arch/arm/probes/kprobes/test-core.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * arch/arm/kernel/kprobes-test.c
   4  *
   5  * Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>.
   6  */
   7
   8 /*
   9  * This file contains test code for ARM kprobes.
  10  *
  11  * The top level function run_all_tests() executes tests for all of the
  12  * supported instruction sets: ARM, 16-bit Thumb, and 32-bit Thumb. These tests
  13  * fall into two categories; run_api_tests() checks basic functionality of the
  14  * kprobes API, and run_test_cases() is a comprehensive test for kprobes
  15  * instruction decoding and simulation.
  16  *
  17  * run_test_cases() first checks the kprobes decoding table for self consistency
  18  * (using table_test()) then executes a series of test cases for each of the CPU
  19  * instruction forms. coverage_start() and coverage_end() are used to verify
  20  * that these test cases cover all of the possible combinations of instructions
  21  * described by the kprobes decoding tables.
  22  *
  23  * The individual test cases are in kprobes-test-arm.c and kprobes-test-thumb.c
  24  * which use the macros defined in kprobes-test.h. The rest of this
  25  * documentation will describe the operation of the framework used by these
  26  * test cases.
  27  */
  28
  29 /*
  30  * TESTING METHODOLOGY
  31  * -------------------
  32  *
  33  * The methodology used to test an ARM instruction 'test_insn' is to use
  34  * inline assembler like:
  35  *
  36  * test_before: nop
  37  * test_case:   test_insn
  38  * test_after:  nop
  39  *
  40  * When the test case is run a kprobe is placed of each nop. The
  41  * post-handler of the test_before probe is used to modify the saved CPU
  42  * register context to that which we require for the test case. The
  43  * pre-handler of the of the test_after probe saves a copy of the CPU
  44  * register context. In this way we can execute test_insn with a specific
  45  * register context and see the results afterwards.
  46  *
  47  * To actually test the kprobes instruction emulation we perform the above
  48  * step a second time but with an additional kprobe on the test_case
  49  * instruction itself. If the emulation is accurate then the results seen
  50  * by the test_after probe will be identical to the first run which didn't
  51  * have a probe on test_case.
  52  *
  53  * Each test case is run several times with a variety of variations in the
  54  * flags value of stored in CPSR, and for Thumb code, different ITState.
  55  *
  56  * For instructions which can modify PC, a second test_after probe is used
  57  * like this:
  58  *
  59  * test_before: nop
  60  * test_case:   test_insn
  61  * test_after:  nop
  62  *              b test_done
  63  * test_after2: nop
  64  * test_done:
  65  *
  66  * The test case is constructed such that test_insn branches to
  67  * test_after2, or, if testing a conditional instruction, it may just
  68  * continue to test_after. The probes inserted at both locations let us
  69  * determine which happened. A similar approach is used for testing
  70  * backwards branches...
  71  *
  72  *              b test_before
  73  *              b test_done  @ helps to cope with off by 1 branches
  74  * test_after2: nop
  75  *              b test_done
  76  * test_before: nop
  77  * test_case:   test_insn
  78  * test_after:  nop
  79  * test_done:
  80  *
  81  * The macros used to generate the assembler instructions describe above
  82  * are TEST_INSTRUCTION, TEST_BRANCH_F (branch forwards) and TEST_BRANCH_B
  83  * (branch backwards). In these, the local variables numbered 1, 50, 2 and
  84  * 99 represent: test_before, test_case, test_after2 and test_done.
  85  *
  86  * FRAMEWORK
  87  * ---------
  88  *
  89  * Each test case is wrapped between the pair of macros TESTCASE_START and
  90  * TESTCASE_END. As well as performing the inline assembler boilerplate,
  91  * these call out to the kprobes_test_case_start() and
  92  * kprobes_test_case_end() functions which drive the execution of the test
  93  * case. The specific arguments to use for each test case are stored as
  94  * inline data constructed using the various TEST_ARG_* macros. Putting
  95  * this all together, a simple test case may look like:
  96  *
  97  *      TESTCASE_START("Testing mov r0, r7")
  98  *      TEST_ARG_REG(7, 0x12345678) // Set r7=0x12345678
  99  *      TEST_ARG_END("")
 100  *      TEST_INSTRUCTION("mov r0, r7")
 101  *      TESTCASE_END
 102  *
 103  * Note, in practice the single convenience macro TEST_R would be used for this
 104  * instead.
 105  *
 106  * The above would expand to assembler looking something like:
 107  *
 108  *      @ TESTCASE_START
 109  *      bl      __kprobes_test_case_start
 110  *      .pushsection .rodata
 111  *      "10:
 112  *      .ascii "mov r0, r7"     @ text title for test case
 113  *      .byte   0
 114  *      .popsection
 115  *      @ start of inline data...
 116  *      .word   10b             @ pointer to title in .rodata section
 117  *
 118  *      @ TEST_ARG_REG
 119  *      .byte   ARG_TYPE_REG
 120  *      .byte   7
 121  *      .short  0
 122  *      .word   0x1234567
 123  *
 124  *      @ TEST_ARG_END
 125  *      .byte   ARG_TYPE_END
 126  *      .byte   TEST_ISA        @ flags, including ISA being tested
 127  *      .short  50f-0f          @ offset of 'test_before'
 128  *      .short  2f-0f           @ offset of 'test_after2' (if relevent)
 129  *      .short  99f-0f          @ offset of 'test_done'
 130  *      @ start of test case code...
 131  *      0:
 132  *      .code   TEST_ISA        @ switch to ISA being tested
 133  *
 134  *      @ TEST_INSTRUCTION
 135  *      50:     nop             @ location for 'test_before' probe
 136  *      1:      mov r0, r7      @ the test case instruction 'test_insn'
 137  *              nop             @ location for 'test_after' probe
 138  *
 139  *      // TESTCASE_END
 140  *      2:
 141  *      99:     bl __kprobes_test_case_end_##TEST_ISA
 142  *      .code   NONMAL_ISA
 143  *
 144  * When the above is execute the following happens...
 145  *
 146  * __kprobes_test_case_start() is an assembler wrapper which sets up space
 147  * for a stack buffer and calls the C function kprobes_test_case_start().
 148  * This C function will do some initial processing of the inline data and
 149  * setup some global state. It then inserts the test_before and test_after
 150  * kprobes and returns a value which causes the assembler wrapper to jump
 151  * to the start of the test case code, (local label '0').
 152  *
 153  * When the test case code executes, the test_before probe will be hit and
 154  * test_before_post_handler will call setup_test_context(). This fills the
 155  * stack buffer and CPU registers with a test pattern and then processes
 156  * the test case arguments. In our example there is one TEST_ARG_REG which
 157  * indicates that R7 should be loaded with the value 0x12345678.
 158  *
 159  * When the test_before probe ends, the test case continues and executes
 160  * the "mov r0, r7" instruction. It then hits the test_after probe and the
 161  * pre-handler for this (test_after_pre_handler) will save a copy of the
 162  * CPU register context. This should now have R0 holding the same value as
 163  * R7.
 164  *
 165  * Finally we get to the call to __kprobes_test_case_end_{32,16}. This is
 166  * an assembler wrapper which switches back to the ISA used by the test
 167  * code and calls the C function kprobes_test_case_end().
 168  *
 169  * For each run through the test case, test_case_run_count is incremented
 170  * by one. For even runs, kprobes_test_case_end() saves a copy of the
 171  * register and stack buffer contents from the test case just run. It then
 172  * inserts a kprobe on the test case instruction 'test_insn' and returns a
 173  * value to cause the test case code to be re-run.
 174  *
 175  * For odd numbered runs, kprobes_test_case_end() compares the register and
 176  * stack buffer contents to those that were saved on the previous even
 177  * numbered run (the one without the kprobe on test_insn). These should be
 178  * the same if the kprobe instruction simulation routine is correct.
