xref: /openbmc/u-boot/cmd/tpm_test.c (revision 5396b2a9)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (c) 2015 Google, Inc
4  */
5 
6 #include <common.h>
7 #include <command.h>
8 #include <environment.h>
9 #include <tpm-v1.h>
10 #include "tpm-user-utils.h"
11 
12 /* Prints error and returns on failure */
13 #define TPM_CHECK(tpm_command) do { \
14 	uint32_t result; \
15 	\
16 	result = (tpm_command); \
17 	if (result != TPM_SUCCESS) { \
18 		printf("TEST FAILED: line %d: " #tpm_command ": 0x%x\n", \
19 			__LINE__, result); \
20 		return result; \
21 	} \
22 } while (0)
23 
24 #define INDEX0			0xda70
25 #define INDEX1			0xda71
26 #define INDEX2			0xda72
27 #define INDEX3			0xda73
28 #define INDEX_INITIALISED	0xda80
29 #define PHYS_PRESENCE		4
30 #define PRESENCE		8
31 
32 static uint32_t TlclStartupIfNeeded(struct udevice *dev)
33 {
34 	uint32_t result = tpm_startup(dev, TPM_ST_CLEAR);
35 
36 	return result == TPM_INVALID_POSTINIT ? TPM_SUCCESS : result;
37 }
38 
39 static int test_timer(struct udevice *dev)
40 {
41 	printf("get_timer(0) = %lu\n", get_timer(0));
42 	return 0;
43 }
44 
45 static uint32_t tpm_get_flags(struct udevice *dev, uint8_t *disable,
46 			      uint8_t *deactivated, uint8_t *nvlocked)
47 {
48 	struct tpm_permanent_flags pflags;
49 	uint32_t result;
50 
51 	result = tpm_get_permanent_flags(dev, &pflags);
52 	if (result)
53 		return result;
54 	if (disable)
55 		*disable = pflags.disable;
56 	if (deactivated)
57 		*deactivated = pflags.deactivated;
58 	if (nvlocked)
59 		*nvlocked = pflags.nv_locked;
60 	debug("TPM: Got flags disable=%d, deactivated=%d, nvlocked=%d\n",
61 	      pflags.disable, pflags.deactivated, pflags.nv_locked);
62 
63 	return 0;
64 }
65 
66 static uint32_t tpm_nv_write_value_lock(struct udevice *dev, uint32_t index)
67 {
68 	debug("TPM: Write lock 0x%x\n", index);
69 
70 	return tpm_nv_write_value(dev, index, NULL, 0);
71 }
72 
73 static int tpm_is_owned(struct udevice *dev)
74 {
75 	uint8_t response[TPM_PUBEK_SIZE];
76 	uint32_t result;
77 
78 	result = tpm_read_pubek(dev, response, sizeof(response));
79 
80 	return result != TPM_SUCCESS;
81 }
82 
83 static int test_early_extend(struct udevice *dev)
84 {
85 	uint8_t value_in[20];
86 	uint8_t value_out[20];
87 
88 	printf("Testing earlyextend ...");
89 	tpm_init(dev);
90 	TPM_CHECK(tpm_startup(dev, TPM_ST_CLEAR));
91 	TPM_CHECK(tpm_continue_self_test(dev));
92 	TPM_CHECK(tpm_extend(dev, 1, value_in, value_out));
93 	printf("done\n");
94 	return 0;
95 }
96 
97 static int test_early_nvram(struct udevice *dev)
98 {
99 	uint32_t x;
100 
101 	printf("Testing earlynvram ...");
102 	tpm_init(dev);
103 	TPM_CHECK(tpm_startup(dev, TPM_ST_CLEAR));
104 	TPM_CHECK(tpm_continue_self_test(dev));
105 	TPM_CHECK(tpm_tsc_physical_presence(dev, PRESENCE));
106 	TPM_CHECK(tpm_nv_read_value(dev, INDEX0, (uint8_t *)&x, sizeof(x)));
107 	printf("done\n");
108 	return 0;
109 }
110 
111 static int test_early_nvram2(struct udevice *dev)
112 {
113 	uint32_t x;
114 
115 	printf("Testing earlynvram2 ...");
116 	tpm_init(dev);
117 	TPM_CHECK(tpm_startup(dev, TPM_ST_CLEAR));
118 	TPM_CHECK(tpm_continue_self_test(dev));
