target/arm: Recalculate hflags correctly after writes to CONTROL

A write to the CONTROL register can change our current EL (by
writing to the nPRIV bit). That means that we can't assume
that s->current_el is still valid in trans_MSR_v7m() when
we try to rebuild the hflags.

Add a new helper rebuild_hflags_m32_newel() which, like the
existing rebuild_hflags_a32_newel(), recalculates the current
EL from scratch, and use it in trans_MSR_v7m().

This fixes an assertion about an hflags mismatch when the
guest changes privilege by writing to CONTROL.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200303174950.3298-4-peter.maydell@linaro.org

1 files changed, 12 insertions, 0 deletions

diff --git a/target/arm/helper.c b/target/arm/helper.c
index f91e5d5345..bc64077ec7 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -12468,6 +12468,18 @@ void arm_rebuild_hflags(CPUARMState *env)
     env->hflags = rebuild_hflags_internal(env);
 }
 
+/*
+ * If we have triggered a EL state change we can't rely on the
+ * translator having passed it to us, we need to recompute.
+ */
+void HELPER(rebuild_hflags_m32_newel)(CPUARMState *env)
+{
+    int el = arm_current_el(env);
+    int fp_el = fp_exception_el(env, el);
+    ARMMMUIdx mmu_idx = arm_mmu_idx_el(env, el);
+    env->hflags = rebuild_hflags_m32(env, fp_el, mmu_idx);
+}
+
 void HELPER(rebuild_hflags_m32)(CPUARMState *env, int el)
 {
     int fp_el = fp_exception_el(env, el);