From 34c5d537aff74321bc23a66820c6580aa169bef5 Mon Sep 17 00:00:00 2001
From: Yu-hsin Wang <yuhsingw@google.com>
Date: Tue, 30 Mar 2021 16:07:03 +0800
Subject: [PATCH] fastmodel: handling amba far atomic transaction

Change-Id: I360c2a2bd415524b2a76434a13920f94360afa0f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/44646
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
---
 src/arch/arm/fastmodel/SConscript            |  2 +
 src/arch/arm/fastmodel/amba_to_tlm_bridge.cc | 79 ++++++++++++++++++++
 src/arch/arm/fastmodel/amba_to_tlm_bridge.hh |  1 +
 3 files changed, 82 insertions(+)

diff --git a/src/arch/arm/fastmodel/SConscript b/src/arch/arm/fastmodel/SConscript
index c659434b48..257c001531 100644
--- a/src/arch/arm/fastmodel/SConscript
+++ b/src/arch/arm/fastmodel/SConscript
@@ -104,6 +104,8 @@ def staticify(env, name):
 env.Append(CCFLAGS='-pthread')
 
 cpppaths = (
+    pvlib_home.Dir('examples/SystemCExport/Common/include'),
+    pvlib_home.Dir('include'),
     pvlib_home.Dir('include/fmruntime'),
     pvlib_home.Dir('include/fmruntime/eslapi'),
     pvlib_home.Dir('Iris/include'),
diff --git a/src/arch/arm/fastmodel/amba_to_tlm_bridge.cc b/src/arch/arm/fastmodel/amba_to_tlm_bridge.cc
index 82f84d80cb..8826f3e815 100644
--- a/src/arch/arm/fastmodel/amba_to_tlm_bridge.cc
+++ b/src/arch/arm/fastmodel/amba_to_tlm_bridge.cc
@@ -27,7 +27,43 @@
 
 #include "arch/arm/fastmodel/amba_to_tlm_bridge.hh"
 
+#include "base/amo.hh"
 #include "params/AmbaToTlmBridge64.hh"
+#include "pv/FarAtomicService.h"
+#include "pv_userpayload_extension.h"
+#include "systemc/tlm_bridge/sc_ext.hh"
+
+namespace {
+
+// According to AbstractMemory::access in mem/abstract_mem.cc, the gem5 memory
+// model would set original data into the packet buffer. However, the TLM
+// request with atomic operation doesn't carry a valid buffer because the
+// resource is all allocated in atomic extension. Preventing from segmentation
+// fault, we allocate a random buffer and share it with all atomic transactions
+// since we don't really care about the content of it.
+uint8_t dummy_buffer[64] = {};
+
+struct FarAtomicOpFunctor : public AtomicOpFunctor
+{
+    FarAtomicOpFunctor(far_atomic::FarAtomic *_fa) : fa(_fa) {}
+
+    void
+    operator() (uint8_t *p) override
+    {
+        fa->serviceWasFound();
+        fa->doAtomicOperation(p);
+    }
+
+    AtomicOpFunctor *
+    clone() override
+    {
+        return new FarAtomicOpFunctor(*this);
+    }
+
+    far_atomic::FarAtomic *fa;
+};
+
+}
 
 namespace FastModel
 {
@@ -63,6 +99,7 @@ void
 AmbaToTlmBridge64::bTransport(amba_pv::amba_pv_transaction &trans,
                               sc_core::sc_time &t)
 {
+    maybeSetupAtomicExtension(trans);
     return initiatorProxy->b_transport(trans, t);
 }
 
@@ -86,6 +123,48 @@ AmbaToTlmBridge64::invalidateDirectMemPtr(sc_dt::uint64 start_range,
     targetProxy->invalidate_direct_mem_ptr(start_range, end_range);
 }
 
+void
+AmbaToTlmBridge64::maybeSetupAtomicExtension(
+    amba_pv::amba_pv_transaction &trans)
+{
+    Gem5SystemC::AtomicExtension *atomic_ex = nullptr;
+    trans.get_extension(atomic_ex);
+    if (atomic_ex)
+        return;
+
+    pv_userpayload_extension *user_ex = nullptr;
+    trans.get_extension(user_ex);
+    if (!user_ex)
+        return;
+
+    pv::UserPayloadBase *upb = user_ex->get_user_payload();
+    uint32_t appid = upb->get_appID();
+    if (appid != pv::UserPayloadBase::SERVICE_REQUEST)
+        return;
+
+    std::pair<void *, std::size_t> u_data = user_ex->get_user_data();
+    far_atomic::FarAtomic *fa = static_cast<far_atomic::FarAtomic *>(
+        u_data.first);
+
+    // Correct the request size manually and give it a dummy buffer preventing
+    // from segmentation fault.
+    fatal_if(
+        fa->getDataValueSizeInBytes() > sizeof(dummy_buffer),
+        "atomic operation(%d) is larger than dummy buffer(%d)",
+        fa->getDataValueSizeInBytes(), sizeof(dummy_buffer));
+    trans.set_data_length(fa->getDataValueSizeInBytes());
+    trans.set_data_ptr(dummy_buffer);
+
+    // The return value would store in the extension. We don't need to specify
+    // need_return here.
+    atomic_ex = new Gem5SystemC::AtomicExtension(
+        std::make_shared<FarAtomicOpFunctor>(fa), false);
+    if (trans.has_mm())
+        trans.set_auto_extension(atomic_ex);
+    else
+        trans.set_extension(atomic_ex);
+}
+
 } // namespace FastModel
 
 FastModel::AmbaToTlmBridge64 *
diff --git a/src/arch/arm/fastmodel/amba_to_tlm_bridge.hh b/src/arch/arm/fastmodel/amba_to_tlm_bridge.hh
index d0e52d00cd..0bb4c20f2b 100644
--- a/src/arch/arm/fastmodel/amba_to_tlm_bridge.hh
+++ b/src/arch/arm/fastmodel/amba_to_tlm_bridge.hh
@@ -54,6 +54,7 @@ class AmbaToTlmBridge64 : public amba_pv::amba_pv_to_tlm_bridge<64>
     unsigned int transportDbg(amba_pv::amba_pv_transaction &trans);
     void invalidateDirectMemPtr(sc_dt::uint64 start_range,
                                 sc_dt::uint64 end_range);
+    void maybeSetupAtomicExtension(amba_pv::amba_pv_transaction &trans);
 
     tlm_utils::simple_target_socket<
         AmbaToTlmBridge64, 64, tlm::tlm_base_protocol_types> targetProxy;