Gabe Black has submitted this change. (
https://gem5-review.googlesource.com/c/public/gem5/+/55247 )
(
3 is the latest approved patch-set.
No files were changed between the latest approved patch-set and the
submitted one.
)Change subject: arch-x86: Make sure the TLB checks against CS for fetches.
......................................................................
arch-x86: Make sure the TLB checks against CS for fetches.
When instructions perform accesses, they embed the segment being used
into the request flags. When the CPU creates a request instead, for
instance when fetching an instruction, it doesn't know to do that.
This change adds a check in the TLB when makes sure CS is used when
checking a fetch, even if the flags didn't say to.
Change-Id: Ie9da3afc0b10eeb96247353150c64f1829cea41b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55247
Reviewed-by: Matthew Poremba <matthew.pore...@amd.com>
Maintainer: Gabe Black <gabe.bl...@gmail.com>
Tested-by: kokoro <noreply+kok...@google.com>
---
M src/arch/x86/tlb.cc
1 file changed, 25 insertions(+), 0 deletions(-)
Approvals:
Matthew Poremba: Looks good to me, approved
Gabe Black: Looks good to me, approved
kokoro: Regressions pass
diff --git a/src/arch/x86/tlb.cc b/src/arch/x86/tlb.cc
index 7d20e00..3992d73 100644
--- a/src/arch/x86/tlb.cc
+++ b/src/arch/x86/tlb.cc
@@ -335,6 +335,11 @@
if (m5Reg.mode != LongMode) {
DPRINTF(TLB, "Not in long mode. Checking segment
protection.\n");
+ // CPUs won't know to use CS when building fetch requests, so
we
+ // need to override the value of "seg" here if this is a fetch.
+ if (mode == BaseMMU::Execute)
+ seg = SEGMENT_REG_CS;
+
SegAttr attr = tc->readMiscRegNoEffect(MISCREG_SEG_ATTR(seg));
// Check for an unusable segment.
if (attr.unusable) {
--
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: Ie9da3afc0b10eeb96247353150c64f1829cea41b
Gerrit-Change-Number: 55247
Gerrit-PatchSet: 16
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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