Merge pull request #1967 from mslijepc/mslijepc_20250429_observability-hooks

adding observability hooks to mmu

riscv/mmu.h

@@ -20,6 +20,21 @@
 const reg_t PGSIZE = 1 << PGSHIFT;
 #define MAX_PADDR_BITS 64
 
+// observability hooks for load, store and fetch
+// intentionally empty not to cause runtime overhead
+// can be redefined if needed 
+#ifndef MMU_OBSERVE_FETCH
+#define MMU_OBSERVE_FETCH(addr, insn, length)
+#endif
+
+#ifndef MMU_OBSERVE_LOAD
+#define MMU_OBSERVE_LOAD(addr, data, length)
+#endif
+
+#ifndef MMU_OBSERVE_STORE
+#define MMU_OBSERVE_STORE(addr, data, length)
+#endif
+
 struct insn_fetch_t
 {
   insn_func_t func;
@@ -89,6 +104,8 @@ public:
       load_slow_path(addr, sizeof(T), (uint8_t*)&res, xlate_flags);
     }
 
+    MMU_OBSERVE_LOAD(addr,from_target(res),sizeof(T));
+
     return from_target(res);
   }
 
@@ -117,6 +134,7 @@ public:
 
   template<typename T>
   void ALWAYS_INLINE store(reg_t addr, T val, xlate_flags_t xlate_flags = {}) {
+    MMU_OBSERVE_STORE(addr, val, sizeof(T));
     bool aligned = (addr & (sizeof(T) - 1)) == 0;
     auto [tlb_hit, host_addr, _] = access_tlb(tlb_store, addr);
 
@@ -323,15 +341,17 @@ public:
         tracer.trace(paddr, paddr + length, FETCH);
       }
     }
-
+    MMU_OBSERVE_FETCH(addr, insn, length);
     return entry;
   }
 
   inline icache_entry_t* access_icache(reg_t addr)
   {
     icache_entry_t* entry = &icache[icache_index(addr)];
-    if (likely(entry->tag == addr))
+    if (likely(entry->tag == addr)){
+      MMU_OBSERVE_FETCH(addr, entry->data.insn, insn_length(entry->data.insn.bits()));
       return entry;
+    }
     return refill_icache(addr, entry);
   }