119 	TPM_CHECK(tpm_tsc_physical_presence(dev, PRESENCE));
120 	TPM_CHECK(tpm_nv_write_value(dev, INDEX0, (uint8_t *)&x, sizeof(x)));
121 	printf("done\n");
122 	return 0;
123 }
124 
125 static int test_enable(struct udevice *dev)
126 {
127 	uint8_t disable = 0, deactivated = 0;
128 
129 	printf("Testing enable ...\n");
130 	tpm_init(dev);
131 	TPM_CHECK(TlclStartupIfNeeded(dev));
132 	TPM_CHECK(tpm_self_test_full(dev));
133 	TPM_CHECK(tpm_tsc_physical_presence(dev, PRESENCE));
134 	TPM_CHECK(tpm_get_flags(dev, &disable, &deactivated, NULL));
135 	printf("\tdisable is %d, deactivated is %d\n", disable, deactivated);
136 	TPM_CHECK(tpm_physical_enable(dev));
137 	TPM_CHECK(tpm_physical_set_deactivated(dev, 0));
138 	TPM_CHECK(tpm_get_flags(dev, &disable, &deactivated, NULL));
139 	printf("\tdisable is %d, deactivated is %d\n", disable, deactivated);
140 	if (disable == 1 || deactivated == 1)
141 		printf("\tfailed to enable or activate\n");
142 	printf("\tdone\n");
143 	return 0;
144 }
145 
146 #define reboot() do { \
147 	printf("\trebooting...\n"); \
148 	reset_cpu(0); \
149 } while (0)
150 
151 static int test_fast_enable(struct udevice *dev)
152 {
153 	uint8_t disable = 0, deactivated = 0;
154 	int i;
155 
156 	printf("Testing fastenable ...\n");
157 	tpm_init(dev);
158 	TPM_CHECK(TlclStartupIfNeeded(dev));
159 	TPM_CHECK(tpm_self_test_full(dev));
160 	TPM_CHECK(tpm_tsc_physical_presence(dev, PRESENCE));
161 	TPM_CHECK(tpm_get_flags(dev, &disable, &deactivated, NULL));
162 	printf("\tdisable is %d, deactivated is %d\n", disable, deactivated);
163 	for (i = 0; i < 2; i++) {
164 		TPM_CHECK(tpm_force_clear(dev));
165 		TPM_CHECK(tpm_get_flags(dev, &disable, &deactivated, NULL));
166 		printf("\tdisable is %d, deactivated is %d\n", disable,
167 		       deactivated);
168 		assert(disable == 1 && deactivated == 1);
169 		TPM_CHECK(tpm_physical_enable(dev));
170 		TPM_CHECK(tpm_physical_set_deactivated(dev, 0));
171 		TPM_CHECK(tpm_get_flags(dev, &disable, &deactivated, NULL));
172 		printf("\tdisable is %d, deactivated is %d\n", disable,
173 		       deactivated);
174 		assert(disable == 0 && deactivated == 0);
175 	}
176 	printf("\tdone\n");
177 	return 0;
178 }
179 
180 static int test_global_lock(struct udevice *dev)
181 {
182 	uint32_t zero = 0;
183 	uint32_t result;
184 	uint32_t x;
185 
186 	printf("Testing globallock ...\n");
187 	tpm_init(dev);
188 	TPM_CHECK(TlclStartupIfNeeded(dev));
189 	TPM_CHECK(tpm_self_test_full(dev));
190 	TPM_CHECK(tpm_tsc_physical_presence(dev, PRESENCE));
191 	TPM_CHECK(tpm_nv_read_value(dev, INDEX0, (uint8_t *)&x, sizeof(x)));
192 	TPM_CHECK(tpm_nv_write_value(dev, INDEX0, (uint8_t *)&zero,
193 				     sizeof(uint32_t)));
194 	TPM_CHECK(tpm_nv_read_value(dev, INDEX1, (uint8_t *)&x, sizeof(x)));
195 	TPM_CHECK(tpm_nv_write_value(dev, INDEX1, (uint8_t *)&zero,
196 				     sizeof(uint32_t)));
197 	TPM_CHECK(tpm_set_global_lock(dev));
198 	/* Verifies that write to index0 fails */
199 	x = 1;
200 	result = tpm_nv_write_value(dev, INDEX0, (uint8_t *)&x, sizeof(x));
201 	assert(result == TPM_AREA_LOCKED);
202 	TPM_CHECK(tpm_nv_read_value(dev, INDEX0, (uint8_t *)&x, sizeof(x)));
