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Diffstat (limited to 'arch/arm/kernel/kprobes-test.c')
| -rw-r--r-- | arch/arm/kernel/kprobes-test.c | 1748 |
1 files changed, 1748 insertions, 0 deletions
diff --git a/arch/arm/kernel/kprobes-test.c b/arch/arm/kernel/kprobes-test.c new file mode 100644 index 00000000000..e17cdd6d90d --- /dev/null +++ b/arch/arm/kernel/kprobes-test.c @@ -0,0 +1,1748 @@ +/* + * arch/arm/kernel/kprobes-test.c + * + * Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +/* + * This file contains test code for ARM kprobes. + * + * The top level function run_all_tests() executes tests for all of the + * supported instruction sets: ARM, 16-bit Thumb, and 32-bit Thumb. These tests + * fall into two categories; run_api_tests() checks basic functionality of the + * kprobes API, and run_test_cases() is a comprehensive test for kprobes + * instruction decoding and simulation. + * + * run_test_cases() first checks the kprobes decoding table for self consistency + * (using table_test()) then executes a series of test cases for each of the CPU + * instruction forms. coverage_start() and coverage_end() are used to verify + * that these test cases cover all of the possible combinations of instructions + * described by the kprobes decoding tables. + * + * The individual test cases are in kprobes-test-arm.c and kprobes-test-thumb.c + * which use the macros defined in kprobes-test.h. The rest of this + * documentation will describe the operation of the framework used by these + * test cases. + */ + +/* + * TESTING METHODOLOGY + * ------------------- + * + * The methodology used to test an ARM instruction 'test_insn' is to use + * inline assembler like: + * + * test_before: nop + * test_case: test_insn + * test_after: nop + * + * When the test case is run a kprobe is placed of each nop. The + * post-handler of the test_before probe is used to modify the saved CPU + * register context to that which we require for the test case. The + * pre-handler of the of the test_after probe saves a copy of the CPU + * register context. In this way we can execute test_insn with a specific + * register context and see the results afterwards. + * + * To actually test the kprobes instruction emulation we perform the above + * step a second time but with an additional kprobe on the test_case + * instruction itself. If the emulation is accurate then the results seen + * by the test_after probe will be identical to the first run which didn't + * have a probe on test_case. + * + * Each test case is run several times with a variety of variations in the + * flags value of stored in CPSR, and for Thumb code, different ITState. + * + * For instructions which can modify PC, a second test_after probe is used + * like this: + * + * test_before: nop + * test_case: test_insn + * test_after: nop + * b test_done + * test_after2: nop + * test_done: + * + * The test case is constructed such that test_insn branches to + * test_after2, or, if testing a conditional instruction, it may just + * continue to test_after. The probes inserted at both locations let us + * determine which happened. A similar approach is used for testing + * backwards branches... + * + * b test_before + * b test_done @ helps to cope with off by 1 branches + * test_after2: nop + * b test_done + * test_before: nop + * test_case: test_insn + * test_after: nop + * test_done: + * + * The macros used to generate the assembler instructions describe above + * are TEST_INSTRUCTION, TEST_BRANCH_F (branch forwards) and TEST_BRANCH_B + * (branch backwards). In these, the local variables numbered 1, 50, 2 and + * 99 represent: test_before, test_case, test_after2 and test_done. + * + * FRAMEWORK + * --------- + * + * Each test case is wrapped between the pair of macros TESTCASE_START and + * TESTCASE_END. As well as performing the inline assembler boilerplate, + * these call out to the kprobes_test_case_start() and + * kprobes_test_case_end() functions which drive the execution of the test + * case. The specific arguments to use for each test case are stored as + * inline data constructed using the various TEST_ARG_* macros. Putting + * this all together, a simple test case may look like: + * + * TESTCASE_START("Testing mov r0, r7") + * TEST_ARG_REG(7, 0x12345678) // Set r7=0x12345678 + * TEST_ARG_END("") + * TEST_INSTRUCTION("mov r0, r7") + * TESTCASE_END + * + * Note, in practice the single convenience macro TEST_R would be used for this + * instead. + * + * The above would expand to assembler looking something like: + * + * @ TESTCASE_START + * bl __kprobes_test_case_start + * @ start of inline data... + * .ascii "mov r0, r7" @ text title for test case + * .byte 0 + * .align 2 + * + * @ TEST_ARG_REG + * .byte ARG_TYPE_REG + * .byte 7 + * .short 0 + * .word 0x1234567 + * + * @ TEST_ARG_END + * .byte ARG_TYPE_END + * .byte TEST_ISA @ flags, including ISA being tested + * .short 50f-0f @ offset of 'test_before' + * .short 2f-0f @ offset of 'test_after2' (if relevent) + * .short 99f-0f @ offset of 'test_done' + * @ start of test case code... + * 0: + * .code TEST_ISA @ switch to ISA being tested + * + * @ TEST_INSTRUCTION + * 50: nop @ location for 'test_before' probe + * 1: mov r0, r7 @ the test case instruction 'test_insn' + * nop @ location for 'test_after' probe + * + * // TESTCASE_END + * 2: + * 99: bl __kprobes_test_case_end_##TEST_ISA + * .code NONMAL_ISA + * + * When the above is execute the following happens... + * + * __kprobes_test_case_start() is an assembler wrapper which sets up space + * for a stack buffer and calls the C function kprobes_test_case_start(). + * This C function will do some initial processing of the inline data and + * setup some global state. It then inserts the test_before and test_after + * kprobes and returns a value which causes the assembler wrapper to jump + * to the start of the test case code, (local label '0'). + * + * When the test case code executes, the test_before probe will be hit and + * test_before_post_handler will call setup_test_context(). This fills the + * stack buffer and CPU registers with a test pattern and then processes + * the test case arguments. In our example there is one TEST_ARG_REG which + * indicates that R7 should be loaded with the value 0x12345678. + * + * When the test_before probe ends, the test case continues and executes + * the "mov r0, r7" instruction. It then hits the test_after probe and the + * pre-handler for this (test_after_pre_handler) will save a copy of the + * CPU register context. This should now have R0 holding the same value as + * R7. + * + * Finally we get to the call to __kprobes_test_case_end_{32,16}. This is + * an assembler wrapper which switches back to the ISA used by the test + * code and calls the C function kprobes_test_case_end(). + * + * For each run through the test case, test_case_run_count is incremented + * by one. For even runs, kprobes_test_case_end() saves a copy of the + * register and stack buffer contents from the test case just run. It then + * inserts a kprobe on the test case instruction 'test_insn' and returns a + * value to cause the test case code to be re-run. + * + * For odd numbered runs, kprobes_test_case_end() compares the register and + * stack buffer contents to those that were saved on the previous even + * numbered run (the one without the kprobe on test_insn). These should be + * the same if the kprobe instruction simulation routine is correct. + * + * The pair of test case runs is repeated with different combinations of + * flag values in CPSR and, for Thumb, different ITState. This is + * controlled by test_context_cpsr(). + * + * BUILDING TEST CASES + * ------------------- + * + * + * As an aid to building test cases, the stack buffer is initialised with + * some special values: + * + * [SP+13*4] Contains SP+120. This can be used to test instructions + * which load a value into SP. + * + * [SP+15*4] When testing branching instructions using TEST_BRANCH_{F,B}, + * this holds the target address of the branch, 'test_after2'. + * This can be used to test instructions which load a PC value + * from memory. