context: May sleep. |
66 | * Return: -ve on error, 0 otherwise. |
67 | */ |
68 | static int rtas_ibm_get_vpd(struct rtas_ibm_get_vpd_params *params) |
69 | { |
70 | const struct papr_location_code *loc_code = params->loc_code; |
71 | struct rtas_work_area *work_area = params->work_area; |
72 | u32 rets[2]; |
73 | s32 fwrc; |
74 | int ret; |
75 | |
76 | lockdep_assert_held(&rtas_ibm_get_vpd_lock); |
77 | |
78 | do { |
79 | fwrc = rtas_call(rtas_function_token(RTAS_FN_IBM_GET_VPD), 4, 3, |
80 | rets, |
81 | __pa(loc_code), |
82 | rtas_work_area_phys(work_area), |
83 | rtas_work_area_size(work_area), |
84 | params->sequence); |
85 | } while (rtas_busy_delay(fwrc)); |
86 | |
87 | switch (fwrc) { |
88 | case RTAS_HARDWARE_ERROR: |
89 | ret = -EIO; |
90 | break; |
91 | case RTAS_INVALID_PARAMETER: |
92 | ret = -EINVAL; |
93 | break; |
94 | case RTAS_IBM_GET_VPD_START_OVER: |
95 | ret = -EAGAIN; |
96 | break; |
97 | case RTAS_IBM_GET_VPD_MORE_DATA: |
98 | params->sequence = rets[0]; |
99 | fallthrough; |
100 | case RTAS_IBM_GET_VPD_COMPLETE: |
101 | params->written = rets[1]; |
102 | /* |
103 | * Kernel or firmware bug, do not continue. |
104 | */ |
105 | if (WARN(params->written > rtas_work_area_size(work_area), |
106 | "possible write beyond end of work area" )) |
107 | ret = -EFAULT; |
108 | else |
109 | ret = 0; |
110 | break; |
111 | default: |
112 | ret = -EIO; |
113 | pr_err_ratelimited("unexpected ibm,get-vpd status %d\n" , fwrc); |
114 | break; |
115 | } |
116 | |
117 | params->status = fwrc; |
118 | return ret; |
119 | } |
120 | |
121 | /* |
122 | * Internal VPD "blob" APIs for accumulating ibm,get-vpd results into |
123 | * an immutable buffer to be attached to a file descriptor. |
124 | */ |
125 | struct vpd_blob { |
126 | const char *data; |
127 | size_t len; |
128 | }; |
129 | |
130 | static bool vpd_blob_has_data(const struct vpd_blob *blob) |
131 | { |
132 | return blob->data && blob->len; |
133 | } |
134 | |
135 | static void vpd_blob_free(const struct vpd_blob *blob) |
136 | { |
137 | if (blob) { |
138 | kvfree(addr: blob->data); |
139 | kfree(objp: blob); |
140 | } |
141 | } |
142 | |
143 | /** |
144 | * vpd_blob_extend() - Append data to a &struct vpd_blob. |
145 | * @blob: The blob to extend. |
146 | * @data: The new data to append to @blob. |
147 | * @len: The length of @data. |
148 | * |
149 | * Context: May sleep. |
150 | * Return: -ENOMEM on allocation failure, 0 otherwise. |
151 | */ |
152 | static int vpd_blob_extend(struct vpd_blob *blob, const char *data, size_t len) |
153 | { |
154 | const size_t new_len = blob->len + len; |
155 | const size_t old_len = blob->len; |
156 | const char *old_ptr = blob->data; |
157 | char *new_ptr; |
158 | |
159 | new_ptr = old_ptr ? |
160 | kvrealloc(p: old_ptr, oldsize: old_len, newsize: new_len, GFP_KERNEL_ACCOUNT) : |
161 | kvmalloc(size: len, GFP_KERNEL_ACCOUNT); |
162 | |
163 | if (!new_ptr) |
164 | return -ENOMEM; |
165 | |
166 | memcpy(&new_ptr[old_len], data, len); |
167 | blob->data = new_ptr; |
168 | blob->len = new_len; |
169 | return 0; |
170 | } |
171 | |
172 | /** |
173 | * vpd_blob_generate() - Construct a new &struct vpd_blob. |
174 | * @generator: Function that supplies the blob data. |
175 | * @arg: Context pointer supplied by caller, passed to @generator. |
176 | * |
177 | * The @generator callback is invoked until it returns NULL. @arg is |
178 | * passed to @generator in its first argument on each call. When |
179 | * @generator returns data, it should store the data length in its |
180 | * second argument. |
181 | * |
182 | * Context: May sleep. |
183 | * Return: A completely populated &struct vpd_blob, or NULL on error. |
184 | */ |
185 | static const struct vpd_blob * |
186 | vpd_blob_generate(const char * (*generator)(void *, size_t *), void *arg) |
187 | { |
188 | struct vpd_blob *blob; |
189 | const char *buf; |
190 | size_t len; |
191 | int err = 0; |
192 | |
