From: Rohan McLure <rmclure@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Rohan McLure <rmclure@linux.ibm.com>, npiggin@gmail.com
Subject: [PATCH v2 2/5] powerpc: kcsan: Exclude udelay to prevent recursive instrumentation
Date: Wed, 1 Feb 2023 15:34:35 +1100 [thread overview]
Message-ID: <20230201043438.1301212-3-rmclure@linux.ibm.com> (raw)
In-Reply-To: <20230201043438.1301212-1-rmclure@linux.ibm.com>
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>
---
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 d68de3618741..b894029f53db 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);
}
--
2.37.2
next prev parent reply other threads:[~2023-02-01 4:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-01 4:34 [PATCH v2 0/5] powerpc: Add KCSAN support Rohan McLure
2023-02-01 4:34 ` [PATCH v2 1/5] powerpc: kcsan: Add exclusions from instrumentation Rohan McLure
2023-02-01 4:34 ` Rohan McLure [this message]
2023-02-01 4:34 ` [PATCH v2 3/5] powerpc: kcsan: Memory barriers semantics Rohan McLure
2023-02-01 4:34 ` [PATCH v2 4/5] powerpc: kcsan: Prevent recursive instrumentation with IRQ save/restores Rohan McLure
2023-02-01 4:34 ` [PATCH v2 5/5] powerpc: kcsan: Add KCSAN Support Rohan McLure
2023-02-04 12:10 ` kernel test robot
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