[Qemu-arm] [PATCH 07/10] armv7m: Report no-coprocessor faults correctly

[Peter Maydell]

For v7M attempts to access a nonexistent coprocessor are reported
differently from plain undefined instructions (as UsageFaults of type
NOCP rather than type UNDEFINSTR).  Split them out into a new
EXCP_NOCP so we can report the FSR value correctly.

Signed-off-by: Peter Maydell <address@hidden>
---
 target/arm/cpu.h       | 1 +
 linux-user/main.c      | 1 +
 target/arm/helper.c    | 4 ++++
 target/arm/translate.c | 8 ++++++++
 4 files changed, 14 insertions(+)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 4b062d2..39bff86 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -53,6 +53,7 @@
 #define EXCP_VIRQ           14
 #define EXCP_VFIQ           15
 #define EXCP_SEMIHOST       16   /* semihosting call */
+#define EXCP_NOCP           17   /* v7M NOCP UsageFault */
 
 #define ARMV7M_EXCP_RESET   1
 #define ARMV7M_EXCP_NMI     2
diff --git a/linux-user/main.c b/linux-user/main.c
index db4eb68..f40d45a 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -570,6 +570,7 @@ void cpu_loop(CPUARMState *env)
 
         switch(trapnr) {
         case EXCP_UDEF:
+        case EXCP_NOCP:
             {
                 TaskState *ts = cs->opaque;
                 uint32_t opcode;
diff --git a/target/arm/helper.c b/target/arm/helper.c
index e6b1c36..c23df1b 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6074,6 +6074,10 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
         armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE);
         env->v7m.cfsr |= R_V7M_CFSR_UNDEFINSTR_MASK;
         return;
+    case EXCP_NOCP:
+        armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE);
+        env->v7m.cfsr |= R_V7M_CFSR_NOCP_MASK;
+        return;
     case EXCP_SWI:
         /* The PC already points to the next instruction.  */
         armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SVC);
diff --git a/target/arm/translate.c b/target/arm/translate.c
index a7c2abe..493c627 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -10217,6 +10217,14 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
         break;
     case 6: case 7: case 14: case 15:
         /* Coprocessor.  */
+        if (arm_dc_feature(s, ARM_FEATURE_M)) {
+            /* We don't currently implement M profile FP support,
+             * so this entire space should give a NOCP fault.
+             */
+            gen_exception_insn(s, 4, EXCP_NOCP, syn_uncategorized(),
+                               default_exception_el(s));
+            break;
+        }
         if (((insn >> 24) & 3) == 3) {
             /* Translate into the equivalent ARM encoding.  */
             insn = (insn & 0xe2ffffff) | ((insn & (1 << 28)) >> 4) | (1 << 28);
-- 
2.7.4