Gabe Black has submitted this change. ( https://gem5-review.googlesource.com/c/public/gem5/+/55884 )

Change subject: arch-x86: Specialize LLDT for 64 bit and non-64 bit.
......................................................................

arch-x86: Specialize LLDT for 64 bit and non-64 bit.

In 64 bit mode the LLDT has a 128 bit descriptor which takes up two
slots. In any other mode, the descriptor is still 64 bits.

Change-Id: I88d3758a66dec3482153df5ec08565427d6c9269
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55884
Maintainer: Gabe Black <gabe.bl...@gmail.com>
Reviewed-by: Matt Sinclair <mattdsincl...@gmail.com>
Maintainer: Matt Sinclair <mattdsincl...@gmail.com>
Tested-by: kokoro <noreply+kok...@google.com>
---
M src/arch/x86/isa/decoder/two_byte_opcodes.isa
M src/arch/x86/isa/insts/system/segmentation.py
2 files changed, 78 insertions(+), 24 deletions(-)

Approvals:
  Matt Sinclair: Looks good to me, approved; Looks good to me, approved
  Gabe Black: Looks good to me, approved
  kokoro: Regressions pass




diff --git a/src/arch/x86/isa/decoder/two_byte_opcodes.isa b/src/arch/x86/isa/decoder/two_byte_opcodes.isa
index b82afb0..e993b18 100644
--- a/src/arch/x86/isa/decoder/two_byte_opcodes.isa
+++ b/src/arch/x86/isa/decoder/two_byte_opcodes.isa
@@ -48,7 +48,10 @@
             0x00: decode MODRM_REG {
                 0x0: sldt_Mw_or_Rv();
                 0x1: str_Mw_or_Rv();
-                0x2: Inst::LLDT(Ew);
+                0x2: decode MODE_SUBMODE {
+                    0x0: Inst::LLDT_64(Ew);
+                    default: Inst::LLDT(Ew);
+                }
                 0x3: Inst::LTR(Ew);
                 0x4: verr_Mw_or_Rv();
                 0x5: verw_Mw_or_Rv();
diff --git a/src/arch/x86/isa/insts/system/segmentation.py b/src/arch/x86/isa/insts/system/segmentation.py
index 814a32c..3915a73 100644
--- a/src/arch/x86/isa/insts/system/segmentation.py
+++ b/src/arch/x86/isa/insts/system/segmentation.py
@@ -211,6 +211,60 @@
     st t1, tsg, [8, t4, t0], dataSize=8
 };

+def macroop LLDT_64_R
+{
+    .serialize_after
+    chks reg, t0, InGDTCheck, flags=(EZF,)
+    br label("end"), flags=(CEZF,)
+    limm t4, 0, dataSize=8
+    srli t4, reg, 3, dataSize=2
+    ld t1, tsg, [8, t4, t0], dataSize=8
+    ld t2, tsg, [8, t4, t0], 8, dataSize=8
+    chks reg, t1, LDTCheck
+    wrdh t3, t1, t2
+    wrdl tsl, t1, reg
+    wrbase tsl, t3, dataSize=8
+end:
+    fault "NoFault"
+};
+
+def macroop LLDT_64_M
+{
+    .serialize_after
+    ld t5, seg, sib, disp, dataSize=2
+    chks t5, t0, InGDTCheck, flags=(EZF,)
+    br label("end"), flags=(CEZF,)
+    limm t4, 0, dataSize=8
+    srli t4, t5, 3, dataSize=2
+    ld t1, tsg, [8, t4, t0], dataSize=8
+    ld t2, tsg, [8, t4, t0], 8, dataSize=8
+    chks t5, t1, LDTCheck
+    wrdh t3, t1, t2
+    wrdl tsl, t1, t5
+    wrbase tsl, t3, dataSize=8
+end:
+    fault "NoFault"
+};
+
+def macroop LLDT_64_P
+{
+    .serialize_after
+    rdip t7
+    ld t5, seg, riprel, disp, dataSize=2
+    chks t5, t0, InGDTCheck, flags=(EZF,)
+    br label("end"), flags=(CEZF,)
+    limm t4, 0, dataSize=8
+    srli t4, t5, 3, dataSize=2
+    ld t1, tsg, [8, t4, t0], dataSize=8
+    ld t2, tsg, [8, t4, t0], 8, dataSize=8
+    chks t5, t1, LDTCheck
+    wrdh t3, t1, t2
+    wrdl tsl, t1, t5
+    wrbase tsl, t3, dataSize=8
+end:
+    fault "NoFault"
+};
+
 def macroop LLDT_R
 {
     .serialize_after
@@ -218,12 +272,9 @@
     br label("end"), flags=(CEZF,)
     limm t4, 0, dataSize=8
     srli t4, reg, 3, dataSize=2
-    ldst t1, tsg, [8, t4, t0], dataSize=8
-    ld t2, tsg, [8, t4, t0], 8, dataSize=8
+    ld t1, tsg, [8, t4, t0], dataSize=8
     chks reg, t1, LDTCheck
-    wrdh t3, t1, t2
     wrdl tsl, t1, reg
-    wrbase tsl, t3, dataSize=8
 end:
     fault "NoFault"
 };
@@ -236,33 +287,16 @@
     br label("end"), flags=(CEZF,)
     limm t4, 0, dataSize=8
     srli t4, t5, 3, dataSize=2
-    ldst t1, tsg, [8, t4, t0], dataSize=8
-    ld t2, tsg, [8, t4, t0], 8, dataSize=8
+    ld t1, tsg, [8, t4, t0], dataSize=8
     chks t5, t1, LDTCheck
-    wrdh t3, t1, t2
     wrdl tsl, t1, t5
-    wrbase tsl, t3, dataSize=8
 end:
     fault "NoFault"
 };

 def macroop LLDT_P
 {
-    .serialize_after
-    rdip t7
-    ld t5, seg, riprel, disp, dataSize=2
-    chks t5, t0, InGDTCheck, flags=(EZF,)
-    br label("end"), flags=(CEZF,)
-    limm t4, 0, dataSize=8
-    srli t4, t5, 3, dataSize=2
-    ldst t1, tsg, [8, t4, t0], dataSize=8
-    ld t2, tsg, [8, t4, t0], 8, dataSize=8
-    chks t5, t1, LDTCheck
-    wrdh t3, t1, t2
-    wrdl tsl, t1, t5
-    wrbase tsl, t3, dataSize=8
-end:
-    fault "NoFault"
+    panic "LLDT in non-64 bit mode doesn't support RIP addressing."
 };

 def macroop SWAPGS

--
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: I88d3758a66dec3482153df5ec08565427d6c9269
Gerrit-Change-Number: 55884
Gerrit-PatchSet: 13
Gerrit-Owner: Gabe Black <gabe.bl...@gmail.com>
Gerrit-Reviewer: Bradford Beckmann <bradford.beckm...@gmail.com>
Gerrit-Reviewer: Gabe Black <gabe.bl...@gmail.com>
Gerrit-Reviewer: Matt Sinclair <mattdsincl...@gmail.com>
Gerrit-Reviewer: Matthew Poremba <matthew.pore...@amd.com>
Gerrit-Reviewer: kokoro <noreply+kok...@google.com>
Gerrit-MessageType: merged
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