perf/hw_breakpoint: Add KUnit test for constraints accounting
Add KUnit test for hw_breakpoint constraints accounting, with various interesting mixes of breakpoint targets (some care was taken to catch interesting corner cases via bug-injection). The test cannot be built as a module because it requires access to hw_breakpoint_slots(), which is not inlinable or exported on all architectures. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Ian Rogers <irogers@google.com> Link: https://lore.kernel.org/r/20220829124719.675715-2-elver@google.com
This commit is contained in:
Marco Elver
Peter Zijlstra
parent
f4054e5225
commit
724c299c6a
@ -2,4 +2,5 @@
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obj-y := core.o ring_buffer.o callchain.o
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obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
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obj-$(CONFIG_HW_BREAKPOINT_KUNIT_TEST) += hw_breakpoint_test.o
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obj-$(CONFIG_UPROBES) += uprobes.o
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323
kernel/events/hw_breakpoint_test.c
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323
kernel/events/hw_breakpoint_test.c
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@ -0,0 +1,323 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* KUnit test for hw_breakpoint constraints accounting logic.
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*
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* Copyright (C) 2022, Google LLC.
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*/
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#include <kunit/test.h>
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#include <linux/cpumask.h>
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#include <linux/hw_breakpoint.h>
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#include <linux/kthread.h>
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#include <linux/perf_event.h>
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#include <asm/hw_breakpoint.h>
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#define TEST_REQUIRES_BP_SLOTS(test, slots) \
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do { \
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if ((slots) > get_test_bp_slots()) { \
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kunit_skip((test), "Requires breakpoint slots: %d > %d", slots, \
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get_test_bp_slots()); \
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} \
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} while (0)
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#define TEST_EXPECT_NOSPC(expr) KUNIT_EXPECT_EQ(test, -ENOSPC, PTR_ERR(expr))
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#define MAX_TEST_BREAKPOINTS 512
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static char break_vars[MAX_TEST_BREAKPOINTS];
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static struct perf_event *test_bps[MAX_TEST_BREAKPOINTS];
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static struct task_struct *__other_task;
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static struct perf_event *register_test_bp(int cpu, struct task_struct *tsk, int idx)
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{
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struct perf_event_attr attr = {};
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if (WARN_ON(idx < 0 || idx >= MAX_TEST_BREAKPOINTS))
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return NULL;
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hw_breakpoint_init(&attr);
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attr.bp_addr = (unsigned long)&break_vars[idx];
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attr.bp_len = HW_BREAKPOINT_LEN_1;
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attr.bp_type = HW_BREAKPOINT_RW;
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return perf_event_create_kernel_counter(&attr, cpu, tsk, NULL, NULL);
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}
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static void unregister_test_bp(struct perf_event **bp)
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{
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if (WARN_ON(IS_ERR(*bp)))
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return;
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if (WARN_ON(!*bp))
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return;
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unregister_hw_breakpoint(*bp);
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*bp = NULL;
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}
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static int get_test_bp_slots(void)
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{
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static int slots;
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if (!slots)
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slots = hw_breakpoint_slots(TYPE_DATA);
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return slots;
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}
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static void fill_one_bp_slot(struct kunit *test, int *id, int cpu, struct task_struct *tsk)
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{
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struct perf_event *bp = register_test_bp(cpu, tsk, *id);
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KUNIT_ASSERT_NOT_NULL(test, bp);
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KUNIT_ASSERT_FALSE(test, IS_ERR(bp));
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KUNIT_ASSERT_NULL(test, test_bps[*id]);
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test_bps[(*id)++] = bp;
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}
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/*
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* Fills up the given @cpu/@tsk with breakpoints, only leaving @skip slots free.
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*
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* Returns true if this can be called again, continuing at @id.
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*/
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static bool fill_bp_slots(struct kunit *test, int *id, int cpu, struct task_struct *tsk, int skip)
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{
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for (int i = 0; i < get_test_bp_slots() - skip; ++i)
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fill_one_bp_slot(test, id, cpu, tsk);
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return *id + get_test_bp_slots() <= MAX_TEST_BREAKPOINTS;
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}
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static int dummy_kthread(void *arg)
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{
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return 0;
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}
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static struct task_struct *get_other_task(struct kunit *test)
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{
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struct task_struct *tsk;
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if (__other_task)
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return __other_task;
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tsk = kthread_create(dummy_kthread, NULL, "hw_breakpoint_dummy_task");
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KUNIT_ASSERT_FALSE(test, IS_ERR(tsk));
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__other_task = tsk;
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return __other_task;
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}
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static int get_test_cpu(int num)
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{
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int cpu;
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WARN_ON(num < 0);
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for_each_online_cpu(cpu) {
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if (num-- <= 0)
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break;
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}
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return cpu;
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}
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/* ===== Test cases ===== */
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static void test_one_cpu(struct kunit *test)
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{
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int idx = 0;
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fill_bp_slots(test, &idx, get_test_cpu(0), NULL, 0);
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TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
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}
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static void test_many_cpus(struct kunit *test)
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{
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int idx = 0;
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int cpu;
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/* Test that CPUs are independent. */
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for_each_online_cpu(cpu) {
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bool do_continue = fill_bp_slots(test, &idx, cpu, NULL, 0);
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TEST_EXPECT_NOSPC(register_test_bp(cpu, NULL, idx));
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if (!do_continue)
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break;
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}
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}
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static void test_one_task_on_all_cpus(struct kunit *test)
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{
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int idx = 0;
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fill_bp_slots(test, &idx, -1, current, 0);
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TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
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/* Remove one and adding back CPU-target should work. */
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unregister_test_bp(&test_bps[0]);
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fill_one_bp_slot(test, &idx, get_test_cpu(0), NULL);
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}
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static void test_two_tasks_on_all_cpus(struct kunit *test)
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{
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int idx = 0;
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/* Test that tasks are independent. */
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fill_bp_slots(test, &idx, -1, current, 0);
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fill_bp_slots(test, &idx, -1, get_other_task(test), 0);
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TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(-1, get_other_task(test), idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), get_other_task(test), idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
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/* Remove one from first task and adding back CPU-target should not work. */
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unregister_test_bp(&test_bps[0]);
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
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}
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static void test_one_task_on_one_cpu(struct kunit *test)
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{
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int idx = 0;
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fill_bp_slots(test, &idx, get_test_cpu(0), current, 0);
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TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
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/*
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* Remove one and adding back CPU-target should work; this case is
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* special vs. above because the task's constraints are CPU-dependent.
