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nios2: use fallback for random_get_entropy() instead of zero

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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>
This commit is contained in:
Jason A. Donenfeld 2022-04-08 18:03:13 +02:00 committed by Greg Kroah-Hartman
parent fdca775081
commit 0b93f40cbe
1 changed files with 3 additions and 0 deletions
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3
arch/nios2/include/asm/timex.h
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@ -8,5 +8,8 @@
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