linuxdebug/kernel/events/hw_breakpoint_test.c

334 lines
9.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* KUnit test for hw_breakpoint constraints accounting logic.
*
* Copyright (C) 2022, Google LLC.
*/
#include <kunit/test.h>
#include <linux/cpumask.h>
#include <linux/hw_breakpoint.h>
#include <linux/kthread.h>
#include <linux/perf_event.h>
#include <asm/hw_breakpoint.h>
#define TEST_REQUIRES_BP_SLOTS(test, slots) \
do { \
if ((slots) > get_test_bp_slots()) { \
kunit_skip((test), "Requires breakpoint slots: %d > %d", slots, \
get_test_bp_slots()); \
} \
} while (0)
#define TEST_EXPECT_NOSPC(expr) KUNIT_EXPECT_EQ(test, -ENOSPC, PTR_ERR(expr))
#define MAX_TEST_BREAKPOINTS 512
static char break_vars[MAX_TEST_BREAKPOINTS];
static struct perf_event *test_bps[MAX_TEST_BREAKPOINTS];
static struct task_struct *__other_task;
static struct perf_event *register_test_bp(int cpu, struct task_struct *tsk, int idx)
{
struct perf_event_attr attr = {};
if (WARN_ON(idx < 0 || idx >= MAX_TEST_BREAKPOINTS))
return NULL;
hw_breakpoint_init(&attr);
attr.bp_addr = (unsigned long)&break_vars[idx];
attr.bp_len = HW_BREAKPOINT_LEN_1;
attr.bp_type = HW_BREAKPOINT_RW;
return perf_event_create_kernel_counter(&attr, cpu, tsk, NULL, NULL);
}
static void unregister_test_bp(struct perf_event **bp)
{
if (WARN_ON(IS_ERR(*bp)))
return;
if (WARN_ON(!*bp))
return;
unregister_hw_breakpoint(*bp);
*bp = NULL;
}
static int get_test_bp_slots(void)
{
static int slots;
if (!slots)
slots = hw_breakpoint_slots(TYPE_DATA);
return slots;
}
static void fill_one_bp_slot(struct kunit *test, int *id, int cpu, struct task_struct *tsk)
{
struct perf_event *bp = register_test_bp(cpu, tsk, *id);
KUNIT_ASSERT_NOT_NULL(test, bp);
KUNIT_ASSERT_FALSE(test, IS_ERR(bp));
KUNIT_ASSERT_NULL(test, test_bps[*id]);
test_bps[(*id)++] = bp;
}
/*
* Fills up the given @cpu/@tsk with breakpoints, only leaving @skip slots free.
*
* Returns true if this can be called again, continuing at @id.
*/
static bool fill_bp_slots(struct kunit *test, int *id, int cpu, struct task_struct *tsk, int skip)
{
for (int i = 0; i < get_test_bp_slots() - skip; ++i)
fill_one_bp_slot(test, id, cpu, tsk);
return *id + get_test_bp_slots() <= MAX_TEST_BREAKPOINTS;
}
static int dummy_kthread(void *arg)
{
return 0;
}
static struct task_struct *get_other_task(struct kunit *test)
{
struct task_struct *tsk;
if (__other_task)
return __other_task;
tsk = kthread_create(dummy_kthread, NULL, "hw_breakpoint_dummy_task");
KUNIT_ASSERT_FALSE(test, IS_ERR(tsk));
__other_task = tsk;
return __other_task;
}
static int get_test_cpu(int num)
{
int cpu;
WARN_ON(num < 0);
for_each_online_cpu(cpu) {
if (num-- <= 0)
break;
}
return cpu;
}
/* ===== Test cases ===== */
static void test_one_cpu(struct kunit *test)
{
int idx = 0;
fill_bp_slots(test, &idx, get_test_cpu(0), NULL, 0);
TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
}
static void test_many_cpus(struct kunit *test)
{
int idx = 0;
int cpu;
/* Test that CPUs are independent. */
for_each_online_cpu(cpu) {
bool do_continue = fill_bp_slots(test, &idx, cpu, NULL, 0);
TEST_EXPECT_NOSPC(register_test_bp(cpu, NULL, idx));
if (!do_continue)
break;
}
}
static void test_one_task_on_all_cpus(struct kunit *test)
{
int idx = 0;
fill_bp_slots(test, &idx, -1, current, 0);
TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
/* Remove one and adding back CPU-target should work. */
unregister_test_bp(&test_bps[0]);
fill_one_bp_slot(test, &idx, get_test_cpu(0), NULL);
}
static void test_two_tasks_on_all_cpus(struct kunit *test)
{
int idx = 0;
/* Test that tasks are independent. */
fill_bp_slots(test, &idx, -1, current, 0);
fill_bp_slots(test, &idx, -1, get_other_task(test), 0);
TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
TEST_EXPECT_NOSPC(register_test_bp(-1, get_other_task(test), idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), get_other_task(test), idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
/* Remove one from first task and adding back CPU-target should not work. */
unregister_test_bp(&test_bps[0]);
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
}
static void test_one_task_on_one_cpu(struct kunit *test)
{
int idx = 0;
fill_bp_slots(test, &idx, get_test_cpu(0), current, 0);
TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
/*
* Remove one and adding back CPU-target should work; this case is
* special vs. above because the task's constraints are CPU-dependent.
