random: account for arch randomness in bits

commit 77fc95f8c0dc9e1f8e620ec14d2fb65028fb7adc upstream.

Rather than accounting in bytes and multiplying (shifting), we can just
account in bits and avoid the shift. The main motivation for this is
there are other patches in flux that expand this code a bit, and
avoiding the duplication of "* 8" everywhere makes things a bit clearer.

Cc: stable@vger.kernel.org
Fixes: 12e45a2a6308 ("random: credit architectural init the exact amount")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/random.c b/drivers/char/random.c
index c9b7e0c..7f6585c 100644 (file)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -813,7 +813,7 @@ early_param("random.trust_bootloader", parse_trust_bootloader);
 int __init random_init(const char *command_line)
 {
        ktime_t now = ktime_get_real();
-       unsigned int i, arch_bytes;
+       unsigned int i, arch_bits;
        unsigned long entropy;
 
 #if defined(LATENT_ENTROPY_PLUGIN)
@@ -821,12 +821,12 @@ int __init random_init(const char *command_line)
        _mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed));
 #endif
 
-       for (i = 0, arch_bytes = BLAKE2S_BLOCK_SIZE;
+       for (i = 0, arch_bits = BLAKE2S_BLOCK_SIZE * 8;
             i < BLAKE2S_BLOCK_SIZE; i += sizeof(entropy)) {
                if (!arch_get_random_seed_long_early(&entropy) &&
                    !arch_get_random_long_early(&entropy)) {
                        entropy = random_get_entropy();
-                       arch_bytes -= sizeof(entropy);
+                       arch_bits -= sizeof(entropy) * 8;
                }
                _mix_pool_bytes(&entropy, sizeof(entropy));
        }
@@ -838,7 +838,7 @@ int __init random_init(const char *command_line)
        if (crng_ready())
                crng_reseed();
        else if (trust_cpu)
-               _credit_init_bits(arch_bytes * 8);
+               _credit_init_bits(arch_bits);
 
        return 0;
 }