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1 /*
2  * arch/arm/kernel/kprobes-test.c
3  *
4  * Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 
11 /*
12  * This file contains test code for ARM kprobes.
13  *
14  * The top level function run_all_tests() executes tests for all of the
15  * supported instruction sets: ARM, 16-bit Thumb, and 32-bit Thumb. These tests
16  * fall into two categories; run_api_tests() checks basic functionality of the
17  * kprobes API, and run_test_cases() is a comprehensive test for kprobes
18  * instruction decoding and simulation.
19  *
20  * run_test_cases() first checks the kprobes decoding table for self consistency
21  * (using table_test()) then executes a series of test cases for each of the CPU
22  * instruction forms. coverage_start() and coverage_end() are used to verify
23  * that these test cases cover all of the possible combinations of instructions
24  * described by the kprobes decoding tables.
25  *
26  * The individual test cases are in kprobes-test-arm.c and kprobes-test-thumb.c
27  * which use the macros defined in kprobes-test.h. The rest of this
28  * documentation will describe the operation of the framework used by these
29  * test cases.
30  */
31 
32 /*
33  * TESTING METHODOLOGY
34  * -------------------
35  *
36  * The methodology used to test an ARM instruction 'test_insn' is to use
37  * inline assembler like:
38  *
39  * test_before: nop
40  * test_case:	test_insn
41  * test_after:	nop
42  *
43  * When the test case is run a kprobe is placed of each nop. The
44  * post-handler of the test_before probe is used to modify the saved CPU
45  * register context to that which we require for the test case. The
46  * pre-handler of the of the test_after probe saves a copy of the CPU
47  * register context. In this way we can execute test_insn with a specific
48  * register context and see the results afterwards.
49  *
50  * To actually test the kprobes instruction emulation we perform the above
51  * step a second time but with an additional kprobe on the test_case
52  * instruction itself. If the emulation is accurate then the results seen
53  * by the test_after probe will be identical to the first run which didn't
54  * have a probe on test_case.
55  *
56  * Each test case is run several times with a variety of variations in the
57  * flags value of stored in CPSR, and for Thumb code, different ITState.
58  *
59  * For instructions which can modify PC, a second test_after probe is used
60  * like this:
61  *
62  * test_before: nop
63  * test_case:	test_insn
64  * test_after:	nop
65  *		b test_done
66  * test_after2: nop
67  * test_done:
68  *
69  * The test case is constructed such that test_insn branches to
70  * test_after2, or, if testing a conditional instruction, it may just
71  * continue to test_after. The probes inserted at both locations let us
72  * determine which happened. A similar approach is used for testing
73  * backwards branches...
74  *
75  *		b test_before
76  *		b test_done  @ helps to cope with off by 1 branches
77  * test_after2: nop
78  *		b test_done
79  * test_before: nop
80  * test_case:	test_insn
81  * test_after:	nop
82  * test_done:
83  *
84  * The macros used to generate the assembler instructions describe above
85  * are TEST_INSTRUCTION, TEST_BRANCH_F (branch forwards) and TEST_BRANCH_B
86  * (branch backwards). In these, the local variables numbered 1, 50, 2 and
87  * 99 represent: test_before, test_case, test_after2 and test_done.
88  *
89  * FRAMEWORK
90  * ---------
91  *
92  * Each test case is wrapped between the pair of macros TESTCASE_START and
93  * TESTCASE_END. As well as performing the inline assembler boilerplate,
94  * these call out to the kprobes_test_case_start() and
95  * kprobes_test_case_end() functions which drive the execution of the test
96  * case. The specific arguments to use for each test case are stored as
97  * inline data constructed using the various TEST_ARG_* macros. Putting
98  * this all together, a simple test case may look like:
99  *
100  *	TESTCASE_START("Testing mov r0, r7")
101  *	TEST_ARG_REG(7, 0x12345678) // Set r7=0x12345678
102  *	TEST_ARG_END("")
103  *	TEST_INSTRUCTION("mov r0, r7")
104  *	TESTCASE_END
105  *
106  * Note, in practice the single convenience macro TEST_R would be used for this
107  * instead.
108  *
109  * The above would expand to assembler looking something like:
110  *
111  *	@ TESTCASE_START
112  *	bl	__kprobes_test_case_start
113  *	.pushsection .rodata
114  *	"10:
115  *	.ascii "mov r0, r7"	@ text title for test case
116  *	.byte	0
117  *	.popsection
118  *	@ start of inline data...
119  *	.word	10b		@ pointer to title in .rodata section
120  *
121  *	@ TEST_ARG_REG
122  *	.byte	ARG_TYPE_REG
123  *	.byte	7
124  *	.short	0
125  *	.word	0x1234567
126  *
127  *	@ TEST_ARG_END
128  *	.byte	ARG_TYPE_END
129  *	.byte	TEST_ISA	@ flags, including ISA being tested
130  *	.short	50f-0f		@ offset of 'test_before'
131  *	.short	2f-0f		@ offset of 'test_after2' (if relevent)
132  *	.short	99f-0f		@ offset of 'test_done'
133  *	@ start of test case code...
134  *	0:
135  *	.code	TEST_ISA	@ switch to ISA being tested
136  *
137  *	@ TEST_INSTRUCTION
138  *	50:	nop		@ location for 'test_before' probe
139  *	1:	mov r0, r7	@ the test case instruction 'test_insn'
140  *		nop		@ location for 'test_after' probe
141  *
142  *	// TESTCASE_END
143  *	2:
144  *	99:	bl __kprobes_test_case_end_##TEST_ISA
145  *	.code	NONMAL_ISA
146  *
147  * When the above is execute the following happens...
148  *
149  * __kprobes_test_case_start() is an assembler wrapper which sets up space
150  * for a stack buffer and calls the C function kprobes_test_case_start().
151  * This C function will do some initial processing of the inline data and
152  * setup some global state. It then inserts the test_before and test_after
153  * kprobes and returns a value which causes the assembler wrapper to jump
154  * to the start of the test case code, (local label '0').
155  *
156  * When the test case code executes, the test_before probe will be hit and
157  * test_before_post_handler will call setup_test_context(). This fills the
158  * stack buffer and CPU registers with a test pattern and then processes
159  * the test case arguments. In our example there is one TEST_ARG_REG which
160  * indicates that R7 should be loaded with the value 0x12345678.
161  *
162  * When the test_before probe ends, the test case continues and executes
163  * the "mov r0, r7" instruction. It then hits the test_after probe and the
164  * pre-handler for this (test_after_pre_handler) will save a copy of the
165  * CPU register context. This should now have R0 holding the same value as
166  * R7.
167  *
168  * Finally we get to the call to __kprobes_test_case_end_{32,16}. This is
169  * an assembler wrapper which switches back to the ISA used by the test
170  * code and calls the C function kprobes_test_case_end().
171  *
172  * For each run through the test case, test_case_run_count is incremented
173  * by one. For even runs, kprobes_test_case_end() saves a copy of the
174  * register and stack buffer contents from the test case just run. It then
175  * inserts a kprobe on the test case instruction 'test_insn' and returns a
176  * value to cause the test case code to be re-run.
177  *
178  * For odd numbered runs, kprobes_test_case_end() compares the register and
179  * stack buffer contents to those that were saved on the previous even
180  * numbered run (the one without the kprobe on test_insn). These should be
181  * the same if the kprobe instruction simulation routine is correct.
182  *
183  * The pair of test case runs is repeated with different combinations of
184  * flag values in CPSR and, for Thumb, different ITState. This is
185  * controlled by test_context_cpsr().
186  *
187  * BUILDING TEST CASES
188  * -------------------
189  *
190  *
191  * As an aid to building test cases, the stack buffer is initialised with
192  * some special values:
193  *
194  *   [SP+13*4]	Contains SP+120. This can be used to test instructions
195  *		which load a value into SP.
196  *
197  *   [SP+15*4]	When testing branching instructions using TEST_BRANCH_{F,B},
198  *		this holds the target address of the branch, 'test_after2'.
199  *		This can be used to test instructions which load a PC value
200  *		from memory.
