Am Freitag, 24. M?rz 2017, 19:26:04 CET schrieb Krzysztof Kozlowski:

Hi Krzysztof,

+static unsigned int exynos_rng_copy_random(struct exynos_rng_dev *rng,
+					   u8 *dst, unsigned int dlen)
+{
+	unsigned int cnt = 0;
+	int i, j;
+	u32 val;
+
+	for (j = 0; j < EXYNOS_RNG_SEED_REGS; j++) {
+		val = exynos_rng_readl(rng, EXYNOS_RNG_OUT(j));
+
+		for (i = 0; i < 4; i++) {
+			dst[cnt] = val & 0xff;
+			val >>= 8;
+			if (++cnt >= dlen)
+				return cnt;
+		}
+		rng->seed_save[j] = val;

Just to clarify: is this call right? Shouldn't that be removed? Any RNG that 
is given to a caller is tainted and should not serve as seed.

+	}
+
+	/*
+	 * Engine filled all output registers, so read the remaining registers
+	 * for storing data as future seed.
+	 */
+	for (; j < EXYNOS_RNG_SEED_REGS; j++)
+		rng->seed_save[j] = exynos_rng_readl(rng, EXYNOS_RNG_OUT(j));

With this call, I guess the questioned line above could go away, right?


Ciao
Stephan