target/arm: Make FAULTMASK register banked for v8M

Make the FAULTMASK register banked if v8M security extensions are enabled.

Note that we do not yet implement the functionality of the new
AIRCR.PRIS bit (which allows the effect of the NS copy of FAULTMASK to
be restricted).

This patch includes the code to determine for v8M which copy
of FAULTMASK should be updated on exception exit; further
changes will be required to the exception exit code in general
to support v8M, so this is just a small piece of that.

The v8M ARM ARM introduces a notation where individual paragraphs
are labelled with R (for rule) or I (for information) followed
by a random group of subscript letters. In comments where we want
to refer to a particular part of the manual we use this convention,
which should be more stable across document revisions than using
section or page numbers.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1503414539-28762-9-git-send-email-peter.maydell@linaro.org

1 files changed, 12 insertions, 2 deletions

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 26ec744af0..5cf2e76ffc 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -432,7 +432,7 @@ typedef struct CPUARMState {
         unsigned mpu_ctrl; /* MPU_CTRL */
         int exception;
         uint32_t primask[2];
-        uint32_t faultmask;
+        uint32_t faultmask[2];
         uint32_t secure; /* Is CPU in Secure state? (not guest visible) */
     } v7m;
 
@@ -1442,6 +1442,16 @@ void armv7m_nvic_acknowledge_irq(void *opaque);
  * (Ignoring -1, this is the same as the RETTOBASE value before completion.)
  */
 int armv7m_nvic_complete_irq(void *opaque, int irq);
+/**
+ * armv7m_nvic_raw_execution_priority: return the raw execution priority
+ * @opaque: the NVIC
+ *
+ * Returns: the raw execution priority as defined by the v8M architecture.
+ * This is the execution priority minus the effects of AIRCR.PRIS,
+ * and minus any PRIMASK/FAULTMASK/BASEPRI priority boosting.
+ * (v8M ARM ARM I_PKLD.)
+ */
+int armv7m_nvic_raw_execution_priority(void *opaque);
 
 /* Interface for defining coprocessor registers.
  * Registers are defined in tables of arm_cp_reginfo structs
@@ -2227,7 +2237,7 @@ static inline int cpu_mmu_index(CPUARMState *env, bool ifetch)
          * we're in a HardFault or NMI handler.
          */
         if ((env->v7m.exception > 0 && env->v7m.exception <= 3)
-            || env->v7m.faultmask) {
+            || env->v7m.faultmask[env->v7m.secure]) {
             mmu_idx = ARMMMUIdx_MNegPri;
         }