ARM: Cleanup and small fixes to some NEON ops to match the spec.

Only certain bits of the cpacr can be written, some must be equal.
Mult instructions that write the same register should do something sane

1 files changed, 14 insertions, 9 deletions

diff --git a/src/arch/arm/isa.cc b/src/arch/arm/isa.cc
index f3f730896..216ae04e7 100644
--- a/src/arch/arm/isa.cc
+++ b/src/arch/arm/isa.cc
@@ -268,19 +268,22 @@ ISA::setMiscReg(int misc_reg, const MiscReg &val, ThreadContext *tc)
         switch (misc_reg) {
           case MISCREG_CPACR:
             {
-                CPACR newCpacr = 0;
-                CPACR valCpacr = val;
-                newCpacr.cp10 = valCpacr.cp10;
-                newCpacr.cp11 = valCpacr.cp11;
-                //XXX d32dis isn't implemented. The manual says whether or not
-                //it works is implementation defined.
-                newCpacr.asedis = valCpacr.asedis;
-                newVal = newCpacr;
+
+                const uint32_t ones = (uint32_t)(-1);
+                CPACR cpacrMask = 0;
+                // Only cp10, cp11, and ase are implemented, nothing else should
+                // be writable
+                cpacrMask.cp10 = ones;
+                cpacrMask.cp11 = ones;
+                cpacrMask.asedis = ones;
+                newVal &= cpacrMask;
+                DPRINTF(MiscRegs, "Writing misc reg %s: %#x\n",
+                        miscRegName[misc_reg], newVal);
             }
             break;
           case MISCREG_CSSELR:
             warn_once("The csselr register isn't implemented.\n");
-            break;
+            return;
           case MISCREG_FPSCR:
             {
                 const uint32_t ones = (uint32_t)(-1);
@@ -320,6 +323,8 @@ ISA::setMiscReg(int misc_reg, const MiscReg &val, ThreadContext *tc)
             break;
           case MISCREG_FPEXC:
             {
+                // vfpv3 architecture, section B.6.1 of DDI04068
+                // bit 29 - valid only if fpexc[31] is 0
                 const uint32_t fpexcMask = 0x60000000;
                 newVal = (newVal & fpexcMask) |
                          (miscRegs[MISCREG_FPEXC] & ~fpexcMask);