From: Matthew Poremba <matthew.poremba@amd.com>
Date: Mon, 6 Apr 2020 18:09:32 +0000 (-0500)
Subject: arch-x86: Do not fixup faults in TLB
X-Git-Tag: v20.0.0.0~208
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=553d2079ad8687944cc1912217cecb09e30afba0;p=gem5.git

arch-x86: Do not fixup faults in TLB

Faults in the TLB ought to cause a page walk. Force that by removing
the fixup in X86 TLB.

This fixes rare race conditions where a timing page walk is
intercepted by a TLB miss which fixes up the fault resulting in
double calls to allocateMem in Process class.

Change-Id: Iaef4d636cd2997144d8bc5012cd7c2a0a97102e5
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/27507
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
---

diff --git a/src/arch/x86/tlb.cc b/src/arch/x86/tlb.cc
index 53492b033..baeeb66bd 100644
--- a/src/arch/x86/tlb.cc
+++ b/src/arch/x86/tlb.cc
@@ -397,13 +397,6 @@ TLB::translate(const RequestPtr &req,
                     Process *p = tc->getProcessPtr();
                     const EmulationPageTable::Entry *pte =
                         p->pTable->lookup(vaddr);
-                    if (!pte && mode != Execute) {
-                        // Check if we just need to grow the stack.
-                        if (p->fixupFault(vaddr)) {
-                            // If we did, lookup the entry for the new page.
-                            pte = p->pTable->lookup(vaddr);
-                        }
-                    }
                     if (!pte) {
                         return std::make_shared<PageFault>(vaddr, true, mode,
                                                            true, false);