target/arm: Introduce ARM_FEATURE_M_MAIN

This feature is intended to distinguish ARMv8-M variants: Baseline and
Mainline. ARMv7-M compatibility requires the Main Extension. ARMv6-M
compatibility is provided by all ARMv8-M implementations.
Signed-off-by: NJulia Suvorova <jusual@mail.ru>
Message-id: 20180622080138.17702-2-jusual@mail.ru
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

target/arm/cpu.c

@@ -1238,6 +1238,7 @@ static void cortex_m3_initfn(Object *obj)
     ARMCPU *cpu = ARM_CPU(obj);
     set_feature(&cpu->env, ARM_FEATURE_V7);
     set_feature(&cpu->env, ARM_FEATURE_M);
+    set_feature(&cpu->env, ARM_FEATURE_M_MAIN);
     cpu->midr = 0x410fc231;
     cpu->pmsav7_dregion = 8;
     cpu->id_pfr0 = 0x00000030;
@@ -1262,6 +1263,7 @@ static void cortex_m4_initfn(Object *obj)
 
     set_feature(&cpu->env, ARM_FEATURE_V7);
     set_feature(&cpu->env, ARM_FEATURE_M);
+    set_feature(&cpu->env, ARM_FEATURE_M_MAIN);
     set_feature(&cpu->env, ARM_FEATURE_THUMB_DSP);
     cpu->midr = 0x410fc240; /* r0p0 */
     cpu->pmsav7_dregion = 8;
@@ -1287,6 +1289,7 @@ static void cortex_m33_initfn(Object *obj)
 
     set_feature(&cpu->env, ARM_FEATURE_V8);
     set_feature(&cpu->env, ARM_FEATURE_M);
+    set_feature(&cpu->env, ARM_FEATURE_M_MAIN);
     set_feature(&cpu->env, ARM_FEATURE_M_SECURITY);
     set_feature(&cpu->env, ARM_FEATURE_THUMB_DSP);
     cpu->midr = 0x410fd213; /* r0p3 */

target/arm/cpu.h

@@ -1482,6 +1482,7 @@ enum arm_features {
     ARM_FEATURE_V8_RDM, /* implements v8.1 simd round multiply */
     ARM_FEATURE_V8_FP16, /* implements v8.2 half-precision float */
     ARM_FEATURE_V8_FCMA, /* has complex number part of v8.3 extensions.  */
+    ARM_FEATURE_M_MAIN, /* M profile Main Extension */
 };
 
 static inline int arm_feature(CPUARMState *env, int feature)