203 	assert(x == 0);
204 	/* Verifies that write to index1 is still possible */
205 	x = 2;
206 	TPM_CHECK(tpm_nv_write_value(dev, INDEX1, (uint8_t *)&x, sizeof(x)));
207 	TPM_CHECK(tpm_nv_read_value(dev, INDEX1, (uint8_t *)&x, sizeof(x)));
208 	assert(x == 2);
209 	/* Turns off PP */
210 	tpm_tsc_physical_presence(dev, PHYS_PRESENCE);
211 	/* Verifies that write to index1 fails */
212 	x = 3;
213 	result = tpm_nv_write_value(dev, INDEX1, (uint8_t *)&x, sizeof(x));
214 	assert(result == TPM_BAD_PRESENCE);
215 	TPM_CHECK(tpm_nv_read_value(dev, INDEX1, (uint8_t *)&x, sizeof(x)));
216 	assert(x == 2);
217 	printf("\tdone\n");
218 	return 0;
219 }
220 
221 static int test_lock(struct udevice *dev)
222 {
223 	printf("Testing lock ...\n");
224 	tpm_init(dev);
225 	tpm_startup(dev, TPM_ST_CLEAR);
226 	tpm_self_test_full(dev);
227 	tpm_tsc_physical_presence(dev, PRESENCE);
228 	tpm_nv_write_value_lock(dev, INDEX0);
229 	printf("\tLocked 0x%x\n", INDEX0);
230 	printf("\tdone\n");
231 	return 0;
232 }
233 
234 static void initialise_spaces(struct udevice *dev)
235 {
236 	uint32_t zero = 0;
237 	uint32_t perm = TPM_NV_PER_WRITE_STCLEAR | TPM_NV_PER_PPWRITE;
238 
239 	printf("\tInitialising spaces\n");
240 	tpm_nv_set_locked(dev);  /* useful only the first time */
241 	tpm_nv_define_space(dev, INDEX0, perm, 4);
242 	tpm_nv_write_value(dev, INDEX0, (uint8_t *)&zero, 4);
243 	tpm_nv_define_space(dev, INDEX1, perm, 4);
244 	tpm_nv_write_value(dev, INDEX1, (uint8_t *)&zero, 4);
245 	tpm_nv_define_space(dev, INDEX2, perm, 4);
246 	tpm_nv_write_value(dev, INDEX2, (uint8_t *)&zero, 4);
247 	tpm_nv_define_space(dev, INDEX3, perm, 4);
248 	tpm_nv_write_value(dev, INDEX3, (uint8_t *)&zero, 4);
249 	perm = TPM_NV_PER_READ_STCLEAR | TPM_NV_PER_WRITE_STCLEAR |
250 		TPM_NV_PER_PPWRITE;
251 	tpm_nv_define_space(dev, INDEX_INITIALISED, perm, 1);
252 }
253 
254 static int test_readonly(struct udevice *dev)
255 {
256 	uint8_t c;
257 	uint32_t index_0, index_1, index_2, index_3;
258 	int read0, read1, read2, read3;
259 
260 	printf("Testing readonly ...\n");
261 	tpm_init(dev);
262 	tpm_startup(dev, TPM_ST_CLEAR);
263 	tpm_self_test_full(dev);
264 	tpm_tsc_physical_presence(dev, PRESENCE);
265 	/*
266 	 * Checks if initialisation has completed by trying to read-lock a
267 	 * space that's created at the end of initialisation
268 	 */
269 	if (tpm_nv_read_value(dev, INDEX_INITIALISED, &c, 0) == TPM_BADINDEX) {
270 		/* The initialisation did not complete */
271 		initialise_spaces(dev);
272 	}
273 
274 	/* Checks if spaces are OK or messed up */
275 	read0 = tpm_nv_read_value(dev, INDEX0, (uint8_t *)&index_0,
276 				  sizeof(index_0));
277 	read1 = tpm_nv_read_value(dev, INDEX1, (uint8_t *)&index_1,
278 				  sizeof(index_1));
279 	read2 = tpm_nv_read_value(dev, INDEX2, (uint8_t *)&index_2,
280 				  sizeof(index_2));
281 	read3 = tpm_nv_read_value(dev, INDEX3, (uint8_t *)&index_3,
282 				  sizeof(index_3));
283 	if (read0 || read1 || read2 || read3) {
284 		printf("Invalid contents\n");
285 		return 0;
286 	}
287 
288 	/*
289 	 * Writes space, and locks it.  Then attempts to write again.