193 | blob = kzalloc(size: sizeof(*blob), GFP_KERNEL_ACCOUNT); |
194 | if (!blob) |
195 | return NULL; |
196 | |
197 | while (err == 0 && (buf = generator(arg, &len))) |
198 | err = vpd_blob_extend(blob, data: buf, len); |
199 | |
200 | if (err != 0 || !vpd_blob_has_data(blob)) |
201 | goto free_blob; |
202 | |
203 | return blob; |
204 | free_blob: |
205 | vpd_blob_free(blob); |
206 | return NULL; |
207 | } |
208 | |
209 | /* |
210 | * Internal VPD sequence APIs. A VPD sequence is a series of calls to |
211 | * ibm,get-vpd for a given location code. The sequence ends when an |
212 | * error is encountered or all VPD for the location code has been |
213 | * returned. |
214 | */ |
215 | |
216 | /** |
217 | * struct vpd_sequence - State for managing a VPD sequence. |
218 | * @error: Shall be zero as long as the sequence has not encountered an error, |
219 | * -ve errno otherwise. Use vpd_sequence_set_err() to update this. |
220 | * @params: Parameter block to pass to rtas_ibm_get_vpd(). |
221 | */ |
222 | struct vpd_sequence { |
223 | int error; |
224 | struct rtas_ibm_get_vpd_params params; |
225 | }; |
226 | |
227 | /** |
228 | * vpd_sequence_begin() - Begin a VPD retrieval sequence. |
229 | * @seq: Uninitialized sequence state. |
230 | * @loc_code: Location code that defines the scope of the VPD to return. |
231 | * |
232 | * Initializes @seq with the resources necessary to carry out a VPD |
233 | * sequence. Callers must pass @seq to vpd_sequence_end() regardless |
234 | * of whether the sequence succeeds. |
235 | * |
236 | * Context: May sleep. |
237 | */ |
238 | static void vpd_sequence_begin(struct vpd_sequence *seq, |
239 | const struct papr_location_code *loc_code) |
240 | { |
241 | /* |
242 | * Use a static data structure for the location code passed to |
243 | * RTAS to ensure it's in the RMA and avoid a separate work |
244 | * area allocation. Guarded by the function lock. |
245 | */ |
246 | static struct papr_location_code static_loc_code; |
247 | |
248 | /* |
249 | * We could allocate the work area before acquiring the |
250 | * function lock, but that would allow concurrent requests to |
251 | * exhaust the limited work area pool for no benefit. So |
252 | * allocate the work area under the lock. |
253 | */ |
254 | mutex_lock(&rtas_ibm_get_vpd_lock); |
255 | static_loc_code = *loc_code; |
256 | *seq = (struct vpd_sequence) { |
257 | .params = { |
258 | .work_area = rtas_work_area_alloc(SZ_4K), |
259 | .loc_code = &static_loc_code, |
260 | .sequence = 1, |
261 | }, |
262 | }; |
263 | } |
264 | |
265 | /** |
266 | * vpd_sequence_end() - Finalize a VPD retrieval sequence. |
267 | * @seq: Sequence state. |
268 | * |
269 | * Releases resources obtained by vpd_sequence_begin(). |
270 | */ |
271 | static void vpd_sequence_end(struct vpd_sequence *seq) |
272 | { |
273 | rtas_work_area_free(seq->params.work_area); |
274 | mutex_unlock(lock: &rtas_ibm_get_vpd_lock); |
275 | } |
276 | |
277 | /** |
278 | * vpd_sequence_should_stop() - Determine whether a VPD retrieval sequence |
279 | * should continue. |
280 | * @seq: VPD sequence state. |
281 | * |
282 | * Examines the sequence error state and outputs of the last call to |
283 | * ibm,get-vpd to determine whether the sequence in progress should |
284 | * continue or stop. |
285 | * |
286 | * Return: True if the sequence has encountered an error or if all VPD for |
287 | * this sequence has been retrieved. False otherwise. |
288 | */ |
289 | static bool vpd_sequence_should_stop(const struct vpd_sequence *seq) |
290 | { |
291 | bool done; |
292 | |
293 | if (seq->error) |
294 | return true; |
295 | |
296 | switch (seq->params.status) { |
297 | case 0: |
298 | if (seq->params.written == 0) |
299 | done = false; /* Initial state. */ |
300 | else |
301 | done = true; /* All data consumed. */ |
302 | break; |
303 | case 1: |
304 | done = false; /* More data available. */ |
305 | break; |
306 | default: |
307 | done = true; /* Error encountered. */ |
