From: Jason A. Donenfeld Date: Fri, 8 Apr 2022 16:03:13 +0000 (+0200) Subject: riscv: use fallback for random_get_entropy() instead of zero X-Git-Tag: v5.15.73~4010 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=2ab416043a94087a8bc28ce748db0d7bce850b43;p=platform%2Fkernel%2Flinux-rpi.git riscv: use fallback for random_get_entropy() instead of zero commit 6d01238623faa9425f820353d2066baf6c9dc872 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 Cc: Arnd Bergmann Cc: Paul Walmsley Acked-by: Palmer Dabbelt Reviewed-by: Palmer Dabbelt Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/riscv/include/asm/timex.h b/arch/riscv/include/asm/timex.h index 507cae2..d6a7428 100644 --- a/arch/riscv/include/asm/timex.h +++ b/arch/riscv/include/asm/timex.h @@ -41,7 +41,7 @@ static inline u32 get_cycles_hi(void) static inline unsigned long random_get_entropy(void) { if (unlikely(clint_time_val == NULL)) - return 0; + return random_get_entropy_fallback(); return get_cycles(); } #define random_get_entropy() random_get_entropy()