290 	 * I really wish I could use the imperative.
291 	 */
292 	index_0 += 1;
293 	if (tpm_nv_write_value(dev, INDEX0, (uint8_t *)&index_0,
294 			       sizeof(index_0) !=
295 		TPM_SUCCESS)) {
296 		pr_err("\tcould not write index 0\n");
297 	}
298 	tpm_nv_write_value_lock(dev, INDEX0);
299 	if (tpm_nv_write_value(dev, INDEX0, (uint8_t *)&index_0,
300 			       sizeof(index_0)) ==
301 			TPM_SUCCESS)
302 		pr_err("\tindex 0 is not locked\n");
303 
304 	printf("\tdone\n");
305 	return 0;
306 }
307 
308 static int test_redefine_unowned(struct udevice *dev)
309 {
310 	uint32_t perm;
311 	uint32_t result;
312 	uint32_t x;
313 
314 	printf("Testing redefine_unowned ...");
315 	tpm_init(dev);
316 	TPM_CHECK(TlclStartupIfNeeded(dev));
317 	TPM_CHECK(tpm_self_test_full(dev));
318 	TPM_CHECK(tpm_tsc_physical_presence(dev, PRESENCE));
319 	assert(!tpm_is_owned(dev));
320 
321 	/* Ensures spaces exist. */
322 	TPM_CHECK(tpm_nv_read_value(dev, INDEX0, (uint8_t *)&x, sizeof(x)));
323 	TPM_CHECK(tpm_nv_read_value(dev, INDEX1, (uint8_t *)&x, sizeof(x)));
324 
325 	/* Redefines spaces a couple of times. */
326 	perm = TPM_NV_PER_PPWRITE | TPM_NV_PER_GLOBALLOCK;
327 	TPM_CHECK(tpm_nv_define_space(dev, INDEX0, perm, 2 * sizeof(uint32_t)));
328 	TPM_CHECK(tpm_nv_define_space(dev, INDEX0, perm, sizeof(uint32_t)));
329 	perm = TPM_NV_PER_PPWRITE;
330 	TPM_CHECK(tpm_nv_define_space(dev, INDEX1, perm, 2 * sizeof(uint32_t)));
331 	TPM_CHECK(tpm_nv_define_space(dev, INDEX1, perm, sizeof(uint32_t)));
332 
333 	/* Sets the global lock */
334 	tpm_set_global_lock(dev);
335 
336 	/* Verifies that index0 cannot be redefined */
337 	result = tpm_nv_define_space(dev, INDEX0, perm, sizeof(uint32_t));
338 	assert(result == TPM_AREA_LOCKED);
339 
340 	/* Checks that index1 can */
341 	TPM_CHECK(tpm_nv_define_space(dev, INDEX1, perm, 2 * sizeof(uint32_t)));
342 	TPM_CHECK(tpm_nv_define_space(dev, INDEX1, perm, sizeof(uint32_t)));
343 
344 	/* Turns off PP */
345 	tpm_tsc_physical_presence(dev, PHYS_PRESENCE);
346 
347 	/* Verifies that neither index0 nor index1 can be redefined */
348 	result = tpm_nv_define_space(dev, INDEX0, perm, sizeof(uint32_t));
349 	assert(result == TPM_BAD_PRESENCE);
350 	result = tpm_nv_define_space(dev, INDEX1, perm, sizeof(uint32_t));
351 	assert(result == TPM_BAD_PRESENCE);
352 
353 	printf("done\n");
354 	return 0;
355 }
356 
357 #define PERMPPGL (TPM_NV_PER_PPWRITE | TPM_NV_PER_GLOBALLOCK)
358 #define PERMPP TPM_NV_PER_PPWRITE
359 
360 static int test_space_perm(struct udevice *dev)
361 {
362 	uint32_t perm;
363 
364 	printf("Testing spaceperm ...");
365 	tpm_init(dev);
366 	TPM_CHECK(TlclStartupIfNeeded(dev));
367 	TPM_CHECK(tpm_continue_self_test(dev));
368 	TPM_CHECK(tpm_tsc_physical_presence(dev, PRESENCE));