201  */
202 
203 #include <linux/kernel.h>
204 #include <linux/module.h>
205 #include <linux/slab.h>
206 #include <linux/kprobes.h>
207 #include <linux/errno.h>
208 #include <linux/stddef.h>
209 #include <linux/bug.h>
210 #include <asm/opcodes.h>
211 
212 #include "kprobes.h"
213 #include "probes-arm.h"
214 #include "probes-thumb.h"
215 #include "kprobes-test.h"
216 
217 
218 #define BENCHMARKING	1
219 
220 
221 /*
222  * Test basic API
223  */
224 
225 static bool test_regs_ok;
226 static int test_func_instance;
227 static int pre_handler_called;
228 static int post_handler_called;
229 static int jprobe_func_called;
230 static int kretprobe_handler_called;
231 static int tests_failed;
232 
233 #define FUNC_ARG1 0x12345678
234 #define FUNC_ARG2 0xabcdef
235 
236 
237 #ifndef CONFIG_THUMB2_KERNEL
238 
239 long arm_func(long r0, long r1);
240 
__arm_kprobes_test_func(void)241 static void __used __naked __arm_kprobes_test_func(void)
242 {
243 	__asm__ __volatile__ (
244 		".arm					\n\t"
245 		".type arm_func, %%function		\n\t"
246 		"arm_func:				\n\t"
247 		"adds	r0, r0, r1			\n\t"
248 		"bx	lr				\n\t"
249 		".code "NORMAL_ISA	 /* Back to Thumb if necessary */
250 		: : : "r0", "r1", "cc"
251 	);
252 }
253 
254 #else /* CONFIG_THUMB2_KERNEL */
255 
256 long thumb16_func(long r0, long r1);
257 long thumb32even_func(long r0, long r1);
258 long thumb32odd_func(long r0, long r1);
259 
__thumb_kprobes_test_funcs(void)260 static void __used __naked __thumb_kprobes_test_funcs(void)
261 {
262 	__asm__ __volatile__ (
263 		".type thumb16_func, %%function		\n\t"
264 		"thumb16_func:				\n\t"
265 		"adds.n	r0, r0, r1			\n\t"
266 		"bx	lr				\n\t"
267 
268 		".align					\n\t"
269 		".type thumb32even_func, %%function	\n\t"
270 		"thumb32even_func:			\n\t"
271 		"adds.w	r0, r0, r1			\n\t"
272 		"bx	lr				\n\t"
273 
274 		".align					\n\t"
275 		"nop.n					\n\t"
276 		".type thumb32odd_func, %%function	\n\t"
277 		"thumb32odd_func:			\n\t"
278 		"adds.w	r0, r0, r1			\n\t"
279 		"bx	lr				\n\t"
280 
281 		: : : "r0", "r1", "cc"
282 	);
283 }
284 
285 #endif /* CONFIG_THUMB2_KERNEL */
286 
287 
call_test_func(long (* func)(long,long),bool check_test_regs)288 static int call_test_func(long (*func)(long, long), bool check_test_regs)
289 {
290 	long ret;
291 
292 	++test_func_instance;
293 	test_regs_ok = false;
294 
295 	ret = (*func)(FUNC_ARG1, FUNC_ARG2);
296 	if (ret != FUNC_ARG1 + FUNC_ARG2) {
297 		pr_err("FAIL: call_test_func: func returned %lx\n", ret);
298 		return false;
299 	}
300 
301 	if (check_test_regs && !test_regs_ok) {
302 		pr_err("FAIL: test regs not OK\n");
303 		return false;
304 	}
305 
306 	return true;
307 }
308 
pre_handler(struct kprobe * p,struct pt_regs * regs)309 static int __kprobes pre_handler(struct kprobe *p, struct pt_regs *regs)
310 {
311 	pre_handler_called = test_func_instance;
312 	if (regs->ARM_r0 == FUNC_ARG1 && regs->ARM_r1 == FUNC_ARG2)
313 		test_regs_ok = true;
314 	return 0;
315 }
316 
post_handler(struct kprobe * p,struct pt_regs * regs,unsigned long flags)317 static void __kprobes post_handler(struct kprobe *p, struct pt_regs *regs,
318 				unsigned long flags)
319 {
320 	post_handler_called = test_func_instance;
321 	if (regs->ARM_r0 != FUNC_ARG1 + FUNC_ARG2 || regs->ARM_r1 != FUNC_ARG2)
322 		test_regs_ok = false;
323 }
324 
325 static struct kprobe the_kprobe = {
326 	.addr		= 0,
327 	.pre_handler	= pre_handler,
328 	.post_handler	= post_handler
329 };
330 
test_kprobe(long (* func)(long,long))331 static int test_kprobe(long (*func)(long, long))
332 {
333 	int ret;
334 
335 	the_kprobe.addr = (kprobe_opcode_t *)func;
336 	ret = register_kprobe(&the_kprobe);
337 	if (ret < 0) {
338 		pr_err("FAIL: register_kprobe failed with %d\n", ret);
339 		return ret;
340 	}
341 
342 	ret = call_test_func(func, true);
343 
344 	unregister_kprobe(&the_kprobe);
345 	the_kprobe.flags = 0; /* Clear disable flag to allow reuse */
346 
347 	if (!ret)
348 		return -EINVAL;
349 	if (pre_handler_called != test_func_instance) {
350 		pr_err("FAIL: kprobe pre_handler not called\n");
351 		return -EINVAL;
352 	}
353 	if (post_handler_called != test_func_instance) {
354 		pr_err("FAIL: kprobe post_handler not called\n");
355 		return -EINVAL;
356 	}
357 	if (!call_test_func(func, false))
358 		return -EINVAL;
359 	if (pre_handler_called == test_func_instance ||
360 				post_handler_called == test_func_instance) {
361 		pr_err("FAIL: probe called after unregistering\n");
362 		return -EINVAL;
363 	}
364 
365 	return 0;
366 }
367 
jprobe_func(long r0,long r1)368 static void __kprobes jprobe_func(long r0, long r1)
369 {
370 	jprobe_func_called = test_func_instance;
371 	if (r0 == FUNC_ARG1 && r1 == FUNC_ARG2)
372 		test_regs_ok = true;
373 	jprobe_return();
374 }
375 
376 static struct jprobe the_jprobe = {
377 	.entry		= jprobe_func,
378 };
379 
test_jprobe(long (* func)(long,long))380 static int test_jprobe(long (*func)(long, long))
381 {
382 	int ret;
383 
384 	the_jprobe.kp.addr = (kprobe_opcode_t *)func;
385 	ret = register_jprobe(&the_jprobe);
386 	if (ret < 0) {
387 		pr_err("FAIL: register_jprobe failed with %d\n", ret);
388 		return ret;
389 	}
390 
391 	ret = call_test_func(func, true);
392 
393 	unregister_jprobe(&the_jprobe);
394 	the_jprobe.kp.flags = 0; /* Clear disable flag to allow reuse */
395 
