ARM: BXJ should be BX when there is no J support

2 files changed, 8 insertions, 5 deletions

diff --git a/src/arch/arm/isa/decoder/arm.isa b/src/arch/arm/isa/decoder/arm.isa
index 31456dfc6..4c5d71ad9 100644
--- a/src/arch/arm/isa/decoder/arm.isa
+++ b/src/arch/arm/isa/decoder/arm.isa
@@ -67,10 +67,8 @@ format DataOp {
             1: decode OPCODE_7 {
                 0x0: decode MISC_OPCODE {
                     0x0: ArmMsrMrs::armMsrMrs();
-                    0x1: ArmBxClz::armBxClz();
-                    0x2: decode OPCODE {
-                        0x9: WarnUnimpl::bxj();
-                    }
+                    // bxj unimplemented, treated as bx
+                    0x1,0x2: ArmBxClz::armBxClz();
                     0x3: decode OPCODE {
                         0x9: ArmBlxReg::armBlxReg();
                     }
diff --git a/src/arch/arm/isa/formats/branch.isa b/src/arch/arm/isa/formats/branch.isa
index dbb6f9f9d..055955520 100644
--- a/src/arch/arm/isa/formats/branch.isa
+++ b/src/arch/arm/isa/formats/branch.isa
@@ -207,7 +207,12 @@ def format Thumb32BranchesAndMiscCtrl() {{
                         break;
                     }
                   case 0x3c:
-                    return new WarnUnimplemented("bxj", machInst);
+                    {
+                        // On systems that don't support bxj, bxj == bx
+                        return new BxReg(machInst,
+                                 (IntRegIndex)(uint32_t)bits(machInst, 19, 16),
+                                 COND_UC);
+                    }
                   case 0x3d:
                     {
                         const uint32_t imm32 = bits(machInst, 7, 0);