Author | Tokens | Token Proportion | Commits | Commit Proportion |
---|---|---|---|---|
Jon Medhurst (Tixy) | 5568 | 98.64% | 14 | 56.00% |
Ben Dooks | 24 | 0.43% | 1 | 4.00% |
Leif Lindholm | 23 | 0.41% | 1 | 4.00% |
David A. Long | 16 | 0.28% | 2 | 8.00% |
Wang Nan | 4 | 0.07% | 1 | 4.00% |
Ingo Molnar | 3 | 0.05% | 1 | 4.00% |
Kees Cook | 2 | 0.04% | 1 | 4.00% |
Thomas Gleixner | 2 | 0.04% | 1 | 4.00% |
Arnd Bergmann | 1 | 0.02% | 1 | 4.00% |
Masanari Iida | 1 | 0.02% | 1 | 4.00% |
Masami Hiramatsu | 1 | 0.02% | 1 | 4.00% |
Total | 5645 | 25 |
// SPDX-License-Identifier: GPL-2.0-only /* * arch/arm/kernel/kprobes-test.c * * Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>. */ /* * 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 * .pushsection .rodata * "10: * .ascii "mov r0, r7" @ text title for test case * .byte 0 * .popsection * @ start of inline data... * .word 10b @ pointer to title in .rodata section * * @ 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/sched/clock.h> #include <linux/kprobes.h> #include <linux/errno.h> #include <linux/stddef.h> #include <linux/bug.h> #include <asm/opcodes.h> #include "core.h" #include "test-core.h" #include "../decode-arm.h" #include "../decode-thumb.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 kretprobe_handler_called; static int tests_failed; #define FUNC_ARG1 0x12345678 #define FUNC_ARG2 0xabcdef #ifndef CONFIG_THUMB2_KERNEL #define RET(reg) "mov pc, "#reg 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" "mov pc, lr \n\t" ".code "NORMAL_ISA /* Back to Thumb if necessary */ : : : "r0", "r1", "cc" ); } #else /* CONFIG_THUMB2_KERNEL */ #define RET(reg) "bx "#reg 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 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 (kretprobe_handler_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(" 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" RET(lr)" \n\t" ); } #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, }; static 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_array(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__ ( "mov r2, sp \n\t" "bic r3, r2, #7 \n\t" "mov sp, r3 \n\t" "stmdb sp!, {r2-r11} \n\t" "sub sp, sp, #"__stringify(TEST_MEMORY_SIZE)"\n\t" "bic r0, lr, #1 @ r0 = inline data \n\t" "mov r1, sp \n\t" "bl kprobes_test_case_start \n\t" RET(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!, {r2-r11} \n\t" "mov sp, r2 \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!, {r2-r11} \n\t" "mov sp, r2 \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; static unsigned long test_check_cc(int cc, unsigned long cpsr) { int ret = arm_check_condition(cc << 28, cpsr); return (ret != ARM_OPCODE_CONDTEST_FAIL); } 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 */ int cc = current_instruction >> 28; probe_should_run = test_check_cc(cc, 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 = (scenario & 1) ? VALM : ~VALM; for (i = 0; i < TEST_MEMORY_SIZE / sizeof(current_stack[0]); ++i) current_stack[i] = val + (i << 8); /* Put target of branch on stack for tests which load PC from memory */ if (current_branch_target) current_stack[15] = current_branch_target; /* Put a value for SP on stack for tests which load SP from memory */ current_stack[13] = (u32)current_stack + 120; /* Initialise register values to their default state */ val = (scenario & 2) ? VALR : ~VALR; for (i = 0; i < 13; ++i) regs->uregs[i] = val ^ (i << 8); regs->ARM_lr = val ^ (14 << 8); regs->ARM_cpsr &= ~(APSR_MASK | PSR_IT_MASK); regs->ARM_cpsr |= test_context_cpsr(scenario); /* Perform testcase specific register setup */ args = current_args; for (; args[0].type != ARG_TYPE_END; ++args) switch (args[0].type) { case ARG_TYPE_REG: { struct test_arg_regptr *arg = (struct test_arg_regptr *)args; regs->uregs[arg->reg] = arg->val; break; } case ARG_TYPE_PTR: { struct test_arg_regptr *arg = (struct test_arg_regptr *)args; regs->uregs[arg->reg] = (unsigned