From 038225a6cae8ce1d8fc5246440b7f697eeb3c90a Mon Sep 17 00:00:00 2001
From: Gabe Black <gblack@eecs.umich.edu>
Date: Sun, 19 Apr 2009 03:42:41 -0700
Subject: X86: Implement far jmp.

---
 src/arch/x86/isa/decoder/one_byte_opcodes.isa      | 13 ++-
 .../insts/general_purpose/control_transfer/jump.py | 99 ++++++++++++++++++++++
 src/arch/x86/isa/microops/regop.isa                |  7 +-
 3 files changed, 116 insertions(+), 3 deletions(-)

diff --git a/src/arch/x86/isa/decoder/one_byte_opcodes.isa b/src/arch/x86/isa/decoder/one_byte_opcodes.isa
index 817986232..84d18441d 100644
--- a/src/arch/x86/isa/decoder/one_byte_opcodes.isa
+++ b/src/arch/x86/isa/decoder/one_byte_opcodes.isa
@@ -519,7 +519,10 @@
             0x1: JMP(Jz);
             0x2: decode MODE_SUBMODE {
                 0x0: UD2();
-                default: WarnUnimpl::jmp_far_Ap();
+                0x1: JMP_FAR(Iz);
+                0x2: JMP_FAR(Iz);
+                0x3: JMP_FAR_REAL(Iz);
+                0x4: JMP_FAR_REAL(Iz);
             }
             0x3: JMP(Jb);
             0x4: IN(rAb,rD);
@@ -581,7 +584,13 @@
                 0x2: CALL_NEAR(Ev);
                 0x3: WarnUnimpl::call_far_Mp();
                 0x4: JMP(Ev);
-                0x5: WarnUnimpl::jmp_far_Mp();
+                0x5: decode MODE_SUBMODE {
+                    0x0: JMP_FAR(Mz);
+                    0x1: JMP_FAR(Mz);
+                    0x2: JMP_FAR(Mz);
+                    0x3: JMP_FAR_REAL(Mz);
+                    0x4: JMP_FAR_REAL(Mz);
+                }
                 0x6: PUSH(Ev);
                 0x7: UD2();
             }
diff --git a/src/arch/x86/isa/insts/general_purpose/control_transfer/jump.py b/src/arch/x86/isa/insts/general_purpose/control_transfer/jump.py
index bb3ae4213..4f0cdf770 100644
--- a/src/arch/x86/isa/insts/general_purpose/control_transfer/jump.py
+++ b/src/arch/x86/isa/insts/general_purpose/control_transfer/jump.py
@@ -90,4 +90,103 @@ def macroop JMP_P
     ld t1, seg, riprel, disp
     wripi t1, 0
 };
+
+def macroop JMP_FAR_M
+{
+    limm t1, 0, dataSize=8
+    limm t2, 0, dataSize=8
+    lea t1, seg, sib, disp, dataSize=asz
+    ld t2, seg, [1, t0, t1], dsz
+    ld t1, seg, [1, t0, t1]
+    br rom_label("jmpFarWork")
+};
+
+def macroop JMP_FAR_P
+{
+    limm t1, 0, dataSize=8
+    limm t2, 0, dataSize=8
+    rdip t7, dataSize=asz
+    lea t1, seg, riprel, disp, dataSize=asz
+    ld t2, seg, [1, t0, t1], dsz
+    ld t1, seg, [1, t0, t1]
+    br rom_label("jmpFarWork")
+};
+
+def macroop JMP_FAR_I
+{
+    # Put the whole far pointer into a register.
+    limm t2, imm, dataSize=8
+    # Figure out the width of the offset.
+    limm t3, dsz, dataSize=8
+    sll t3, t3, 3, dataSize=8
+    # Get the selector into t1.
+    sll t1, t2, t3, dataSize=8
+    mov t1, t0, t1, dataSize=2
+    # And get the offset into t2
+    mov t2, t0, t2
+    br rom_label("jmpFarWork")
+};
+
+def rom
+{
+    extern jmpFarWork:
+    # t1 has the offset and t2 has the new selector.
+    # This is intended to run in protected mode.
+    andi t0, t2, 0xFC, flags=(EZF,), dataSize=2
+    fault "new GeneralProtection(0)", flags=(CEZF,)
+    andi t3, t2, 0xF8, dataSize=8
+    andi t0, t2, 0x4, flags=(EZF,), dataSize=2
+    br rom_local_label("farJmpGlobalDescriptor"), flags=(CEZF,)
+    ld t4, tsl, [1, t0, t3], dataSize=8, addressSize=8, atCPL0=True
+    br rom_local_label("farJmpProcessDescriptor")
+farJmpGlobalDescriptor:
+    ld t4, tsg, [1, t0, t3], dataSize=8, addressSize=8, atCPL0=True
+farJmpProcessDescriptor:
+    rcri t0, t4, 13, flags=(ECF,), dataSize=2
+    br rom_local_label("farJmpSystemDescriptor"), flags=(nCECF,)
+    chks t2, t4, CSCheck, dataSize=8
+    wrdl cs, t4, t2
+    wrsel cs, t2
+    wrip t0, t1
+    eret
+
+farJmpSystemDescriptor:
+    panic "Far jumps to system descriptors aren't implemented"
+    eret
+};
+
+def macroop JMP_FAR_REAL_M
+{
+    lea t1, seg, sib, disp, dataSize=asz
+    ld t2, seg, [1, t0, t1], dsz
+    ld t1, seg, [1, t0, t1]
+    zexti t3, t1, 15, dataSize=8
+    slli t3, t3, 4, dataSize=8
+    wrsel cs, t1, dataSize=2
+    wrbase cs, t3
+    wrip t0, t2, dataSize=asz
+};
+
+def macroop JMP_FAR_REAL_P
+{
+    panic "Real mode far jump executed in 64 bit mode!"
+};
+
+def macroop JMP_FAR_REAL_I
+{
+    # Put the whole far pointer into a register.
+    limm t2, imm, dataSize=8
+    # Figure out the width of the offset.
+    limm t3, dsz, dataSize=8
+    sll t3, t3, 3, dataSize=8
+    # Get the selector into t1.
+    sll t1, t2, t3, dataSize=8
+    mov t1, t0, t1, dataSize=2
+    # And get the offset into t2
+    mov t2, t0, t2
+    slli t3, t3, 4, dataSize=8
+    wrsel cs, t1, dataSize=2
+    wrbase cs, t3
+    wrip t0, t2, dataSize=asz
+};
 '''
diff --git a/src/arch/x86/isa/microops/regop.isa b/src/arch/x86/isa/microops/regop.isa
index 35227a4fb..6935c780d 100644
--- a/src/arch/x86/isa/microops/regop.isa
+++ b/src/arch/x86/isa/microops/regop.isa
@@ -1102,7 +1102,12 @@ let {{
               case SegNoCheck:
                 break;
               case SegCSCheck:
-                panic("CS checks for far calls/jumps not implemented.\\n");
+                // Make sure it's the right type
+                if (desc.s == 0 || desc.type.codeOrData != 1) {
+                    fault = new GeneralProtection(0);
+                } else if (m5reg.cpl != desc.dpl) {
+                    fault = new GeneralProtection(0);
+                }
                 break;
               case SegCallGateCheck:
                 panic("CS checks for far calls/jumps through call gates"
-- 
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