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mem-cache: Fix possible crash in base prefetcher (#871)

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When processing memory Packets for prefetch, the `PrefetchInfo` class
constructor will attempt to copy the `Packet` data. In cases where the
`Packet` under consideration does not contain data, an assertion will be
triggered in the Packet's `getConstPtr` method, causing the simulation
to crash.

This problem was first exposed by Bug #580 when processing an
`UpgradeReq` memory packet.

This patch addresses the problem by suppressing the copying of the
`Packet` data during construction of a `PrefetchInfo` object in cases
where the `Packet` has no data.

This patch addresses Bug #580 [1], which was exposed by PR #564 [2],
subsequently reverted by PR #581 [3]

[1] https://github.com/gem5/gem5/issues/580
[2] https://github.com/gem5/gem5/pull/564
[3] https://github.com/gem5/gem5/pull/581

Change-Id: Ic1e828c0887f4003441b61647440c8e912bf0fbc
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
This commit is contained in:
Richard Cooper
2024-02-17 22:14:57 +00:00
committed by GitHub
parent 47c4dad869
commit 308fef6b46
1 changed files with 2 additions and 2 deletions
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4
src/mem/cache/prefetch/base.cc vendored
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2013-2014, 2023 ARM Limited
* Copyright (c) 2013-2014, 2023-2024 Arm Limited
* All rights reserved.
*
* The license below extends only to copyright in the software and shall
@@ -65,7 +65,7 @@ Base::PrefetchInfo::PrefetchInfo(PacketPtr pkt, Addr addr, bool miss)
paddress(pkt->req->getPaddr()), cacheMiss(miss)
{
unsigned int req_size = pkt->req->getSize();
if (!write && miss) {
if ((!write && miss) || !pkt->hasData()) {
data = nullptr;
} else {
data = new uint8_t[req_size];