target/arm: Restore security state on exception return

Now that we can handle the CONTROL.SPSEL bit not necessarily being
in sync with the current stack pointer, we can restore the correct
security state on exception return. This happens before we start
to read registers off the stack frame, but after we have taken
possible usage faults for bad exception return magic values and
updated CONTROL.SPSEL.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1506092407-26985-5-git-send-email-peter.maydell@linaro.org

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 36173e21a7c8ebc1a2e472ab9642f33ab0c41c57..b82fc9f163feb0425cd1da2429fad5a12b921c8c 100644 (file)
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6381,6 +6381,8 @@ static void do_v7m_exception_exit(ARMCPU *cpu)
      */
     write_v7m_control_spsel(env, return_to_sp_process);
 
+    switch_v7m_security_state(env, return_to_secure);
+
     {
         /* The stack pointer we should be reading the exception frame from
          * depends on bits in the magic exception return type value (and