*/
unregister_test_bp(&test_bps[0]);
fill_one_bp_slot(test, &idx, get_test_cpu(0), NULL);
}
static void test_one_task_mixed(struct kunit *test)
{
int idx = 0;
TEST_REQUIRES_BP_SLOTS(test, 3);
fill_one_bp_slot(test, &idx, get_test_cpu(0), current);
fill_bp_slots(test, &idx, -1, current, 1);
TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
/* Transition from CPU-dependent pinned count to CPU-independent. */
unregister_test_bp(&test_bps[0]);
unregister_test_bp(&test_bps[1]);
fill_one_bp_slot(test, &idx, get_test_cpu(0), NULL);
fill_one_bp_slot(test, &idx, get_test_cpu(0), NULL);
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
}
static void test_two_tasks_on_one_cpu(struct kunit *test)
{
int idx = 0;
fill_bp_slots(test, &idx, get_test_cpu(0), current, 0);
fill_bp_slots(test, &idx, get_test_cpu(0), get_other_task(test), 0);
TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
TEST_EXPECT_NOSPC(register_test_bp(-1, get_other_task(test), idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), get_other_task(test), idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
/* Can still create breakpoints on some other CPU. */
fill_bp_slots(test, &idx, get_test_cpu(1), NULL, 0);
}
static void test_two_tasks_on_one_all_cpus(struct kunit *test)
{
int idx = 0;
fill_bp_slots(test, &idx, get_test_cpu(0), current, 0);
fill_bp_slots(test, &idx, -1, get_other_task(test), 0);
TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
TEST_EXPECT_NOSPC(register_test_bp(-1, get_other_task(test), idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), get_other_task(test), idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
/* Cannot create breakpoints on some other CPU either. */
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(1), NULL, idx));
}
static void test_task_on_all_and_one_cpu(struct kunit *test)
{
int tsk_on_cpu_idx, cpu_idx;
int idx = 0;
TEST_REQUIRES_BP_SLOTS(test, 3);
fill_bp_slots(test, &idx, -1, current, 2);
/* Transitioning from only all CPU breakpoints to mixed. */
tsk_on_cpu_idx = idx;
fill_one_bp_slot(test, &idx, get_test_cpu(0), current);
fill_one_bp_slot(test, &idx, -1, current);
TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
/* We should still be able to use up another CPU's slots. */
cpu_idx = idx;
fill_one_bp_slot(test, &idx, get_test_cpu(1), NULL);
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(1), NULL, idx));
/* Transitioning back to task target on all CPUs. */
unregister_test_bp(&test_bps[tsk_on_cpu_idx]);
/* Still have a CPU target breakpoint in get_test_cpu(1). */
TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
/* Remove it and try again. */
unregister_test_bp(&test_bps[cpu_idx]);
fill_one_bp_slot(test, &idx, -1, current);
TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(1), NULL, idx));
}
static struct kunit_case hw_breakpoint_test_cases[] = {
KUNIT_CASE(test_one_cpu),
KUNIT_CASE(test_many_cpus),
KUNIT_CASE(test_one_task_on_all_cpus),
KUNIT_CASE(test_two_tasks_on_all_cpus),
KUNIT_CASE(test_one_task_on_one_cpu),
KUNIT_CASE(test_one_task_mixed),
KUNIT_CASE(test_two_tasks_on_one_cpu),
KUNIT_CASE(test_two_tasks_on_one_all_cpus),
KUNIT_CASE(test_task_on_all_and_one_cpu),
{},
};
static int test_init(struct kunit *test)
{
/* Most test cases want 2 distinct CPUs. */
if (num_online_cpus() < 2)
kunit_skip(test, "not enough cpus");
/* Want the system to not use breakpoints elsewhere. */
if (hw_breakpoint_is_used())
kunit_skip(test, "hw breakpoint already in use");
return 0;
}
static void test_exit(struct kunit *test)
{
for (int i = 0; i < MAX_TEST_BREAKPOINTS; ++i) {
if (test_bps[i])
unregister_test_bp(&test_bps[i]);
}
if (__other_task) {
kthread_stop(__other_task);
__other_task = NULL;
}
/* Verify that internal state agrees that no breakpoints are in use. */
KUNIT_EXPECT_FALSE(test, hw_breakpoint_is_used());
}
static struct kunit_suite hw_breakpoint_test_suite = {
.name = "hw_breakpoint",
.test_cases = hw_breakpoint_test_cases,
.init = test_init,
.exit = test_exit,
};
kunit_test_suites(&hw_breakpoint_test_suite);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marco Elver <elver@google.com>");