From: Gabe Black <gblack@eecs.umich.edu>
Date: Thu, 12 Jun 2008 04:51:50 +0000 (-0400)
Subject: X86: In non 64bit mode, throw a fault when a NULL segment is accessed.
X-Git-Tag: m5_2.0_beta6~151
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b05299253fdd5a8a913f2799b7cdd2df040c8559;p=gem5.git

X86: In non 64bit mode, throw a fault when a NULL segment is accessed.
---

diff --git a/src/arch/x86/tlb.cc b/src/arch/x86/tlb.cc
index f5e214a88..5d101a5ae 100644
--- a/src/arch/x86/tlb.cc
+++ b/src/arch/x86/tlb.cc
@@ -571,6 +571,9 @@ TLB::translate(RequestPtr &req, ThreadContext *tc, bool write, bool execute)
         // If we're not in 64-bit mode, do protection/limit checks
         if (!efer.lma || !csAttr.longMode) {
             DPRINTF(TLB, "Not in long mode. Checking segment protection.\n");
+            // Check for a NULL segment selector.
+            if (!tc->readMiscRegNoEffect(MISCREG_SEG_SEL(seg)))
+                return new GeneralProtection(0);
             SegAttr attr = tc->readMiscRegNoEffect(MISCREG_SEG_ATTR(seg));
             if (!attr.writable && write)
                 return new GeneralProtection(0);