target-arm: Correct sense of the DCZID DZP bit

The DZP bit in the DCZID system register should be set if
the control bits which prohibit use of the DC ZVA instruction
have been set (it stands for Data Zero Prohibited). However
we had the sense of the test inverted; fix this so that the
bit reads correctly.

To avoid this regressing the behaviour of the user-mode
emulator, we must set the DZE bit in the SCTLR for that
config so that userspace continues to see DZP as zero (it
was getting the correct result by accident previously).

Reported-by: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Christopher Covington <cov@codeaurora.org>
Message-id: 1412959792-20708-1-git-send-email-peter.maydell@linaro.org

diff --git a/target-arm/cpu.c b/target-arm/cpu.c
index e837f6453868808ed1ba0b1dabc45f09ee5d8448..e0b82a6704f03b8a04415866dba52908bfbcac67 100644 (file)
--- a/target-arm/cpu.c
+++ b/target-arm/cpu.c
@@ -108,8 +108,8 @@ static void arm_cpu_reset(CPUState *s)
         env->aarch64 = 1;
 #if defined(CONFIG_USER_ONLY)
         env->pstate = PSTATE_MODE_EL0t;
-        /* Userspace expects access to CTL_EL0 and the cache ops */
-        env->cp15.c1_sys |= SCTLR_UCT | SCTLR_UCI;
+        /* Userspace expects access to DC ZVA, CTL_EL0 and the cache ops */
+        env->cp15.c1_sys |= SCTLR_UCT | SCTLR_UCI | SCTLR_DZE;
         /* and to the FP/Neon instructions */
         env->cp15.c1_coproc = deposit64(env->cp15.c1_coproc, 20, 2, 3);
 #else

diff --git a/target-arm/helper.c b/target-arm/helper.c
index d837820f274070d1ac54593bf1c0117957f1692e..53527c2003405af575c878d8cbd7d67d7db3f801 100644 (file)
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -2018,7 +2018,7 @@ static uint64_t aa64_dczid_read(CPUARMState *env, const ARMCPRegInfo *ri)
     int dzp_bit = 1 << 4;
 
     /* DZP indicates whether DC ZVA access is allowed */
-    if (aa64_zva_access(env, NULL) != CP_ACCESS_OK) {
+    if (aa64_zva_access(env, NULL) == CP_ACCESS_OK) {
         dzp_bit = 0;
     }
     return cpu->dcz_blocksize | dzp_bit;