[Qemu-devel] [PATCH 08/14] target-arm: Allow cp access functions to indicate traps to EL2 or EL3

[Peter Maydell <peter.maydell@linaro.org>]

Some coprocessor access functions will need to indicate that the
instruction should trap to EL2 or EL3 rather than the default
target exception level; add corresponding CPAccessResult enum
entries and handling code.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target-arm/cpu.h       |  6 +++++-
 target-arm/op_helper.c | 14 +++++++++++++-
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 9119a94..e431372 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -1252,7 +1252,8 @@ typedef enum CPAccessResult {
     /* Access fails due to a configurable trap or enable which would
      * result in a categorized exception syndrome giving information about
      * the failing instruction (ie syndrome category 0x3, 0x4, 0x5, 0x6,
-     * 0xc or 0x18).
+     * 0xc or 0x18). The exception is taken to the usual target EL (EL1 or
+     * PL1 if in EL0, otherwise to the current EL).
      */
     CP_ACCESS_TRAP = 1,
     /* Access fails and results in an exception syndrome 0x0 ("uncategorized").
@@ -1260,6 +1261,9 @@ typedef enum CPAccessResult {
      * result in this failure is specifically defined by the architecture.
      */
     CP_ACCESS_TRAP_UNCATEGORIZED = 2,
+    /* As CP_ACCESS_TRAP, but for traps directly to EL2 or EL3 */
+    CP_ACCESS_TRAP_EL2 = 3,
+    CP_ACCESS_TRAP_EL3 = 4,
 } CPAccessResult;
 
 /* Access functions for coprocessor registers. These cannot fail and
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index d693b01..5963f3b 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -335,6 +335,7 @@ void HELPER(set_user_reg)(CPUARMState *env, uint32_t regno, uint32_t val)
 void HELPER(access_check_cp_reg)(CPUARMState *env, void *rip, uint32_t syndrome)
 {
     const ARMCPRegInfo *ri = rip;
+    int target_el;
 
     if (arm_feature(env, ARM_FEATURE_XSCALE) && ri->cp < 14
         && extract32(env->cp15.c15_cpar, ri->cp, 1) == 0) {
@@ -349,6 +350,17 @@ void HELPER(access_check_cp_reg)(CPUARMState *env, void *rip, uint32_t syndrome)
     case CP_ACCESS_OK:
         return;
     case CP_ACCESS_TRAP:
+        target_el = exception_target_el(env);
+        break;
+    case CP_ACCESS_TRAP_EL2:
+        /* Requesting a trap to EL2 when we're in EL3 or S-EL0/1 is
+         * a bug in the access function.
+         */
+        assert(!arm_is_secure(env) && !arm_current_el(env) == 3);
+        target_el = 2;
+        break;
+    case CP_ACCESS_TRAP_EL3:
+        target_el = 3;
         break;
     case CP_ACCESS_TRAP_UNCATEGORIZED:
         syndrome = syn_uncategorized();
@@ -357,7 +369,7 @@ void HELPER(access_check_cp_reg)(CPUARMState *env, void *rip, uint32_t syndrome)
         g_assert_not_reached();
     }
 
-    raise_exception(env, EXCP_UDEF, syndrome, exception_target_el(env));
+    raise_exception(env, EXCP_UDEF, syndrome, target_el);
 }
 
 void HELPER(set_cp_reg)(CPUARMState *env, void *rip, uint32_t value)
-- 
1.9.1