[PATCH v4 06/11] nios2: use fallback for random_get_entropy() instead of zero

Jason A. Donenfeld
2022-04-13T11:55:55Z

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 <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
arch/nios2/include/asm/timex.h | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/nios2/include/asm/timex.h b/arch/nios2/include/asm/timex.h
index a769f871b28d..d9a3f426cdda 100644
--- a/arch/nios2/include/asm/timex.h
+++ b/arch/nios2/include/asm/timex.h
@@ -9,4 +9,6 @@ typedef unsigned long cycles_t;

extern cycles_t get_cycles(void);

+#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback())
+
#endif
--
2.35.1