369 	TPM_CHECK(tpm_get_permissions(dev, INDEX0, &perm));
370 	assert((perm & PERMPPGL) == PERMPPGL);
371 	TPM_CHECK(tpm_get_permissions(dev, INDEX1, &perm));
372 	assert((perm & PERMPP) == PERMPP);
373 	printf("done\n");
374 	return 0;
375 }
376 
377 static int test_startup(struct udevice *dev)
378 {
379 	uint32_t result;
380 
381 	printf("Testing startup ...\n");
382 
383 	tpm_init(dev);
384 	result = tpm_startup(dev, TPM_ST_CLEAR);
385 	if (result != 0 && result != TPM_INVALID_POSTINIT)
386 		printf("\ttpm startup failed with 0x%x\n", result);
387 	result = tpm_get_flags(dev, NULL, NULL, NULL);
388 	if (result != 0)
389 		printf("\ttpm getflags failed with 0x%x\n", result);
390 	printf("\texecuting SelfTestFull\n");
391 	tpm_self_test_full(dev);
392 	result = tpm_get_flags(dev, NULL, NULL, NULL);
393 	if (result != 0)
394 		printf("\ttpm getflags failed with 0x%x\n", result);
395 	printf("\tdone\n");
396 	return 0;
397 }
398 
399 /*
400  * Runs [op] and ensures it returns success and doesn't run longer than
401  * [time_limit] in milliseconds.
402  */
403 #define TTPM_CHECK(op, time_limit) do { \
404 	ulong start, time; \
405 	uint32_t __result; \
406 	\
407 	start = get_timer(0); \
408 	__result = op; \
409 	if (__result != TPM_SUCCESS) { \
410 		printf("\t" #op ": error 0x%x\n", __result); \
411 		return -1; \
412 	} \
413 	time = get_timer(start); \
414 	printf("\t" #op ": %lu ms\n", time); \
415 	if (time > (ulong)time_limit) { \
416 		printf("\t" #op " exceeded " #time_limit " ms\n"); \
417 	} \
418 } while (0)
419 
420 
421 static int test_timing(struct udevice *dev)
422 {
423 	uint8_t in[20], out[20];
424 	uint32_t x;
425 
426 	printf("Testing timing ...");
427 	tpm_init(dev);
428 	TTPM_CHECK(TlclStartupIfNeeded(dev), 50);
429 	TTPM_CHECK(tpm_continue_self_test(dev), 100);
430 	TTPM_CHECK(tpm_self_test_full(dev), 1000);
431 	TTPM_CHECK(tpm_tsc_physical_presence(dev, PRESENCE), 100);
432 	TTPM_CHECK(tpm_nv_write_value(dev, INDEX0, (uint8_t *)&x, sizeof(x)),
433 		   100);
434 	TTPM_CHECK(tpm_nv_read_value(dev, INDEX0, (uint8_t *)&x, sizeof(x)),
435 		   100);
436 	TTPM_CHECK(tpm_extend(dev, 0, in, out), 200);
437 	TTPM_CHECK(tpm_set_global_lock(dev), 50);
438 	TTPM_CHECK(tpm_tsc_physical_presence(dev, PHYS_PRESENCE), 100);
439 	printf("done\n");
440 	return 0;
441 }
442 
443 #define TPM_MAX_NV_WRITES_NOOWNER 64
444 
445 static int test_write_limit(struct udevice *dev)
446 {
447 	uint32_t result;
448 	int i;
449 
450 	printf("Testing writelimit ...\n");
451 	tpm_init(dev);
452 	TPM_CHECK(TlclStartupIfNeeded(dev));
453 	TPM_CHECK(tpm_self_test_full(dev));
454 	TPM_CHECK(tpm_tsc_physical_presence(dev, PRESENCE));
455 	TPM_CHECK(tpm_force_clear(dev));
456 	TPM_CHECK(tpm_physical_enable(dev));
