Gabe Black has uploaded this change for review. (
https://gem5-review.googlesource.com/c/public/gem5/+/55626 )
Change subject: arch-x86: Fix the immediate size for the 0x9a one byte
opcode.
......................................................................
arch-x86: Fix the immediate size for the 0x9a one byte opcode.
This is a far call direct, which has a far pointer (a 16 bit segment
selector and a 16 or 32 bit offset) as an immediate value. The gem5
decoder was expecting no immediate, and so was not gathering one. The
actual microcode for the instruction was taking the junk immediate and
trying to use it which did not work.
This change makes a small update to the table which says how big the
immediate values are for various instructions, changing the entry for
one byte opcode 0x9a from 0 (no immediate) to PO (pointer sized). The
immediate size will be automatically selected by the decoder based on
the PO rule, and the currently active operand size.
Change-Id: Ic290e7bb01dc6165c4eabed214887e4b5adb42da
---
M src/arch/x86/decoder_tables.cc
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/src/arch/x86/decoder_tables.cc b/src/arch/x86/decoder_tables.cc
index 8deb63f..2fba889 100644
--- a/src/arch/x86/decoder_tables.cc
+++ b/src/arch/x86/decoder_tables.cc
@@ -236,7 +236,7 @@
/* 6 */ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , ZW, ZW, BY, BY, 0 , 0 , 0 , 0 ,
/* 7 */ BY, BY, BY, BY, BY, BY, BY, BY, BY, BY, BY, BY, BY, BY, BY, BY,
/* 8 */ BY, ZW, BY, BY, 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 ,
-/* 9 */ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 ,
+/* 9 */ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , PO, 0 , 0 , 0 , 0 , 0 ,
/* A */ VW, VW, VW, VW, 0 , 0 , 0 , 0 , BY, ZW, 0 , 0 , 0 , 0 , 0 , 0 ,
/* B */ BY, BY, BY, BY, BY, BY, BY, BY, VW, VW, VW, VW, VW, VW, VW, VW,
/* C */ BY, BY, WO, 0 , 0 , 0 , BY, ZW, EN, 0 , WO, 0 , 0 , BY, 0 , 0 ,
--
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: Ic290e7bb01dc6165c4eabed214887e4b5adb42da
Gerrit-Change-Number: 55626
Gerrit-PatchSet: 1
Gerrit-Owner: Gabe Black <gabe.bl...@gmail.com>
Gerrit-MessageType: newchange
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