target/arm: ensure we use current exception state after SCR update

A write to the SCR can change the effective EL by droppping the system
from secure to non-secure mode. However if we use a cached current_el
from before the change we'll rebuild the flags incorrectly. To fix
this we introduce the ARM_CP_NEWEL CP flag to indicate the new EL
should be used when recomputing the flags.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20191212114734.6962-1-alex.bennee@linaro.org
Cc: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20191209143723.6368-1-alex.bennee@linaro.org>
Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 13 insertions, 1 deletions

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 3a93844a3b..5074b5f69c 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -5133,7 +5133,7 @@ static const ARMCPRegInfo el3_cp_reginfo[] = {
       .opc0 = 3, .opc1 = 6, .crn = 1, .crm = 1, .opc2 = 0,
       .access = PL3_RW, .fieldoffset = offsetof(CPUARMState, cp15.scr_el3),
       .resetvalue = 0, .writefn = scr_write },
-    { .name = "SCR",  .type = ARM_CP_ALIAS,
+    { .name = "SCR",  .type = ARM_CP_ALIAS | ARM_CP_NEWEL,
       .cp = 15, .opc1 = 0, .crn = 1, .crm = 1, .opc2 = 0,
       .access = PL1_RW, .accessfn = access_trap_aa32s_el1,
       .fieldoffset = offsetoflow32(CPUARMState, cp15.scr_el3),
@@ -11472,6 +11472,18 @@ void HELPER(rebuild_hflags_m32)(CPUARMState *env, int el)
     env->hflags = rebuild_hflags_m32(env, fp_el, mmu_idx);
 }
 
+/*
+ * If we have triggered a EL state change we can't rely on the
+ * translator having passed it too us, we need to recompute.
+ */
+void HELPER(rebuild_hflags_a32_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_a32(env, fp_el, mmu_idx);
+}
+
 void HELPER(rebuild_hflags_a32)(CPUARMState *env, int el)
 {
     int fp_el = fp_exception_el(env, el);