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powerpc/kcsan: Exclude udelay to prevent recursive instrumentation

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[ 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>
This commit is contained in:
Rohan McLure
2023-02-06 13:17:58 +11:00
committed by Greg Kroah-Hartman
parent 5ddcb0a348
commit 9a61a3a6ec
1 changed files with 2 additions and 2 deletions
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4
arch/powerpc/kernel/time.c
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@@ -436,7 +436,7 @@ void vtime_flush(struct task_struct *tsk)
#define calc_cputime_factors() #define calc_cputime_factors()
#endif #endif
void __delay(unsigned long loops) void __no_kcsan __delay(unsigned long loops)
{ {
unsigned long start; unsigned long start;
@@ -457,7 +457,7 @@ void __delay(unsigned long loops)
} }
EXPORT_SYMBOL(__delay); EXPORT_SYMBOL(__delay);
void udelay(unsigned long usecs) void __no_kcsan udelay(unsigned long usecs)
{ {
__delay(tb_ticks_per_usec * usecs); __delay(tb_ticks_per_usec * usecs);
} }