summaryrefslogtreecommitdiff
path: root/src/arch/x86/tlb.cc
diff options
context:
space:
mode:
authorGabe Black <gblack@eecs.umich.edu>2012-04-14 23:24:18 -0700
committerGabe Black <gblack@eecs.umich.edu>2012-04-14 23:24:18 -0700
commitaacb676220ac1e6049304bef31a39090487da71e (patch)
tree3a5b4c951e6be13b59b2a0574e8b31032911acf8 /src/arch/x86/tlb.cc
parentd6031d72df091a71567a7f43649d62b24c80f496 (diff)
downloadgem5-aacb676220ac1e6049304bef31a39090487da71e.tar.xz
X86: Use the AddrTrie class to implement the TLB.
This change also adjusts the TlbEntry class so that it stores the number of address bits wide a page is rather than its size in bytes. In other words, instead of storing 4K for a 4K page, it stores 12. 12 is easy to turn into 4K, but it's a little harder going the other way.
Diffstat (limited to 'src/arch/x86/tlb.cc')
-rw-r--r--src/arch/x86/tlb.cc105
1 files changed, 54 insertions, 51 deletions
diff --git a/src/arch/x86/tlb.cc b/src/arch/x86/tlb.cc
index 100f8cf0f..caa3efc1e 100644
--- a/src/arch/x86/tlb.cc
+++ b/src/arch/x86/tlb.cc
@@ -60,75 +60,79 @@
namespace X86ISA {
-TLB::TLB(const Params *p) : BaseTLB(p), configAddress(0), size(p->size)
+TLB::TLB(const Params *p) : BaseTLB(p), configAddress(0), size(p->size),
+ lruSeq(0)
{
+ if (!size)
+ fatal("TLBs must have a non-zero size.\n");
tlb = new TlbEntry[size];
std::memset(tlb, 0, sizeof(TlbEntry) * size);
- for (int x = 0; x < size; x++)
+ for (int x = 0; x < size; x++) {
+ tlb[x].trieHandle = NULL;
freeList.push_back(&tlb[x]);
+ }
walker = p->walker;
walker->setTLB(this);
}
+void
+TLB::evictLRU()
+{
+ // Find the entry with the lowest (and hence least recently updated)
+ // sequence number.
+
+ unsigned lru = 0;
+ for (unsigned i = 1; i < size; i++) {
+ if (tlb[i].lruSeq < tlb[lru].lruSeq)
+ lru = i;
+ }
+
+ assert(tlb[lru].trieHandle);
+ trie.remove(tlb[lru].trieHandle);
+ tlb[lru].trieHandle = NULL;
+ freeList.push_back(&tlb[lru]);
+}
+
TlbEntry *
TLB::insert(Addr vpn, TlbEntry &entry)
{
//TODO Deal with conflicting entries
TlbEntry *newEntry = NULL;
- if (!freeList.empty()) {
- newEntry = freeList.front();
- freeList.pop_front();
- } else {
- newEntry = entryList.back();
- entryList.pop_back();
- }
+ if (freeList.empty())
+ evictLRU();
+ newEntry = freeList.front();
+ freeList.pop_front();
+
*newEntry = entry;
+ newEntry->lruSeq = nextSeq();
newEntry->vaddr = vpn;
- entryList.push_front(newEntry);
+ newEntry->trieHandle =
+ trie.insert(vpn, TlbEntryTrie::MaxBits - entry.logBytes, newEntry);
return newEntry;
}
-TLB::EntryList::iterator
-TLB::lookupIt(Addr va, bool update_lru)
-{
- //TODO make this smarter at some point
- EntryList::iterator entry;
- for (entry = entryList.begin(); entry != entryList.end(); entry++) {
- if ((*entry)->vaddr <= va && (*entry)->vaddr + (*entry)->size > va) {
- DPRINTF(TLB, "Matched vaddr %#x to entry starting at %#x "
- "with size %#x.\n", va, (*entry)->vaddr, (*entry)->size);
- if (update_lru) {
- entryList.push_front(*entry);
- entryList.erase(entry);
- entry = entryList.begin();
- }
- break;
- }
- }
- return entry;
-}
-
TlbEntry *
TLB::lookup(Addr va, bool update_lru)
{
- EntryList::iterator entry = lookupIt(va, update_lru);
- if (entry == entryList.end())
- return NULL;
- else
- return *entry;
+ TlbEntry *entry = trie.lookup(va);
+ if (entry && update_lru)
+ entry->lruSeq = nextSeq();
+ return entry;
}
void
TLB::invalidateAll()
{
DPRINTF(TLB, "Invalidating all entries.\n");
- while (!entryList.empty()) {
- TlbEntry *entry = entryList.front();
- entryList.pop_front();
- freeList.push_back(entry);
+ for (unsigned i = 0; i < size; i++) {
+ if (tlb[i].trieHandle) {
+ trie.remove(tlb[i].trieHandle);
+ tlb[i].trieHandle = NULL;
+ freeList.push_back(&tlb[i]);
+ }
}
}
@@ -142,13 +146,11 @@ void
TLB::invalidateNonGlobal()
{
DPRINTF(TLB, "Invalidating all non global entries.\n");
- EntryList::iterator entryIt;
- for (entryIt = entryList.begin(); entryIt != entryList.end();) {
- if (!(*entryIt)->global) {
- freeList.push_back(*entryIt);
- entryList.erase(entryIt++);
- } else {
- entryIt++;
+ for (unsigned i = 0; i < size; i++) {
+ if (tlb[i].trieHandle && !tlb[i].global) {
+ trie.remove(tlb[i].trieHandle);
+ tlb[i].trieHandle = NULL;
+ freeList.push_back(&tlb[i]);
}
}
}
@@ -156,10 +158,11 @@ TLB::invalidateNonGlobal()
void
TLB::demapPage(Addr va, uint64_t asn)
{
- EntryList::iterator entry = lookupIt(va, false);
- if (entry != entryList.end()) {
- freeList.push_back(*entry);
- entryList.erase(entry);
+ TlbEntry *entry = trie.lookup(va);
+ if (entry) {
+ trie.remove(entry->trieHandle);
+ entry->trieHandle = NULL;
+ freeList.push_back(entry);
}
}
@@ -345,7 +348,7 @@ TLB::translate(RequestPtr req, ThreadContext *tc, Translation *translation,
return new PageFault(vaddr, true, Write, inUser, false);
}
- Addr paddr = entry->paddr | (vaddr & (entry->size-1));
+ Addr paddr = entry->paddr | (vaddr & mask(entry->logBytes));
DPRINTF(TLB, "Translated %#x -> %#x.\n", vaddr, paddr);
req->setPaddr(paddr);
if (entry->uncacheable)