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/kprobes.h> + +#include "kprobes.h" +#include "kprobes-test.h" + + +#define BENCHMARKING 1 + + +/* + * Test basic API + */ + +static bool test_regs_ok; +static int test_func_instance; +static int pre_handler_called; +static int post_handler_called; +static int jprobe_func_called; +static int kretprobe_handler_called; + +#define FUNC_ARG1 0x12345678 +#define FUNC_ARG2 0xabcdef + + +#ifndef CONFIG_THUMB2_KERNEL + +long arm_func(long r0, long r1); + +static void __used __naked __arm_kprobes_test_func(void) +{ + __asm__ __volatile__ ( + ".arm \n\t" + ".type arm_func, %%function \n\t" + "arm_func: \n\t" + "adds r0, r0, r1 \n\t" + "bx lr \n\t" + ".code "NORMAL_ISA /* Back to Thumb if necessary */ + : : : "r0", "r1", "cc" + ); +} + +#else /* CONFIG_THUMB2_KERNEL */ + +long thumb16_func(long r0, long r1); +long thumb32even_func(long r0, long r1); +long thumb32odd_func(long r0, long r1); + +static void __used __naked __thumb_kprobes_test_funcs(void) +{ + __asm__ __volatile__ ( + ".type thumb16_func, %%function \n\t" + "thumb16_func: \n\t" + "adds.n r0, r0, r1 \n\t" + "bx lr \n\t" + + ".align \n\t" + ".type thumb32even_func, %%function \n\t" + "thumb32even_func: \n\t" + "adds.w r0, r0, r1 \n\t" + "bx lr \n\t" + + ".align \n\t" + "nop.n \n\t" + ".type thumb32odd_func, %%function \n\t" + "thumb32odd_func: \n\t" + "adds.w r0, r0, r1 \n\t" + "bx lr \n\t" + + : : : "r0", "r1", "cc" + ); +} + +#endif /* CONFIG_THUMB2_KERNEL */ + + +static int call_test_func(long (*func)(long, long), bool check_test_regs) +{ + long ret; + + ++test_func_instance; + test_regs_ok = false; + + ret = (*func)(FUNC_ARG1, FUNC_ARG2); + if (ret != FUNC_ARG1 + FUNC_ARG2) { + pr_err("FAIL: call_test_func: func returned %lx\n", ret); + return false; + } + + if (check_test_regs && !test_regs_ok) { + pr_err("FAIL: test regs not OK\n"); + return false; + } + + return true; +} + +static int __kprobes pre_handler(struct kprobe *p, struct pt_regs *regs) +{ + pre_handler_called = test_func_instance; + if (regs->ARM_r0 == FUNC_ARG1 && regs->ARM_r1 == FUNC_ARG2) + test_regs_ok = true; + return 0; +} + +static void __kprobes post_handler(struct kprobe *p, struct pt_regs *regs, + unsigned long flags) +{ + post_handler_called = test_func_instance; + if (regs->ARM_r0 != FUNC_ARG1 + FUNC_ARG2 || regs->ARM_r1 != FUNC_ARG2) + test_regs_ok = false; +} + +static struct kprobe the_kprobe = { + .addr = 0, + .pre_handler = pre_handler, + .post_handler = post_handler +}; + +static int test_kprobe(long (*func)(long, long)) +{ + int ret; + + the_kprobe.addr = (kprobe_opcode_t *)func; + ret = register_kprobe(&the_kprobe); + if (ret < 0) { + pr_err("FAIL: register_kprobe failed with %d\n", ret); + return ret; + } + + ret = call_test_func(func, true); + + unregister_kprobe(&the_kprobe); + the_kprobe.flags = 0; /* Clear disable flag to allow reuse */ + + if (!ret) + return -EINVAL; + if (pre_handler_called != test_func_instance) { + pr_err("FAIL: kprobe pre_handler not called\n"); + return -EINVAL; + } + if (post_handler_called != test_func_instance) { + pr_err("FAIL: kprobe post_handler not called\n"); + return -EINVAL; + } + if (!call_test_func(func, false)) + return -EINVAL; + if (pre_handler_called == test_func_instance || + post_handler_called == test_func_instance) { + pr_err("FAIL: probe called after unregistering\n"); + return -EINVAL; + } + + return 0; +} + +static void __kprobes jprobe_func(long r0, long r1) +{ + jprobe_func_called = test_func_instance; + if (r0 == FUNC_ARG1 && r1 == FUNC_ARG2) + test_regs_ok = true; + jprobe_return(); +} + +static struct jprobe the_jprobe = { + .entry = jprobe_func, +}; + +static