Messages in this thread Patch in this message |  | | From | "Jason A. Donenfeld" <> | Subject | [PATCH v2 06/11] arm: use ktime_read_raw_clock() for random_get_entropy() instead of zero | Date | Sun, 10 Apr 2022 23:49:46 +0200 |
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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 ktime_read_raw_clock() would be preferable, because that always needs to return _something_, even falling back to jiffies eventually. It's not as though ktime_read_raw_clock() 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: Russell King <linux@armlinux.org.uk> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> --- arch/arm/include/asm/timex.h | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/arm/include/asm/timex.h b/arch/arm/include/asm/timex.h index 7c3b3671d6c2..d0b32ce87254 100644 --- a/arch/arm/include/asm/timex.h +++ b/arch/arm/include/asm/timex.h @@ -11,5 +11,6 @@ typedef unsigned long cycles_t; #define get_cycles() ({ cycles_t c; read_current_timer(&c) ? 0 : c; }) +#define random_get_entropy() ((unsigned long)(get_cycles() ?: ktime_read_raw_clock())) #endif -- 2.35.1
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