396 	if (!ret)
397 		return -EINVAL;
398 	if (jprobe_func_called != test_func_instance) {
399 		pr_err("FAIL: jprobe handler function not called\n");
400 		return -EINVAL;
401 	}
402 	if (!call_test_func(func, false))
403 		return -EINVAL;
404 	if (jprobe_func_called == test_func_instance) {
405 		pr_err("FAIL: probe called after unregistering\n");
406 		return -EINVAL;
407 	}
408 
409 	return 0;
410 }
411 
412 static int __kprobes
kretprobe_handler(struct kretprobe_instance * ri,struct pt_regs * regs)413 kretprobe_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
414 {
415 	kretprobe_handler_called = test_func_instance;
416 	if (regs_return_value(regs) == FUNC_ARG1 + FUNC_ARG2)
417 		test_regs_ok = true;
418 	return 0;
419 }
420 
421 static struct kretprobe the_kretprobe = {
422 	.handler	= kretprobe_handler,
423 };
424 
test_kretprobe(long (* func)(long,long))425 static int test_kretprobe(long (*func)(long, long))
426 {
427 	int ret;
428 
429 	the_kretprobe.kp.addr = (kprobe_opcode_t *)func;
430 	ret = register_kretprobe(&the_kretprobe);
431 	if (ret < 0) {
432 		pr_err("FAIL: register_kretprobe failed with %d\n", ret);
433 		return ret;
434 	}
435 
436 	ret = call_test_func(func, true);
437 
438 	unregister_kretprobe(&the_kretprobe);
439 	the_kretprobe.kp.flags = 0; /* Clear disable flag to allow reuse */
440 
441 	if (!ret)
442 		return -EINVAL;
443 	if (kretprobe_handler_called != test_func_instance) {
444 		pr_err("FAIL: kretprobe handler not called\n");
445 		return -EINVAL;
446 	}
447 	if (!call_test_func(func, false))
448 		return -EINVAL;
449 	if (jprobe_func_called == test_func_instance) {
450 		pr_err("FAIL: kretprobe called after unregistering\n");
451 		return -EINVAL;
452 	}
453 
454 	return 0;
455 }
456 
run_api_tests(long (* func)(long,long))457 static int run_api_tests(long (*func)(long, long))
458 {
459 	int ret;
460 
461 	pr_info("    kprobe\n");
462 	ret = test_kprobe(func);
463 	if (ret < 0)
464 		return ret;
465 
466 	pr_info("    jprobe\n");
467 	ret = test_jprobe(func);
468 #if defined(CONFIG_THUMB2_KERNEL) && !defined(MODULE)
469 	if (ret == -EINVAL) {
470 		pr_err("FAIL: Known longtime bug with jprobe on Thumb kernels\n");
471 		tests_failed = ret;
472 		ret = 0;
473 	}
474 #endif
475 	if (ret < 0)
476 		return ret;
477 
478 	pr_info("    kretprobe\n");
479 	ret = test_kretprobe(func);
480 	if (ret < 0)
481 		return ret;
482 
483 	return 0;
484 }
485 
486 
487 /*
488  * Benchmarking
489  */
490 
491 #if BENCHMARKING
492 
benchmark_nop(void)493 static void __naked benchmark_nop(void)
494 {
495 	__asm__ __volatile__ (
496 		"nop		\n\t"
497 		"bx	lr"
498 	);
499 }
500 
501 #ifdef CONFIG_THUMB2_KERNEL
502 #define wide ".w"
503 #else
504 #define wide
505 #endif
506 
benchmark_pushpop1(void)507 static void __naked benchmark_pushpop1(void)
508 {
509 	__asm__ __volatile__ (
510 		"stmdb"wide"	sp!, {r3-r11,lr}  \n\t"
511 		"ldmia"wide"	sp!, {r3-r11,pc}"
512 	);
513 }
514 
benchmark_pushpop2(void)515 static void __naked benchmark_pushpop2(void)
516 {
517 	__asm__ __volatile__ (
518 		"stmdb"wide"	sp!, {r0-r8,lr}  \n\t"
519 		"ldmia"wide"	sp!, {r0-r8,pc}"
520 	);
521 }
522 
benchmark_pushpop3(void)523 static void __naked benchmark_pushpop3(void)
524 {
525 	__asm__ __volatile__ (
526 		"stmdb"wide"	sp!, {r4,lr}  \n\t"
527 		"ldmia"wide"	sp!, {r4,pc}"
528 	);
529 }
530 
benchmark_pushpop4(void)531 static void __naked benchmark_pushpop4(void)
532 {
533 	__asm__ __volatile__ (
534 		"stmdb"wide"	sp!, {r0,lr}  \n\t"
535 		"ldmia"wide"	sp!, {r0,pc}"
536 	);
537 }
538 
539 
540 #ifdef CONFIG_THUMB2_KERNEL
541 
benchmark_pushpop_thumb(void)542 static void __naked benchmark_pushpop_thumb(void)
543 {
544 	__asm__ __volatile__ (
545 		"push.n	{r0-r7,lr}  \n\t"
546 		"pop.n	{r0-r7,pc}"
547 	);
548 }
549 
550 #endif
551 
552 static int __kprobes
benchmark_pre_handler(struct kprobe * p,struct pt_regs * regs)553 benchmark_pre_handler(struct kprobe *p, struct pt_regs *regs)
554 {
555 	return 0;
556 }
557 
benchmark(void (* fn)(void))558 static int benchmark(void(*fn)(void))
559 {
560 	unsigned n, i, t, t0;
561 
562 	for (n = 1000; ; n *= 2) {
563 		t0 = sched_clock();
564 		for (i = n; i > 0; --i)
565 			fn();
566 		t = sched_clock() - t0;
567 		if (t >= 250000000)
568 			break; /* Stop once we took more than 0.25 seconds */
569 	}
570 	return t / n; /* Time for one iteration in nanoseconds */
571 };
572 
kprobe_benchmark(void (* fn)(void),unsigned offset)573 static int kprobe_benchmark(void(*fn)(void), unsigned offset)
574 {
575 	struct kprobe k = {
576 		.addr		= (kprobe_opcode_t *)((uintptr_t)fn + offset),
577 		.pre_handler	= benchmark_pre_handler,
578 	};
579 
580 	int ret = register_kprobe(&k);
581 	if (ret < 0) {
582 		pr_err("FAIL: register_kprobe failed with %d\n", ret);
583 		return ret;
584 	}
585 
586 	ret = benchmark(fn);
587 
588 	unregister_kprobe(&k);
589 	return ret;
590 };
591 
592 struct benchmarks {
593 	void		(*fn)(void);
594 	unsigned	offset;
595 	const char	*title;
596 };
597 
run_benchmarks(void)598 static int run_benchmarks(void)
599 {
600 	int ret;
601 	struct benchmarks list[] = {
602 		{&benchmark_nop, 0, "nop"},
603 		/*
604 		 * benchmark_pushpop{1,3} will have the optimised
605 		 * instruction emulation, whilst benchmark_pushpop{2,4} will
606 		 * be the equivalent unoptimised instructions.
