diff options
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/translation.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/translation.hh')
-rw-r--r-- | src/cpu/translation.hh | 32 |
1 files changed, 28 insertions, 4 deletions
diff --git a/src/cpu/translation.hh b/src/cpu/translation.hh index 7db7c381a..60953540f 100644 --- a/src/cpu/translation.hh +++ b/src/cpu/translation.hh @@ -1,4 +1,16 @@ /* + * Copyright (c) 2011 ARM Limited + * All rights reserved. + * + * The license below extends only to copyright in the software and shall + * not be construed as granting a license to any other intellectual + * property including but not limited to intellectual property relating + * to a hardware implementation of the functionality of the software + * licensed hereunder. You may use the software subject to the license + * terms below provided that you ensure that this notice is replicated + * unmodified and in its entirety in all distributions of the software, + * modified or unmodified, in source code or in binary form. + * * Copyright (c) 2002-2005 The Regents of The University of Michigan * Copyright (c) 2009 The University of Edinburgh * All rights reserved. @@ -53,6 +65,7 @@ class WholeTranslationState Fault faults[2]; public: + bool delay; bool isSplit; RequestPtr mainReq; RequestPtr sreqLow; @@ -67,8 +80,8 @@ class WholeTranslationState */ WholeTranslationState(RequestPtr _req, uint8_t *_data, uint64_t *_res, BaseTLB::Mode _mode) - : outstanding(1), isSplit(false), mainReq(_req), sreqLow(NULL), - sreqHigh(NULL), data(_data), res(_res), mode(_mode) + : outstanding(1), delay(false), isSplit(false), mainReq(_req), + sreqLow(NULL), sreqHigh(NULL), data(_data), res(_res), mode(_mode) { faults[0] = faults[1] = NoFault; assert(mode == BaseTLB::Read || mode == BaseTLB::Write); @@ -82,8 +95,9 @@ class WholeTranslationState WholeTranslationState(RequestPtr _req, RequestPtr _sreqLow, RequestPtr _sreqHigh, uint8_t *_data, uint64_t *_res, BaseTLB::Mode _mode) - : outstanding(2), isSplit(true), mainReq(_req), sreqLow(_sreqLow), - sreqHigh(_sreqHigh), data(_data), res(_res), mode(_mode) + : outstanding(2), delay(false), isSplit(true), mainReq(_req), + sreqLow(_sreqLow), sreqHigh(_sreqHigh), data(_data), res(_res), + mode(_mode) { faults[0] = faults[1] = NoFault; assert(mode == BaseTLB::Read || mode == BaseTLB::Write); @@ -221,6 +235,16 @@ class DataTranslation : public BaseTLB::Translation } /** + * Signal the translation state that the translation has been delayed due + * to a hw page table walk. Split requests are transparently handled. + */ + void + markDelayed() + { + state->delay = true; + } + + /** * Finish this part of the translation and indicate that the whole * translation is complete if the state says so. */ |