arch: [Patch 1/5] Added RISC-V base instruction set RV64I

First of five patches adding RISC-V to GEM5. This patch introduces the
base 64-bit ISA (RV64I) in src/arch/riscv for use with syscall emulation.
The multiply, floating point, and atomic memory instructions will be added
in additional patches, as well as support for more detailed CPU models.
The loader is also modified to be able to parse RISC-V ELF files, and a
"Hello world\!" example for RISC-V is added to test-progs.

Patch 2 will implement the multiply extension, RV64M; patch 3 will implement
the floating point (single- and double-precision) extensions, RV64FD;
patch 4 will implement the atomic memory instructions, RV64A, and patch 5
will add support for timing, minor, and detailed CPU models that is missing
from the first four patches (such as handling locked memory).

[Removed several unused parameters and imports from RiscvInterrupts.py,
RiscvISA.py, and RiscvSystem.py.]
[Fixed copyright information in RISC-V files copied from elsewhere that had
ARM licenses attached.]
[Reorganized instruction definitions in decoder.isa so that they are sorted
by opcode in preparation for the addition of ISA extensions M, A, F, D.]
[Fixed formatting of several files, removed some variables and
instructions that were missed when moving them to other patches, fixed
RISC-V Foundation copyright attribution, and fixed history of files
copied from other architectures using hg copy.]
[Fixed indentation of switch cases in isa.cc.]
[Reorganized syscall descriptions in linux/process.cc to remove large
number of repeated unimplemented system calls and added implmementations
to functions that have received them since it process.cc was first
created.]
[Fixed spacing for some copyright attributions.]
[Replaced the rest of the file copies using hg copy.]
[Fixed style check errors and corrected unaligned memory accesses.]
[Fix some minor formatting mistakes.]
Signed-off by: Alec Roelke

