From: Nikos Nikoleris <nikos.nikoleris@arm.com>
Date: Tue, 21 Feb 2017 14:14:44 +0000 (+0000)
Subject: arm: Blame the right instruction address on a Prefetch Abort
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=2213fba5c5c4ea85477b7c5985e10d2f17f027c6;p=gem5.git

arm: Blame the right instruction address on a Prefetch Abort

CPU models (e.g., O3CPU) issue instruction fetches for the whole cache
block rather than a specific instruction. Consequently the TLB lookups
translate the cache block virtual address. When the TLB lookup fails,
however, the Prefetch Abort must be raised for the PC of the
instruction that caused the fault rather than for the address of the
block.

This change fixes the way we instantiate the PrefetchAbort faults to
use the PC of the request rather the address of the instruction fetch
request.

Change-Id: I8e45549da1c3be55ad204a060029c95ce822a851
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>
Reviewed-by: Rekai Gonzalez Alberquilla <rekai.gonzalezalberquilla@arm.com>
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
---

diff --git a/src/arch/arm/tlb.cc b/src/arch/arm/tlb.cc
index 85bc12c5b..eeccca0c0 100644
--- a/src/arch/arm/tlb.cc
+++ b/src/arch/arm/tlb.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2013, 2016 ARM Limited
+ * Copyright (c) 2010-2013, 2016-2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -642,12 +642,15 @@ TLB::checkPermissions(TlbEntry *te, RequestPtr req, Mode mode)
             DPRINTF(TLB, "TLB Fault: Data abort on domain. DACR: %#x"
                     " domain: %#x write:%d\n", dacr,
                     static_cast<uint8_t>(te->domain), is_write);
-            if (is_fetch)
+            if (is_fetch) {
+                // Use PC value instead of vaddr because vaddr might
+                // be aligned to cache line and should not be the
+                // address reported in FAR
                 return std::make_shared<PrefetchAbort>(
-                    vaddr,
+                    req->getPC(),
                     ArmFault::DomainLL + te->lookupLevel,
                     isStage2, tranMethod);
-            else
+            } else
                 return std::make_shared<DataAbort>(
                     vaddr, te->domain, is_write,
                     ArmFault::DomainLL + te->lookupLevel,
@@ -735,8 +738,10 @@ TLB::checkPermissions(TlbEntry *te, RequestPtr req, Mode mode)
         DPRINTF(TLB, "TLB Fault: Prefetch abort on permission check. AP:%d "
                      "priv:%d write:%d ns:%d sif:%d sctlr.afe: %d \n",
                      ap, is_priv, is_write, te->ns, scr.sif,sctlr.afe);
+        // Use PC value instead of vaddr because vaddr might be aligned to
+        // cache line and should not be the address reported in FAR
         return std::make_shared<PrefetchAbort>(
-            vaddr,
+            req->getPC(),
             ArmFault::PermissionLL + te->lookupLevel,
             isStage2, tranMethod);
     } else if (abt | hapAbt) {