607 		 */
608 		{&benchmark_pushpop1, 0, "stmdb	sp!, {r3-r11,lr}"},
609 		{&benchmark_pushpop1, 4, "ldmia	sp!, {r3-r11,pc}"},
610 		{&benchmark_pushpop2, 0, "stmdb	sp!, {r0-r8,lr}"},
611 		{&benchmark_pushpop2, 4, "ldmia	sp!, {r0-r8,pc}"},
612 		{&benchmark_pushpop3, 0, "stmdb	sp!, {r4,lr}"},
613 		{&benchmark_pushpop3, 4, "ldmia	sp!, {r4,pc}"},
614 		{&benchmark_pushpop4, 0, "stmdb	sp!, {r0,lr}"},
615 		{&benchmark_pushpop4, 4, "ldmia	sp!, {r0,pc}"},
616 #ifdef CONFIG_THUMB2_KERNEL
617 		{&benchmark_pushpop_thumb, 0, "push.n	{r0-r7,lr}"},
618 		{&benchmark_pushpop_thumb, 2, "pop.n	{r0-r7,pc}"},
619 #endif
620 		{0}
621 	};
622 
623 	struct benchmarks *b;
624 	for (b = list; b->fn; ++b) {
625 		ret = kprobe_benchmark(b->fn, b->offset);
626 		if (ret < 0)
627 			return ret;
628 		pr_info("    %dns for kprobe %s\n", ret, b->title);
629 	}
630 
631 	pr_info("\n");
632 	return 0;
633 }
634 
635 #endif /* BENCHMARKING */
636 
637 
638 /*
639  * Decoding table self-consistency tests
640  */
641 
642 static const int decode_struct_sizes[NUM_DECODE_TYPES] = {
643 	[DECODE_TYPE_TABLE]	= sizeof(struct decode_table),
644 	[DECODE_TYPE_CUSTOM]	= sizeof(struct decode_custom),
645 	[DECODE_TYPE_SIMULATE]	= sizeof(struct decode_simulate),
646 	[DECODE_TYPE_EMULATE]	= sizeof(struct decode_emulate),
647 	[DECODE_TYPE_OR]	= sizeof(struct decode_or),
648 	[DECODE_TYPE_REJECT]	= sizeof(struct decode_reject)
649 };
650 
table_iter(const union decode_item * table,int (* fn)(const struct decode_header *,void *),void * args)651 static int table_iter(const union decode_item *table,
652 			int (*fn)(const struct decode_header *, void *),
653 			void *args)
654 {
655 	const struct decode_header *h = (struct decode_header *)table;
656 	int result;
657 
658 	for (;;) {
659 		enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK;
660 
661 		if (type == DECODE_TYPE_END)
662 			return 0;
663 
664 		result = fn(h, args);
665 		if (result)
666 			return result;
667 
668 		h = (struct decode_header *)
669 			((uintptr_t)h + decode_struct_sizes[type]);
670 
671 	}
672 }
673 
table_test_fail(const struct decode_header * h,const char * message)674 static int table_test_fail(const struct decode_header *h, const char* message)
675 {
676 
677 	pr_err("FAIL: kprobes test failure \"%s\" (mask %08x, value %08x)\n",
678 					message, h->mask.bits, h->value.bits);
679 	return -EINVAL;
680 }
681 
682 struct table_test_args {
683 	const union decode_item *root_table;
684 	u32			parent_mask;
685 	u32			parent_value;
686 };
687 
table_test_fn(const struct decode_header * h,void * args)688 static int table_test_fn(const struct decode_header *h, void *args)
689 {
690 	struct table_test_args *a = (struct table_test_args *)args;
691 	enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK;
692 
693 	if (h->value.bits & ~h->mask.bits)
694 		return table_test_fail(h, "Match value has bits not in mask");
695 
696 	if ((h->mask.bits & a->parent_mask) != a->parent_mask)
697 		return table_test_fail(h, "Mask has bits not in parent mask");
698 
699 	if ((h->value.bits ^ a->parent_value) & a->parent_mask)
700 		return table_test_fail(h, "Value is inconsistent with parent");
701 
702 	if (type == DECODE_TYPE_TABLE) {
703 		struct decode_table *d = (struct decode_table *)h;
704 		struct table_test_args args2 = *a;
705 		args2.parent_mask = h->mask.bits;
706 		args2.parent_value = h->value.bits;
707 		return table_iter(d->table.table, table_test_fn, &args2);
708 	}
709 
710 	return 0;
711 }
712 
table_test(const union decode_item * table)713 static int table_test(const union decode_item *table)
714 {
715 	struct table_test_args args = {
716 		.root_table	= table,
717 		.parent_mask	= 0,
718 		.parent_value	= 0
719 	};
720 	return table_iter(args.root_table, table_test_fn, &args);
721 }
722 
723 
724 /*
725  * Decoding table test coverage analysis
726  *
727  * coverage_start() builds a coverage_table which contains a list of
728  * coverage_entry's to match each entry in the specified kprobes instruction
729  * decoding table.
730  *
731  * When test cases are run, coverage_add() is called to process each case.
732  * This looks up the corresponding entry in the coverage_table and sets it as
733  * being matched, as well as clearing the regs flag appropriate for the test.
734  *
735  * After all test cases have been run, coverage_end() is called to check that
736  * all entries in coverage_table have been matched and that all regs flags are
737  * cleared. I.e. that all possible combinations of instructions described by
738  * the kprobes decoding tables have had a test case executed for them.
739  */
740 
741 bool coverage_fail;
742 
743 #define MAX_COVERAGE_ENTRIES 256
744 
745 struct coverage_entry {
746 	const struct decode_header	*header;
747 	unsigned			regs;
748 	unsigned			nesting;
749 	char				matched;
750 };
751 
752 struct coverage_table {
753 	struct coverage_entry	*base;
754 	unsigned		num_entries;
755 	unsigned		nesting;
756 };
757 
758 struct coverage_table coverage;
759 
760 #define COVERAGE_ANY_REG	(1<<0)
761 #define COVERAGE_SP		(1<<1)
762 #define COVERAGE_PC		(1<<2)
763 #define COVERAGE_PCWB		(1<<3)
764 
765 static const char coverage_register_lookup[16] = {
766 	[REG_TYPE_ANY]		= COVERAGE_ANY_REG | COVERAGE_SP | COVERAGE_PC,
767 	[REG_TYPE_SAMEAS16]	= COVERAGE_ANY_REG,
768 	[REG_TYPE_SP]		= COVERAGE_SP,
769 	[REG_TYPE_PC]		= COVERAGE_PC,
770 	[REG_TYPE_NOSP]		= COVERAGE_ANY_REG | COVERAGE_SP,
771 	[REG_TYPE_NOSPPC]	= COVERAGE_ANY_REG | COVERAGE_SP | COVERAGE_PC,
772 	[REG_TYPE_NOPC]		= COVERAGE_ANY_REG | COVERAGE_PC,
773 	[REG_TYPE_NOPCWB]	= COVERAGE_ANY_REG | COVERAGE_PC | COVERAGE_PCWB,
774 	[REG_TYPE_NOPCX]	= COVERAGE_ANY_REG,
775 	[REG_TYPE_NOSPPCX]	= COVERAGE_ANY_REG | COVERAGE_SP,
776 };
777 
coverage_start_registers(const struct decode_header * h)778 unsigned coverage_start_registers(const struct decode_header *h)
779 {
780 	unsigned regs = 0;
781 	int i;
782 	for (i = 0; i < 20; i += 4) {
783 		int r = (h->type_regs.bits >> (DECODE_TYPE_BITS + i)) & 0xf;
784 		regs |= coverage_register_lookup[r] << i;
785 	}
786 	return regs;
787 }
788 
coverage_start_fn(const struct decode_header * h,void * args)789 static int coverage_start_fn(const struct decode_header *h, void *args)
790 {
791 	struct coverage_table *coverage = (struct coverage_table *)args;
792 	enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK;
793 	struct coverage_entry *entry = coverage->base + coverage->num_entries;
794 
795 	if (coverage->num_entries == MAX_COVERAGE_ENTRIES - 1) {
796 		pr_err("FAIL: Out of space for test coverage data");
797 		return -ENOMEM;
798 	}
799 
800 	++coverage->num_entries;
801 
802 	entry->header = h;
803 	entry->regs = coverage_start_registers(h);
804 	entry->nesting = coverage->nesting;
805 	entry->matched = false;
806 
807 	if (type == DECODE_TYPE_TABLE) {