Signed-off by: Jason Lowe-Power <jason@lowepower.com>

1 files changed, 361 insertions, 0 deletions

diff --git a/src/arch/riscv/tlb.cc b/src/arch/riscv/tlb.cc
new file mode 100644
index 000000000..841be2488
--- /dev/null
+++ b/src/arch/riscv/tlb.cc
@@ -0,0 +1,361 @@
+/*
+ * Copyright (c) 2001-2005 The Regents of The University of Michigan
+ * Copyright (c) 2007 MIPS Technologies, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Nathan Binkert
+ *          Steve Reinhardt
+ *          Jaidev Patwardhan
+ *          Zhengxing Li
+ *          Deyuan Guo
+ */
+
+#include "arch/riscv/tlb.hh"
+
+#include <string>
+#include <vector>
+
+#include "arch/riscv/faults.hh"
+#include "arch/riscv/pagetable.hh"
+#include "arch/riscv/pra_constants.hh"
+#include "arch/riscv/utility.hh"
+#include "base/inifile.hh"
+#include "base/str.hh"
+#include "base/trace.hh"
+#include "cpu/thread_context.hh"
+#include "debug/RiscvTLB.hh"
+#include "debug/TLB.hh"
+#include "mem/page_table.hh"
+#include "params/RiscvTLB.hh"
+#include "sim/full_system.hh"
+#include "sim/process.hh"
+
+using namespace std;
+using namespace RiscvISA;
+
+///////////////////////////////////////////////////////////////////////
+//
+//  RISC-V TLB
+//
+
+TLB::TLB(const Params *p)
+    : BaseTLB(p), size(p->size), nlu(0)
+{
+    table = new PTE[size];
+    memset(table, 0, sizeof(PTE[size]));
+    smallPages = 0;
+}
+
+TLB::~TLB()
+{
+    if (table)
+        delete [] table;
+}
+
+// look up an entry in the TLB
+RiscvISA::PTE *
+TLB::lookup(Addr vpn, uint8_t asn) const
+{
+    // assume not found...
+    PTE *retval = nullptr;
+    PageTable::const_iterator i = lookupTable.find(vpn);
+    if (i != lookupTable.end()) {
+        while (i->first == vpn) {
+            int index = i->second;
+            PTE *pte = &table[index];
+
+            /* 1KB TLB Lookup code - from MIPS ARM Volume III - Rev. 2.50 */
+            Addr Mask = pte->Mask;
+            Addr InvMask = ~Mask;
+            Addr VPN  = pte->VPN;
+            if (((vpn & InvMask) == (VPN & InvMask)) &&
+                    (pte->G  || (asn == pte->asid))) {
+                // We have a VPN + ASID Match
+                retval = pte;
+                break;
+            }
+            ++i;
+        }
+    }
+
+    DPRINTF(TLB, "lookup %#x, asn %#x -> %s ppn %#x\n", vpn, (int)asn,
+            retval ? "hit" : "miss", retval ? retval->PFN1 : 0);
+    return retval;
+}
+
+RiscvISA::PTE*
+TLB::getEntry(unsigned Index) const
+{
+    // Make sure that Index is valid
+    assert(Index<size);
+    return &table[Index];
+}
+
+int
+TLB::probeEntry(Addr vpn, uint8_t asn) const
+{
+    // assume not found...
+    int Ind = -1;
+    PageTable::const_iterator i = lookupTable.find(vpn);
+    if (i != lookupTable.end()) {
+        while (i->first == vpn) {
+            int index = i->second;
+            PTE *pte = &table[index];
+
+            /* 1KB TLB Lookup code - from MIPS ARM Volume III - Rev. 2.50 */
+            Addr Mask = pte->Mask;
+            Addr InvMask = ~Mask;
+            Addr VPN = pte->VPN;
+            if (((vpn & InvMask) == (VPN & InvMask)) &&
+                    (pte->G  || (asn == pte->asid))) {
+                // We have a VPN + ASID Match
+                Ind = index;
+                break;
+            }
+            ++i;
+        }
+    }
+    DPRINTF(RiscvTLB,"VPN: %x, asid: %d, Result of TLBP: %d\n",vpn,asn,Ind);
+    return Ind;
+}
+
+inline Fault
+TLB::checkCacheability(RequestPtr &req)
+{
+    Addr VAddrUncacheable = 0xA0000000;
+    // In MIPS, cacheability is controlled by certain bits of the virtual
+    // address or by the TLB entry
+    if ((req->getVaddr() & VAddrUncacheable) == VAddrUncacheable) {
+        // mark request as uncacheable
+        req->setFlags(Request::UNCACHEABLE | Request::STRICT_ORDER);
+    }
+    return NoFault;
+}
+
+void
+TLB::insertAt(PTE &pte, unsigned Index, int _smallPages)
+{
+    smallPages = _smallPages;
+    if (Index > size) {
+        warn("Attempted to write at index (%d) beyond TLB size (%d)",
+                Index, size);
+    } else {
+        // Update TLB
+        DPRINTF(TLB, "TLB[%d]: %x %x %x %x\n",