 179  *
 180  * The pair of test case runs is repeated with different combinations of
 181  * flag values in CPSR and, for Thumb, different ITState. This is
 182  * controlled by test_context_cpsr().
 183  *
 184  * BUILDING TEST CASES
 185  * -------------------
 186  *
 187  *
 188  * As an aid to building test cases, the stack buffer is initialised with
 189  * some special values:
 190  *
 191  *   [SP+13*4]  Contains SP+120. This can be used to test instructions
 192  *              which load a value into SP.
 193  *
 194  *   [SP+15*4]  When testing branching instructions using TEST_BRANCH_{F,B},
 195  *              this holds the target address of the branch, 'test_after2'.
 196  *              This can be used to test instructions which load a PC value
 197  *              from memory.
 198  */
 199
 200 #include <linux/kernel.h>
 201 #include <linux/module.h>
 202 #include <linux/slab.h>
 203 #include <linux/sched/clock.h>
 204 #include <linux/kprobes.h>
 205 #include <linux/errno.h>
 206 #include <linux/stddef.h>
 207 #include <linux/bug.h>
 208 #include <asm/opcodes.h>
 209
 210 #include "core.h"
 211 #include "test-core.h"
 212 #include "../decode-arm.h"
 213 #include "../decode-thumb.h"
 214
 215
 216 #define BENCHMARKING    1
 217
 218
 219 /*
 220  * Test basic API
 221  */
 222
 223 static bool test_regs_ok;
 224 static int test_func_instance;
 225 static int pre_handler_called;
 226 static int post_handler_called;
 227 static int kretprobe_handler_called;
 228 static int tests_failed;
 229
 230 #define FUNC_ARG1 0x12345678
 231 #define FUNC_ARG2 0xabcdef
 232
 233
 234 #ifndef CONFIG_THUMB2_KERNEL
 235
 236 #define RET(reg)        "mov    pc, "#reg
 237
 238 long arm_func(long r0, long r1);
 239
 240 static void __used __naked __arm_kprobes_test_func(void)
 241 {
 242         __asm__ __volatile__ (
 243                 ".arm                                   \n\t"
 244                 ".type arm_func, %%function             \n\t"
 245                 "arm_func:                              \n\t"
 246                 "adds   r0, r0, r1                      \n\t"
 247                 "mov    pc, lr                          \n\t"
 248                 ".code "NORMAL_ISA       /* Back to Thumb if necessary */
 249                 : : : "r0", "r1", "cc"
 250         );
 251 }
 252
 253 #else /* CONFIG_THUMB2_KERNEL */
 254
 255 #define RET(reg)        "bx     "#reg
 256
 257 long thumb16_func(long r0, long r1);
 258 long thumb32even_func(long r0, long r1);
 259 long thumb32odd_func(long r0, long r1);
 260
 261 static void __used __naked __thumb_kprobes_test_funcs(void)
 262 {
 263         __asm__ __volatile__ (
 264                 ".type thumb16_func, %%function         \n\t"
 265                 "thumb16_func:                          \n\t"
 266                 "adds.n r0, r0, r1                      \n\t"
 267                 "bx     lr                              \n\t"
 268
 269                 ".align                                 \n\t"
 270                 ".type thumb32even_func, %%function     \n\t"
 271                 "thumb32even_func:                      \n\t"
 272                 "adds.w r0, r0, r1                      \n\t"
 273                 "bx     lr                              \n\t"
 274
 275                 ".align                                 \n\t"
 276                 "nop.n                                  \n\t"
 277                 ".type thumb32odd_func, %%function      \n\t"
 278                 "thumb32odd_func:                       \n\t"
 279                 "adds.w r0, r0, r1                      \n\t"
 280                 "bx     lr                              \n\t"
 281
 282                 : : : "r0", "r1", "cc"
 283         );
 284 }
 285
 286 #endif /* CONFIG_THUMB2_KERNEL */
 287
 288
 289 static int call_test_func(long (*func)(long, long), bool check_test_regs)
 290 {
 291         long ret;
 292
 293         ++test_func_instance;
 294         test_regs_ok = false;
 295
 296         ret = (*func)(FUNC_ARG1, FUNC_ARG2);
 297         if (ret != FUNC_ARG1 + FUNC_ARG2) {
 298                 pr_err("FAIL: call_test_func: func returned %lx\n", ret);
 299                 return false;
 300         }
 301
 302         if (check_test_regs && !test_regs_ok) {
 303                 pr_err("FAIL: test regs not OK\n");
 304                 return false;
 305         }
 306
 307         return true;
 308 }
 309
 310 static int __kprobes pre_handler(struct kprobe *p, struct pt_regs *regs)
 311 {
 312         pre_handler_called = test_func_instance;
 313         if (regs->ARM_r0 == FUNC_ARG1 && regs->ARM_r1 == FUNC_ARG2)
 314                 test_regs_ok = true;
 315         return 0;
 316 }
 317
 318 static void __kprobes post_handler(struct kprobe *p, struct pt_regs *regs,
 319                                 unsigned long flags)
 320 {
 321         post_handler_called = test_func_instance;
 322         if (regs->ARM_r0 != FUNC_ARG1 + FUNC_ARG2 || regs->ARM_r1 != FUNC_ARG2)
 323                 test_regs_ok = false;
 324 }
 325
 326 static struct kprobe the_kprobe = {
 327         .addr           = 0,
 328         .pre_handler    = pre_handler,
 329         .post_handler   = post_handler
 330 };
 331
 332 static int test_kprobe(long (*func)(long, long))
 333 {
 334         int ret;
 335
 336         the_kprobe.addr = (kprobe_opcode_t *)func;
 337         ret = register_kprobe(&the_kprobe);
 338         if (ret < 0) {
 339                 pr_err("FAIL: register_kprobe failed with %d\n", ret);
 340                 return ret;
 341         }
 342
 343         ret = call_test_func(func, true);
 344
 345         unregister_kprobe(&the_kprobe);
 346         the_kprobe.flags = 0; /* Clear disable flag to allow reuse */
 347
 348         if (!ret)
 349                 return -EINVAL;
 350         if (pre_handler_called != test_func_instance) {
 351                 pr_err("FAIL: kprobe pre_handler not called\n");
 352                 return -EINVAL;
 353         }
 354         if (post_handler_called != test_func_instance) {
 355                 pr_err("FAIL: kprobe post_handler not called\n");
 356                 return -EINVAL;
 357         }
 358         if (!call_test_func(func, false))
 359                 return -EINVAL;
 360         if (pre_handler_called == test_func_instance ||
 361                                 post_handler_called == test_func_instance) {
 362                 pr_err("FAIL: probe called after unregistering\n");
 363                 return -EINVAL;
 364         }
 365
 366         return 0;
 367 }
 368
 369 static int __kprobes
 370 kretprobe_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
 371 {
 372         kretprobe_handler_called = test_func_instance;
 373         if (regs_return_value(regs) == FUNC_ARG1 + FUNC_ARG2)
 374                 test_regs_ok = true;
 375         return 0;
 376 }
 377
 378 static struct kretprobe the_kretprobe = {
 379         .handler        = kretprobe_handler,
 380 };
 381
 382 static int test_kretprobe(long (*func)(long, long))
 383 {
 384         int ret;
 385
 386         the_kretprobe.kp.addr = (kprobe_opcode_t *)func;
 387         ret = register_kretprobe(&the_kretprobe);
 388         if (ret < 0) {
 389                 pr_err("FAIL: register_kretprobe failed with %d\n", ret);
 390                 return ret;
 391         }
 392
 393         ret = call_test_func(func, true);
 394
 395         unregister_kretprobe(&the_kretprobe);
 396         the_kretprobe.kp.flags = 0; /* Clear disable flag to allow reuse */
 397
 398         if (!ret)
 399                 return -EINVAL;
 400         if (kretprobe_handler_called != test_func_instance) {
 401                 pr_err("FAIL: kretprobe handler not called\n");
 402                 return -EINVAL;
 403         }
 404         if (!call_test_func(func, false))
 405                 return -EINVAL;
 406         if (kretprobe_handler_called == test_func_instance) {
 407                 pr_err("FAIL: kretprobe called after unregistering\n");
 408                 return -EINVAL;
 409         }
 410
 411         return 0;
 412 }
 413
 414 static int run_api_tests(long (*func)(long, long))
 415 {
 416         int ret;
 417
 418         pr_info("    kprobe\n");
 419         ret = test_kprobe(func);
 420         if (ret < 0)
 421                 return ret;
