BUG/MEDIUM: random: align the state on 2*64 bits for ARM64

x86_64 and ARM64 do support the double-word atomic CAS. However on
ARM it must be done only on aligned data. The random generator makes
use of such double-word atomic CAS when available but didn't enforce
alignment, which causes ARM64 to crash early in the startup since
commit 52bf839 ("BUG/MEDIUM: random: implement a thread-safe and
process-safe PRNG").

This commit just unconditionally aligns the arrays. It must be
backported to all branches where the commit above is backported
(likely till 2.0).

diff --git a/src/standard.c b/src/standard.c
index d16eebfea83248dbc8478d5de2d6f7611f161c69..3afaf5a9947f20ed30400bfe7906daa401e9ac34 100644 (file)
--- a/src/standard.c
+++ b/src/standard.c
@@ -4530,7 +4530,7 @@ int varint_bytes(uint64_t v)
 
 
 /* Random number generator state, see below */
-static uint64_t ha_random_state[2];
+static uint64_t ha_random_state[2] ALIGNED(2*sizeof(uint64_t));
 
 /* This is a thread-safe implementation of xoroshiro128** described below:
  *     http://prng.di.unimi.it/
@@ -4542,8 +4542,8 @@ static uint64_t ha_random_state[2];
 uint64_t ha_random64()
 {
        uint64_t result;
-       uint64_t old[2];
-       uint64_t new[2];
+       uint64_t old[2] ALIGNED(2*sizeof(uint64_t));
+       uint64_t new[2] ALIGNED(2*sizeof(uint64_t));
 
 #if defined(USE_THREAD) && (!defined(HA_CAS_IS_8B) || !defined(HA_HAVE_CAS_DW))
        static HA_SPINLOCK_T rand_lock;