ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

B3.13.3 Address translation
Virtual Memory System Architecture (VMSA)
The following pseudocode describes address translation in a VMSA implementation:
// TranslateAddressV()
// ===================
AddressDescriptor TranslateAddressV(bits(32) va, boolean ispriv, boolean iswrite)
mva = FCSETranslate(va);
if SCTLR.M == ‘1’ then // MMU is enabled
(tlbhit, tlbrecord) = CheckTLB(CONTEXTIDR.ASID, mva);
if !tlbhit then
tlbrecord = TranslationTableWalk(mva, iswrite);
if CheckDomain(tlbrecord.domain, mva, tlbrecord.sectionnotpage, iswrite) then
CheckPermission(tlbrecord.perms, mva, tlbrecord.sectionnotpage, iswrite, ispriv);
else
tlbrecord = TranslationTableWalk(mva, iswrite);
return tlbrecord.addrdesc;
B3.13.4 Domain checking
The following pseudocode describes domain checking:
// CheckDomain()
// =============
boolean CheckDomain(bits(4) domain, bits(32) mva, boolean sectionnotpage, boolean iswrite)
bitpos = 2*UInt(domain);
case DACR of
when ‘00’ DataAbort(mva, domain, sectionnotpage, iswrite, DAbort_Domain);
when ‘01’ permissioncheck = TRUE;
when ‘10’ UNPREDICTABLE;
when ‘11’ permissioncheck = FALSE;
return permissioncheck;
ARM DDI 0406B Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. B3-157