target-arm: Don't handle c15_cpar changes via tb_flush()

At the moment we try to handle c15_cpar with the strategy of:
 * emit generated code which makes assumptions about its value
 * when the register value changes call tb_flush() to throw
   away the now-invalid generated code
This works because XScale CPUs are always uniprocessor, but
it's confusing because it suggests that the same approach can
be taken for other registers. It also means we do a tb_flush()
on CPU reset, which makes multithreaded linux-user binaries
even more likely to fail than would otherwise be the case.

Replace it with a combination of TB flags for the access
checks done on cp0/cp1 for the XScale and iwMMXt instructions,
plus a runtime check for cp2..cp13 coprocessor accesses.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1411056959-23070-1-git-send-email-peter.maydell@linaro.org

1 files changed, 9 insertions, 0 deletions

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index fa6ae0a..7bd3af9 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -1224,6 +1224,11 @@ static inline bool arm_singlestep_active(CPUARMState *env)
 #define ARM_TBFLAG_SS_ACTIVE_MASK (1 << ARM_TBFLAG_SS_ACTIVE_SHIFT)
 #define ARM_TBFLAG_PSTATE_SS_SHIFT 19
 #define ARM_TBFLAG_PSTATE_SS_MASK (1 << ARM_TBFLAG_PSTATE_SS_SHIFT)
+/* We store the bottom two bits of the CPAR as TB flags and handle
+ * checks on the other bits at runtime
+ */
+#define ARM_TBFLAG_XSCALE_CPAR_SHIFT 20
+#define ARM_TBFLAG_XSCALE_CPAR_MASK (3 << ARM_TBFLAG_XSCALE_CPAR_SHIFT)
 
 /* Bit usage when in AArch64 state */
 #define ARM_TBFLAG_AA64_EL_SHIFT    0
@@ -1258,6 +1263,8 @@ static inline bool arm_singlestep_active(CPUARMState *env)
     (((F) & ARM_TBFLAG_SS_ACTIVE_MASK) >> ARM_TBFLAG_SS_ACTIVE_SHIFT)
 #define ARM_TBFLAG_PSTATE_SS(F) \
     (((F) & ARM_TBFLAG_PSTATE_SS_MASK) >> ARM_TBFLAG_PSTATE_SS_SHIFT)
+#define ARM_TBFLAG_XSCALE_CPAR(F) \
+    (((F) & ARM_TBFLAG_XSCALE_CPAR_MASK) >> ARM_TBFLAG_XSCALE_CPAR_SHIFT)
 #define ARM_TBFLAG_AA64_EL(F) \
     (((F) & ARM_TBFLAG_AA64_EL_MASK) >> ARM_TBFLAG_AA64_EL_SHIFT)
 #define ARM_TBFLAG_AA64_FPEN(F) \
@@ -1335,6 +1342,8 @@ static inline void cpu_get_tb_cpu_state(CPUARMState *env, target_ulong *pc,
                 *flags |= ARM_TBFLAG_PSTATE_SS_MASK;
             }
         }
+        *flags |= (extract32(env->cp15.c15_cpar, 0, 2)
+                   << ARM_TBFLAG_XSCALE_CPAR_SHIFT);
     }
 
     *cs_base = 0;