 422
 423         pr_info("    kretprobe\n");
 424         ret = test_kretprobe(func);
 425         if (ret < 0)
 426                 return ret;
 427
 428         return 0;
 429 }
 430
 431
 432 /*
 433  * Benchmarking
 434  */
 435
 436 #if BENCHMARKING
 437
 438 static void __naked benchmark_nop(void)
 439 {
 440         __asm__ __volatile__ (
 441                 "nop            \n\t"
 442                 RET(lr)"        \n\t"
 443         );
 444 }
 445
 446 #ifdef CONFIG_THUMB2_KERNEL
 447 #define wide ".w"
 448 #else
 449 #define wide
 450 #endif
 451
 452 static void __naked benchmark_pushpop1(void)
 453 {
 454         __asm__ __volatile__ (
 455                 "stmdb"wide"    sp!, {r3-r11,lr}  \n\t"
 456                 "ldmia"wide"    sp!, {r3-r11,pc}"
 457         );
 458 }
 459
 460 static void __naked benchmark_pushpop2(void)
 461 {
 462         __asm__ __volatile__ (
 463                 "stmdb"wide"    sp!, {r0-r8,lr}  \n\t"
 464                 "ldmia"wide"    sp!, {r0-r8,pc}"
 465         );
 466 }
 467
 468 static void __naked benchmark_pushpop3(void)
 469 {
 470         __asm__ __volatile__ (
 471                 "stmdb"wide"    sp!, {r4,lr}  \n\t"
 472                 "ldmia"wide"    sp!, {r4,pc}"
 473         );
 474 }
 475
 476 static void __naked benchmark_pushpop4(void)
 477 {
 478         __asm__ __volatile__ (
 479                 "stmdb"wide"    sp!, {r0,lr}  \n\t"
 480                 "ldmia"wide"    sp!, {r0,pc}"
 481         );
 482 }
 483
 484
 485 #ifdef CONFIG_THUMB2_KERNEL
 486
 487 static void __naked benchmark_pushpop_thumb(void)
 488 {
 489         __asm__ __volatile__ (
 490                 "push.n {r0-r7,lr}  \n\t"
 491                 "pop.n  {r0-r7,pc}"
 492         );
 493 }
 494
 495 #endif
 496
 497 static int __kprobes
 498 benchmark_pre_handler(struct kprobe *p, struct pt_regs *regs)
 499 {
 500         return 0;
 501 }
 502
 503 static int benchmark(void(*fn)(void))
 504 {
 505         unsigned n, i, t, t0;
 506
 507         for (n = 1000; ; n *= 2) {
 508                 t0 = sched_clock();
 509                 for (i = n; i > 0; --i)
 510                         fn();
 511                 t = sched_clock() - t0;
 512                 if (t >= 250000000)
 513                         break; /* Stop once we took more than 0.25 seconds */
 514         }
 515         return t / n; /* Time for one iteration in nanoseconds */
 516 };
 517
 518 static int kprobe_benchmark(void(*fn)(void), unsigned offset)
 519 {
 520         struct kprobe k = {
 521                 .addr           = (kprobe_opcode_t *)((uintptr_t)fn + offset),
 522                 .pre_handler    = benchmark_pre_handler,
 523         };
 524
 525         int ret = register_kprobe(&k);
 526         if (ret < 0) {
 527                 pr_err("FAIL: register_kprobe failed with %d\n", ret);
 528                 return ret;
 529         }
 530
 531         ret = benchmark(fn);
 532
 533         unregister_kprobe(&k);
 534         return ret;
 535 };
 536
 537 struct benchmarks {
 538         void            (*fn)(void);
 539         unsigned        offset;
 540         const char      *title;
 541 };
 542
 543 static int run_benchmarks(void)
 544 {
 545         int ret;
 546         struct benchmarks list[] = {
 547                 {&benchmark_nop, 0, "nop"},
 548                 /*
 549                  * benchmark_pushpop{1,3} will have the optimised
 550                  * instruction emulation, whilst benchmark_pushpop{2,4} will
 551                  * be the equivalent unoptimised instructions.
 552                  */
 553                 {&benchmark_pushpop1, 0, "stmdb sp!, {r3-r11,lr}"},
 554                 {&benchmark_pushpop1, 4, "ldmia sp!, {r3-r11,pc}"},
 555                 {&benchmark_pushpop2, 0, "stmdb sp!, {r0-r8,lr}"},
 556                 {&benchmark_pushpop2, 4, "ldmia sp!, {r0-r8,pc}"},
 557                 {&benchmark_pushpop3, 0, "stmdb sp!, {r4,lr}"},
 558                 {&benchmark_pushpop3, 4, "ldmia sp!, {r4,pc}"},
 559                 {&benchmark_pushpop4, 0, "stmdb sp!, {r0,lr}"},
 560                 {&benchmark_pushpop4, 4, "ldmia sp!, {r0,pc}"},
 561 #ifdef CONFIG_THUMB2_KERNEL
 562                 {&benchmark_pushpop_thumb, 0, "push.n   {r0-r7,lr}"},
 563                 {&benchmark_pushpop_thumb, 2, "pop.n    {r0-r7,pc}"},
 564 #endif
 565                 {0}
 566         };
 567
 568         struct benchmarks *b;
 569         for (b = list; b->fn; ++b) {
 570                 ret = kprobe_benchmark(b->fn, b->offset);
 571                 if (ret < 0)
 572                         return ret;
 573                 pr_info("    %dns for kprobe %s\n", ret, b->title);
 574         }
 575
 576         pr_info("\n");
 577         return 0;
 578 }
 579
 580 #endif /* BENCHMARKING */
 581
 582
 583 /*
 584  * Decoding table self-consistency tests
 585  */
 586
 587 static const int decode_struct_sizes[NUM_DECODE_TYPES] = {
 588         [DECODE_TYPE_TABLE]     = sizeof(struct decode_table),
 589         [DECODE_TYPE_CUSTOM]    = sizeof(struct decode_custom),
 590         [DECODE_TYPE_SIMULATE]  = sizeof(struct decode_simulate),
 591         [DECODE_TYPE_EMULATE]   = sizeof(struct decode_emulate),
 592         [DECODE_TYPE_OR]        = sizeof(struct decode_or),
 593         [DECODE_TYPE_REJECT]    = sizeof(struct decode_reject)
 594 };
 595
 596 static int table_iter(const union decode_item *table,
 597                         int (*fn)(const struct decode_header *, void *),
 598                         void *args)
 599 {
 600         const struct decode_header *h = (struct decode_header *)table;
 601         int result;
 602
 603         for (;;) {
 604                 enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK;
 605
 606                 if (type == DECODE_TYPE_END)
 607                         return 0;
 608
 609                 result = fn(h, args);
 610                 if (result)
 611                         return result;
 612
 613                 h = (struct decode_header *)
 614                         ((uintptr_t)h + decode_struct_sizes[type]);
 615
 616         }
 617 }
 618
 619 static int table_test_fail(const struct decode_header *h, const char* message)
 620 {
 621
 622         pr_err("FAIL: kprobes test failure \"%s\" (mask %08x, value %08x)\n",
 623                                         message, h->mask.bits, h->value.bits);
 624         return -EINVAL;
 625 }
 626
 627 struct table_test_args {
 628         const union decode_item *root_table;
 629         u32                     parent_mask;
 630         u32                     parent_value;
 631 };
 632
 633 static int table_test_fn(const struct decode_header *h, void *args)
 634 {
 635         struct table_test_args *a = (struct table_test_args *)args;
 636         enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK;
 637
 638         if (h->value.bits & ~h->mask.bits)
 639                 return table_test_fail(h, "Match value has bits not in mask");
 640
 641         if ((h->mask.bits & a->parent_mask) != a->parent_mask)
 642                 return table_test_fail(h, "Mask has bits not in parent mask");
 643
 644         if ((h->value.bits ^ a->parent_value) & a->parent_mask)
 645                 return table_test_fail(h, "Value is inconsistent with parent");
 646
 647         if (type == DECODE_TYPE_TABLE) {
 648                 struct decode_table *d = (struct decode_table *)h;
 649                 struct table_test_args args2 = *a;
 650                 args2.parent_mask = h->mask.bits;
 651                 args2.parent_value = h->value.bits;
 652                 return table_iter(d->table.table, table_test_fn, &args2);
 653         }
 654
 655         return 0;
 656 }
 657
 658 static int table_test(const union decode_item *table)
 659 {
 660         struct table_test_args args = {
 661                 .root_table     = table,
 662                 .parent_mask    = 0,
 663                 .parent_value   = 0
 664         };
 665         return table_iter(args.root_table, table_test_fn, &args);
 666 }
 667
 668
 669 /*
 670  * Decoding table test coverage analysis
 671  *
 672  * coverage_start() builds a coverage_table which contains a list of
 673  * coverage_entry's to match each entry in the specified kprobes instruction
 674  * decoding table.
