Messages in this thread | | | From | Ian Rogers <> | Date | Wed, 20 Jul 2022 08:22:56 -0700 | Subject | Re: [PATCH v3 02/14] perf/hw_breakpoint: Provide hw_breakpoint_is_used() and use in test |
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On Mon, Jul 4, 2022 at 8:10 AM Dmitry Vyukov <dvyukov@google.com> wrote: > > On Mon, 4 Jul 2022 at 17:06, Marco Elver <elver@google.com> wrote: > > > > Provide hw_breakpoint_is_used() to check if breakpoints are in use on > > the system. > > > > Use it in the KUnit test to verify the global state before and after a > > test case. > > > > Signed-off-by: Marco Elver <elver@google.com> > > Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Ian Rogers <irogers@google.com>
Thanks, Ian
> > --- > > v3: > > * New patch. > > --- > > include/linux/hw_breakpoint.h | 3 +++ > > kernel/events/hw_breakpoint.c | 29 +++++++++++++++++++++++++++++ > > kernel/events/hw_breakpoint_test.c | 12 +++++++++++- > > 3 files changed, 43 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h > > index 78dd7035d1e5..a3fb846705eb 100644 > > --- a/include/linux/hw_breakpoint.h > > +++ b/include/linux/hw_breakpoint.h > > @@ -74,6 +74,7 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, > > extern int register_perf_hw_breakpoint(struct perf_event *bp); > > extern void unregister_hw_breakpoint(struct perf_event *bp); > > extern void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events); > > +extern bool hw_breakpoint_is_used(void); > > > > extern int dbg_reserve_bp_slot(struct perf_event *bp); > > extern int dbg_release_bp_slot(struct perf_event *bp); > > @@ -121,6 +122,8 @@ register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; } > > static inline void unregister_hw_breakpoint(struct perf_event *bp) { } > > static inline void > > unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events) { } > > +static inline bool hw_breakpoint_is_used(void) { return false; } > > + > > static inline int > > reserve_bp_slot(struct perf_event *bp) {return -ENOSYS; } > > static inline void release_bp_slot(struct perf_event *bp) { } > > diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c > > index f32320ac02fd..fd5cd1f9e7fc 100644 > > --- a/kernel/events/hw_breakpoint.c > > +++ b/kernel/events/hw_breakpoint.c > > @@ -604,6 +604,35 @@ void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events) > > } > > EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint); > > > > +/** > > + * hw_breakpoint_is_used - check if breakpoints are currently used > > + * > > + * Returns: true if breakpoints are used, false otherwise. > > + */ > > +bool hw_breakpoint_is_used(void) > > +{ > > + int cpu; > > + > > + if (!constraints_initialized) > > + return false; > > + > > + for_each_possible_cpu(cpu) { > > + for (int type = 0; type < TYPE_MAX; ++type) { > > + struct bp_cpuinfo *info = get_bp_info(cpu, type); > > + > > + if (info->cpu_pinned) > > + return true; > > + > > + for (int slot = 0; slot < nr_slots[type]; ++slot) { > > + if (info->tsk_pinned[slot]) > > + return true; > > + } > > + } > > + } > > + > > + return false; > > +} > > + > > static struct notifier_block hw_breakpoint_exceptions_nb = { > > .notifier_call = hw_breakpoint_exceptions_notify, > > /* we need to be notified first */ > > diff --git a/kernel/events/hw_breakpoint_test.c b/kernel/events/hw_breakpoint_test.c > > index 433c5c45e2a5..5ced822df788 100644 > > --- a/kernel/events/hw_breakpoint_test.c > > +++ b/kernel/events/hw_breakpoint_test.c > > @@ -294,7 +294,14 @@ static struct kunit_case hw_breakpoint_test_cases[] = { > > static int test_init(struct kunit *test) > > { > > /* Most test cases want 2 distinct CPUs. */ > > - return num_online_cpus() < 2 ? -EINVAL : 0; > > + if (num_online_cpus() < 2) > > + return -EINVAL; > > + > > + /* Want the system to not use breakpoints elsewhere. */ > > + if (hw_breakpoint_is_used()) > > + return -EBUSY; > > + > > + return 0; > > } > > > > static void test_exit(struct kunit *test) > > @@ -308,6 +315,9 @@ static void test_exit(struct kunit *test) > > 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 = { > > -- > > 2.37.0.rc0.161.g10f37bed90-goog > >
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