long)current_stack + arg->val; memory_needs_checking = true; /* * Test memory at an address below SP is in danger of * being altered by an interrupt occurring and pushing * data onto the stack. Disable interrupts to stop this. */ if (arg->reg == 13) regs->ARM_cpsr |= PSR_I_BIT; break; } case ARG_TYPE_MEM: { struct test_arg_mem *arg = (struct test_arg_mem *)args; current_stack[arg->index] = arg->val; break; } default: break; } } struct test_probe { struct kprobe kprobe; bool registered; int hit; }; static void unregister_test_probe(struct test_probe *probe) { if (probe->registered) { unregister_kprobe(&probe->kprobe); probe->kprobe.flags = 0; /* Clear disable flag to allow reuse */ } probe->registered = false; } static int register_test_probe(struct test_probe *probe) { int ret; if (probe->registered) BUG(); ret = register_kprobe(&probe->kprobe); if (ret >= 0) { probe->registered = true; probe->hit = -1; } return ret; } static int __kprobes test_before_pre_handler(struct kprobe *p, struct pt_regs *regs) { container_of(p, struct test_probe, kprobe)->hit = test_instance; return 0; } static void __kprobes test_before_post_handler(struct kprobe *p, struct pt_regs *regs, unsigned long flags) { setup_test_context(regs); initial_regs = *regs; initial_regs.ARM_cpsr &= ~PSR_IGNORE_BITS; } static int __kprobes test_case_pre_handler(struct kprobe *p, struct pt_regs *regs) { container_of(p, struct test_probe, kprobe)->hit = test_instance; return 0; } static int __kprobes test_after_pre_handler(struct kprobe *p, struct pt_regs *regs) { struct test_arg *args; if (container_of(p, struct test_probe, kprobe)->hit == test_instance) return 0; /* Already run for this test instance */ result_regs = *regs; /* Mask out results which are indeterminate */ result_regs.ARM_cpsr &= ~PSR_IGNORE_BITS; for (args = current_args; args[0].type != ARG_TYPE_END; ++args) if (args[0].type == ARG_TYPE_REG_MASKED) { struct test_arg_regptr *arg = (struct test_arg_regptr *)args; result_regs.uregs[arg->reg] &= arg->val; } /* Undo any changes done to SP by the test case */ regs->ARM_sp = (unsigned long)current_stack; /* Enable interrupts in case setup_test_context disabled them */ regs->ARM_cpsr &= ~PSR_I_BIT; container_of(p, struct test_probe, kprobe)->hit = test_instance; return 0; } static struct test_probe test_before_probe = { .kprobe.pre_handler = test_before_pre_handler, .kprobe.post_handler = test_before_post_handler, }; static struct test_probe test_case_probe = { .kprobe.pre_handler = test_case_pre_handler, }; static struct test_probe test_after_probe = { .kprobe.pre_handler = test_after_pre_handler, }; static struct test_probe test_after2_probe = { .kprobe.pre_handler = test_after_pre_handler, }; static void test_case_cleanup(void) { unregister_test_probe(&test_before_probe); unregister_test_probe(&test_case_probe); unregister_test_probe(&test_after_probe); unregister_test_probe(&test_after2_probe); } static void print_registers(struct pt_regs *regs) { pr_err("r0 %08lx | r1 %08lx | r2 %08lx | r3 %08lx\n", regs->ARM_r0, regs->ARM_r1, regs->ARM_r2, regs->ARM_r3); pr_err("r4 %08lx | r5 %08lx | r6 %08lx | r7 %08lx\n", regs->ARM_r4, regs->ARM_r5, regs->ARM_r6, regs->ARM_r7); pr_err("r8 %08lx | r9 %08lx | r10 %08lx | r11 %08lx\n", regs->ARM_r8, regs->ARM_r9, regs->ARM_r10, regs->ARM_fp); pr_err("r12 %08lx | sp %08lx | lr %08lx | pc %08lx\n", regs->ARM_ip, regs->ARM_sp, regs->ARM_lr, regs->ARM_pc); pr_err("cpsr %08lx\n", regs->ARM_cpsr); } static void print_memory(u32 *mem, size_t size) { int i; for (i = 0; i < size / sizeof(u32); i += 4) pr_err("%08x %08x %08x %08x\n", mem[i], mem[i+1], mem[i+2], mem[i+3]); } static size_t expected_memory_size(u32 *sp) { size_t size = sizeof(expected_memory); int offset = (uintptr_t)sp - (uintptr_t)current_stack; if (offset > 0) size -= offset; return size; } static void test_case_failed(const char *message) { test_case_cleanup(); pr_err("FAIL: %s\n", message); pr_err("FAIL: Test %s\n", current_title); pr_err("FAIL: Scenario %d\n", test_case_run_count >> 1); } static unsigned long next_instruction(unsigned long pc) { #ifdef CONFIG_THUMB2_KERNEL if ((pc & 1) && !is_wide_instruction(__mem_to_opcode_thumb16(*(u16 *)(pc - 1)))) return pc + 2; else #endif return pc + 4; } static uintptr_t __used kprobes_test_case_start(const char **title, void *stack) { struct test_arg *args; struct test_arg_end *end_arg; unsigned long test_code; current_title = *title++; args = (struct test_arg *)title; current_args = args; current_stack = stack; ++test_try_count; while (args->type != ARG_TYPE_END) ++args; end_arg = (struct test_arg_end *)args; test_code = (unsigned long)(args + 1); /* Code starts after args */ test_case_is_thumb = end_arg->flags & ARG_FLAG_THUMB; if (test_case_is_thumb) test_code |= 1; current_code_start = test_code; current_branch_target = 0; if (end_arg->branch_offset != end_arg->end_offset) current_branch_target = test_code + end_arg->branch_offset; test_code += end_arg->code_offset; test_before_probe.kprobe.addr = (kprobe_opcode_t *)test_code; test_code = next_instruction(test_code); test_case_probe.kprobe.addr = (kprobe_opcode_t *)test_code; if (test_case_is_thumb) { u16 *p = (u16 *)(test_code & ~1); current_instruction = __mem_to_opcode_thumb16(p[0]); if (is_wide_instruction(current_instruction)) { u16 instr2 = __mem_to_opcode_thumb16(p[1]); current_instruction = __opcode_thumb32_compose(current_instruction, instr2); } } else { current_instruction = __mem_to_opcode_arm(*(u32 *)test_code); } if (current_title[0] == '.') verbose("%s\n", current_title); else verbose("%s\t@ %0*x\n", current_title, test_case_is_thumb ? 4 : 8, current_instruction); test_code = next_instruction(test_code); test_after_probe.kprobe.addr = (kprobe_opcode_t *)test_code; if (kprobe_test_flags & TEST_FLAG_NARROW_INSTR) { if (!test_case_is_thumb || is_wide_instruction(current_instruction)) { test_case_failed("expected 16-bit instruction"); goto fail; } } else { if (test_case_is_thumb && !is_wide_instruction(current_instruction)) { test_case_failed("expected 32-bit instruction"); goto fail; } } coverage_add(current_instruction); if (end_arg->flags & ARG_FLAG_UNSUPPORTED) { if (register_test_probe(&test_case_probe) < 0) goto pass; test_case_failed("registered probe for unsupported instruction"); goto fail; } if (end_arg->flags & ARG_FLAG_SUPPORTED) { if (register_test_probe(&test_case_probe) >= 0) goto pass; test_case_failed("couldn't register probe for supported instruction"); goto fail; } if (register_test_probe(&test_before_probe) < 0) { test_case_failed("register test_before_probe failed"); goto fail; } if (register_test_probe(&test_after_probe) < 0) { test_case_failed("register test_after_probe failed"); goto fail; } if (current_branch_target) { test_after2_probe.kprobe.addr = (kprobe_opcode_t *)current_branch_target; if (register_test_probe(&test_after2_probe) < 0) { test_case_failed("register test_after2_probe failed"); goto fail; } } /* Start first run of test case */ test_case_run_count = 0; ++test_instance; return current_code_start; pass: test_case_run_count = TEST_CASE_PASSED; return (uintptr_t)test_after_probe.kprobe.addr; fail: test_case_run_count = TEST_CASE_FAILED; return (uintptr_t)test_after_probe.kprobe.addr; } static bool check_test_results(void) { size_t mem_size = 0; u32 *mem = 0; if (memcmp(&expected_regs, &result_regs, sizeof(expected_regs))) { test_case_failed("registers differ"); goto fail; } if (memory_needs_checking) { mem = (u32 *)result_regs.ARM_sp; mem_size = expected_memory_size(mem); if (memcmp(expected_memory, mem, mem_size)) { test_case_failed("test memory differs"); goto fail; } } return true; fail: pr_err("initial_regs:\n"); print_registers(&initial_regs); pr_err("expected_regs:\n"); print_registers(&expected_regs); pr_err("result_regs:\n"); print_registers(&result_regs); if (mem) { pr_err("expected_memory:\n"); print_memory(expected_memory, mem_size); pr_err("result_memory:\n"); print_memory(mem, mem_size); } return