 675  *
 676  * When test cases are run, coverage_add() is called to process each case.
 677  * This looks up the corresponding entry in the coverage_table and sets it as
 678  * being matched, as well as clearing the regs flag appropriate for the test.
 679  *
 680  * After all test cases have been run, coverage_end() is called to check that
 681  * all entries in coverage_table have been matched and that all regs flags are
 682  * cleared. I.e. that all possible combinations of instructions described by
 683  * the kprobes decoding tables have had a test case executed for them.
 684  */
 685
 686 bool coverage_fail;
 687
 688 #define MAX_COVERAGE_ENTRIES 256
 689
 690 struct coverage_entry {
 691         const struct decode_header      *header;
 692         unsigned                        regs;
 693         unsigned                        nesting;
 694         char                            matched;
 695 };
 696
 697 struct coverage_table {
 698         struct coverage_entry   *base;
 699         unsigned                num_entries;
 700         unsigned                nesting;
 701 };
 702
 703 struct coverage_table coverage;
 704
 705 #define COVERAGE_ANY_REG        (1<<0)
 706 #define COVERAGE_SP             (1<<1)
 707 #define COVERAGE_PC             (1<<2)
 708 #define COVERAGE_PCWB           (1<<3)
 709
 710 static const char coverage_register_lookup[16] = {
 711         [REG_TYPE_ANY]          = COVERAGE_ANY_REG | COVERAGE_SP | COVERAGE_PC,
 712         [REG_TYPE_SAMEAS16]     = COVERAGE_ANY_REG,
 713         [REG_TYPE_SP]           = COVERAGE_SP,
 714         [REG_TYPE_PC]           = COVERAGE_PC,
 715         [REG_TYPE_NOSP]         = COVERAGE_ANY_REG | COVERAGE_SP,
 716         [REG_TYPE_NOSPPC]       = COVERAGE_ANY_REG | COVERAGE_SP | COVERAGE_PC,
 717         [REG_TYPE_NOPC]         = COVERAGE_ANY_REG | COVERAGE_PC,
 718         [REG_TYPE_NOPCWB]       = COVERAGE_ANY_REG | COVERAGE_PC | COVERAGE_PCWB,
 719         [REG_TYPE_NOPCX]        = COVERAGE_ANY_REG,
 720         [REG_TYPE_NOSPPCX]      = COVERAGE_ANY_REG | COVERAGE_SP,
 721 };
 722
 723 static unsigned coverage_start_registers(const struct decode_header *h)
 724 {
 725         unsigned regs = 0;
 726         int i;
 727         for (i = 0; i < 20; i += 4) {
 728                 int r = (h->type_regs.bits >> (DECODE_TYPE_BITS + i)) & 0xf;
 729                 regs |= coverage_register_lookup[r] << i;
 730         }
 731         return regs;
 732 }
 733
 734 static int coverage_start_fn(const struct decode_header *h, void *args)
 735 {
 736         struct coverage_table *coverage = (struct coverage_table *)args;
 737         enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK;
 738         struct coverage_entry *entry = coverage->base + coverage->num_entries;
 739
 740         if (coverage->num_entries == MAX_COVERAGE_ENTRIES - 1) {
 741                 pr_err("FAIL: Out of space for test coverage data");
 742                 return -ENOMEM;
 743         }
 744
 745         ++coverage->num_entries;
 746
 747         entry->header = h;
 748         entry->regs = coverage_start_registers(h);
 749         entry->nesting = coverage->nesting;
 750         entry->matched = false;
 751
 752         if (type == DECODE_TYPE_TABLE) {
 753                 struct decode_table *d = (struct decode_table *)h;
 754                 int ret;
 755                 ++coverage->nesting;
 756                 ret = table_iter(d->table.table, coverage_start_fn, coverage);
 757                 --coverage->nesting;
 758                 return ret;
 759         }
 760
 761         return 0;
 762 }
 763
 764 static int coverage_start(const union decode_item *table)
 765 {
 766         coverage.base = kmalloc_array(MAX_COVERAGE_ENTRIES,
 767                                       sizeof(struct coverage_entry),
 768                                       GFP_KERNEL);
 769         coverage.num_entries = 0;
 770         coverage.nesting = 0;
 771         return table_iter(table, coverage_start_fn, &coverage);
 772 }
 773
 774 static void
 775 coverage_add_registers(struct coverage_entry *entry, kprobe_opcode_t insn)
 776 {
 777         int regs = entry->header->type_regs.bits >> DECODE_TYPE_BITS;
 778         int i;
 779         for (i = 0; i < 20; i += 4) {
 780                 enum decode_reg_type reg_type = (regs >> i) & 0xf;
 781                 int reg = (insn >> i) & 0xf;
 782                 int flag;
 783
 784                 if (!reg_type)
 785                         continue;
 786
 787                 if (reg == 13)
 788                         flag = COVERAGE_SP;
 789                 else if (reg == 15)
 790                         flag = COVERAGE_PC;
 791                 else
 792                         flag = COVERAGE_ANY_REG;
 793                 entry->regs &= ~(flag << i);
 794
 795                 switch (reg_type) {
 796
 797                 case REG_TYPE_NONE:
 798                 case REG_TYPE_ANY:
 799                 case REG_TYPE_SAMEAS16:
 800                         break;
 801
 802                 case REG_TYPE_SP:
 803                         if (reg != 13)
 804                                 return;
 805                         break;
 806
 807                 case REG_TYPE_PC:
 808                         if (reg != 15)
 809                                 return;
 810                         break;
 811
 812                 case REG_TYPE_NOSP:
 813                         if (reg == 13)
 814                                 return;
 815                         break;
 816
 817                 case REG_TYPE_NOSPPC:
 818                 case REG_TYPE_NOSPPCX:
 819                         if (reg == 13 || reg == 15)
 820                                 return;
 821                         break;
 822
 823                 case REG_TYPE_NOPCWB:
 824                         if (!is_writeback(insn))
 825                                 break;
 826                         if (reg == 15) {
 827                                 entry->regs &= ~(COVERAGE_PCWB << i);
 828                                 return;
 829                         }
 830                         break;
 831
 832                 case REG_TYPE_NOPC:
 833                 case REG_TYPE_NOPCX:
 834                         if (reg == 15)
 835                                 return;
 836                         break;
 837                 }
 838
 839         }
 840 }
 841
 842 static void coverage_add(kprobe_opcode_t insn)
 843 {
 844         struct coverage_entry *entry = coverage.base;
 845         struct coverage_entry *end = coverage.base + coverage.num_entries;
 846         bool matched = false;
 847         unsigned nesting = 0;
 848
 849         for (; entry < end; ++entry) {
 850                 const struct decode_header *h = entry->header;
