target-arm: Add user-mode transaction attribute

Add a transaction attribute indicating that a memory access is being
done from user-mode (unprivileged). This corresponds to an equivalent
signal in ARM AMBA buses.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>

include/exec/memattrs.h

@@ -31,6 +31,8 @@ typedef struct MemTxAttrs {
     unsigned int unspecified:1;
     /* ARM/AMBA TrustZone Secure access */
     unsigned int secure:1;
+    /* Memory access is usermode (unprivileged) */
+    unsigned int user:1;
 } MemTxAttrs;
 
 /* Bus masters which don't specify any attributes will get this,

target-arm/helper.c

@@ -5749,6 +5749,7 @@ static inline int get_phys_addr(CPUARMState *env, target_ulong address,
      * to secure.
      */
     attrs->secure = regime_is_secure(env, mmu_idx);
+    attrs->user = regime_is_user(env, mmu_idx);
 
     /* Fast Context Switch Extension. This doesn't exist at all in v8.
      * In v7 and earlier it affects all stage 1 translations.