diff mbox series

[RFC,v1,02/10] m68k: use sched_clock() for random_get_entropy() instead of zero

Message ID 20220408182145.142506-3-Jason@zx2c4.com (mailing list archive)
State New, archived
Headers show
Series archs/random: fallback to using sched_clock() if no cycle counter | expand

Commit Message

Jason A. Donenfeld April 8, 2022, 6:21 p.m. UTC 
In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is really not the best we can do.
Instead, at least calling sched_clock() would be preferable, because
that always needs to return _something_, even falling back to jiffies
eventually. It's not as though sched_clock() is super high precision or
guaranteed to be entropic, but basically anything that's not zero all
the time is better than returning zero all the time.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/m68k/include/asm/timex.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/arch/m68k/include/asm/timex.h b/arch/m68k/include/asm/timex.h
index 6a21d9358280..2cd0942097f8 100644
--- a/arch/m68k/include/asm/timex.h
+++ b/arch/m68k/include/asm/timex.h
@@ -7,6 +7,8 @@ 
 #ifndef _ASMm68K_TIMEX_H
 #define _ASMm68K_TIMEX_H
 
+#include <linux/sched/clock.h>
+
 #ifdef CONFIG_COLDFIRE
 /*
  * CLOCK_TICK_RATE should give the underlying frequency of the tick timer
@@ -35,7 +37,7 @@  static inline unsigned long random_get_entropy(void)
 {
 	if (mach_random_get_entropy)
 		return mach_random_get_entropy();
-	return 0;
+	return sched_clock();
 }
 #define random_get_entropy	random_get_entropy