target/arm: Remove CP_ACCESS_TRAP_UNCATEGORIZED_{EL2, EL3}

We added the CPAccessResult values CP_ACCESS_TRAP_UNCATEGORIZED_EL2
and CP_ACCESS_TRAP_UNCATEGORIZED_EL3 purely in order to use them in
the ats_access() function, but doing so was incorrect (a bug fixed in
a previous commit).  There aren't any cases where we want an access
function to be able to request a trap to EL2 or EL3 with a zero
syndrome value, so remove these enum values.

As well as cleaning up dead code, the motivation here is that
we'd like to implement fine-grained-trap handling in
helper_access_check_cp_reg(). Although the fine-grained traps
to EL2 are always lower priority than trap-to-same-EL and
higher priority than trap-to-EL3, they are in the middle of
various other kinds of trap-to-EL2. Knowing that a trap-to-EL2
must always for us have the same syndrome (ie that an access
function will return CP_ACCESS_TRAP_EL2 and there is no other
kind of trap-to-EL2 enum value) means we don't have to try
to choose which of the two syndrome values to report if the
access would trap to EL2 both for the fine-grained-trap and
because the access function requires it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Fuad Tabba <tabba@google.com>
Message-id: 20230130182459.3309057-4-peter.maydell@linaro.org
Message-id: 20230127175507.2895013-4-peter.maydell@linaro.org

target/arm/cpregs.h

@@ -224,10 +224,10 @@ typedef enum CPAccessResult {
      * Access fails and results in an exception syndrome 0x0 ("uncategorized").
      * Note that this is not a catch-all case -- the set of cases which may
      * result in this failure is specifically defined by the architecture.
+     * This trap is always to the usual target EL, never directly to a
+     * specified target EL.
      */
     CP_ACCESS_TRAP_UNCATEGORIZED = (2 << 2),
-    CP_ACCESS_TRAP_UNCATEGORIZED_EL2 = CP_ACCESS_TRAP_UNCATEGORIZED | 2,
-    CP_ACCESS_TRAP_UNCATEGORIZED_EL3 = CP_ACCESS_TRAP_UNCATEGORIZED | 3,
 } CPAccessResult;
 
 typedef struct ARMCPRegInfo ARMCPRegInfo;

target/arm/op_helper.c

@@ -673,6 +673,8 @@ const void *HELPER(access_check_cp_reg)(CPUARMState *env, uint32_t key,
     case CP_ACCESS_TRAP:
         break;
     case CP_ACCESS_TRAP_UNCATEGORIZED:
+        /* Only CP_ACCESS_TRAP traps are direct to a specified EL */
+        assert((res & CP_ACCESS_EL_MASK) == 0);
         if (cpu_isar_feature(aa64_ids, cpu) && isread &&
             arm_cpreg_in_idspace(ri)) {
             /*