808 		struct decode_table *d = (struct decode_table *)h;
809 		int ret;
810 		++coverage->nesting;
811 		ret = table_iter(d->table.table, coverage_start_fn, coverage);
812 		--coverage->nesting;
813 		return ret;
814 	}
815 
816 	return 0;
817 }
818 
coverage_start(const union decode_item * table)819 static int coverage_start(const union decode_item *table)
820 {
821 	coverage.base = kmalloc(MAX_COVERAGE_ENTRIES *
822 				sizeof(struct coverage_entry), GFP_KERNEL);
823 	coverage.num_entries = 0;
824 	coverage.nesting = 0;
825 	return table_iter(table, coverage_start_fn, &coverage);
826 }
827 
828 static void
coverage_add_registers(struct coverage_entry * entry,kprobe_opcode_t insn)829 coverage_add_registers(struct coverage_entry *entry, kprobe_opcode_t insn)
830 {
831 	int regs = entry->header->type_regs.bits >> DECODE_TYPE_BITS;
832 	int i;
833 	for (i = 0; i < 20; i += 4) {
834 		enum decode_reg_type reg_type = (regs >> i) & 0xf;
835 		int reg = (insn >> i) & 0xf;
836 		int flag;
837 
838 		if (!reg_type)
839 			continue;
840 
841 		if (reg == 13)
842 			flag = COVERAGE_SP;
843 		else if (reg == 15)
844 			flag = COVERAGE_PC;
845 		else
846 			flag = COVERAGE_ANY_REG;
847 		entry->regs &= ~(flag << i);
848 
849 		switch (reg_type) {
850 
851 		case REG_TYPE_NONE:
852 		case REG_TYPE_ANY:
853 		case REG_TYPE_SAMEAS16:
854 			break;
855 
856 		case REG_TYPE_SP:
857 			if (reg != 13)
858 				return;
859 			break;
860 
861 		case REG_TYPE_PC:
862 			if (reg != 15)
863 				return;
864 			break;
865 
866 		case REG_TYPE_NOSP:
867 			if (reg == 13)
868 				return;
869 			break;
870 
871 		case REG_TYPE_NOSPPC:
872 		case REG_TYPE_NOSPPCX:
873 			if (reg == 13 || reg == 15)
874 				return;
875 			break;
876 
877 		case REG_TYPE_NOPCWB:
878 			if (!is_writeback(insn))
879 				break;
880 			if (reg == 15) {
881 				entry->regs &= ~(COVERAGE_PCWB << i);
882 				return;
883 			}
884 			break;
885 
886 		case REG_TYPE_NOPC:
887 		case REG_TYPE_NOPCX:
888 			if (reg == 15)
889 				return;
890 			break;
891 		}
892 
893 	}
894 }
895 
coverage_add(kprobe_opcode_t insn)896 static void coverage_add(kprobe_opcode_t insn)
897 {
898 	struct coverage_entry *entry = coverage.base;
899 	struct coverage_entry *end = coverage.base + coverage.num_entries;
900 	bool matched = false;
901 	unsigned nesting = 0;
902 
903 	for (; entry < end; ++entry) {
904 		const struct decode_header *h = entry->header;
905 		enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK;
906 
907 		if (entry->nesting > nesting)
908 			continue; /* Skip sub-table we didn't match */
909 
910 		if (entry->nesting < nesting)
911 			break; /* End of sub-table we were scanning */
912 
913 		if (!matched) {
914 			if ((insn & h->mask.bits) != h->value.bits)
915 				continue;
916 			entry->matched = true;
917 		}
918 
919 		switch (type) {
920 
921 		case DECODE_TYPE_TABLE:
922 			++nesting;
923 			break;
924 
925 		case DECODE_TYPE_CUSTOM:
926 		case DECODE_TYPE_SIMULATE:
927 		case DECODE_TYPE_EMULATE:
928 			coverage_add_registers(entry, insn);
929 			return;
930 
931 		case DECODE_TYPE_OR:
932 			matched = true;
933 			break;
934 
935 		case DECODE_TYPE_REJECT:
936 		default:
937 			return;
938 		}
939 
940 	}
941 }
942 
coverage_end(void)943 static void coverage_end(void)
944 {
945 	struct coverage_entry *entry = coverage.base;
946 	struct coverage_entry *end = coverage.base + coverage.num_entries;
947 
948 	for (; entry < end; ++entry) {
949 		u32 mask = entry->header->mask.bits;
950 		u32 value = entry->header->value.bits;
951 
952 		if (entry->regs) {
953 			pr_err("FAIL: Register test coverage missing for %08x %08x (%05x)\n",
954 				mask, value, entry->regs);
955 			coverage_fail = true;
956 		}
957 		if (!entry->matched) {
958 			pr_err("FAIL: Test coverage entry missing for %08x %08x\n",
959 				mask, value);
960 			coverage_fail = true;
961 		}
962 	}
963 
964 	kfree(coverage.base);
965 }
966 
967 
968 /*
969  * Framework for instruction set test cases
970  */
971 
__kprobes_test_case_start(void)972 void __naked __kprobes_test_case_start(void)
973 {
974 	__asm__ __volatile__ (
975 		"stmdb	sp!, {r4-r11}				\n\t"
976 		"sub	sp, sp, #"__stringify(TEST_MEMORY_SIZE)"\n\t"
977 		"bic	r0, lr, #1  @ r0 = inline data		\n\t"
978 		"mov	r1, sp					\n\t"
979 		"bl	kprobes_test_case_start			\n\t"
980 		"bx	r0					\n\t"
981 	);
982 }
983 
984 #ifndef CONFIG_THUMB2_KERNEL
985 
__kprobes_test_case_end_32(void)986 void __naked __kprobes_test_case_end_32(void)
987 {
988 	__asm__ __volatile__ (
989 		"mov	r4, lr					\n\t"
990 		"bl	kprobes_test_case_end			\n\t"
991 		"cmp	r0, #0					\n\t"
992 		"movne	pc, r0					\n\t"
993 		"mov	r0, r4					\n\t"
994 		"add	sp, sp, #"__stringify(TEST_MEMORY_SIZE)"\n\t"
995 		"ldmia	sp!, {r4-r11}				\n\t"
996 		"mov	pc, r0					\n\t"
997 	);
998 }
999 
1000 #else /* CONFIG_THUMB2_KERNEL */
1001 
__kprobes_test_case_end_16(void)1002 void __naked __kprobes_test_case_end_16(void)
1003 {
1004 	__asm__ __volatile__ (
1005 		"mov	r4, lr					\n\t"
1006 		"bl	kprobes_test_case_end			\n\t"
1007 		"cmp	r0, #0					\n\t"
1008 		"bxne	r0					\n\t"
1009 		"mov	r0, r4					\n\t"
1010 		"add	sp, sp, #"__stringify(TEST_MEMORY_SIZE)"\n\t"
1011 		"ldmia	sp!, {r4-r11}				\n\t"
1012 		"bx	r0					\n\t"
1013 	);
1014 }
1015 
__kprobes_test_case_end_32(void)1016 void __naked __kprobes_test_case_end_32(void)
1017 {
1018 	__asm__ __volatile__ (
1019 		".arm						\n\t"
1020 		"orr	lr, lr, #1  @ will return to Thumb code	\n\t"
1021 		"ldr	pc, 1f					\n\t"
1022 		"1:						\n\t"
1023 		".word	__kprobes_test_case_end_16		\n\t"
1024 	);
1025 }
1026 
1027 #endif
1028 
1029 
1030 int kprobe_test_flags;
1031 int kprobe_test_cc_position;
1032 
1033 static int test_try_count;
1034 static int test_pass_count;
1035 static int test_fail_count;
1036 
1037 static struct pt_regs initial_regs;
1038 static struct pt_regs expected_regs;
1039 static struct pt_regs result_regs;
1040 
1041 static u32 expected_memory[TEST_MEMORY_SIZE/sizeof(u32)];
1042 
1043 static const char *current_title;
1044 static struct test_arg *current_args;
1045 static u32 *current_stack;
1046 static uintptr_t current_branch_target;
1047 
1048 static uintptr_t current_code_start;
1049 static kprobe_opcode_t current_instruction;
1050 
1051 
1052 #define TEST_CASE_PASSED -1
1053 #define TEST_CASE_FAILED -2
1054 
1055 static int test_case_run_count;
1056 static bool test_case_is_thumb;
1057 static int test_instance;
1058 
1059 /*
1060  * We ignore the state of the imprecise abort disable flag (CPSR.A) because this
1061  * can change randomly as the kernel doesn't take care to preserve or initialise
1062  * this across context switches. Also, with Security Extentions, the flag may
1063  * not be under control of the kernel; for this reason we ignore the state of
1064  * the FIQ disable flag CPSR.F as well.
