ARM Cortex-A15 MPCore Processor Technical Reference Manual

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Memory Management Unit5.6 Intermediate table walk cachesThe Cortex-A15 MPCore processor implements dedicated caches that store intermediate levelsof translation table entries as part of a table walk. Cached entries are associated with an ASID.The TLB and the intermediate caches must be invalidated using the standard architectural rulethat states, if you change a translation table entry at any level of the walk that is associated witha particular ASID, you must invalidate entries that correspond to that ASID and its associatedVA range.Care is required when using the reserved ASID method for context switch. See the ARM ®Architecture Reference Manual ARMv7-A and ARMv7-R edition for more information.Example 5-1 shows how to synchronize ASID and TTBR changes using a reserved ASID.Example 5-1 Using a reserved ASID to synchronize ASID and TTBR changesIn this example, the operating system uses a particular reserved ASID value for thesynchronization of the ASID and the Translation Table Base Register. You can use this approachonly when the size of the mapping for any given virtual address is the same in the old and newtranslation tables. The example uses the value of 0.The software uses the following sequences that must be executed from memory marked asglobal:Change ASID to 0ISBChange Translation Table Base RegisterISBChange ASID to new valueISBIf the code relies on only leaf translation table entries that are cached, it can incorrectly assumethat entries tagged with the reserved ASID are not required to be flushed. For example:• Global leaf entries that remain valid or must be flushed for all ASIDs when modified.• Non-global leaf entries that are not used because the reserved ASID is not set outside thecontext switch code.The incorrect assumption leads to the following failure:• The context switch code sets the ASID to the reserved value.• Speculative fetching reads and caches the first level page table entry, using the currentTTBR, and tagging the entry with the reserved ASID. This is a pointer to a second leveltable.• Context switch completes.• Processing continues, and the process with the page tables terminates. The OS frees andreallocates the page table memory.• A later context switch sets the ASID to the reserved value• Speculative fetching makes use of the cached first level page table entry, because it istagged with the reserved ASID, and uses it to fetch a second level page table entry.Because the memory is reallocated and reused, the entry contains random data that canappear to be a valid, global entry. This second level page table entry is cached.ARM DDI 0438I Copyright © 2011-2013 ARM. All rights reserved. 5-8ID062913Non-Confidential
Memory Management Unit• Context switch completes, and application execution continues.• The application references the address range covered by the cached second level pagetable entry. Because the entry is marked as global, a match occurs and so data is fetchedfrom a random address.NoteWhen you use a reserved ASID, you must invalidate the TLB to deallocate the translation tablememory.ARM DDI 0438I Copyright © 2011-2013 ARM. All rights reserved. 5-9ID062913Non-Confidential
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®ARM®Cortex -A15 MPCoreProcessorR
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ContentsARM Cortex-A15 MPCore Proce
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Contents11.4 PMU register descripti
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PrefaceAbout this bookThis book is
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Preface(continued)Stylemonospace bo
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PrefaceFeedbackARM welcomes feedbac
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Introduction1.1 About the Cortex-A1
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Introduction1.2.3 Debug architectur
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Introduction1.4 InterfacesThe proce
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Introduction• The L2 tag RAM regi
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IntroductionThe ARM product deliver
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Introduction1.7.5 r1p0 - r2p0The fo
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Introduction• Added L1 data TLB s
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Functional Description2.1 About the
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Functional DescriptionLoad/Store un
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Functional Description2.2 Interface
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Functional Description2.3 Clocking
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Functional DescriptionFigure 2-5 sh
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Functional DescriptionAll resets ar
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Functional DescriptionPowerup reset
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Functional Description• nPRESETDB
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Functional Description• L2 unifie
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Functional DescriptionOn entry into
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Functional DescriptionWhen the proc
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Functional DescriptionNoteFigure 2-
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Functional DescriptionRegional cloc
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Functional DescriptionTable 2-3 Val
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Functional Description4. Release th
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Functional DescriptionDebug power d
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Functional DescriptionNoteAfter a p
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Functional DescriptionThe external
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Programmers Model3.1 About the prog
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Programmers Model3.3 Advanced SIMD
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Programmers ModelYou can use the CP
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Programmers Model3.6 Large Physical
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Programmers Model3.8 Modes of opera
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Chapter 4System ControlThis chapter
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System Control4.2 Register summaryT
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System ControlOp1 CRm Op2 Name Rese
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System ControlTable 4-6 c5 register
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System ControlTable 4-8 c7 register
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System ControlTable 4-10 c9 registe
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System Control4.2.14 c15 registersT
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System ControlName CRn Op1 CRm Op2
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System Control4.2.19 Other system c
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System Control4.2.24 Performance mo
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System Control4.2.26 Virtualization
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System Control4.3 Register descript
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System ControlTo access the CTR, re
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System ControlTable 4-34 shows the
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System Control4.3.12 Memory Model F
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System ControlTable 4-40 ID_MMFR3 b
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System Control31 28 27 24 23 20 19
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System ControlTable 4-43 ID_ISAR2 b
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System ControlConfigurationsAvailab
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System ControlMCR p15, 4, , c0, c0,
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System ControlTable 4-52 SCTLR bit
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System Control31 30 29 28 27 26 25
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System ControlTable 4-53 ACTLR bit