457 	TPM_CHECK(tpm_physical_set_deactivated(dev, 0));
458 
459 	for (i = 0; i < TPM_MAX_NV_WRITES_NOOWNER + 2; i++) {
460 		printf("\twriting %d\n", i);
461 		result = tpm_nv_write_value(dev, INDEX0, (uint8_t *)&i,
462 					    sizeof(i));
463 		switch (result) {
464 		case TPM_SUCCESS:
465 			break;
466 		case TPM_MAXNVWRITES:
467 			assert(i >= TPM_MAX_NV_WRITES_NOOWNER);
468 		default:
469 			pr_err("\tunexpected error code %d (0x%x)\n",
470 			      result, result);
471 		}
472 	}
473 
474 	/* Reset write count */
475 	TPM_CHECK(tpm_force_clear(dev));
476 	TPM_CHECK(tpm_physical_enable(dev));
477 	TPM_CHECK(tpm_physical_set_deactivated(dev, 0));
478 
479 	/* Try writing again. */
480 	TPM_CHECK(tpm_nv_write_value(dev, INDEX0, (uint8_t *)&i, sizeof(i)));
481 	printf("\tdone\n");
482 	return 0;
483 }
484 
485 #define VOIDTEST(XFUNC) \
486 	int do_test_##XFUNC(cmd_tbl_t *cmd_tbl, int flag, int argc, \
487 	char * const argv[]) \
488 	{ \
489 		struct udevice *dev; \
490 		int ret; \
491 \
492 		ret = get_tpm(&dev); \
493 		if (ret) \
494 			return ret; \
495 		return test_##XFUNC(dev); \
496 	}
497 
498 #define VOIDENT(XNAME) \
499 	U_BOOT_CMD_MKENT(XNAME, 0, 1, do_test_##XNAME, "", ""),
500 
501 VOIDTEST(early_extend)
502 VOIDTEST(early_nvram)
503 VOIDTEST(early_nvram2)
504 VOIDTEST(enable)
505 VOIDTEST(fast_enable)
506 VOIDTEST(global_lock)
507 VOIDTEST(lock)
508 VOIDTEST(readonly)
509 VOIDTEST(redefine_unowned)
510 VOIDTEST(space_perm)
511 VOIDTEST(startup)
512 VOIDTEST(timing)
513 VOIDTEST(write_limit)
514 VOIDTEST(timer)
515 
516 static cmd_tbl_t cmd_cros_tpm_sub[] = {
517 	VOIDENT(early_extend)
518 	VOIDENT(early_nvram)
519 	VOIDENT(early_nvram2)
520 	VOIDENT(enable)
521 	VOIDENT(fast_enable)
522 	VOIDENT(global_lock)
523 	VOIDENT(lock)
524 	VOIDENT(readonly)
525 	VOIDENT(redefine_unowned)
526 	VOIDENT(space_perm)
527 	VOIDENT(startup)
528 	VOIDENT(timing)
529 	VOIDENT(write_limit)
530 	VOIDENT(timer)
531 };
532 
533 static int do_tpmtest(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
534 {
535 	cmd_tbl_t *c;
536 	int i;
537 
538 	printf("argc = %d, argv = ", argc);
539 
540 	for (i = 0; i < argc; i++)
541 		printf(" %s", argv[i]);
542 
543 	printf("\n------\n");
544 
545 	argc--;
546 	argv++;
547 	c = find_cmd_tbl(argv[0], cmd_cros_tpm_sub,
548 			 ARRAY_SIZE(cmd_cros_tpm_sub));
549 	return c ? c->cmd(cmdtp, flag, argc, argv) : cmd_usage(cmdtp);
550 }
551 
552 U_BOOT_CMD(tpmtest, 2, 1, do_tpmtest, "TPM tests",
553 	"\n\tearly_extend\n"
554 	"\tearly_nvram\n"
555 	"\tearly_nvram2\n"
556 	"\tenable\n"
557 	"\tfast_enable\n"
558 	"\tglobal_lock\n"
559 	"\tlock\n"
560 	"\treadonly\n"
561 	"\tredefine_unowned\n"
562 	"\tspace_perm\n"
563 	"\tstartup\n"
564 	"\ttiming\n"
565 	"\twrite_limit\n");
566