308 | break; |
309 | } |
310 | |
311 | return done; |
312 | } |
313 | |
314 | static int vpd_sequence_set_err(struct vpd_sequence *seq, int err) |
315 | { |
316 | /* Preserve the first error recorded. */ |
317 | if (seq->error == 0) |
318 | seq->error = err; |
319 | |
320 | return seq->error; |
321 | } |
322 | |
323 | /* |
324 | * Generator function to be passed to vpd_blob_generate(). |
325 | */ |
326 | static const char *vpd_sequence_fill_work_area(void *arg, size_t *len) |
327 | { |
328 | struct vpd_sequence *seq = arg; |
329 | struct rtas_ibm_get_vpd_params *p = &seq->params; |
330 | |
331 | if (vpd_sequence_should_stop(seq)) |
332 | return NULL; |
333 | if (vpd_sequence_set_err(seq, err: rtas_ibm_get_vpd(params: p))) |
334 | return NULL; |
335 | *len = p->written; |
336 | return rtas_work_area_raw_buf(p->work_area); |
337 | } |
338 | |
339 | /* |
340 | * Higher-level VPD retrieval code below. These functions use the |
341 | * vpd_blob_* and vpd_sequence_* APIs defined above to create fd-based |
342 | * VPD handles for consumption by user space. |
343 | */ |
344 | |
345 | /** |
346 | * papr_vpd_run_sequence() - Run a single VPD retrieval sequence. |
347 | * @loc_code: Location code that defines the scope of VPD to return. |
348 | * |
349 | * Context: May sleep. Holds a mutex and an RTAS work area for its |
350 | * duration. Typically performs multiple sleepable slab |
351 | * allocations. |
352 | * |
353 | * Return: A populated &struct vpd_blob on success. Encoded error |
354 | * pointer otherwise. |
355 | */ |
356 | static const struct vpd_blob *papr_vpd_run_sequence(const struct papr_location_code *loc_code) |
357 | { |
358 | const struct vpd_blob *blob; |
359 | struct vpd_sequence seq; |
360 | |
361 | vpd_sequence_begin(seq: &seq, loc_code); |
362 | blob = vpd_blob_generate(generator: vpd_sequence_fill_work_area, arg: &seq); |
363 | if (!blob) |
364 | vpd_sequence_set_err(seq: &seq, err: -ENOMEM); |
365 | vpd_sequence_end(seq: &seq); |
366 | |
367 | if (seq.error) { |
368 | vpd_blob_free(blob); |
369 | return ERR_PTR(error: seq.error); |
370 | } |
371 | |
372 | return blob; |
373 | } |
374 | |
375 | /** |
376 | * papr_vpd_retrieve() - Return the VPD for a location code. |
377 | * @loc_code: Location code that defines the scope of VPD to return. |
378 | * |
379 | * Run VPD sequences against @loc_code until a blob is successfully |
380 | * instantiated, or a hard error is encountered, or a fatal signal is |
381 | * pending. |
382 | * |
383 | * Context: May sleep. |
384 | * Return: A fully populated VPD blob when successful. Encoded error |
385 | * pointer otherwise. |
386 | */ |
387 | static const struct vpd_blob *papr_vpd_retrieve(const struct papr_location_code *loc_code) |
388 | { |
389 | const struct vpd_blob *blob; |
390 | |
391 | /* |
392 | * EAGAIN means the sequence errored with a -4 (VPD changed) |
393 | * status from ibm,get-vpd, and we should attempt a new |
394 | * sequence. PAPR+ v2.13 R1–7.3.20–5 indicates that this |
395 | * should be a transient condition, not something that happens |
396 | * continuously. But we'll stop trying on a fatal signal. |
397 | */ |
398 | do { |
399 | blob = papr_vpd_run_sequence(loc_code); |
400 | if (!IS_ERR(ptr: blob)) /* Success. */ |
401 | break; |
402 | if (PTR_ERR(ptr: blob) != -EAGAIN) /* Hard error. */ |
403 | break; |
404 | pr_info_ratelimited("VPD changed during retrieval, retrying\n" ); |
405 | cond_resched(); |
406 | } while (!fatal_signal_pending(current)); |
407 | |
408 | return blob; |
409 | } |
410 | |
411 | static ssize_t papr_vpd_handle_read(struct file *file, char __user *buf, size_t size, loff_t *off) |
412 | { |
413 | const struct vpd_blob *blob = file->private_data; |
414 | |
415 | /* bug: we should not instantiate a handle without any data attached. */ |
416 | if (!vpd_blob_has_data(blob)) { |
417 | pr_err_once("handle without data\n" ); |
418 | return -EIO; |
419 | } |
420 | |
