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, 1 insertions, 6 deletions

diff --git a/target-arm/helper.c b/target-arm/helper.c
index d246d36de4..dd9fca56f6 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -1714,12 +1714,7 @@ static const ARMCPRegInfo omap_cp_reginfo[] = {
 static void xscale_cpar_write(CPUARMState *env, const ARMCPRegInfo *ri,
                               uint64_t value)
 {
-    value &= 0x3fff;
-    if (env->cp15.c15_cpar != value) {
-        /* Changes cp0 to cp13 behavior, so needs a TB flush.  */
-        tb_flush(env);
-        env->cp15.c15_cpar = value;
-    }
+    env->cp15.c15_cpar = value & 0x3fff;
 }
 
 static const ARMCPRegInfo xscale_cp_reginfo[] = {