commit 3e52d9fb3328258139f3523175d28ae8f11af702
author Maximilian Stein <maximilian.stein@tu-dresden.de> Mon Jan 29 12:21:32 2018 +0100
committer Christian Menard <christian.menard@tu-dresden.de> Tue Jan 30 09:52:13 2018 +0000
tree 41340b7487e2aae28167a68cd0e1b9a44b43e3fb
parent 89f2871168bcd2a69f3edc2e9f12f3bc66101128

arch-x86: Granularity bit and segment limit

If set, the granularity bit indicates that the segment limit of segment
descriptors shall be interpreted as number of 4K blocks rather than
bytes.

The high part (bit 48 to 51) of segment descriptor limits is only 4 bits
wide while the low part (bit 0 to 15) spans 16 bits.

Change-Id: Ie386224ca815275fdb31498fe68310ed9c62cc87
Reviewed-on: https://gem5-review.googlesource.com/7601
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/arch/x86/system.cc

diff --git a/src/arch/x86/system.cc b/src/arch/x86/system.cc
index ecde836..69e013f 100644
--- a/src/arch/x86/system.cc
+++ b/src/arch/x86/system.cc
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2007 The Hewlett-Packard Development Company
+ * Copyright (c) 2018 TU Dresden
  * All rights reserved.
  *
  * The license below extends only to copyright in the software and shall
@@ -35,6 +36,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * Authors: Gabe Black
+ *          Maximilian Stein
  */
 
 #include "arch/x86/system.hh"
@@ -67,6 +69,8 @@
                                   seg == SEGMENT_REG_TSL ||
                                   seg == SYS_SEGMENT_REG_TR;
     uint64_t limit = desc.limitLow | (desc.limitHigh << 16);
+    if (desc.g)
+        limit = (limit << 12) | mask(12);
 
     SegAttr attr = 0;
 
@@ -155,8 +159,8 @@
     initDesc.d = 0;               // operand size
     initDesc.g = 1;               // granularity
     initDesc.s = 1;               // system segment
-    initDesc.limitHigh = 0xFFFF;
-    initDesc.limitLow = 0xF;
+    initDesc.limitHigh = 0xF;
+    initDesc.limitLow = 0xFFFF;
     initDesc.baseHigh = 0x0;
     initDesc.baseLow = 0x0;