1065  */
1066 #define PSR_IGNORE_BITS (PSR_A_BIT | PSR_F_BIT)
1067 
test_check_cc(int cc,unsigned long cpsr)1068 static unsigned long test_check_cc(int cc, unsigned long cpsr)
1069 {
1070 	int ret = arm_check_condition(cc << 28, cpsr);
1071 
1072 	return (ret != ARM_OPCODE_CONDTEST_FAIL);
1073 }
1074 
1075 static int is_last_scenario;
1076 static int probe_should_run; /* 0 = no, 1 = yes, -1 = unknown */
1077 static int memory_needs_checking;
1078 
test_context_cpsr(int scenario)1079 static unsigned long test_context_cpsr(int scenario)
1080 {
1081 	unsigned long cpsr;
1082 
1083 	probe_should_run = 1;
1084 
1085 	/* Default case is that we cycle through 16 combinations of flags */
1086 	cpsr  = (scenario & 0xf) << 28; /* N,Z,C,V flags */
1087 	cpsr |= (scenario & 0xf) << 16; /* GE flags */
1088 	cpsr |= (scenario & 0x1) << 27; /* Toggle Q flag */
1089 
1090 	if (!test_case_is_thumb) {
1091 		/* Testing ARM code */
1092 		int cc = current_instruction >> 28;
1093 
1094 		probe_should_run = test_check_cc(cc, cpsr) != 0;
1095 		if (scenario == 15)
1096 			is_last_scenario = true;
1097 
1098 	} else if (kprobe_test_flags & TEST_FLAG_NO_ITBLOCK) {
1099 		/* Testing Thumb code without setting ITSTATE */
1100 		if (kprobe_test_cc_position) {
1101 			int cc = (current_instruction >> kprobe_test_cc_position) & 0xf;
1102 			probe_should_run = test_check_cc(cc, cpsr) != 0;
1103 		}
1104 
1105 		if (scenario == 15)
1106 			is_last_scenario = true;
1107 
1108 	} else if (kprobe_test_flags & TEST_FLAG_FULL_ITBLOCK) {
1109 		/* Testing Thumb code with all combinations of ITSTATE */
1110 		unsigned x = (scenario >> 4);
1111 		unsigned cond_base = x % 7; /* ITSTATE<7:5> */
1112 		unsigned mask = x / 7 + 2;  /* ITSTATE<4:0>, bits reversed */
1113 
1114 		if (mask > 0x1f) {
1115 			/* Finish by testing state from instruction 'itt al' */
1116 			cond_base = 7;
1117 			mask = 0x4;
1118 			if ((scenario & 0xf) == 0xf)
1119 				is_last_scenario = true;
1120 		}
1121 
1122 		cpsr |= cond_base << 13;	/* ITSTATE<7:5> */
1123 		cpsr |= (mask & 0x1) << 12;	/* ITSTATE<4> */
1124 		cpsr |= (mask & 0x2) << 10;	/* ITSTATE<3> */
1125 		cpsr |= (mask & 0x4) << 8;	/* ITSTATE<2> */
1126 		cpsr |= (mask & 0x8) << 23;	/* ITSTATE<1> */
1127 		cpsr |= (mask & 0x10) << 21;	/* ITSTATE<0> */
1128 
1129 		probe_should_run = test_check_cc((cpsr >> 12) & 0xf, cpsr) != 0;
1130 
1131 	} else {
1132 		/* Testing Thumb code with several combinations of ITSTATE */
1133 		switch (scenario) {
1134 		case 16: /* Clear NZCV flags and 'it eq' state (false as Z=0) */
1135 			cpsr = 0x00000800;
1136 			probe_should_run = 0;
1137 			break;
1138 		case 17: /* Set NZCV flags and 'it vc' state (false as V=1) */
1139 			cpsr = 0xf0007800;
1140 			probe_should_run = 0;
1141 			break;
1142 		case 18: /* Clear NZCV flags and 'it ls' state (true as C=0) */
1143 			cpsr = 0x00009800;
1144 			break;
1145 		case 19: /* Set NZCV flags and 'it cs' state (true as C=1) */
1146 			cpsr = 0xf0002800;
1147 			is_last_scenario = true;
1148 			break;
1149 		}
1150 	}
1151 
1152 	return cpsr;
1153 }
1154 
setup_test_context(struct pt_regs * regs)1155 static void setup_test_context(struct pt_regs *regs)
1156 {
1157 	int scenario = test_case_run_count>>1;
1158 	unsigned long val;
1159 	struct test_arg *args;
1160 	int i;
1161 
1162 	is_last_scenario = false;
1163 	memory_needs_checking = false;
1164 
1165 	/* Initialise test memory on stack */
1166 	val = (scenario & 1) ? VALM : ~VALM;
1167 	for (i = 0; i < TEST_MEMORY_SIZE / sizeof(current_stack[0]); ++i)
1168 		current_stack[i] = val + (i << 8);
1169 	/* Put target of branch on stack for tests which load PC from memory */
1170 	if (current_branch_target)
1171 		current_stack[15] = current_branch_target;
1172 	/* Put a value for SP on stack for tests which load SP from memory */
1173 	current_stack[13] = (u32)current_stack + 120;
1174 
1175 	/* Initialise register values to their default state */
1176 	val = (scenario & 2) ? VALR : ~VALR;
1177 	for (i = 0; i < 13; ++i)
1178 		regs->uregs[i] = val ^ (i << 8);
1179 	regs->ARM_lr = val ^ (14 << 8);
1180 	regs->ARM_cpsr &= ~(APSR_MASK | PSR_IT_MASK);
1181 	regs->ARM_cpsr |= test_context_cpsr(scenario);
1182 
1183 	/* Perform testcase specific register setup  */
1184 	args = current_args;
1185 	for (; args[0].type != ARG_TYPE_END; ++args)
1186 		switch (args[0].type) {
1187 		case ARG_TYPE_REG: {
1188 			struct test_arg_regptr *arg =
1189 				(struct test_arg_regptr *)args;
1190 			regs->uregs[arg->reg] = arg->val;
1191 			break;
1192 		}
1193 		case ARG_TYPE_PTR: {
1194 			struct test_arg_regptr *arg =
1195 				(struct test_arg_regptr *)args;
1196 			regs->uregs[arg->reg] =
1197 				(unsigned long)current_stack + arg->val;
1198 			memory_needs_checking = true;
1199 			break;
1200 		}
1201 		case ARG_TYPE_MEM: {
1202 			struct test_arg_mem *arg = (struct test_arg_mem *)args;
1203 			current_stack[arg->index] = arg->val;
1204 			break;
1205 		}
1206 		default:
1207 			break;
1208 		}
1209 }
1210 
1211 struct test_probe {
1212 	struct kprobe	kprobe;
1213 	bool		registered;
1214 	int		hit;
1215 };
1216 
unregister_test_probe(struct test_probe * probe)1217 static void unregister_test_probe(struct test_probe *probe)
1218 {
1219 	if (probe->registered) {
1220 		unregister_kprobe(&probe->kprobe);
1221 		probe->kprobe.flags = 0; /* Clear disable flag to allow reuse */
1222 	}
1223 	probe->registered = false;
1224 }
1225 
register_test_probe(struct test_probe * probe)1226 static int register_test_probe(struct test_probe *probe)
1227 {
1228 	int ret;
1229 
1230 	if (probe->registered)
1231 		BUG();
1232 
1233 	ret = register_kprobe(&probe->kprobe);
1234 	if (ret >= 0) {
1235 		probe->registered = true;
1236 		probe->hit = -1;
1237 	}
1238 	return ret;
1239 }
1240 
1241 static int __kprobes
test_before_pre_handler(struct kprobe * p,struct pt_regs * regs)1242 test_before_pre_handler(struct kprobe *p, struct pt_regs *regs)
1243 {
1244 	container_of(p, struct test_probe, kprobe)->hit = test_instance;
1245 	return 0;
1246 }
1247 
1248 static void __kprobes
test_before_post_handler(struct kprobe * p,struct pt_regs * regs,unsigned long flags)1249 test_before_post_handler(struct kprobe *p, struct pt_regs *regs,
1250 							unsigned long flags)
1251 {
1252 	setup_test_context(regs);
1253 	initial_regs = *regs;
1254 	initial_regs.ARM_cpsr &= ~PSR_IGNORE_BITS;
1255 }
1256 
1257 static int __kprobes
test_case_pre_handler(struct kprobe * p,struct pt_regs * regs)1258 test_case_pre_handler(struct kprobe *p, struct pt_regs *regs)
1259 {
1260 	container_of(p, struct test_probe, kprobe)->hit = test_instance;
1261 	return 0;
1262 }
1263 