 851                 enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK;
 852
 853                 if (entry->nesting > nesting)
 854                         continue; /* Skip sub-table we didn't match */
 855
 856                 if (entry->nesting < nesting)
 857                         break; /* End of sub-table we were scanning */
 858
 859                 if (!matched) {
 860                         if ((insn & h->mask.bits) != h->value.bits)
 861                                 continue;
 862                         entry->matched = true;
 863                 }
 864
 865                 switch (type) {
 866
 867                 case DECODE_TYPE_TABLE:
 868                         ++nesting;
 869                         break;
 870
 871                 case DECODE_TYPE_CUSTOM:
 872                 case DECODE_TYPE_SIMULATE:
 873                 case DECODE_TYPE_EMULATE:
 874                         coverage_add_registers(entry, insn);
 875                         return;
 876
 877                 case DECODE_TYPE_OR:
 878                         matched = true;
 879                         break;
 880
 881                 case DECODE_TYPE_REJECT:
 882                 default:
 883                         return;
 884                 }
 885
 886         }
 887 }
 888
 889 static void coverage_end(void)
 890 {
 891         struct coverage_entry *entry = coverage.base;
 892         struct coverage_entry *end = coverage.base + coverage.num_entries;
 893
 894         for (; entry < end; ++entry) {
 895                 u32 mask = entry->header->mask.bits;
 896                 u32 value = entry->header->value.bits;
 897
 898                 if (entry->regs) {
 899                         pr_err("FAIL: Register test coverage missing for %08x %08x (%05x)\n",
 900                                 mask, value, entry->regs);
 901                         coverage_fail = true;
 902                 }
 903                 if (!entry->matched) {
 904                         pr_err("FAIL: Test coverage entry missing for %08x %08x\n",
 905                                 mask, value);
 906                         coverage_fail = true;
 907                 }
 908         }
 909
 910         kfree(coverage.base);
 911 }
 912
 913
 914 /*
 915  * Framework for instruction set test cases
 916  */
 917
 918 void __naked __kprobes_test_case_start(void)
 919 {
 920         __asm__ __volatile__ (
 921                 "mov    r2, sp                                  \n\t"
 922                 "bic    r3, r2, #7                              \n\t"
 923                 "mov    sp, r3                                  \n\t"
 924                 "stmdb  sp!, {r2-r11}                           \n\t"
 925                 "sub    sp, sp, #"__stringify(TEST_MEMORY_SIZE)"\n\t"
 926                 "bic    r0, lr, #1  @ r0 = inline data          \n\t"
 927                 "mov    r1, sp                                  \n\t"
 928                 "bl     kprobes_test_case_start                 \n\t"
 929                 RET(r0)"                                        \n\t"
 930         );
 931 }
 932
 933 #ifndef CONFIG_THUMB2_KERNEL
 934
 935 void __naked __kprobes_test_case_end_32(void)
 936 {
 937         __asm__ __volatile__ (
 938                 "mov    r4, lr                                  \n\t"
 939                 "bl     kprobes_test_case_end                   \n\t"
 940                 "cmp    r0, #0                                  \n\t"
 941                 "movne  pc, r0                                  \n\t"
 942                 "mov    r0, r4                                  \n\t"
 943                 "add    sp, sp, #"__stringify(TEST_MEMORY_SIZE)"\n\t"
 944                 "ldmia  sp!, {r2-r11}                           \n\t"
 945                 "mov    sp, r2                                  \n\t"
 946                 "mov    pc, r0                                  \n\t"
 947         );
 948 }
 949
 950 #else /* CONFIG_THUMB2_KERNEL */
 951
 952 void __naked __kprobes_test_case_end_16(void)
 953 {
 954         __asm__ __volatile__ (
 955                 "mov    r4, lr                                  \n\t"
 956                 "bl     kprobes_test_case_end                   \n\t"
 957                 "cmp    r0, #0                                  \n\t"
 958                 "bxne   r0                                      \n\t"
 959                 "mov    r0, r4                                  \n\t"
 960                 "add    sp, sp, #"__stringify(TEST_MEMORY_SIZE)"\n\t"
 961                 "ldmia  sp!, {r2-r11}                           \n\t"
 962                 "mov    sp, r2                                  \n\t"
 963                 "bx     r0                                      \n\t"
 964         );
 965 }
 966
 967 void __naked __kprobes_test_case_end_32(void)
 968 {
 969         __asm__ __volatile__ (
 970                 ".arm                                           \n\t"
 971                 "orr    lr, lr, #1  @ will return to Thumb code \n\t"
 972                 "ldr    pc, 1f                                  \n\t"
 973                 "1:                                             \n\t"
 974                 ".word  __kprobes_test_case_end_16              \n\t"
 975         );
 976 }
 977
 978 #endif
 979
 980
 981 int kprobe_test_flags;
 982 int kprobe_test_cc_position;
 983
 984 static int test_try_count;
 985 static int test_pass_count;
 986 static int test_fail_count;
 987
 988 static struct pt_regs initial_regs;
 989 static struct pt_regs expected_regs;
 990 static struct pt_regs result_regs;
 991
 992 static u32 expected_memory[TEST_MEMORY_SIZE/sizeof(u32)];
 993
 994 static const char *current_title;
 995 static struct test_arg *current_args;
 996 static u32 *current_stack;
 997 static uintptr_t current_branch_target;
 998
 999 static uintptr_t current_code_start;
1000 static kprobe_opcode_t current_instruction;
1001
1002
1003 #define TEST_CASE_PASSED -1
1004 #define TEST_CASE_FAILED -2
1005
1006 static int test_case_run_count;
1007 static bool test_case_is_thumb;
1008 static int test_instance;
1009
1010 static unsigned long test_check_cc(int cc, unsigned long cpsr)
1011 {
1012         int ret = arm_check_condition(cc << 28, cpsr);
1013
1014         return (ret != ARM_OPCODE_CONDTEST_FAIL);
1015 }
1016
1017 static int is_last_scenario;
1018 static int probe_should_run; /* 0 = no, 1 = yes, -1 = unknown */
1019 static int memory_needs_checking;
1020
1021 static unsigned long test_context_cpsr(int scenario)
1022 {
1023         unsigned long cpsr;
1024
1025         probe_should_run = 1;
1026
1027         /* Default case is that we cycle through 16 combinations of flags */
1028         cpsr  = (scenario & 0xf) << 28; /* N,Z,C,V flags */
