Commit 609f8097 authored by Mark Rutland's avatar Mark Rutland Committed by Paul E. McKenney
Browse files

kcsan: Remove kcsan_report_type 



Now that the reporting code has been refactored, it's clear by
construction that print_report() can only be passed
KCSAN_REPORT_RACE_SIGNAL or KCSAN_REPORT_RACE_UNKNOWN_ORIGIN, and these
can also be distinguished by the presence of `other_info`.

Let's simplify things and remove the report type enum, and instead let's
check `other_info` to distinguish these cases. This allows us to remove
code for cases which are impossible and generally makes the code simpler.

There should be no functional change as a result of this patch.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
[ elver@google.com: add updated comments to kcsan_report_*() functions ]
Signed-off-by: default avatarMarco Elver <elver@google.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 19dfdc05

kernel/kcsan/kcsan.h

+13 −20
Original line number Diff line number Diff line
@@ -116,32 +116,25 @@ enum kcsan_value_change { 
	KCSAN_VALUE_CHANGE_TRUE,

};



enum kcsan_report_type {

/*

	 * The thread that set up the watchpoint and briefly stalled was

	 * signalled that another thread triggered the watchpoint.

 * The calling thread hit and consumed a watchpoint: set the access information

 * to be consumed by the reporting thread. No report is printed yet.

 */

	KCSAN_REPORT_RACE_SIGNAL,



	/*

	 * A thread found and consumed a matching watchpoint.

	 */

	KCSAN_REPORT_CONSUMED_WATCHPOINT,

void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_type,

			   int watchpoint_idx);



/*

	 * No other thread was observed to race with the access, but the data

	 * value before and after the stall differs.

 * The calling thread observed that the watchpoint it set up was hit and

 * consumed: print the full report based on information set by the racing

 * thread.

 */

	KCSAN_REPORT_RACE_UNKNOWN_ORIGIN,

};

void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access_type,

			       enum kcsan_value_change value_change, int watchpoint_idx);



/*

 * Notify the report code that a race occurred.

 * No other thread was observed to race with the access, but the data value

 * before and after the stall differs. Reports a race of "unknown origin".

 */

void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_type,

			   int watchpoint_idx);

void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access_type,

			       enum kcsan_value_change value_change, int watchpoint_idx);

void kcsan_report_unknown_origin(const volatile void *ptr, size_t size, int access_type);



#endif /* _KERNEL_KCSAN_KCSAN_H */

kernel/kcsan/report.c

+7 −22
Original line number Diff line number Diff line
@@ -326,7 +326,6 @@ static void print_verbose_info(struct task_struct *task) 
}



static void print_report(enum kcsan_value_change value_change,

			 enum kcsan_report_type type,

			 const struct access_info *ai,

			 const struct other_info *other_info)

{
@@ -343,7 +342,7 @@ static void print_report(enum kcsan_value_change value_change, 
	if (skip_report(KCSAN_VALUE_CHANGE_TRUE, stack_entries[skipnr]))

		return;



	if (type == KCSAN_REPORT_RACE_SIGNAL) {

	if (other_info) {

		other_skipnr = get_stack_skipnr(other_info->stack_entries,

						other_info->num_stack_entries);

		other_frame = other_info->stack_entries[other_skipnr];
@@ -358,8 +357,7 @@ static void print_report(enum kcsan_value_change value_change, 


	/* Print report header. */

	pr_err("==================================================================\n");

	switch (type) {

	case KCSAN_REPORT_RACE_SIGNAL: {

	if (other_info) {

		int cmp;



		/*
@@ -371,22 +369,15 @@ static void print_report(enum kcsan_value_change value_change, 
		       get_bug_type(ai->access_type | other_info->ai.access_type),

		       (void *)(cmp < 0 ? other_frame : this_frame),

		       (void *)(cmp < 0 ? this_frame : other_frame));

	} break;



	case KCSAN_REPORT_RACE_UNKNOWN_ORIGIN:

	} else {

		pr_err("BUG: KCSAN: %s in %pS\n", get_bug_type(ai->access_type),

		       (void *)this_frame);

		break;



	default:

		BUG();

	}



	pr_err("\n");



	/* Print information about the racing accesses. */

	switch (type) {

	case KCSAN_REPORT_RACE_SIGNAL:

	if (other_info) {

		pr_err("%s to 0x%px of %zu bytes by %s on cpu %i:\n",

		       get_access_type(other_info->ai.access_type), other_info->ai.ptr,

		       other_info->ai.size, get_thread_desc(other_info->ai.task_pid),
@@ -404,16 +395,10 @@ static void print_report(enum kcsan_value_change value_change, 
		pr_err("%s to 0x%px of %zu bytes by %s on cpu %i:\n",

		       get_access_type(ai->access_type), ai->ptr, ai->size,

		       get_thread_desc(ai->task_pid), ai->cpu_id);

		break;



	case KCSAN_REPORT_RACE_UNKNOWN_ORIGIN:

	} else {

		pr_err("race at unknown origin, with %s to 0x%px of %zu bytes by %s on cpu %i:\n",

		       get_access_type(ai->access_type), ai->ptr, ai->size,

		       get_thread_desc(ai->task_pid), ai->cpu_id);

		break;



	default:

		BUG();

	}

	/* Print stack trace of this thread. */

	stack_trace_print(stack_entries + skipnr, num_stack_entries - skipnr,
@@ -623,7 +608,7 @@ void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access 
	 * be done once we know the full stack trace in print_report().

	 */

	if (value_change != KCSAN_VALUE_CHANGE_FALSE)

		print_report(value_change, KCSAN_REPORT_RACE_SIGNAL, &ai, other_info);

		print_report(value_change, &ai, other_info);



	release_report(&flags, other_info);

out:
@@ -640,7 +625,7 @@ void kcsan_report_unknown_origin(const volatile void *ptr, size_t size, int acce 
	lockdep_off(); /* See kcsan_report_known_origin(). */



	raw_spin_lock_irqsave(&report_lock, flags);

	print_report(KCSAN_VALUE_CHANGE_TRUE, KCSAN_REPORT_RACE_UNKNOWN_ORIGIN, &ai, NULL);

	print_report(KCSAN_VALUE_CHANGE_TRUE, &ai, NULL);

	raw_spin_unlock_irqrestore(&report_lock, flags);



	lockdep_on();