421 | return simple_read_from_buffer(to: buf, count: size, ppos: off, from: blob->data, available: blob->len); |
422 | } |
423 | |
424 | static int papr_vpd_handle_release(struct inode *inode, struct file *file) |
425 | { |
426 | const struct vpd_blob *blob = file->private_data; |
427 | |
428 | vpd_blob_free(blob); |
429 | |
430 | return 0; |
431 | } |
432 | |
433 | static loff_t papr_vpd_handle_seek(struct file *file, loff_t off, int whence) |
434 | { |
435 | const struct vpd_blob *blob = file->private_data; |
436 | |
437 | return fixed_size_llseek(file, offset: off, whence, size: blob->len); |
438 | } |
439 | |
440 | |
441 | static const struct file_operations papr_vpd_handle_ops = { |
442 | .read = papr_vpd_handle_read, |
443 | .llseek = papr_vpd_handle_seek, |
444 | .release = papr_vpd_handle_release, |
445 | }; |
446 | |
447 | /** |
448 | * papr_vpd_create_handle() - Create a fd-based handle for reading VPD. |
449 | * @ulc: Location code in user memory; defines the scope of the VPD to |
450 | * retrieve. |
451 | * |
452 | * Handler for PAPR_VPD_IOC_CREATE_HANDLE ioctl command. Validates |
453 | * @ulc and instantiates an immutable VPD "blob" for it. The blob is |
454 | * attached to a file descriptor for reading by user space. The memory |
455 | * backing the blob is freed when the file is released. |
456 | * |
457 | * The entire requested VPD is retrieved by this call and all |
458 | * necessary RTAS interactions are performed before returning the fd |
459 | * to user space. This keeps the read handler simple and ensures that |
460 | * the kernel can prevent interleaving of ibm,get-vpd call sequences. |
461 | * |
462 | * Return: The installed fd number if successful, -ve errno otherwise. |
463 | */ |
464 | static long papr_vpd_create_handle(struct papr_location_code __user *ulc) |
465 | { |
466 | struct papr_location_code klc; |
467 | const struct vpd_blob *blob; |
468 | struct file *file; |
469 | long err; |
470 | int fd; |
471 | |
472 | if (copy_from_user(to: &klc, from: ulc, n: sizeof(klc))) |
473 | return -EFAULT; |
474 | |
475 | if (!string_is_terminated(s: klc.str, ARRAY_SIZE(klc.str))) |
476 | return -EINVAL; |
477 | |
478 | blob = papr_vpd_retrieve(loc_code: &klc); |
479 | if (IS_ERR(ptr: blob)) |
480 | return PTR_ERR(ptr: blob); |
481 | |
482 | fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC); |
483 | if (fd < 0) { |
484 | err = fd; |
485 | goto free_blob; |
486 | } |
487 | |
488 | file = anon_inode_getfile(name: "[papr-vpd]" , fops: &papr_vpd_handle_ops, |
489 | priv: (void *)blob, O_RDONLY); |
490 | if (IS_ERR(ptr: file)) { |
491 | err = PTR_ERR(ptr: file); |
492 | goto put_fd; |
493 | } |
494 | |
495 | file->f_mode |= FMODE_LSEEK | FMODE_PREAD; |
496 | fd_install(fd, file); |
497 | return fd; |
498 | put_fd: |
499 | put_unused_fd(fd); |
500 | free_blob: |
501 | vpd_blob_free(blob); |
502 | return err; |
503 | } |
504 | |
505 | /* |
506 | * Top-level ioctl handler for /dev/papr-vpd. |
507 | */ |
508 | static long papr_vpd_dev_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) |
509 | { |
510 | void __user *argp = (__force void __user *)arg; |
511 | long ret; |
512 | |
513 | switch (ioctl) { |
514 | case PAPR_VPD_IOC_CREATE_HANDLE: |
515 | ret = papr_vpd_create_handle(ulc: argp); |
516 | break; |
517 | default: |
518 | ret = -ENOIOCTLCMD; |
519 | break; |
520 | } |
521 | return ret; |
522 | } |
523 | |
524 | static const struct file_operations papr_vpd_ops = { |
525 | .unlocked_ioctl = papr_vpd_dev_ioctl, |
526 | }; |
527 | |
528 | static struct miscdevice papr_vpd_dev = { |
529 | .minor = MISC_DYNAMIC_MINOR, |
530 | .name = "papr-vpd" , |
531 | .fops = &papr_vpd_ops, |
532 | }; |
533 | |
534 | static __init int papr_vpd_init(void) |
535 | { |
536 | if (!rtas_function_implemented(RTAS_FN_IBM_GET_VPD)) |
537 | return -ENODEV; |
538 | |
539 | return misc_register(misc: &papr_vpd_dev); |
540 | } |
541 | machine_device_initcall(pseries, papr_vpd_init); |
542 | |