1029         cpsr |= (scenario & 0xf) << 16; /* GE flags */
1030         cpsr |= (scenario & 0x1) << 27; /* Toggle Q flag */
1031
1032         if (!test_case_is_thumb) {
1033                 /* Testing ARM code */
1034                 int cc = current_instruction >> 28;
1035
1036                 probe_should_run = test_check_cc(cc, cpsr) != 0;
1037                 if (scenario == 15)
1038                         is_last_scenario = true;
1039
1040         } else if (kprobe_test_flags & TEST_FLAG_NO_ITBLOCK) {
1041                 /* Testing Thumb code without setting ITSTATE */
1042                 if (kprobe_test_cc_position) {
1043                         int cc = (current_instruction >> kprobe_test_cc_position) & 0xf;
1044                         probe_should_run = test_check_cc(cc, cpsr) != 0;
1045                 }
1046
1047                 if (scenario == 15)
1048                         is_last_scenario = true;
1049
1050         } else if (kprobe_test_flags & TEST_FLAG_FULL_ITBLOCK) {
1051                 /* Testing Thumb code with all combinations of ITSTATE */
1052                 unsigned x = (scenario >> 4);
1053                 unsigned cond_base = x % 7; /* ITSTATE<7:5> */
1054                 unsigned mask = x / 7 + 2;  /* ITSTATE<4:0>, bits reversed */
1055
1056                 if (mask > 0x1f) {
1057                         /* Finish by testing state from instruction 'itt al' */
1058                         cond_base = 7;
1059                         mask = 0x4;
1060                         if ((scenario & 0xf) == 0xf)
1061                                 is_last_scenario = true;
1062                 }
1063
1064                 cpsr |= cond_base << 13;        /* ITSTATE<7:5> */
1065                 cpsr |= (mask & 0x1) << 12;     /* ITSTATE<4> */
1066                 cpsr |= (mask & 0x2) << 10;     /* ITSTATE<3> */
1067                 cpsr |= (mask & 0x4) << 8;      /* ITSTATE<2> */
1068                 cpsr |= (mask & 0x8) << 23;     /* ITSTATE<1> */
1069                 cpsr |= (mask & 0x10) << 21;    /* ITSTATE<0> */
1070
1071                 probe_should_run = test_check_cc((cpsr >> 12) & 0xf, cpsr) != 0;
1072
1073         } else {
1074                 /* Testing Thumb code with several combinations of ITSTATE */
1075                 switch (scenario) {
1076                 case 16: /* Clear NZCV flags and 'it eq' state (false as Z=0) */
1077                         cpsr = 0x00000800;
1078                         probe_should_run = 0;
1079                         break;
1080                 case 17: /* Set NZCV flags and 'it vc' state (false as V=1) */
1081                         cpsr = 0xf0007800;
1082                         probe_should_run = 0;
1083                         break;
1084                 case 18: /* Clear NZCV flags and 'it ls' state (true as C=0) */
1085                         cpsr = 0x00009800;
1086                         break;
1087                 case 19: /* Set NZCV flags and 'it cs' state (true as C=1) */
1088                         cpsr = 0xf0002800;
1089                         is_last_scenario = true;
1090                         break;
1091                 }
1092         }
1093
1094         return cpsr;
1095 }
1096
1097 static void setup_test_context(struct pt_regs *regs)
1098 {
1099         int scenario = test_case_run_count>>1;
1100         unsigned long val;
1101         struct test_arg *args;
1102         int i;
1103
1104         is_last_scenario = false;
1105         memory_needs_checking = false;
1106
1107         /* Initialise test memory on stack */
1108         val = (scenario & 1) ? VALM : ~VALM;
1109         for (i = 0; i < TEST_MEMORY_SIZE / sizeof(current_stack[0]); ++i)
1110                 current_stack[i] = val + (i << 8);
1111         /* Put target of branch on stack for tests which load PC from memory */
1112         if (current_branch_target)
1113                 current_stack[15] = current_branch_target;
1114         /* Put a value for SP on stack for tests which load SP from memory */
1115         current_stack[13] = (u32)current_stack + 120;
1116
1117         /* Initialise register values to their default state */
1118         val = (scenario & 2) ? VALR : ~VALR;
1119         for (i = 0; i < 13; ++i)
1120                 regs->uregs[i] = val ^ (i << 8);
1121         regs->ARM_lr = val ^ (14 << 8);
1122         regs->ARM_cpsr &= ~(APSR_MASK | PSR_IT_MASK);
1123         regs->ARM_cpsr |= test_context_cpsr(scenario);
1124
1125         /* Perform testcase specific register setup  */
1126         args = current_args;
1127         for (; args[0].type != ARG_TYPE_END; ++args)
1128                 switch (args[0].type) {
1129                 case ARG_TYPE_REG: {
1130                         struct test_arg_regptr *arg =
1131                                 (struct test_arg_regptr *)args;
1132                         regs->uregs[arg->reg] = arg->val;
1133                         break;
1134                 }
1135                 case ARG_TYPE_PTR: {
1136                         struct test_arg_regptr *arg =
1137                                 (struct test_arg_regptr *)args;
1138                         regs->uregs[arg->reg] =
1139                                 (unsigned long)current_stack + arg->val;
1140                         memory_needs_checking = true;
1141                         /*
1142                          * Test memory at an address below SP is in danger of
1143                          * being altered by an interrupt occurring and pushing
1144                          * data onto the stack. Disable interrupts to stop this.
1145                          */
1146                         if (arg->reg == 13)
1147                                 regs->ARM_cpsr |= PSR_I_BIT;
1148                         break;
1149                 }
1150                 case ARG_TYPE_MEM: {
1151                         struct test_arg_mem *arg = (struct test_arg_mem *)args;
1152                         current_stack[arg->index] = arg->val;
1153                         break;
1154                 }
1155                 default:
1156                         break;
1157                 }
1158 }
1159
1160 struct test_probe {
1161         struct kprobe   kprobe;
1162         bool            registered;
1163         int             hit;
1164 };
1165
1166 static void unregister_test_probe(struct test_probe *probe)
1167 {
1168         if (probe->registered) {
1169                 unregister_kprobe(&probe->kprobe);
1170                 probe->kprobe.flags = 0; /* Clear disable flag to allow reuse */
1171         }
1172         probe->registered = false;
1173 }
1174
1175 static int register_test_probe(struct test_probe *probe)
1176 {
1177         int ret;
1178
1179         if (probe->registered)
1180                 BUG();
1181