1264 static int __kprobes
test_after_pre_handler(struct kprobe * p,struct pt_regs * regs)1265 test_after_pre_handler(struct kprobe *p, struct pt_regs *regs)
1266 {
1267 	if (container_of(p, struct test_probe, kprobe)->hit == test_instance)
1268 		return 0; /* Already run for this test instance */
1269 
1270 	result_regs = *regs;
1271 	result_regs.ARM_cpsr &= ~PSR_IGNORE_BITS;
1272 
1273 	/* Undo any changes done to SP by the test case */
1274 	regs->ARM_sp = (unsigned long)current_stack;
1275 
1276 	container_of(p, struct test_probe, kprobe)->hit = test_instance;
1277 	return 0;
1278 }
1279 
1280 static struct test_probe test_before_probe = {
1281 	.kprobe.pre_handler	= test_before_pre_handler,
1282 	.kprobe.post_handler	= test_before_post_handler,
1283 };
1284 
1285 static struct test_probe test_case_probe = {
1286 	.kprobe.pre_handler	= test_case_pre_handler,
1287 };
1288 
1289 static struct test_probe test_after_probe = {
1290 	.kprobe.pre_handler	= test_after_pre_handler,
1291 };
1292 
1293 static struct test_probe test_after2_probe = {
1294 	.kprobe.pre_handler	= test_after_pre_handler,
1295 };
1296 
test_case_cleanup(void)1297 static void test_case_cleanup(void)
1298 {
1299 	unregister_test_probe(&test_before_probe);
1300 	unregister_test_probe(&test_case_probe);
1301 	unregister_test_probe(&test_after_probe);
1302 	unregister_test_probe(&test_after2_probe);
1303 }
1304 
print_registers(struct pt_regs * regs)1305 static void print_registers(struct pt_regs *regs)
1306 {
1307 	pr_err("r0  %08lx | r1  %08lx | r2  %08lx | r3  %08lx\n",
1308 		regs->ARM_r0, regs->ARM_r1, regs->ARM_r2, regs->ARM_r3);
1309 	pr_err("r4  %08lx | r5  %08lx | r6  %08lx | r7  %08lx\n",
1310 		regs->ARM_r4, regs->ARM_r5, regs->ARM_r6, regs->ARM_r7);
1311 	pr_err("r8  %08lx | r9  %08lx | r10 %08lx | r11 %08lx\n",
1312 		regs->ARM_r8, regs->ARM_r9, regs->ARM_r10, regs->ARM_fp);
1313 	pr_err("r12 %08lx | sp  %08lx | lr  %08lx | pc  %08lx\n",
1314 		regs->ARM_ip, regs->ARM_sp, regs->ARM_lr, regs->ARM_pc);
1315 	pr_err("cpsr %08lx\n", regs->ARM_cpsr);
1316 }
1317 
print_memory(u32 * mem,size_t size)1318 static void print_memory(u32 *mem, size_t size)
1319 {
1320 	int i;
1321 	for (i = 0; i < size / sizeof(u32); i += 4)
1322 		pr_err("%08x %08x %08x %08x\n", mem[i], mem[i+1],
1323 						mem[i+2], mem[i+3]);
1324 }
1325 
expected_memory_size(u32 * sp)1326 static size_t expected_memory_size(u32 *sp)
1327 {
1328 	size_t size = sizeof(expected_memory);
1329 	int offset = (uintptr_t)sp - (uintptr_t)current_stack;
1330 	if (offset > 0)
1331 		size -= offset;
1332 	return size;
1333 }
1334 
test_case_failed(const char * message)1335 static void test_case_failed(const char *message)
1336 {
1337 	test_case_cleanup();
1338 
1339 	pr_err("FAIL: %s\n", message);
1340 	pr_err("FAIL: Test %s\n", current_title);
1341 	pr_err("FAIL: Scenario %d\n", test_case_run_count >> 1);
1342 }
1343 
next_instruction(unsigned long pc)1344 static unsigned long next_instruction(unsigned long pc)
1345 {
1346 #ifdef CONFIG_THUMB2_KERNEL
1347 	if ((pc & 1) &&
1348 	    !is_wide_instruction(__mem_to_opcode_thumb16(*(u16 *)(pc - 1))))
1349 		return pc + 2;
1350 	else
1351 #endif
1352 	return pc + 4;
1353 }
1354 
kprobes_test_case_start(const char ** title,void * stack)1355 static uintptr_t __used kprobes_test_case_start(const char **title, void *stack)
1356 {
1357 	struct test_arg *args;
1358 	struct test_arg_end *end_arg;
1359 	unsigned long test_code;
1360 
1361 	current_title = *title++;
1362 	args = (struct test_arg *)title;
1363 	current_args = args;
1364 	current_stack = stack;
1365 
1366 	++test_try_count;
1367 
1368 	while (args->type != ARG_TYPE_END)
1369 		++args;
1370 	end_arg = (struct test_arg_end *)args;
1371 
1372 	test_code = (unsigned long)(args + 1); /* Code starts after args */
1373 
1374 	test_case_is_thumb = end_arg->flags & ARG_FLAG_THUMB;
1375 	if (test_case_is_thumb)
1376 		test_code |= 1;
1377 
1378 	current_code_start = test_code;
1379 
1380 	current_branch_target = 0;
1381 	if (end_arg->branch_offset != end_arg->end_offset)
1382 		current_branch_target = test_code + end_arg->branch_offset;
1383 
1384 	test_code += end_arg->code_offset;
1385 	test_before_probe.kprobe.addr = (kprobe_opcode_t *)test_code;
1386 
1387 	test_code = next_instruction(test_code);
1388 	test_case_probe.kprobe.addr = (kprobe_opcode_t *)test_code;
1389 
1390 	if (test_case_is_thumb) {
1391 		u16 *p = (u16 *)(test_code & ~1);
1392 		current_instruction = __mem_to_opcode_thumb16(p[0]);
1393 		if (is_wide_instruction(current_instruction)) {
1394 			u16 instr2 = __mem_to_opcode_thumb16(p[1]);
1395 			current_instruction = __opcode_thumb32_compose(current_instruction, instr2);
1396 		}
1397 	} else {
1398 		current_instruction = __mem_to_opcode_arm(*(u32 *)test_code);
1399 	}
1400 
1401 	if (current_title[0] == '.')
1402 		verbose("%s\n", current_title);
1403 	else
1404 		verbose("%s\t@ %0*x\n", current_title,
1405 					test_case_is_thumb ? 4 : 8,
1406 					current_instruction);
1407 
1408 	test_code = next_instruction(test_code);
1409 	test_after_probe.kprobe.addr = (kprobe_opcode_t *)test_code;
1410 
1411 	if (kprobe_test_flags & TEST_FLAG_NARROW_INSTR) {
1412 		if (!test_case_is_thumb ||
1413 			is_wide_instruction(current_instruction)) {
1414 				test_case_failed("expected 16-bit instruction");
1415 				goto fail;
1416 		}
1417 	} else {
1418 		if (test_case_is_thumb &&
1419 			!is_wide_instruction(current_instruction)) {
1420 				test_case_failed("expected 32-bit instruction");
1421 				goto fail;
1422 		}
1423 	}
1424 
1425 	coverage_add(current_instruction);
1426 
1427 	if (end_arg->flags & ARG_FLAG_UNSUPPORTED) {
1428 		if (register_test_probe(&test_case_probe) < 0)
1429 			goto pass;
1430 		test_case_failed("registered probe for unsupported instruction");
1431 		goto fail;
1432 	}
1433 
1434 	if (end_arg->flags & ARG_FLAG_SUPPORTED) {
1435 		if (register_test_probe(&test_case_probe) >= 0)
1436 			goto pass;
1437 		test_case_failed("couldn't register probe for supported instruction");
1438 		goto fail;
1439 	}
1440 
1441 	if (register_test_probe(&test_before_probe) < 0) {
1442 		test_case_failed("register test_before_probe failed");
1443 		goto fail;
1444 	}
1445 	if (register_test_probe(&test_after_probe) < 0) {
1446 		test_case_failed("register test_after_probe failed");
1447 		goto fail;
1448 	}
1449 	if (current_branch_target) {
1450 		test_after2_probe.kprobe.addr =
1451 				(kprobe_opcode_t *)current_branch_target;
1452 		if (register_test_probe(&test_after2_probe) < 0) {
1453 			test_case_failed("register test_after2_probe failed");
1454 			goto fail;
1455 		}
1456 	}
1457 
1458 	/* Start first run of test case */