false; } static uintptr_t __used kprobes_test_case_end(void) { if (test_case_run_count < 0) { if (test_case_run_count == TEST_CASE_PASSED) /* kprobes_test_case_start did all the needed testing */ goto pass; else /* kprobes_test_case_start failed */ goto fail; } if (test_before_probe.hit != test_instance) { test_case_failed("test_before_handler not run"); goto fail; } if (test_after_probe.hit != test_instance && test_after2_probe.hit != test_instance) { test_case_failed("test_after_handler not run"); goto fail; } /* * Even numbered test runs ran without a probe on the test case so * we can gather reference results. The subsequent odd numbered run * will have the probe inserted. */ if ((test_case_run_count & 1) == 0) { /* Save results from run without probe */ u32 *mem = (u32 *)result_regs.ARM_sp; expected_regs = result_regs; memcpy(expected_memory, mem, expected_memory_size(mem)); /* Insert probe onto test case instruction */ if (register_test_probe(&test_case_probe) < 0) { test_case_failed("register test_case_probe failed"); goto fail; } } else { /* Check probe ran as expected */ if (probe_should_run == 1) { if (test_case_probe.hit != test_instance) { test_case_failed("test_case_handler not run"); goto fail; } } else if (probe_should_run == 0) { if (test_case_probe.hit == test_instance) { test_case_failed("test_case_handler ran"); goto fail; } } /* Remove probe for any subsequent reference run */ unregister_test_probe(&test_case_probe); if (!check_test_results()) goto fail; if (is_last_scenario) goto pass; } /* Do next test run */ ++test_case_run_count; ++test_instance; return current_code_start; fail: ++test_fail_count; goto end; pass: ++test_pass_count; end: test_case_cleanup(); return 0; } /* * Top level test functions */ static int run_test_cases(void (*tests)(void), const union decode_item *table) { int ret; pr_info(" Check decoding tables\n"); ret = table_test(table); if (ret) return ret; pr_info(" Run test cases\n"); ret = coverage_start(table); if (ret) return ret; tests(); coverage_end(); return 0; } static int __init run_all_tests(void) { int ret = 0; pr_info("Beginning kprobe tests...\n"); #ifndef CONFIG_THUMB2_KERNEL pr_info("Probe ARM code\n"); ret = run_api_tests(arm_func); if (ret) goto out; pr_info("ARM instruction simulation\n"); ret = run_test_cases(kprobe_arm_test_cases, probes_decode_arm_table); if (ret) goto out; #else /* CONFIG_THUMB2_KERNEL */ pr_info("Probe 16-bit Thumb code\n"); ret = run_api_tests(thumb16_func); if (ret) goto out; pr_info("Probe 32-bit Thumb code, even halfword\n"); ret = run_api_tests(thumb32even_func); if (ret) goto out; pr_info("Probe 32-bit Thumb code, odd halfword\n"); ret = run_api_tests(thumb32odd_func); if (ret) goto out; pr_info("16-bit Thumb instruction simulation\n"); ret = run_test_cases(kprobe_thumb16_test_cases, probes_decode_thumb16_table); if (ret) goto out; pr_info("32-bit Thumb instruction simulation\n"); ret = run_test_cases(kprobe_thumb32_test_cases, probes_decode_thumb32_table); if (ret) goto out; #endif pr_info("Total instruction simulation tests=%d, pass=%d fail=%d\n", test_try_count, test_pass_count, test_fail_count); if (test_fail_count) { ret = -EINVAL; goto out; } #if BENCHMARKING pr_info("Benchmarks\n"); ret = run_benchmarks(); if (ret) goto out; #endif #if __LINUX_ARM_ARCH__ >= 7 /* We are able to run all test cases so coverage should be complete */ if (coverage_fail) { pr_err("FAIL: Test coverage checks failed\n"); ret = -EINVAL; goto out; } #endif out: if (ret == 0) ret = tests_failed; if (ret == 0) pr_info("Finished kprobe tests OK\n"); else pr_err("kprobe tests failed\n"); return ret; } /* * Module setup */ #ifdef MODULE static void __exit kprobe_test_exit(void) { } module_init(run_all_tests) module_exit(kprobe_test_exit) MODULE_LICENSE("GPL"); #else /* !MODULE */ late_initcall(run_all_tests); #endif
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