[lkml]   [2022]   [Apr]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH v6 11/17] openrisc: use fallback for random_get_entropy() instead of zero
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 random_get_entropy_fallback() would be
preferable, because that always needs to return _something_, even
falling back to jiffies eventually. It's not as though
random_get_entropy_fallback() 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: Thomas Gleixner <>
Cc: Arnd Bergmann <>
Cc: Jonas Bonn <>
Cc: Stefan Kristiansson <>
Cc: Stafford Horne <>
Signed-off-by: Jason A. Donenfeld <>
arch/openrisc/include/asm/timex.h | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/openrisc/include/asm/timex.h b/arch/openrisc/include/asm/timex.h
index d52b4e536e3f..115e89b336cd 100644
--- a/arch/openrisc/include/asm/timex.h
+++ b/arch/openrisc/include/asm/timex.h
@@ -23,6 +23,9 @@ static inline cycles_t get_cycles(void)
return mfspr(SPR_TTCR);
+#define get_cycles get_cycles
+#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback())

/* This isn't really used any more */
#define CLOCK_TICK_RATE 1000
 \ /
  Last update: 2022-04-23 23:29    [W:0.304 / U:0.396 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site