From 9d7deb299780b1ff5491ccc61be9ec41014065b8 Mon Sep 17 00:00:00 2001
From: Julia Suvorova <jusual@mail.ru>
Date: Thu, 16 Aug 2018 06:36:25 -0400
Subject: [PATCH] arm: Add ARMv6-M programmer's model support

Forbid stack alignment change. (CCR)
Reserve FAULTMASK, BASEPRI registers.
Report any fault as a HardFault. Disable MemManage, BusFault and
UsageFault, so they always escalated to HardFault. (SHCSR)

Backports commit 22ab3460017cfcfb6b50f05838ad142e08becce5 from qemu
---
 qemu/target/arm/cpu.c    |  4 ++++
 qemu/target/arm/helper.c | 13 +++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/qemu/target/arm/cpu.c b/qemu/target/arm/cpu.c
index 72247650..8c2b93a2 100644
--- a/qemu/target/arm/cpu.c
+++ b/qemu/target/arm/cpu.c
@@ -222,6 +222,10 @@ static void arm_cpu_reset(CPUState *s)
             env->v7m.ccr[M_REG_NS] |= R_V7M_CCR_NONBASETHRDENA_MASK;
             env->v7m.ccr[M_REG_S] |= R_V7M_CCR_NONBASETHRDENA_MASK;
         }
+        if (!arm_feature(env, ARM_FEATURE_M_MAIN)) {
+            env->v7m.ccr[M_REG_NS] |= R_V7M_CCR_UNALIGN_TRP_MASK;
+            env->v7m.ccr[M_REG_S] |= R_V7M_CCR_UNALIGN_TRP_MASK;
+        }
 
         /* Unlike A/R profile, M profile defines the reset LR value */
         env->regs[14] = 0xffffffff;
diff --git a/qemu/target/arm/helper.c b/qemu/target/arm/helper.c
index 56741667..1f955d7e 100644
--- a/qemu/target/arm/helper.c
+++ b/qemu/target/arm/helper.c
@@ -9915,13 +9915,13 @@ void HELPER(v7m_msr)(CPUARMState *env, uint32_t maskreg, uint32_t val)
             env->v7m.primask[M_REG_NS] = val & 1;
             return;
         case 0x91: /* BASEPRI_NS */
-            if (!env->v7m.secure) {
+            if (!env->v7m.secure || !arm_feature(env, ARM_FEATURE_M_MAIN)) {
                 return;
             }
             env->v7m.basepri[M_REG_NS] = val & 0xff;
             return;
         case 0x93: /* FAULTMASK_NS */
-            if (!env->v7m.secure) {
+            if (!env->v7m.secure || !arm_feature(env, ARM_FEATURE_M_MAIN)) {
                 return;
             }
             env->v7m.faultmask[M_REG_NS] = val & 1;
@@ -10012,9 +10012,15 @@ void HELPER(v7m_msr)(CPUARMState *env, uint32_t maskreg, uint32_t val)
         env->v7m.primask[env->v7m.secure] = val & 1;
         break;
     case 17: /* BASEPRI */
+        if (!arm_feature(env, ARM_FEATURE_M_MAIN)) {
+            goto bad_reg;
+        }
         env->v7m.basepri[env->v7m.secure] = val & 0xff;
         break;
     case 18: /* BASEPRI_MAX */
+        if (!arm_feature(env, ARM_FEATURE_M_MAIN)) {
+            goto bad_reg;
+        }
         val &= 0xff;
         if (val != 0 && (val < env->v7m.basepri[env->v7m.secure]
                          || env->v7m.basepri[env->v7m.secure] == 0)) {
@@ -10022,6 +10028,9 @@ void HELPER(v7m_msr)(CPUARMState *env, uint32_t maskreg, uint32_t val)
         }
         break;
     case 19: /* FAULTMASK */
+        if (!arm_feature(env, ARM_FEATURE_M_MAIN)) {
+            goto bad_reg;
+        }
         env->v7m.faultmask[env->v7m.secure] = val & 1;
         break;
     case 20: /* CONTROL */