int test_jprobe(long (*func)(long, long)) +{ + int ret; + + the_jprobe.kp.addr = (kprobe_opcode_t *)func; + ret = register_jprobe(&the_jprobe); + if (ret < 0) { + pr_err("FAIL: register_jprobe failed with %d\n", ret); + return ret; + } + + ret = call_test_func(func, true); + + unregister_jprobe(&the_jprobe); + the_jprobe.kp.flags = 0; /* Clear disable flag to allow reuse */ + + if (!ret) + return -EINVAL; + if (jprobe_func_called != test_func_instance) { + pr_err("FAIL: jprobe handler function not called\n"); + return -EINVAL; + } + if (!call_test_func(func, false)) + return -EINVAL; + if (jprobe_func_called == test_func_instance) { + pr_err("FAIL: probe called after unregistering\n"); + return -EINVAL; + } + + return 0; +} + +static int __kprobes +kretprobe_handler(struct kretprobe_instance *ri, struct pt_regs *regs) +{ + kretprobe_handler_called = test_func_instance; + if (regs_return_value(regs) == FUNC_ARG1 + FUNC_ARG2) + test_regs_ok = true; + return 0; +} + +static struct kretprobe the_kretprobe = { + .handler = kretprobe_handler, +}; + +static int test_kretprobe(long (*func)(long, long)) +{ + int ret; + + the_kretprobe.kp.addr = (kprobe_opcode_t *)func; + ret = register_kretprobe(&the_kretprobe); + if (ret < 0) { + pr_err("FAIL: register_kretprobe failed with %d\n", ret); + return ret; + } + + ret = call_test_func(func, true); + + unregister_kretprobe(&the_kretprobe); + the_kretprobe.kp.flags = 0; /* Clear disable flag to allow reuse */ + + if (!ret) + return -EINVAL; + if (kretprobe_handler_called != test_func_instance) { + pr_err("FAIL: kretprobe handler not called\n"); + return -EINVAL; + } + if (!call_test_func(func, false)) + return -EINVAL; + if (jprobe_func_called == test_func_instance) { + pr_err("FAIL: kretprobe called after unregistering\n"); + return -EINVAL; + } + + return 0; +} + +static int run_api_tests(long (*func)(long, long)) +{ + int ret; + + pr_info(" kprobe\n"); + ret = test_kprobe(func); + if (ret < 0) + return ret; + + pr_info(" jprobe\n"); + ret = test_jprobe(func); + if (ret < 0) + return ret; + + pr_info(" kretprobe\n"); + ret = test_kretprobe(func); + if (ret < 0) + return ret; + + return 0; +} + + +/* + * Benchmarking + */ + +#if BENCHMARKING + +static void __naked benchmark_nop(void) +{ + __asm__ __volatile__ ( + "nop \n\t" + "bx lr" + ); +} + +#ifdef CONFIG_THUMB2_KERNEL +#define wide ".w" +#else +#define wide +#endif + +static void __naked benchmark_pushpop1(void) +{ + __asm__ __volatile__ ( + "stmdb"wide" sp!, {r3-r11,lr} \n\t" + "ldmia"wide" sp!, {r3-r11,pc}" + ); +} + +static void __naked benchmark_pushpop2(void) +{ + __asm__ __volatile__ ( + "stmdb"wide" sp!, {r0-r8,lr} \n\t" + "ldmia"wide" sp!, {r0-r8,pc}" + ); +} + +static void __naked benchmark_pushpop3(void) +{ + __asm__ __volatile__ ( + "stmdb"wide" sp!, {r4,lr} \n\t" + "ldmia"wide" sp!, {r4,pc}" + ); +} + +static void __naked benchmark_pushpop4(void) +{ + __asm__ __volatile__ ( + "stmdb"wide" sp!, {r0,lr} \n\t" + "ldmia"wide" sp!, {r0,pc}" + ); +} + + +#ifdef CONFIG_THUMB2_KERNEL + +static void __naked benchmark_pushpop_thumb(void) +{ + __asm__ __volatile__ ( + "push.n {r0-r7,lr} \n\t" + "pop.n {r0-r7,pc}" + ); +} + +#endif + +static int __kprobes +benchmark_pre_handler(struct kprobe *p, struct pt_regs *regs) +{ + return 0; +} + +static int benchmark(void(*fn)(void)) +{ + unsigned n, i, t, t0; + + for (n = 1000; ; n *= 2) { + t0 = sched_clock(); + for (i = n; i > 0; --i) + fn(); + t = sched_clock() - t0; + if (t >= 250000000) + break; /* Stop once we took more than 0.25 seconds */ + } + return t / n; /* Time for one iteration in nanoseconds */ +}; + +static int kprobe_benchmark(void(*fn)(void), unsigned offset) +{ + struct kprobe k = { + .addr = (kprobe_opcode_t *)((uintptr_t)fn + offset), + .pre_handler = benchmark_pre_handler, + }; + + int ret = register_kprobe(&k); + if (ret < 0) { + pr_err("FAIL: register_kprobe failed with %d\n", ret); + return