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| author | Giacomo Gabrielli <Giacomo.Gabrielli@arm.com> | 2011-02-11 18:29:35 -0600 |
|---|---|---|
| committer | Giacomo Gabrielli <Giacomo.Gabrielli@arm.com> | 2011-02-11 18:29:35 -0600 |
| commit | e2507407b17188dca802082434cfe0230d9bfa61 (patch) | |
| tree | 6913f9325a7c2fc9c6e99119c61f014e10707842 /src/cpu/o3/iew_impl.hh | |
| parent | 453dbc772dba92dbceb44eaeef3c617d17d63e84 (diff) | |
| download | gem5-e2507407b17188dca802082434cfe0230d9bfa61.tar.xz | |
O3: Enhance data address translation by supporting hardware page table walkers.
Some ISAs (like ARM) relies on hardware page table walkers. For those ISAs,
when a TLB miss occurs, initiateTranslation() can return with NoFault but with
the translation unfinished.
Instructions experiencing a delayed translation due to a hardware page table
walk are deferred until the translation completes and kept into the IQ. In
order to keep track of them, the IQ has been augmented with a queue of the
outstanding delayed memory instructions. When their translation completes,
instructions are re-executed (only their initiateAccess() was already
executed; their DTB translation is now skipped). The IEW stage has been
modified to support such a 2-pass execution.
Diffstat (limited to 'src/cpu/o3/iew_impl.hh')
| -rw-r--r-- | src/cpu/o3/iew_impl.hh | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/src/cpu/o3/iew_impl.hh b/src/cpu/o3/iew_impl.hh index 3f3761ff3..03f73c798 100644 --- a/src/cpu/o3/iew_impl.hh +++ b/src/cpu/o3/iew_impl.hh @@ -1241,12 +1241,33 @@ DefaultIEW<Impl>::executeInsts() // Loads will mark themselves as executed, and their writeback // event adds the instruction to the queue to commit fault = ldstQueue.executeLoad(inst); + + if (inst->isTranslationDelayed() && + fault == NoFault) { + // A hw page table walk is currently going on; the + // instruction must be deferred. + DPRINTF(IEW, "Execute: Delayed translation, deferring " + "load.\n"); + instQueue.deferMemInst(inst); + continue; + } + if (inst->isDataPrefetch() || inst->isInstPrefetch()) { fault = NoFault; } } else if (inst->isStore()) { fault = ldstQueue.executeStore(inst); + if (inst->isTranslationDelayed() && + fault == NoFault) { + // A hw page table walk is currently going on; the + // instruction must be deferred. + DPRINTF(IEW, "Execute: Delayed translation, deferring " + "store.\n"); + instQueue.deferMemInst(inst); + continue; + } + // If the store had a fault then it may not have a mem req if (fault != NoFault || inst->readPredicate() == false || !inst->isStoreConditional()) { |