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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: Marco Elver <elver@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Marco Elver 2021-11-30 12:44:09 +01:00 committed by Paul E. McKenney
parent fa55b7dcdc
commit 12305abe98
1 changed files with 17 additions and 34 deletions
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51
kernel/kcsan/core.c
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@ -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)