1182         ret = register_kprobe(&probe->kprobe);
1183         if (ret >= 0) {
1184                 probe->registered = true;
1185                 probe->hit = -1;
1186         }
1187         return ret;
1188 }
1189
1190 static int __kprobes
1191 test_before_pre_handler(struct kprobe *p, struct pt_regs *regs)
1192 {
1193         container_of(p, struct test_probe, kprobe)->hit = test_instance;
1194         return 0;
1195 }
1196
1197 static void __kprobes
1198 test_before_post_handler(struct kprobe *p, struct pt_regs *regs,
1199                                                         unsigned long flags)
1200 {
1201         setup_test_context(regs);
1202         initial_regs = *regs;
1203         initial_regs.ARM_cpsr &= ~PSR_IGNORE_BITS;
1204 }
1205
1206 static int __kprobes
1207 test_case_pre_handler(struct kprobe *p, struct pt_regs *regs)
1208 {
1209         container_of(p, struct test_probe, kprobe)->hit = test_instance;
1210         return 0;
1211 }
1212
1213 static int __kprobes
1214 test_after_pre_handler(struct kprobe *p, struct pt_regs *regs)
1215 {
1216         struct test_arg *args;
1217
1218         if (container_of(p, struct test_probe, kprobe)->hit == test_instance)
1219                 return 0; /* Already run for this test instance */
1220
1221         result_regs = *regs;
1222
1223         /* Mask out results which are indeterminate */
1224         result_regs.ARM_cpsr &= ~PSR_IGNORE_BITS;
1225         for (args = current_args; args[0].type != ARG_TYPE_END; ++args)
1226                 if (args[0].type == ARG_TYPE_REG_MASKED) {
1227                         struct test_arg_regptr *arg =
1228                                 (struct test_arg_regptr *)args;
1229                         result_regs.uregs[arg->reg] &= arg->val;
1230                 }
1231
1232         /* Undo any changes done to SP by the test case */
1233         regs->ARM_sp = (unsigned long)current_stack;
1234         /* Enable interrupts in case setup_test_context disabled them */
1235         regs->ARM_cpsr &= ~PSR_I_BIT;
1236
1237         container_of(p, struct test_probe, kprobe)->hit = test_instance;
1238         return 0;
1239 }
1240
1241 static struct test_probe test_before_probe = {
1242         .kprobe.pre_handler     = test_before_pre_handler,
1243         .kprobe.post_handler    = test_before_post_handler,
1244 };
1245
1246 static struct test_probe test_case_probe = {
1247         .kprobe.pre_handler     = test_case_pre_handler,
1248 };
1249
1250 static struct test_probe test_after_probe = {
1251         .kprobe.pre_handler     = test_after_pre_handler,
1252 };
1253
1254 static struct test_probe test_after2_probe = {
1255         .kprobe.pre_handler     = test_after_pre_handler,
1256 };
1257
1258 static void test_case_cleanup(void)
1259 {
1260         unregister_test_probe(&test_before_probe);
1261         unregister_test_probe(&test_case_probe);
1262         unregister_test_probe(&test_after_probe);
1263         unregister_test_probe(&test_after2_probe);
1264 }
1265
1266 static void print_registers(struct pt_regs *regs)
1267 {
1268         pr_err("r0  %08lx | r1  %08lx | r2  %08lx | r3  %08lx\n",
1269                 regs->ARM_r0, regs->ARM_r1, regs->ARM_r2, regs->ARM_r3);
1270         pr_err("r4  %08lx | r5  %08lx | r6  %08lx | r7  %08lx\n",
1271                 regs->ARM_r4, regs->ARM_r5, regs->ARM_r6, regs->ARM_r7);
1272         pr_err("r8  %08lx | r9  %08lx | r10 %08lx | r11 %08lx\n",
1273                 regs->ARM_r8, regs->ARM_r9, regs->ARM_r10, regs->ARM_fp);
1274         pr_err("r12 %08lx | sp  %08lx | lr  %08lx | pc  %08lx\n",
1275                 regs->ARM_ip, regs->ARM_sp, regs->ARM_lr, regs->ARM_pc);
1276         pr_err("cpsr %08lx\n", regs->ARM_cpsr);
1277 }
1278
1279 static void print_memory(u32 *mem, size_t size)
1280 {
1281         int i;
1282         for (i = 0; i < size / sizeof(u32); i += 4)
1283                 pr_err("%08x %08x %08x %08x\n", mem[i], mem[i+1],
1284                                                 mem[i+2], mem[i+3]);
1285 }
1286
1287 static size_t expected_memory_size(u32 *sp)
1288 {
1289         size_t size = sizeof(expected_memory);
1290         int offset = (uintptr_t)sp - (uintptr_t)current_stack;
1291         if (offset > 0)
1292                 size -= offset;
1293         return size;
1294 }
1295
1296 static void test_case_failed(const char *message)
1297 {
1298         test_case_cleanup();
1299
1300         pr_err("FAIL: %s\n", message);
1301         pr_err("FAIL: Test %s\n", current_title);
1302         pr_err("FAIL: Scenario %d\n", test_case_run_count >> 1);
1303 }
1304
1305 static unsigned long next_instruction(unsigned long pc)
1306 {
1307 #ifdef CONFIG_THUMB2_KERNEL
1308         if ((pc & 1) &&
1309             !is_wide_instruction(__mem_to_opcode_thumb16(*(u16 *)(pc - 1))))
1310                 return pc + 2;
1311         else
1312 #endif
1313         return pc + 4;
1314 }
1315
1316 static uintptr_t __used kprobes_test_case_start(const char **title, void *stack)
1317 {
1318         struct test_arg *args;
1319         struct test_arg_end *end_arg;
1320         unsigned long test_code;
1321
1322         current_title = *title++;
1323         args = (struct test_arg *)title;
1324         current_args = args;
1325         current_stack = stack;
1326
1327         ++test_try_count;
1328
1329         while (args->type != ARG_TYPE_END)
1330                 ++args;
1331         end_arg = (struct test_arg_end *)args;
1332
1333         test_code = (unsigned long)(args + 1); /* Code starts after args */
1334
1335         test_case_is_thumb = end_arg->flags & ARG_FLAG_THUMB;
1336         if (test_case_is_thumb)
1337                 test_code |= 1;
1338
1339         current_code_start = test_code;
1340
1341         current_branch_target = 0;
1342         if (end_arg->branch_offset != end_arg->end_offset)
1343                 current_branch_target = test_code + end_arg->branch_offset;
1344
1345         test_code += end_arg->code_offset;
1346         test_before_probe.kprobe.addr = (kprobe_opcode_t *)test_code;
1347
1348         test_code = next_instruction(test_code);
1349         test_case_probe.kprobe.addr = (kprobe_opcode_t *)test_code;
1350
1351         if (test_case_is_thumb) {
1352                 u16 *p = (u16 *)(test_code & ~1);
1353                 current_instruction = __mem_to_opcode_thumb16(p[0]);
1354                 if (is_wide_instruction(current_instruction)) {
1355                         u16 instr2 = __mem_to_opcode_thumb16(p[1]);
1356                         current_instruction = __opcode_thumb32_compose(current_instruction, instr2);
1357                 }
1358         } else {
1359                 current_instruction = __mem_to_opcode_arm(*(u32 *)test_code);
1360         }
1361
1362         if (current_title[0] == '.')