ret; + } + + ret = benchmark(fn); + + unregister_kprobe(&k); + return ret; +}; + +struct benchmarks { + void (*fn)(void); + unsigned offset; + const char *title; +}; + +static int run_benchmarks(void) +{ + int ret; + struct benchmarks list[] = { + {&benchmark_nop, 0, "nop"}, + /* + * benchmark_pushpop{1,3} will have the optimised + * instruction emulation, whilst benchmark_pushpop{2,4} will + * be the equivalent unoptimised instructions. + */ + {&benchmark_pushpop1, 0, "stmdb sp!, {r3-r11,lr}"}, + {&benchmark_pushpop1, 4, "ldmia sp!, {r3-r11,pc}"}, + {&benchmark_pushpop2, 0, "stmdb sp!, {r0-r8,lr}"}, + {&benchmark_pushpop2, 4, "ldmia sp!, {r0-r8,pc}"}, + {&benchmark_pushpop3, 0, "stmdb sp!, {r4,lr}"}, + {&benchmark_pushpop3, 4, "ldmia sp!, {r4,pc}"}, + {&benchmark_pushpop4, 0, "stmdb sp!, {r0,lr}"}, + {&benchmark_pushpop4, 4, "ldmia sp!, {r0,pc}"}, +#ifdef CONFIG_THUMB2_KERNEL + {&benchmark_pushpop_thumb, 0, "push.n {r0-r7,lr}"}, + {&benchmark_pushpop_thumb, 2, "pop.n {r0-r7,pc}"}, +#endif + {0} + }; + + struct benchmarks *b; + for (b = list; b->fn; ++b) { + ret = kprobe_benchmark(b->fn, b->offset); + if (ret < 0) + return ret; + pr_info(" %dns for kprobe %s\n", ret, b->title); + } + + pr_info("\n"); + return 0; +} + +#endif /* BENCHMARKING */ + + +/* + * Decoding table self-consistency tests + */ + +static const int decode_struct_sizes[NUM_DECODE_TYPES] = { + [DECODE_TYPE_TABLE] = sizeof(struct decode_table), + [DECODE_TYPE_CUSTOM] = sizeof(struct decode_custom), + [DECODE_TYPE_SIMULATE] = sizeof(struct decode_simulate), + [DECODE_TYPE_EMULATE] = sizeof(struct decode_emulate), + [DECODE_TYPE_OR] = sizeof(struct decode_or), + [DECODE_TYPE_REJECT] = sizeof(struct decode_reject) +}; + +static int table_iter(const union decode_item *table, + int (*fn)(const struct decode_header *, void *), + void *args) +{ + const struct decode_header *h = (struct decode_header *)table; + int result; + + for (;;) { + enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK; + + if (type == DECODE_TYPE_END) + return 0; + + result = fn(h, args); + if (result) + return result; + + h = (struct decode_header *) + ((uintptr_t)h + decode_struct_sizes[type]); + + } +} + +static int table_test_fail(const struct decode_header *h, const char* message) +{ + + pr_err("FAIL: kprobes test failure \"%s\" (mask %08x, value %08x)\n", + message, h->mask.bits, h->value.bits); + return -EINVAL; +} + +struct table_test_args { + const union decode_item *root_table; + u32 parent_mask; + u32 parent_value; +}; + +static int table_test_fn(const struct decode_header *h, void *args) +{ + struct table_test_args *a = (struct table_test_args *)args; + enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK; + + if (h->value.bits & ~h->mask.bits) + return table_test_fail(h, "Match value has bits not in mask"); + + if ((h->mask.bits & a->parent_mask) != a->parent_mask) + return table_test_fail(h, "Mask has bits not in parent mask"); + + if ((h->value.bits ^ a->parent_value) & a->parent_mask) + return table_test_fail(h, "Value is inconsistent with parent"); + + if (type == DECODE_TYPE_TABLE) { + struct decode_table *d = (struct decode_table *)h; + struct table_test_args args2 = *a; + args2.parent_mask = h->mask.bits; + args2.parent_value = h->value.bits; + return table_iter(d->table.table, table_test_fn, &args2); + } + + return 0; +} + +static int table_test(const union decode_item *table) +{ + struct table_test_args args = { + .root_table = table, + .parent_mask = 0, + .parent_value = 0 + }; + return table_iter(args.root_table, table_test_fn, &args); +} + + +/* + * Decoding table test coverage analysis + * + * coverage_start() builds a coverage_table which contains a list of + * coverage_entry's to match each entry in the specified kprobes instruction + * decoding table. + * + * When test cases are run, coverage_add() is called to process each case. + * This looks up the corresponding entry in the coverage_table