From: Rohan McLure <rmclure@linux.ibm.com>
Date: Mon, 6 Feb 2023 13:17:58 +1100
Subject: [PATCH] powerpc/kcsan: Exclude udelay to prevent recursive
instrumentation
References: bsc#1012628
Patch-mainline: 6.2.7
Git-commit: 2a7ce82dc46c591c9244057d89a6591c9639b9b9
[ Upstream commit 2a7ce82dc46c591c9244057d89a6591c9639b9b9 ]
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: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230206021801.105268-3-rmclure@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
arch/powerpc/kernel/time.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index e26eb661..9d866591 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -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);
}
--
2.35.3