1363                 verbose("%s\n", current_title);
1364         else
1365                 verbose("%s\t@ %0*x\n", current_title,
1366                                         test_case_is_thumb ? 4 : 8,
1367                                         current_instruction);
1368
1369         test_code = next_instruction(test_code);
1370         test_after_probe.kprobe.addr = (kprobe_opcode_t *)test_code;
1371
1372         if (kprobe_test_flags & TEST_FLAG_NARROW_INSTR) {
1373                 if (!test_case_is_thumb ||
1374                         is_wide_instruction(current_instruction)) {
1375                                 test_case_failed("expected 16-bit instruction");
1376                                 goto fail;
1377                 }
1378         } else {
1379                 if (test_case_is_thumb &&
1380                         !is_wide_instruction(current_instruction)) {
1381                                 test_case_failed("expected 32-bit instruction");
1382                                 goto fail;
1383                 }
1384         }
1385
1386         coverage_add(current_instruction);
1387
1388         if (end_arg->flags & ARG_FLAG_UNSUPPORTED) {
1389                 if (register_test_probe(&test_case_probe) < 0)
1390                         goto pass;
1391                 test_case_failed("registered probe for unsupported instruction");
1392                 goto fail;
1393         }
1394
1395         if (end_arg->flags & ARG_FLAG_SUPPORTED) {
1396                 if (register_test_probe(&test_case_probe) >= 0)
1397                         goto pass;
1398                 test_case_failed("couldn't register probe for supported instruction");
1399                 goto fail;
1400         }
1401
1402         if (register_test_probe(&test_before_probe) < 0) {
1403                 test_case_failed("register test_before_probe failed");
1404                 goto fail;
1405         }
1406         if (register_test_probe(&test_after_probe) < 0) {
1407                 test_case_failed("register test_after_probe failed");
1408                 goto fail;
1409         }
1410         if (current_branch_target) {
1411                 test_after2_probe.kprobe.addr =
1412                                 (kprobe_opcode_t *)current_branch_target;
1413                 if (register_test_probe(&test_after2_probe) < 0) {
1414                         test_case_failed("register test_after2_probe failed");
1415                         goto fail;
1416                 }
1417         }
1418
1419         /* Start first run of test case */
1420         test_case_run_count = 0;
1421         ++test_instance;
1422         return current_code_start;
1423 pass:
1424         test_case_run_count = TEST_CASE_PASSED;
1425         return (uintptr_t)test_after_probe.kprobe.addr;
1426 fail:
1427         test_case_run_count = TEST_CASE_FAILED;
1428         return (uintptr_t)test_after_probe.kprobe.addr;
1429 }
1430
1431 static bool check_test_results(void)
1432 {
1433         size_t mem_size = 0;
1434         u32 *mem = 0;
1435
1436         if (memcmp(&expected_regs, &result_regs, sizeof(expected_regs))) {
1437                 test_case_failed("registers differ");
1438                 goto fail;
1439         }
1440
1441         if (memory_needs_checking) {
1442                 mem = (u32 *)result_regs.ARM_sp;
1443                 mem_size = expected_memory_size(mem);
1444                 if (memcmp(expected_memory, mem, mem_size)) {
1445                         test_case_failed("test memory differs");
1446                         goto fail;
1447                 }
1448         }
1449
1450         return true;
1451
1452 fail:
1453         pr_err("initial_regs:\n");
1454         print_registers(&initial_regs);
1455         pr_err("expected_regs:\n");
1456         print_registers(&expected_regs);
1457         pr_err("result_regs:\n");
1458         print_registers(&result_regs);
1459
1460         if (mem) {
1461                 pr_err("expected_memory:\n");
1462                 print_memory(expected_memory, mem_size);
1463                 pr_err("result_memory:\n");
1464                 print_memory(mem, mem_size);
1465         }
1466
1467         return false;
1468 }
1469
1470 static uintptr_t __used kprobes_test_case_end(void)
1471 {
1472         if (test_case_run_count < 0) {
1473                 if (test_case_run_count == TEST_CASE_PASSED)
1474                         /* kprobes_test_case_start did all the needed testing */
1475                         goto pass;
1476                 else
1477                         /* kprobes_test_case_start failed */
1478                         goto fail;
1479         }
1480
1481         if (test_before_probe.hit != test_instance) {
1482                 test_case_failed("test_before_handler not run");
1483                 goto fail;
1484         }
1485
1486         if (test_after_probe.hit != test_instance &&
1487                                 test_after2_probe.hit != test_instance) {
1488                 test_case_failed("test_after_handler not run");
1489                 goto fail;
1490         }
1491
1492         /*
1493          * Even numbered test runs ran without a probe on the test case so
1494          * we can gather reference results. The subsequent odd numbered run
1495          * will have the probe inserted.
1496         */
1497         if ((test_case_run_count & 1) == 0) {
1498                 /* Save results from run without probe */
1499                 u32 *mem = (u32 *)result_regs.ARM_sp;
1500                 expected_regs = result_regs;
1501                 memcpy(expected_memory, mem, expected_memory_size(mem));
1502
1503                 /* Insert probe onto test case instruction */
1504                 if (register_test_probe(&test_case_probe) < 0) {
1505                         test_case_failed("register test_case_probe failed");
1506                         goto fail;
1507                 }
1508         } else {
1509                 /* Check probe ran as expected */
1510                 if (probe_should_run == 1) {
1511                         if (test_case_probe.hit != test_instance) {
1512                                 test_case_failed("test_case_handler not run");
1513                                 goto fail;
1514                         }
1515                 } else if (probe_should_run == 0) {
1516                         if (test_case_probe.hit == test_instance) {
1517                                 test_case_failed("test_case_handler ran");
1518                                 goto fail;
1519                         }
1520                 }
1521
1522                 /* Remove probe for any subsequent reference run */
1523                 unregister_test_probe(&test_case_probe);
1524
1525                 if (!check_test_results())
1526                         goto fail;
1527
1528                 if (is_last_scenario)
1529                         goto pass;
1530         }
1531
1532         /* Do next test run */
1533         ++test_case_run_count;
1534         ++test_instance;
1535         return current_code_start;
1536 fail:
1537         ++test_fail_count;
1538         goto end;
1539 pass:
1540         ++test_pass_count;
1541 end:
1542         test_case_cleanup();
1543         return 0;
1544 }
1545
1546
1547 /*
1548  * Top level test functions
1549  */
1550
1551 static int run_test_cases(void (*tests)(void), const union decode_item *table)
1552 {
1553         int ret;
1554
1555         pr_info("    Check decoding tables\n");
1556         ret = table_test(table);
1557         if (ret)
1558                 return ret;
1559
1560         pr_info("    Run test cases\n");
1561         ret = coverage_start(table);
1562         if (ret)
1563                 return ret;
1564
1565         tests();
1566
1567         coverage_end();
1568         return 0;
1569 }
1570
1571
1572 static int __init run_all_tests(void)
1573 {
1574         int ret = 0;
1575
1576         pr_info("Beginning kprobe tests...\n");
1577
1578 #ifndef CONFIG_THUMB2_KERNEL
1579
1580         pr_info("Probe ARM code\n");
1581         ret = run_api_tests(arm_func);
1582         if (ret)
1583                 goto out;
1584
1585         pr_info("ARM instruction simulation\n");
1586         ret = run_test_cases(kprobe_arm_test_cases, probes_decode_arm_table);
1587         if (ret)
1588                 goto out;
1589
1590 #else /* CONFIG_THUMB2_KERNEL */
1591
1592         pr_info("Probe 16-bit Thumb code\n");
1593         ret = run_api_tests(thumb16_func);
1594         if (ret)
1595                 goto out;
1596
1597         pr_info("Probe 32-bit Thumb code, even halfword\n");
1598         ret = run_api_tests(thumb32even_func);
1599         if (ret)
1600                 goto out;
1601
1602         pr_info("Probe 32-bit Thumb code, odd halfword\n");
1603         ret = run_api_tests(thumb32odd_func);
1604         if (ret)
1605                 goto out;
1606
1607         pr_info("16-bit Thumb instruction simulation\n");
1608         ret = run_test_cases(kprobe_thumb16_test_cases,
1609                                 probes_decode_thumb16_table);
1610         if (ret)
1611                 goto out;
1612
1613         pr_info("32-bit Thumb instruction simulation\n");
1614         ret = run_test_cases(kprobe_thumb32_test_cases,
1615                                 probes_decode_thumb32_table);
1616         if (ret)
1617                 goto out;
1618 #endif
1619
1620         pr_info("Total instruction simulation tests=%d, pass=%d fail=%d\n",
1621                 test_try_count, test_pass_count, test_fail_count);
1622         if (test_fail_count) {
1623                 ret = -EINVAL;
1624                 goto out;
1625         }
1626
1627 #if BENCHMARKING
1628         pr_info("Benchmarks\n");
1629         ret = run_benchmarks();
1630         if (ret)
1631                 goto out;
1632 #endif
1633
1634 #if __LINUX_ARM_ARCH__ >= 7
1635         /* We are able to run all test cases so coverage should be complete */
1636         if (coverage_fail) {
1637                 pr_err("FAIL: Test coverage checks failed\n");
1638                 ret = -EINVAL;
1639                 goto out;
1640         }
1641 #endif
1642
1643 out:
1644         if (ret == 0)
1645                 ret = tests_failed;
1646         if (ret == 0)
1647                 pr_info("Finished kprobe tests OK\n");
1648         else
1649                 pr_err("kprobe tests failed\n");
1650
1651         return ret;
1652 }
1653
1654
1655 /*
1656  * Module setup
1657  */
1658
1659 #ifdef MODULE
1660
1661 static void __exit kprobe_test_exit(void)
1662 {
1663 }
1664
1665 module_init(run_all_tests)
1666 module_exit(kprobe_test_exit)
1667 MODULE_LICENSE("GPL");
1668
1669 #else /* !MODULE */
1670
1671 late_initcall(run_all_tests);
1672
1673 #endif