and sets it as + * being matched, as well as clearing the regs flag appropriate for the test. + * + * After all test cases have been run, coverage_end() is called to check that + * all entries in coverage_table have been matched and that all regs flags are + * cleared. I.e. that all possible combinations of instructions described by + * the kprobes decoding tables have had a test case executed for them. + */ + +bool coverage_fail; + +#define MAX_COVERAGE_ENTRIES 256 + +struct coverage_entry { + const struct decode_header *header; + unsigned regs; + unsigned nesting; + char matched; +}; + +struct coverage_table { + struct coverage_entry *base; + unsigned num_entries; + unsigned nesting; +}; + +struct coverage_table coverage; + +#define COVERAGE_ANY_REG (1<<0) +#define COVERAGE_SP (1<<1) +#define COVERAGE_PC (1<<2) +#define COVERAGE_PCWB (1<<3) + +static const char coverage_register_lookup[16] = { + [REG_TYPE_ANY] = COVERAGE_ANY_REG | COVERAGE_SP | COVERAGE_PC, + [REG_TYPE_SAMEAS16] = COVERAGE_ANY_REG, + [REG_TYPE_SP] = COVERAGE_SP, + [REG_TYPE_PC] = COVERAGE_PC, + [REG_TYPE_NOSP] = COVERAGE_ANY_REG | COVERAGE_SP, + [REG_TYPE_NOSPPC] = COVERAGE_ANY_REG | COVERAGE_SP | COVERAGE_PC, + [REG_TYPE_NOPC] = COVERAGE_ANY_REG | COVERAGE_PC, + [REG_TYPE_NOPCWB] = COVERAGE_ANY_REG | COVERAGE_PC | COVERAGE_PCWB, + [REG_TYPE_NOPCX] = COVERAGE_ANY_REG, + [REG_TYPE_NOSPPCX] = COVERAGE_ANY_REG | COVERAGE_SP, +}; + +unsigned coverage_start_registers(const struct decode_header *h) +{ + unsigned regs = 0; + int i; + for (i = 0; i < 20; i += 4) { + int r = (h->type_regs.bits >> (DECODE_TYPE_BITS + i)) & 0xf; + regs |= coverage_register_lookup[r] << i; + } + return regs; +} + +static int coverage_start_fn(const struct decode_header *h, void *args) +{ + struct coverage_table *coverage = (struct coverage_table *)args; + enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK; + struct coverage_entry *entry = coverage->base + coverage->num_entries; + + if (coverage->num_entries == MAX_COVERAGE_ENTRIES - 1) { + pr_err("FAIL: Out of space for test coverage data"); + return -ENOMEM; + } + + ++coverage->num_entries; + + entry->header = h; + entry->regs = coverage_start_registers(h); + entry->nesting = coverage->nesting; + entry->matched = false; + + if (type == DECODE_TYPE_TABLE) { + struct decode_table *d = (struct decode_table *)h; + int ret; + ++coverage->nesting; + ret = table_iter(d->table.table, coverage_start_fn, coverage); + --coverage->nesting; + return ret; + } + + return 0; +} + +static int coverage_start(const union decode_item *table) +{ + coverage.base = kmalloc(MAX_COVERAGE_ENTRIES * + sizeof(struct coverage_entry), GFP_KERNEL); + coverage.num_entries = 0; + coverage.nesting = 0; + return table_iter(table, coverage_start_fn, &coverage); +} + +static void +coverage_add_registers(struct coverage_entry *entry, kprobe_opcode_t insn) +{ + int regs = entry->header->type_regs.bits >> DECODE_TYPE_BITS; + int i; + for (i = 0; i < 20; i += 4) { + enum decode_reg_type reg_type = (regs >> i) & 0xf; + int reg = (insn >> i) & 0xf; + int flag; + + if (!reg_type) + continue; + + if (reg == 13) + flag = COVERAGE_SP; + else if (reg == 15) + flag = COVERAGE_PC; + else + flag = COVERAGE_ANY_REG; + entry->regs &= ~(flag << i); + + switch (reg_type) { + + case REG_TYPE_NONE: + case REG_TYPE_ANY: + case REG_TYPE_SAMEAS16: + break; + + case REG_TYPE_SP: + if (reg != 13) + return; + break; + + case REG_TYPE_PC: + if (reg != 15) + return; + break; + + case REG_TYPE_NOSP: + if (reg == 13) + return; + break; + + case REG_TYPE_NOSPPC: + case REG_TYPE_NOSPPCX: + if (reg == 13 || reg == 15) + return; + break; + + case REG_TYPE_NOPCWB: + if (!is_writeback(insn)) + break; + if (reg == 15) { + entry->regs &= ~(COVERAGE_PCWB << i); + return; + } + break; + + case REG_TYPE_NOPC: + case REG_TYPE_NOPCX: + if (reg == 15) + return; + break; + } + + } +} + +static void coverage_add(kprobe_opcode_t insn) +{ + struct coverage_entry *entry = coverage.base; + struct coverage_entry *end = coverage.base + coverage.num_entries; + bool matched = false; + unsigned nesting = 0; + + for (; entry < end; ++entry) { + const struct decode_header *h = entry->header; + enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK; + + if (entry->nesting > nesting) + continue; /* Skip sub-table we didn't match */ + + if (entry->nesting < nesting) + break; /* End of sub-table we were scanning */ + + if (!matched) { + if ((insn & h->mask.bits) != h->value.bits) + continue; + entry->matched = true; + } + + switch (type) { + + case DECODE_TYPE_TABLE: + ++nesting; + break; + + case DECODE_TYPE_CUSTOM: + case DECODE_TYPE_SIMULATE: + case DECODE_TYPE_EMULATE: + coverage_add_registers(entry, insn); + return; + + case DECODE_TYPE_OR: + matched = true; + break; + + case DECODE_TYPE_REJECT: + default: + return; + } + + } +} + +static void coverage_end(void) +{ + struct coverage_entry *entry = coverage.base; + struct coverage_entry *end = coverage.base + coverage.num_entries; + + for (; entry < end; ++entry) { + u32 mask = entry->header->mask.bits; + u32 value = entry->header->value.bits; + + if (entry->regs) { + pr_err("FAIL: Register test coverage missing for %08x %08x (%05x)\n", + mask, value, entry->regs); + coverage_fail = true; + } + if (!entry->matched) { + pr_err("FAIL: Test coverage entry missing for %08x %08x\n", + mask, value); + coverage_fail = true; + } + } + + kfree(coverage.base); +} + + +/* + * Framework for instruction set test cases + */ + +void __naked __kprobes_test_case_start(void) +{ + __asm__ __volatile__ ( + "stmdb sp!, {r4-r11} \n\t" + "sub sp, sp, #"__stringify(TEST_MEMORY_SIZE)"\n\t" + "bic r0, lr, #1 @ r0 = inline title string \n\t" + "mov r1, sp \n\t" + "bl kprobes_test_case_start \n\t" + "bx r0 \n\t" + ); +} + +#ifndef CONFIG_THUMB2_KERNEL + +void __naked __kprobes_test_case_end_32(void) +{ + __asm__ __volatile__ ( + "mov r4, lr \n\t" + "bl kprobes_test_case_end \n\t" + "cmp r0, #0 \n\t" + "movne pc, r0 \n\t" + "mov r0, r4 \n\t" + "add sp, sp, #"__stringify(TEST_MEMORY_SIZE)"\n\t" + "ldmia sp!, {r4-r11} \n\t" + "mov pc, r0 \n\t" + ); +} + +#else /* CONFIG_THUMB2_KERNEL */ + +void __naked __kprobes_test_case_end_16(void) +{ + __asm__ __volatile__ ( + "mov r4, lr \n\t" + "bl kprobes_test_case_end \n\t" + "cmp r0, #0 \n\t" + "bxne r0 \n\t" + "mov r0, r4 \n\t" + "add sp, sp, #"__stringify(TEST_MEMORY_SIZE)"\n\t" + "ldmia sp!, {r4-r11} \n\t" + "bx r0 \n\t" + ); +} + +void __naked __kprobes_test_case_end_32(void) +{ + __asm__ __volatile__ ( + ".arm \n\t" + "orr lr, lr, #1 @ will return to Thumb code \n\t" + "ldr pc, 1f \n\t" + "1: \n\t" + ".word __kprobes_test_case_end_16 \n\t" + ); +} + +#endif + + +int kprobe_test_flags; +int kprobe_test_cc_position; + +static int test_try_count; +static int test_pass_count; +static int test_fail_count; + +static struct pt_regs initial_regs; +static struct pt_regs expected_regs; +static struct pt_regs result_regs; + +static u32 expected_memory[TEST_MEMORY_SIZE/sizeof(u32)]; + +static const char *current_title; +static struct test_arg *current_args; +static u32 *current_stack; +static uintptr_t current_branch_target; + +static uintptr_t current_code_start; +static kprobe_opcode_t current_instruction; + + +#define TEST_CASE_PASSED -1 +#define TEST_CASE_FAILED -2 + +static int test_case_run_count; +static bool test_case_is_thumb; +static int test_instance; + +/* + * We ignore the state of the imprecise abort disable flag (CPSR.A) because this + * can change randomly as the kernel doesn't take care to preserve or initialise + * this across context switches. Also, with Security Extentions, the flag may + * not be under control of the kernel; for this reason we ignore the state of + * the FIQ disable flag CPSR.F as well. + */ +#define PSR_IGNORE_BITS (PSR_A_BIT | PSR_F_BIT) + +static unsigned long test_check_cc(int cc, unsigned long cpsr) +{ + unsigned long temp; + + switch (cc) { + case 0x0: /* eq */ + return cpsr & PSR_Z_BIT; + + case 0x1: /* ne */ + return (~cpsr) & PSR_Z_BIT; + + case 0x2: /* cs */ + return cpsr & PSR_C_BIT; + + case 0x3: /* cc */ + return (~cpsr) & PSR_C_BIT; + + case 0x4: /* mi */ + return cpsr & PSR_N_BIT; + + case 0x5: /* pl */ + return (~cpsr) & PSR_N_BIT; + + case 0x6: /* vs */ + return cpsr & PSR_V_BIT; + + case 0x7: /* vc */ + return (~cpsr) & PSR_V_BIT; + + case 0x8: /* hi */ + cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ + return cpsr & PSR_C_BIT; + + case 0x9: /* ls */ + cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ + return (~cpsr) & PSR_C_BIT; + + case 0xa: /* ge */ + cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */ + return (~cpsr) & PSR_N_BIT; + + case 0xb: /* lt */ + cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */ + return cpsr & PSR_N_BIT; + + case 0xc: /* gt */ + temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */ + temp |= (cpsr << 1); /* PSR_N_BIT |= PSR_Z_BIT */ + return (~temp) & PSR_N_BIT; + + case 0xd: /* le */ + temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */ + temp |= (cpsr << 1); /* PSR_N_BIT |= PSR_Z_BIT */ + return temp & PSR_N_BIT; + + case 0xe: /* al */ + case 0xf: /* unconditional */ + return true; + } + BUG(); + return false; +} + +static int is_last_scenario; +static int probe_should_run; /* 0 = no, 1 = yes, -1 = unknown */ +static int memory_needs_checking; + +static unsigned long test_context_cpsr(int scenario) +{ + unsigned long cpsr; + + probe_should_run = 1; + + /* Default case is that we cycle through 16 combinations of flags */ + cpsr = (scenario & 0xf) << 28; /* N,Z,C,V flags */ + cpsr |= (scenario & 0xf) << 16; /* GE flags */ + cpsr |= (scenario & 0x1) << 27; /* Toggle Q flag */ + + if (!test_case_is_thumb) { + /* Testing ARM code */ + probe_should_run = test_check_cc(current_instruction >> 28, cpsr) != 0; + if (scenario == 15) + is_last_scenario = true; + + } else if (kprobe_test_flags & TEST_FLAG_NO_ITBLOCK) { + /* Testing Thumb code without setting ITSTATE */ + if (kprobe_test_cc_position) { + int cc = (current_instruction >> kprobe_test_cc_position) & 0xf; + probe_should_run = test_check_cc(cc, cpsr) != 0; + } + + if (scenario == 15) + is_last_scenario = true; + + } else if (kprobe_test_flags & TEST_FLAG_FULL_ITBLOCK) { + /* Testing Thumb code with all combinations of ITSTATE */ + unsigned x = (scenario >> 4); + unsigned cond_base = x % 7; /* ITSTATE<7:5> */ + unsigned mask = x / 7 + 2; /* ITSTATE<4:0>, bits reversed */ + + if (mask > 0x1f) { + /* Finish by testing state from instruction 'itt al' */ + cond_base = 7; + mask = 0x4; + if ((scenario & 0xf) == 0xf) + is_last_scenario = true; + } + + cpsr |= cond_base << 13; /* ITSTATE<7:5> */ + cpsr |= (mask & 0x1) << 12; /* ITSTATE<4> */ + cpsr |= (mask & 0x2) << 10; /* ITSTATE<3> */ + cpsr |= (mask & 0x4) << 8; /* ITSTATE<2> */ + cpsr |= (mask & 0x8) << 23; /* ITSTATE<1> */ + cpsr |= (mask & 0x10) << 21; /* ITSTATE<0> */ + + probe_should_run = test_check_cc((cpsr >> 12) & 0xf, cpsr) != 0; + + } else { + /* Testing Thumb code with several combinations of ITSTATE */ + switch (scenario) { + case 16: /* Clear NZCV flags and 'it eq' state (false as Z=0) */ + cpsr = 0x00000800; + probe_should_run = 0; + break; + case 17: /* Set NZCV flags and 'it vc' state (false as V=1) */ + cpsr = 0xf0007800; + probe_should_run = 0; + break; + case 18: /* Clear NZCV flags and 'it ls' state (true as C=0) */ + cpsr = 0x00009800; + break; + case 19: /* Set NZCV flags and 'it cs' state (true as C=1) */ + cpsr = 0xf0002800; + is_last_scenario = true; + break; + } + } + + return cpsr; +} + +static void setup_test_context(struct pt_regs *regs) +{ + int scenario = test_case_run_count>>1; + unsigned long val; + struct test_arg *args; + int i; + + is_last_scenario = false; + memory_needs_checking = false; + + /* Initialise test memory on stack */ + val = |