1459 	test_case_run_count = 0;
1460 	++test_instance;
1461 	return current_code_start;
1462 pass:
1463 	test_case_run_count = TEST_CASE_PASSED;
1464 	return (uintptr_t)test_after_probe.kprobe.addr;
1465 fail:
1466 	test_case_run_count = TEST_CASE_FAILED;
1467 	return (uintptr_t)test_after_probe.kprobe.addr;
1468 }
1469 
check_test_results(void)1470 static bool check_test_results(void)
1471 {
1472 	size_t mem_size = 0;
1473 	u32 *mem = 0;
1474 
1475 	if (memcmp(&expected_regs, &result_regs, sizeof(expected_regs))) {
1476 		test_case_failed("registers differ");
1477 		goto fail;
1478 	}
1479 
1480 	if (memory_needs_checking) {
1481 		mem = (u32 *)result_regs.ARM_sp;
1482 		mem_size = expected_memory_size(mem);
1483 		if (memcmp(expected_memory, mem, mem_size)) {
1484 			test_case_failed("test memory differs");
1485 			goto fail;
1486 		}
1487 	}
1488 
1489 	return true;
1490 
1491 fail:
1492 	pr_err("initial_regs:\n");
1493 	print_registers(&initial_regs);
1494 	pr_err("expected_regs:\n");
1495 	print_registers(&expected_regs);
1496 	pr_err("result_regs:\n");
1497 	print_registers(&result_regs);
1498 
1499 	if (mem) {
1500 		pr_err("current_stack=%p\n", current_stack);
1501 		pr_err("expected_memory:\n");
1502 		print_memory(expected_memory, mem_size);
1503 		pr_err("result_memory:\n");
1504 		print_memory(mem, mem_size);
1505 	}
1506 
1507 	return false;
1508 }
1509 
kprobes_test_case_end(void)1510 static uintptr_t __used kprobes_test_case_end(void)
1511 {
1512 	if (test_case_run_count < 0) {
1513 		if (test_case_run_count == TEST_CASE_PASSED)
1514 			/* kprobes_test_case_start did all the needed testing */
1515 			goto pass;
1516 		else
1517 			/* kprobes_test_case_start failed */
1518 			goto fail;
1519 	}
1520 
1521 	if (test_before_probe.hit != test_instance) {
1522 		test_case_failed("test_before_handler not run");
1523 		goto fail;
1524 	}
1525 
1526 	if (test_after_probe.hit != test_instance &&
1527 				test_after2_probe.hit != test_instance) {
1528 		test_case_failed("test_after_handler not run");
1529 		goto fail;
1530 	}
1531 
1532 	/*
1533 	 * Even numbered test runs ran without a probe on the test case so
1534 	 * we can gather reference results. The subsequent odd numbered run
1535 	 * will have the probe inserted.
1536 	*/
1537 	if ((test_case_run_count & 1) == 0) {
1538 		/* Save results from run without probe */
1539 		u32 *mem = (u32 *)result_regs.ARM_sp;
1540 		expected_regs = result_regs;
1541 		memcpy(expected_memory, mem, expected_memory_size(mem));
1542 
1543 		/* Insert probe onto test case instruction */
1544 		if (register_test_probe(&test_case_probe) < 0) {
1545 			test_case_failed("register test_case_probe failed");
1546 			goto fail;
1547 		}
1548 	} else {
1549 		/* Check probe ran as expected */
1550 		if (probe_should_run == 1) {
1551 			if (test_case_probe.hit != test_instance) {
1552 				test_case_failed("test_case_handler not run");
1553 				goto fail;
1554 			}
1555 		} else if (probe_should_run == 0) {
1556 			if (test_case_probe.hit == test_instance) {
1557 				test_case_failed("test_case_handler ran");
1558 				goto fail;
1559 			}
1560 		}
1561 
1562 		/* Remove probe for any subsequent reference run */
1563 		unregister_test_probe(&test_case_probe);
1564 
1565 		if (!check_test_results())
1566 			goto fail;
1567 
1568 		if (is_last_scenario)
1569 			goto pass;
1570 	}
1571 
1572 	/* Do next test run */
1573 	++test_case_run_count;
1574 	++test_instance;
1575 	return current_code_start;
1576 fail:
1577 	++test_fail_count;
1578 	goto end;
1579 pass:
1580 	++test_pass_count;
1581 end:
1582 	test_case_cleanup();
1583 	return 0;
1584 }
1585 
1586 
1587 /*
1588  * Top level test functions
1589  */
1590 
run_test_cases(void (* tests)(void),const union decode_item * table)1591 static int run_test_cases(void (*tests)(void), const union decode_item *table)
1592 {
1593 	int ret;
1594 
1595 	pr_info("    Check decoding tables\n");
1596 	ret = table_test(table);
1597 	if (ret)
1598 		return ret;
1599 
1600 	pr_info("    Run test cases\n");
1601 	ret = coverage_start(table);
1602 	if (ret)
1603 		return ret;
1604 
1605 	tests();
1606 
1607 	coverage_end();
1608 	return 0;
1609 }
1610 
1611 
run_all_tests(void)1612 static int __init run_all_tests(void)
1613 {
1614 	int ret = 0;
1615 
1616 	pr_info("Beginning kprobe tests...\n");
1617 
1618 #ifndef CONFIG_THUMB2_KERNEL
1619 
1620 	pr_info("Probe ARM code\n");
1621 	ret = run_api_tests(arm_func);
1622 	if (ret)
1623 		goto out;
1624 
1625 	pr_info("ARM instruction simulation\n");
1626 	ret = run_test_cases(kprobe_arm_test_cases, probes_decode_arm_table);
1627 	if (ret)
1628 		goto out;
1629 
1630 #else /* CONFIG_THUMB2_KERNEL */
1631 
1632 	pr_info("Probe 16-bit Thumb code\n");
1633 	ret = run_api_tests(thumb16_func);
1634 	if (ret)
1635 		goto out;
1636 
1637 	pr_info("Probe 32-bit Thumb code, even halfword\n");
1638 	ret = run_api_tests(thumb32even_func);
1639 	if (ret)
1640 		goto out;
1641 
1642 	pr_info("Probe 32-bit Thumb code, odd halfword\n");
1643 	ret = run_api_tests(thumb32odd_func);
1644 	if (ret)
1645 		goto out;
1646 
1647 	pr_info("16-bit Thumb instruction simulation\n");
1648 	ret = run_test_cases(kprobe_thumb16_test_cases,
1649 				probes_decode_thumb16_table);
1650 	if (ret)
1651 		goto out;
1652 
1653 	pr_info("32-bit Thumb instruction simulation\n");
1654 	ret = run_test_cases(kprobe_thumb32_test_cases,
1655 				probes_decode_thumb32_table);
1656 	if (ret)
1657 		goto out;
1658 #endif
1659 
1660 	pr_info("Total instruction simulation tests=%d, pass=%d fail=%d\n",
1661 		test_try_count, test_pass_count, test_fail_count);
1662 	if (test_fail_count) {
1663 		ret = -EINVAL;
1664 		goto out;
1665 	}
1666 
1667 #if BENCHMARKING
1668 	pr_info("Benchmarks\n");
1669 	ret = run_benchmarks();
1670 	if (ret)
1671 		goto out;
1672 #endif
1673 
1674 #if __LINUX_ARM_ARCH__ >= 7
1675 	/* We are able to run all test cases so coverage should be complete */
1676 	if (coverage_fail) {
1677 		pr_err("FAIL: Test coverage checks failed\n");
1678 		ret = -EINVAL;
1679 		goto out;
1680 	}
1681 #endif
1682 
1683 out:
1684 	if (ret == 0)
1685 		ret = tests_failed;
1686 	if (ret == 0)
1687 		pr_info("Finished kprobe tests OK\n");
1688 	else
1689 		pr_err("kprobe tests failed\n");
1690 
1691 	return ret;
1692 }
1693 
1694 
1695 /*
1696  * Module setup
1697  */
1698 
1699 #ifdef MODULE
1700 
kprobe_test_exit(void)1701 static void __exit kprobe_test_exit(void)
1702 {
1703 }
1704 
1705 module_init(run_all_tests)
1706 module_exit(kprobe_test_exit)
1707 MODULE_LICENSE("GPL");
1708 
1709 #else /* !MODULE */
1710 
1711 late_initcall(run_all_tests);
1712 
1713 #endif
1714