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*/
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unregister_test_bp(&test_bps[0]);
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fill_one_bp_slot(test, &idx, get_test_cpu(0), NULL);
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}
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static void test_one_task_mixed(struct kunit *test)
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{
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int idx = 0;
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TEST_REQUIRES_BP_SLOTS(test, 3);
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fill_one_bp_slot(test, &idx, get_test_cpu(0), current);
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fill_bp_slots(test, &idx, -1, current, 1);
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TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
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/* Transition from CPU-dependent pinned count to CPU-independent. */
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unregister_test_bp(&test_bps[0]);
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unregister_test_bp(&test_bps[1]);
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fill_one_bp_slot(test, &idx, get_test_cpu(0), NULL);
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fill_one_bp_slot(test, &idx, get_test_cpu(0), NULL);
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
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}
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static void test_two_tasks_on_one_cpu(struct kunit *test)
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{
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int idx = 0;
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fill_bp_slots(test, &idx, get_test_cpu(0), current, 0);
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fill_bp_slots(test, &idx, get_test_cpu(0), get_other_task(test), 0);
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TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(-1, get_other_task(test), idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), get_other_task(test), idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
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/* Can still create breakpoints on some other CPU. */
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fill_bp_slots(test, &idx, get_test_cpu(1), NULL, 0);
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}
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static void test_two_tasks_on_one_all_cpus(struct kunit *test)
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{
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int idx = 0;
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fill_bp_slots(test, &idx, get_test_cpu(0), current, 0);
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fill_bp_slots(test, &idx, -1, get_other_task(test), 0);
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TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(-1, get_other_task(test), idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), get_other_task(test), idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
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/* Cannot create breakpoints on some other CPU either. */
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(1), NULL, idx));
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}
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static void test_task_on_all_and_one_cpu(struct kunit *test)
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{
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int tsk_on_cpu_idx, cpu_idx;
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int idx = 0;
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TEST_REQUIRES_BP_SLOTS(test, 3);
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fill_bp_slots(test, &idx, -1, current, 2);
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/* Transitioning from only all CPU breakpoints to mixed. */
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tsk_on_cpu_idx = idx;
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fill_one_bp_slot(test, &idx, get_test_cpu(0), current);
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fill_one_bp_slot(test, &idx, -1, current);
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TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
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/* We should still be able to use up another CPU's slots. */
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cpu_idx = idx;
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fill_one_bp_slot(test, &idx, get_test_cpu(1), NULL);
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(1), NULL, idx));
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/* Transitioning back to task target on all CPUs. */
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unregister_test_bp(&test_bps[tsk_on_cpu_idx]);
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/* Still have a CPU target breakpoint in get_test_cpu(1). */
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TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
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/* Remove it and try again. */
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unregister_test_bp(&test_bps[cpu_idx]);
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fill_one_bp_slot(test, &idx, -1, current);
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TEST_EXPECT_NOSPC(register_test_bp(-1, current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), current, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(0), NULL, idx));
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TEST_EXPECT_NOSPC(register_test_bp(get_test_cpu(1), NULL, idx));
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}
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static struct kunit_case hw_breakpoint_test_cases[] = {
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KUNIT_CASE(test_one_cpu),
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KUNIT_CASE(test_many_cpus),
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KUNIT_CASE(test_one_task_on_all_cpus),
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KUNIT_CASE(test_two_tasks_on_all_cpus),
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KUNIT_CASE(test_one_task_on_one_cpu),
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KUNIT_CASE(test_one_task_mixed),
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KUNIT_CASE(test_two_tasks_on_one_cpu),
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KUNIT_CASE(test_two_tasks_on_one_all_cpus),
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KUNIT_CASE(test_task_on_all_and_one_cpu),
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{},
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};
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static int test_init(struct kunit *test)
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{
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/* Most test cases want 2 distinct CPUs. */
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return num_online_cpus() < 2 ? -EINVAL : 0;
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}
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static void test_exit(struct kunit *test)
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{
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for (int i = 0; i < MAX_TEST_BREAKPOINTS; ++i) {
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if (test_bps[i])
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unregister_test_bp(&test_bps[i]);
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}
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if (__other_task) {
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kthread_stop(__other_task);
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__other_task = NULL;
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}
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}
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static struct kunit_suite hw_breakpoint_test_suite = {
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.name = "hw_breakpoint",
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.test_cases = hw_breakpoint_test_cases,
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.init = test_init,
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.exit = test_exit,
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};
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kunit_test_suites(&hw_breakpoint_test_suite);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Marco Elver <elver@google.com>");
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@ -2530,6 +2530,16 @@ config STACKINIT_KUNIT_TEST
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CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
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or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
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config HW_BREAKPOINT_KUNIT_TEST
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bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
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depends on HAVE_HW_BREAKPOINT
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depends on KUNIT=y
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default KUNIT_ALL_TESTS
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help
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Tests for hw_breakpoint constraints accounting.
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If unsure, say N.
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config TEST_UDELAY
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tristate "udelay test driver"
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help
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