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System ControlTable 4-53 ACTLR bit
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System ControlUsage constraints The
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System Control• The L2 internal a
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Page 144 and 145: System ControlTable 4-58 shows the
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Page 164 and 165: System Control31 0DataFigure 4-40 I
Page 168 and 169: System ControlThe data returned fro
Page 170 and 171: System ControlThe data returned fro
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Page 176 and 177: System ControlTable 4-74 L2ACTLR bi
Page 178 and 179: System Control• Is only accessibl
Page 184 and 185: System ControlTable 4-79 L2MERRSR b
Page 186 and 187: Memory Management Unit5.1 About the
Page 188 and 189: Memory Management Unit5.3 TLB match
Page 190 and 191: Memory Management Unit• The TLB t
Page 194 and 195: Memory Management Unit5.7 External
Page 196 and 197: Level 1 Memory System6.1 About the
Page 198 and 199: Level 1 Memory System6.3 L1 instruc
Page 200 and 201: Level 1 Memory System6.4 L1 data me
Page 202 and 203: Level 1 Memory SystemL1 or L2 cache
Page 204 and 205: Level 1 Memory SystemExternal globa
Page 206 and 207: Level 1 Memory System6.5 Program fl
Page 208 and 209: Level 1 Memory SystemReset:• Disa
Page 210 and 211: Chapter 7Level 2 Memory SystemThis
Page 212 and 213: Level 2 Memory System7.2 Cache orga
Page 214 and 215: Level 2 Memory System7.2.5 Register
Page 216 and 217: Level 2 Memory SystemNote• The L2
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Page 220 and 221: Level 2 Memory System7.6 Asynchrono
Page 222 and 223: Level 2 Memory SystemFor certain tr
Page 224 and 225: Level 2 Memory System7.7.6 Snoop fi
Page 226 and 227: Level 2 Memory SystemTable 7-6 show
Page 228 and 229: Chapter 8Generic Interrupt Controll
Page 230 and 231: Generic Interrupt Controller8.2 GIC
Page 232 and 233: Generic Interrupt Controller8.2.4 I
Page 234 and 235: Generic Interrupt Controller8.3 GIC
Page 236 and 237: Generic Interrupt ControllerOffset
Page 238 and 239: Generic Interrupt ControllerTable 8
Page 240 and 241: Generic Interrupt ControllerPrivate
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Generic Interrupt Controller0x1D043
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Generic Interrupt ControllerThe Cor
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Generic Interrupt ControllerTable 8
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Generic Interrupt Controller8.3.8 V
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Generic Timer9.1 About the Generic
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Generic Timer9.3 Generic Timer prog
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Chapter 10DebugThis chapter describ
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Debug• Operating systems.• Hard
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DebugnPRESETDBGThis signal initiali
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DebugTable 10-1 CP14 debug register
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DebugTable 10-1 CP14 debug register
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DebugTable 10-2 DBGDIDR bit assignm
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DebugTable 10-4 shows the DBGDRCR b
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DebugConfigurationsAttributesThe pr
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DebugTable 10-8 DBGBCR bit assignme
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DebugTable 10-10 shows the DBGWCR b
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Debug31 12 11 2 1 0ROMADDR[31:12]Re
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Debug10.4.12 OS Lock Status Registe
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DebugTable 10-15 shows the DBGPRCR
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DebugTable 10-16 DBGDSAR bit assign
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Debug31 1 0ReservedIntegration mode
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DebugTable 10-22 shows the DBGDEVID
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Debug10.4.23 Component Identificati
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Debug10.6 External debug interfaceT
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DebugIf software running on the pro
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Performance Monitor Unit11.1 About
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Performance Monitor Unit11.3 PMU re
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Performance Monitor UnitTable 11-1
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Performance Monitor Unit11.5 Effect
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Performance Monitor Unit11.7 Interr
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Chapter 12Program Trace MacrocellTh
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Program Trace Macrocell12.2 PTM opt
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Program Trace MacrocellYou can also
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Program Trace Macrocell12.5 PTM pro
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Program Trace Macrocellarchitecture
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Program Trace Macrocell12.6 Registe
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Program Trace MacrocellTable 12-4 P
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Program Trace MacrocellTable 12-5 E
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Program Trace MacrocellTable 12-6 E
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Program Trace Macrocell31 26 25 24
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Program Trace Macrocell12.7.8 Confi
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Program Trace Macrocell12.7.10 Auxi
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Program Trace Macrocell31 4 3 2 0Re
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Program Trace MacrocellTable 12-17
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Program Trace Macrocell31 7 60Reser
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Program Trace MacrocellThe Componen
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Cross Trigger13.1 About the cross t
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Cross Trigger13.3 Cortex-A15 CTIIn
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Chapter 14NEON and VFP UnitThis cha
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NEON and VFP UnitARM DDI 0438I Copy
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NEON and VFP UnitSee the ARM ® Arc
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NEON and VFP UnitConfigurationsAvai
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NEON and VFP UnitTable 14-5 FPSCR b
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NEON and VFP UnitTable 14-6 MVFR1 b
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NEON and VFP Unit31 30 29 0Reserved
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Signal DescriptionsA.1 About the si
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Signal DescriptionsA.3 Reset signal
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Signal DescriptionsA.5 Generic Inte
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Signal DescriptionsA.6 Generic Time
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Signal DescriptionsA.8 Power manage
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Signal DescriptionsA.9 AXI interfac
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Signal DescriptionsWrite address ch
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Signal DescriptionsTable A-14 Read
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Signal DescriptionsTable A-20 Write
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Signal DescriptionsA.10 External de
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Signal DescriptionsTable A-27 Misce
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Signal DescriptionsA.12 Cross trigg
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Signal DescriptionsA.14 DFT and MBI
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Appendix BRevisionsThis appendix de
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RevisionsTable B-3 Differences betw
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