@@ -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)
Factor out the switch statement reading instrumented memory into a helper read_instrumented_memory(). No functional change. Signed-off-by: Marco Elver <elver@google.com> --- kernel/kcsan/core.c | 51 +++++++++++++++------------------------------ 1 file changed, 17 insertions(+), 34 deletions(-)