armv7m: Implement M profile default memory map

Add support for the M profile default memory map which is used
if the MPU is not present or disabled.

The main differences in behaviour from implementing this
correctly are that we set the PAGE_EXEC attribute on
the right regions of memory, such that device regions
are not executable.
Signed-off-by: NMichael Davidsaver <mdavidsaver@gmail.com>
Message-id: 1493122030-32191-10-git-send-email-peter.maydell@linaro.org
[PMM: rephrased comment and commit message; don't mark
 the flash memory region as not-writable; list all
 the cases in the default map explicitly rather than
 using a 'default' case for the non-executable regions]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

target/arm/helper.c

@@ -8129,10 +8129,12 @@ static inline void get_phys_addr_pmsav7_default(CPUARMState *env,
                                                 ARMMMUIdx mmu_idx,
                                                 int32_t address, int *prot)
 {
+    if (!arm_feature(env, ARM_FEATURE_M)) {
         *prot = PAGE_READ | PAGE_WRITE;
         switch (address) {
         case 0xF0000000 ... 0xFFFFFFFF:
-        if (regime_sctlr(env, mmu_idx) & SCTLR_V) { /* hivecs execing is ok */
+            if (regime_sctlr(env, mmu_idx) & SCTLR_V) {
+                /* hivecs execing is ok */
                 *prot |= PAGE_EXEC;
             }
             break;
@@ -8140,7 +8142,28 @@ static inline void get_phys_addr_pmsav7_default(CPUARMState *env,
             *prot |= PAGE_EXEC;
             break;
         }
-
+    } else {
+        /* Default system address map for M profile cores.
+         * The architecture specifies which regions are execute-never;
+         * at the MPU level no other checks are defined.
+         */
+        switch (address) {
+        case 0x00000000 ... 0x1fffffff: /* ROM */
+        case 0x20000000 ... 0x3fffffff: /* SRAM */
+        case 0x60000000 ... 0x7fffffff: /* RAM */
+        case 0x80000000 ... 0x9fffffff: /* RAM */
+            *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
+            break;
+        case 0x40000000 ... 0x5fffffff: /* Peripheral */
+        case 0xa0000000 ... 0xbfffffff: /* Device */
+        case 0xc0000000 ... 0xdfffffff: /* Device */
+        case 0xe0000000 ... 0xffffffff: /* System */
+            *prot = PAGE_READ | PAGE_WRITE;
+            break;
+        default:
+            g_assert_not_reached();
+        }
+    }
 }
 
 static bool get_phys_addr_pmsav7(CPUARMState *env, uint32_t address,