Commit 2a7ce82d authored by Rohan McLure's avatar Rohan McLure Committed by Michael Ellerman
Browse files

powerpc/kcsan: Exclude udelay to prevent recursive instrumentation 



In order for KCSAN to increase its likelihood of observing a data race,
it sets a watchpoint on memory accesses and stalls, allowing for
detection of conflicting accesses by other kernel threads or interrupts.

Stalls are implemented by injecting a call to udelay in instrumented code.
To prevent recursive instrumentation, exclude udelay from being instrumented.

Signed-off-by: default avatarRohan McLure <rmclure@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230206021801.105268-3-rmclure@linux.ibm.com
parent 2fb857bc

arch/powerpc/kernel/time.c

+2 −2
Original line number Diff line number Diff line
@@ -356,7 +356,7 @@ void vtime_flush(struct task_struct *tsk) 
}

#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */



void __delay(unsigned long loops)

void __no_kcsan __delay(unsigned long loops)

{

	unsigned long start;
@@ -377,7 +377,7 @@ void __delay(unsigned long loops) 
}

EXPORT_SYMBOL(__delay);



void udelay(unsigned long usecs)

void __no_kcsan udelay(unsigned long usecs)

{

	__delay(tb_ticks_per_usec * usecs);

}