/*
* 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 <asm/opcodes.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)
{
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;
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)
{
if (container_of(p, struct test_probe, kprobe)->hit == test_instance)
return 0; /* Already run for this test instance */
result_regs = *regs;
result_regs.ARM_cpsr &= ~PSR_IGNORE_BITS;
/* Undo any changes done to SP by the test case */
regs->ARM_sp = (unsigned long)current_stack;
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(*(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;
args = (struct test_arg *)PTR_ALIGN(title + strlen(title) + 1, 4);
current_title = 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 = p[0];
if (is_wide_instruction(current_instruction)) {
current_instruction <<= 16;
current_instruction |= p[1];
}
} else {
current_instruction = *(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("current_stack=%p\n", current_stack);
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, kprobe_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,
kprobe_decode_thumb16_table);
if (ret)
goto out;
pr_info("32-bit Thumb instruction simulation\n");
ret = run_test_cases(kprobe_thumb32_test_cases,
kprobe_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)
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