Commit 590b00e9 authored Apr 08, 2022 by Jason A. Donenfeld Committed by Greg Kroah-Hartman Jun 25, 2022

nios2: use fallback for random_get_entropy() instead of zero



commit c04e72700f2293013dab40208e809369378f224c upstream.

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>
Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent c05a35cd

arch/nios2/include/asm/timex.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -20,5 +20,8 @@
		typedef unsigned long cycles_t;

		extern cycles_t get_cycles(void);
		#define get_cycles get_cycles

		#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback())

		#endif