Commit 12305abe authored by Marco Elver's avatar Marco Elver Committed by Paul E. McKenney
Browse files

kcsan: Refactor reading of instrumented memory 



Factor out the switch statement reading instrumented memory into a
helper read_instrumented_memory().

No functional change.

Signed-off-by: default avatarMarco Elver <elver@google.com>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent fa55b7dc

kernel/kcsan/core.c

+17 −34
Original line number Diff line number Diff line
@@ -325,6 +325,21 @@ static void delay_access(int type) 
	udelay(delay);

}



/*

 * Reads the instrumented memory for value change detection; value change

 * detection is currently done for accesses up to a size of 8 bytes.

 */

static __always_inline u64 read_instrumented_memory(const volatile void *ptr, size_t size)

{

	switch (size) {

	case 1:  return READ_ONCE(*(const u8 *)ptr);

	case 2:  return READ_ONCE(*(const u16 *)ptr);

	case 4:  return READ_ONCE(*(const u32 *)ptr);

	case 8:  return READ_ONCE(*(const u64 *)ptr);

	default: return 0; /* Ignore; we do not diff the values. */

	}

}



void kcsan_save_irqtrace(struct task_struct *task)

{

#ifdef CONFIG_TRACE_IRQFLAGS
@@ -482,23 +497,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned 
	 * Read the current value, to later check and infer a race if the data

	 * was modified via a non-instrumented access, e.g. from a device.

	 */

	old = 0;

	switch (size) {

	case 1:

		old = READ_ONCE(*(const u8 *)ptr);

		break;

	case 2:

		old = READ_ONCE(*(const u16 *)ptr);

		break;

	case 4:

		old = READ_ONCE(*(const u32 *)ptr);

		break;

	case 8:

		old = READ_ONCE(*(const u64 *)ptr);

		break;

	default:

		break; /* ignore; we do not diff the values */

	}

	old = read_instrumented_memory(ptr, size);



	/*

	 * Delay this thread, to increase probability of observing a racy
@@ -511,23 +510,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned 
	 * racy access.

	 */

	access_mask = ctx->access_mask;

	new = 0;

	switch (size) {

	case 1:

		new = READ_ONCE(*(const u8 *)ptr);

		break;

	case 2:

		new = READ_ONCE(*(const u16 *)ptr);

		break;

	case 4:

		new = READ_ONCE(*(const u32 *)ptr);

		break;

	case 8:

		new = READ_ONCE(*(const u64 *)ptr);

		break;

	default:

		break; /* ignore; we do not diff the values */

	}

	new = read_instrumented_memory(ptr, size);



	diff = old ^ new;

	if (access_mask)