+                Index, pte.Mask << 11,
+                ((pte.VPN << 11) | pte.asid),
+                ((pte.PFN0 << 6) | (pte.C0 << 3) |
+                 (pte.D0 << 2) | (pte.V0 <<1) | pte.G),
+                ((pte.PFN1 <<6) | (pte.C1 << 3) |
+                 (pte.D1 << 2) | (pte.V1 <<1) | pte.G));
+        if (table[Index].V0 || table[Index].V1) {
+            // Previous entry is valid
+            PageTable::iterator i = lookupTable.find(table[Index].VPN);
+            lookupTable.erase(i);
+        }
+        table[Index]=pte;
+        // Update fast lookup table
+        lookupTable.insert(make_pair(table[Index].VPN, Index));
+    }
+}
+
+// insert a new TLB entry
+void
+TLB::insert(Addr addr, PTE &pte)
+{
+    fatal("TLB Insert not yet implemented\n");
+}
+
+void
+TLB::flushAll()
+{
+    DPRINTF(TLB, "flushAll\n");
+    memset(table, 0, sizeof(PTE[size]));
+    lookupTable.clear();
+    nlu = 0;
+}
+
+void
+TLB::serialize(CheckpointOut &cp) const
+{
+    SERIALIZE_SCALAR(size);
+    SERIALIZE_SCALAR(nlu);
+
+    for (int i = 0; i < size; i++) {
+        ScopedCheckpointSection sec(cp, csprintf("PTE%d", i));
+        table[i].serialize(cp);
+    }
+}
+
+void
+TLB::unserialize(CheckpointIn &cp)
+{
+    UNSERIALIZE_SCALAR(size);
+    UNSERIALIZE_SCALAR(nlu);
+
+    for (int i = 0; i < size; i++) {
+        ScopedCheckpointSection sec(cp, csprintf("PTE%d", i));
+        table[i].unserialize(cp);
+        if (table[i].V0 || table[i].V1) {
+            lookupTable.insert(make_pair(table[i].VPN, i));
+        }
+    }
+}
+
+void
+TLB::regStats()
+{
+    BaseTLB::regStats();
+
+    read_hits
+        .name(name() + ".read_hits")
+        .desc("DTB read hits")
+        ;
+
+    read_misses
+        .name(name() + ".read_misses")
+        .desc("DTB read misses")
+        ;
+
+
+    read_accesses
+        .name(name() + ".read_accesses")
+        .desc("DTB read accesses")
+        ;
+
+    write_hits
+        .name(name() + ".write_hits")
+        .desc("DTB write hits")
+        ;
+
+    write_misses
+        .name(name() + ".write_misses")
+        .desc("DTB write misses")
+        ;
+
+
+    write_accesses
+        .name(name() + ".write_accesses")
+        .desc("DTB write accesses")
+        ;
+
+    hits
+        .name(name() + ".hits")
+        .desc("DTB hits")
+        ;
+
+    misses
+        .name(name() + ".misses")
+        .desc("DTB misses")
+        ;
+
+    accesses
+        .name(name() + ".accesses")
+        .desc("DTB accesses")
+        ;
+
+    hits = read_hits + write_hits;
+    misses = read_misses + write_misses;
+    accesses = read_accesses + write_accesses;
+}
+
+Fault
+TLB::translateInst(RequestPtr req, ThreadContext *tc)
+{
+    if (FullSystem)
+        panic("translateInst not implemented in RISC-V.\n");
+
+    Process * p = tc->getProcessPtr();
+
+    Fault fault = p->pTable->translate(req);
+    if (fault != NoFault)
+        return fault;
+
+    return NoFault;
+}
+
+Fault
+TLB::translateData(RequestPtr req, ThreadContext *tc, bool write)
+{
+    if (FullSystem)
+        panic("translateData not implemented in RISC-V.\n");
+
+    Process * p = tc->getProcessPtr();
+
+    Fault fault = p->pTable->translate(req);
+    if (fault != NoFault)
+        return fault;
+
+    return NoFault;
+}
+
+Fault
+TLB::translateAtomic(RequestPtr req, ThreadContext *tc, Mode mode)
+{
+    if (mode == Execute)
+        return translateInst(req, tc);
+    else
+        return translateData(req, tc, mode == Write);
+}
+
+void
+TLB::translateTiming(RequestPtr req, ThreadContext *tc,
+        Translation *translation, Mode mode)
+{
+    assert(translation);
+    translation->finish(translateAtomic(req, tc, mode), req, tc, mode);
+}
+
+Fault
+TLB::translateFunctional(RequestPtr req, ThreadContext *tc, Mode mode)
+{
+    panic("Not implemented\n");
+    return NoFault;
+}
+
+Fault
+TLB::finalizePhysical(RequestPtr req, ThreadContext *tc, Mode mode) const
+{
+    return NoFault;
+}
+
+
+RiscvISA::PTE &
+TLB::index(bool advance)
+{
+    PTE *pte = &table[nlu];
+
+    if (advance)
+        nextnlu();
+
+    return *pte;
+}
+
+RiscvISA::TLB *
+RiscvTLBParams::create()
+{
+    return new TLB(this);
+}