random: access input_pool_data directly rather than through pointer

This gets rid of another abstraction we no longer need. It would be nice
if we could instead make pool an array rather than a pointer, but the
latent entropy plugin won't be able to do its magic in that case. So
instead we put all accesses to the input pool's actual data through the
input_pool_data array directly.

Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

diff --git a/drivers/char/random.c b/drivers/char/random.c
index ff672be..6e4218f 100644 (file)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -496,17 +496,12 @@ MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
 static u32 input_pool_data[POOL_WORDS] __latent_entropy;
 
 static struct {
-       /* read-only data: */
-       u32 *pool;
-
-       /* read-write data: */
        spinlock_t lock;
        u16 add_ptr;
        u16 input_rotate;
        int entropy_count;
 } input_pool = {
        .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
-       .pool = input_pool_data
 };
 
 static ssize_t extract_entropy(void *buf, size_t nbytes, int min);
@@ -544,15 +539,15 @@ static void _mix_pool_bytes(const void *in, int nbytes)
                i = (i - 1) & POOL_WORDMASK;
 
                /* XOR in the various taps */
-               w ^= input_pool.pool[i];
-               w ^= input_pool.pool[(i + POOL_TAP1) & POOL_WORDMASK];
-               w ^= input_pool.pool[(i + POOL_TAP2) & POOL_WORDMASK];
-               w ^= input_pool.pool[(i + POOL_TAP3) & POOL_WORDMASK];
-               w ^= input_pool.pool[(i + POOL_TAP4) & POOL_WORDMASK];
-               w ^= input_pool.pool[(i + POOL_TAP5) & POOL_WORDMASK];
+               w ^= input_pool_data[i];
+               w ^= input_pool_data[(i + POOL_TAP1) & POOL_WORDMASK];
+               w ^= input_pool_data[(i + POOL_TAP2) & POOL_WORDMASK];
+               w ^= input_pool_data[(i + POOL_TAP3) & POOL_WORDMASK];
+               w ^= input_pool_data[(i + POOL_TAP4) & POOL_WORDMASK];
+               w ^= input_pool_data[(i + POOL_TAP5) & POOL_WORDMASK];
 
                /* Mix the result back in with a twist */
-               input_pool.pool[i] = (w >> 3) ^ twist_table[w & 7];
+               input_pool_data[i] = (w >> 3) ^ twist_table[w & 7];
 
                /*
                 * Normally, we add 7 bits of rotation to the pool.
@@ -1369,7 +1364,7 @@ static void extract_buf(u8 *out)
 
        /* Generate a hash across the pool */
        spin_lock_irqsave(&input_pool.lock, flags);
-       blake2s_update(&state, (const u8 *)input_pool.pool, POOL_BYTES);
+       blake2s_update(&state, (const u8 *)input_pool_data, POOL_BYTES);
        blake2s_final(&state, hash); /* final zeros out state */
 
        /*