riscv: Implement translateFunctional.

Change-Id: Ibe8adea8f66c7de22ee2ab0da54e866cd05fc257
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/26547
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Matthew Poremba <matthew.poremba@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/riscv/tlb.cc

@@ -380,6 +380,34 @@ TLB::translateTiming(const RequestPtr &req, ThreadContext *tc,
     translation->finish(translateAtomic(req, tc, mode), req, tc, mode);
 }
 
+Fault
+TLB::translateFunctional(const RequestPtr &req, ThreadContext *tc, Mode mode)
+{
+    panic_if(FullSystem,
+            "translateFunctional not implemented for full system.");
+
+    const Addr vaddr = req->getVaddr();
+    Process *process = tc->getProcessPtr();
+    const auto *pte = process->pTable->lookup(vaddr);
+
+    if (!pte && mode != Execute) {
+        // Check if we just need to grow the stack.
+        if (process->fixupStackFault(vaddr)) {
+            // If we did, lookup the entry for the new page.
+            pte = process->pTable->lookup(vaddr);
+        }
+    }
+
+    if (!pte)
+        return std::make_shared<GenericPageTableFault>(req->getVaddr());
+
+    Addr paddr = pte->paddr | process->pTable->pageOffset(vaddr);
+
+    DPRINTF(TLB, "Translated (functional) %#x -> %#x.\n", vaddr, paddr);
+    req->setPaddr(paddr);
+    return NoFault;
+}
+
 Fault
 TLB::finalizePhysical(const RequestPtr &req,
                       ThreadContext *tc, Mode mode) const

src/arch/riscv/tlb.hh

@@ -111,6 +111,8 @@ class TLB : public BaseTLB
     void translateTiming(
             const RequestPtr &req, ThreadContext *tc,
             Translation *translation, Mode mode) override;
+    Fault translateFunctional(
+            const RequestPtr &req, ThreadContext *tc, Mode mode) override;
     Fault finalizePhysical(
             const RequestPtr &req,
             ThreadContext *tc, Mode mode) const override;