target/arm: Split out aarch32_cpsr_valid_mask

Split this helper out of msr_mask in translate.c.  At the same time,
transform the negative reductive logic to positive accumulative logic.
It will be usable along the exception paths.

While touching msr_mask, fix up formatting.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20200208125816.14954-6-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 38 insertions, 23 deletions

diff --git a/target/arm/internals.h b/target/arm/internals.h
index 6be8b2d..4d4896f 100644
--- a/target/arm/internals.h
+++ b/target/arm/internals.h
@@ -1061,6 +1061,27 @@ static inline bool arm_mmu_idx_is_stage1_of_2(ARMMMUIdx mmu_idx)
     }
 }
 
+static inline uint32_t aarch32_cpsr_valid_mask(uint64_t features,
+                                               const ARMISARegisters *id)
+{
+    uint32_t valid = CPSR_M | CPSR_AIF | CPSR_IL | CPSR_NZCV | CPSR_J;
+
+    if ((features >> ARM_FEATURE_V4T) & 1) {
+        valid |= CPSR_T;
+    }
+    if ((features >> ARM_FEATURE_V5) & 1) {
+        valid |= CPSR_Q; /* V5TE in reality*/
+    }
+    if ((features >> ARM_FEATURE_V6) & 1) {
+        valid |= CPSR_E | CPSR_GE;
+    }
+    if ((features >> ARM_FEATURE_THUMB2) & 1) {
+        valid |= CPSR_IT;
+    }
+
+    return valid;
+}
+
 /*
  * Parameters of a given virtual address, as extracted from the
  * translation control register (TCR) for a given regime.
diff --git a/target/arm/translate.c b/target/arm/translate.c
index d58c328..20f89ac 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -2734,39 +2734,33 @@ static inline void gen_mulxy(TCGv_i32 t0, TCGv_i32 t1, int x, int y)
 /* Return the mask of PSR bits set by a MSR instruction.  */
 static uint32_t msr_mask(DisasContext *s, int flags, int spsr)
 {
-    uint32_t mask;
+    uint32_t mask = 0;
 
-    mask = 0;
-    if (flags & (1 << 0))
+    if (flags & (1 << 0)) {
         mask |= 0xff;
-    if (flags & (1 << 1))
-        mask |= 0xff00;
-    if (flags & (1 << 2))
-        mask |= 0xff0000;
-    if (flags & (1 << 3))
-        mask |= 0xff000000;
-
-    /* Mask out undefined bits.  */
-    mask &= ~CPSR_RESERVED;
-    if (!arm_dc_feature(s, ARM_FEATURE_V4T)) {
-        mask &= ~CPSR_T;
     }
-    if (!arm_dc_feature(s, ARM_FEATURE_V5)) {
-        mask &= ~CPSR_Q; /* V5TE in reality*/
+    if (flags & (1 << 1)) {
+        mask |= 0xff00;
     }
-    if (!arm_dc_feature(s, ARM_FEATURE_V6)) {
-        mask &= ~(CPSR_E | CPSR_GE);
+    if (flags & (1 << 2)) {
+        mask |= 0xff0000;
     }
-    if (!arm_dc_feature(s, ARM_FEATURE_THUMB2)) {
-        mask &= ~CPSR_IT;
+    if (flags & (1 << 3)) {
+        mask |= 0xff000000;
     }
-    /* Mask out execution state and reserved bits.  */
+
+    /* Mask out undefined and reserved bits.  */
+    mask &= aarch32_cpsr_valid_mask(s->features, s->isar);
+
+    /* Mask out execution state.  */
     if (!spsr) {
-        mask &= ~(CPSR_EXEC | CPSR_RESERVED);
+        mask &= ~CPSR_EXEC;
     }
+
     /* Mask out privileged bits.  */
-    if (IS_USER(s))
+    if (IS_USER(s)) {
         mask &= CPSR_USER;
+    }
     return mask;
 }