From 7f044bf8ccdc5455801492b5b59e65426ded6dce Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Fri, 2 Mar 2018 13:41:13 -0500
Subject: [PATCH] armv7m: Clear FAULTMASK on return from non-NMI exceptions

FAULTMASK must be cleared on return from all
exceptions other than NMI.

Backports commit a20ee6005564590d33eabec11ed4dc7c432db36b from qemu
---
 qemu/target/arm/helper.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/qemu/target/arm/helper.c b/qemu/target/arm/helper.c
index 8c0b7b01..bd4dcaf6 100644
--- a/qemu/target/arm/helper.c
+++ b/qemu/target/arm/helper.c
@@ -5339,8 +5339,14 @@ static void do_v7m_exception_exit(CPUARMState *env)
     uint32_t xpsr;
 
     type = env->regs[15];
-    //if (env->v7m.exception != 0)
-    //    armv7m_nvic_complete_irq(env->nvic, env->v7m.exception);
+    if (env->v7m.exception != ARMV7M_EXCP_NMI) {
+        /* Auto-clear FAULTMASK on return from other than NMI */
+        env->daif &= ~PSTATE_F;
+    }
+    /* Unicorn: commented out
+    if (env->v7m.exception != 0) {
+        armv7m_nvic_complete_irq(env->nvic, env->v7m.exception);
+    }*/
 
     /* Switch to the target stack.  */
     switch_v7m_sp(env, (type & 4) != 0);