From de79adc50d0143349cfbd3d69306bf13ee8eb39b Mon Sep 17 00:00:00 2001
From: Eyck Jentzsch <eyck@minres.com>
Date: Sat, 17 Aug 2024 12:37:57 +0200
Subject: [PATCH] updates debugger hook to stop before fetching instructions

this relates to https://github.com/Minres/DBT-RISE-RISCV/issues/8 :
Debugger loses control when trap vector fetch fails

and https://github.com/Minres/DBT-RISE-RISCV/issues/7 : Two debugger
single-steps are required at reset vector
---
 gen_input/templates/interp/CORENAME.cpp.gtl | 16 ++++++++++------
 src/iss/arch/riscv_hart_m_p.h               | 18 ++++++++++++------
 src/vm/interp/vm_tgc5c.cpp                  | 16 ++++++++++------
 3 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/gen_input/templates/interp/CORENAME.cpp.gtl b/gen_input/templates/interp/CORENAME.cpp.gtl
index 1c45797..d2ebedd 100644
--- a/gen_input/templates/interp/CORENAME.cpp.gtl
+++ b/gen_input/templates/interp/CORENAME.cpp.gtl
@@ -257,10 +257,14 @@ typename vm_base<ARCH>::virt_addr_t vm_impl<ARCH>::execute_inst(finish_cond_e co
     while(!this->core.should_stop() &&
             !(is_icount_limit_enabled(cond) && icount >= count_limit) &&
             !(is_fcount_limit_enabled(cond) && fetch_count >= count_limit)){
-        fetch_count++;
+        if(this->debugging_enabled())
+            this->tgt_adapter->check_continue(*PC);
+        pc.val=*PC;
         if(fetch_ins(pc, data)!=iss::Ok){
-            this->do_sync(POST_SYNC, std::numeric_limits<unsigned>::max());
-            pc.val = super::core.enter_trap(std::numeric_limits<uint64_t>::max(), pc.val, 0);
+            if(this->sync_exec && PRE_SYNC) this->do_sync(PRE_SYNC, std::numeric_limits<unsigned>::max());
+            process_spawn_blocks();
+            if(this->sync_exec && POST_SYNC) this->do_sync(PRE_SYNC, std::numeric_limits<unsigned>::max());
+            pc.val = super::core.enter_trap(arch::traits<ARCH>::RV_CAUSE_FETCH_ACCESS<<16, pc.val, 0);
         } else {
             if (is_jump_to_self_enabled(cond) &&
                     (instr == 0x0000006f || (instr&0xffff)==0xa001)) throw simulation_stopped(0); // 'J 0' or 'C.J 0'
@@ -311,11 +315,11 @@ typename vm_base<ARCH>::virt_addr_t vm_impl<ARCH>::execute_inst(finish_cond_e co
                 icount++;
                 instret++;
             }
-            cycle++;
-            pc.val=*NEXT_PC;
-            this->core.reg.PC = this->core.reg.NEXT_PC;
+            *PC = *NEXT_PC;
             this->core.reg.trap_state =  this->core.reg.pending_trap;
         }
+        fetch_count++;
+        cycle++;
     }
     return pc;
 }
diff --git a/src/iss/arch/riscv_hart_m_p.h b/src/iss/arch/riscv_hart_m_p.h
index bbd2b49..8b27dec 100644
--- a/src/iss/arch/riscv_hart_m_p.h
+++ b/src/iss/arch/riscv_hart_m_p.h
@@ -689,8 +689,10 @@ iss::status riscv_hart_m_p<BASE, FEAT, LOGCAT>::read(const address_type type, co
                 }
                 return res;
             } catch(trap_access& ta) {
-                this->reg.trap_state = (1UL << 31) | ta.id;
-                fault_data = ta.addr;
+                if( (access & access_type::DEBUG) == 0) {
+                    this->reg.trap_state = (1UL << 31) | ta.id;
+                    fault_data = ta.addr;
+                }
                 return iss::Err;
             }
         } break;
@@ -717,8 +719,10 @@ iss::status riscv_hart_m_p<BASE, FEAT, LOGCAT>::read(const address_type type, co
         }
         return iss::Ok;
     } catch(trap_access& ta) {
-        this->reg.trap_state = (1UL << 31) | ta.id;
-        fault_data = ta.addr;
+        if((access & access_type::DEBUG) == 0) {
+            this->reg.trap_state = (1UL << 31) | ta.id;
+            fault_data = ta.addr;
+        }
         return iss::Err;
     }
 }
@@ -848,8 +852,10 @@ iss::status riscv_hart_m_p<BASE, FEAT, LOGCAT>::write(const address_type type, c
         }
         return iss::Ok;
     } catch(trap_access& ta) {
-        this->reg.trap_state = (1UL << 31) | ta.id;
-        fault_data = ta.addr;
+        if((access & access_type::DEBUG) == 0) {
+            this->reg.trap_state = (1UL << 31) | ta.id;
+            fault_data = ta.addr;
+        }
         return iss::Err;
     }
 }
diff --git a/src/vm/interp/vm_tgc5c.cpp b/src/vm/interp/vm_tgc5c.cpp
index 7cd10ad..7d4161a 100644
--- a/src/vm/interp/vm_tgc5c.cpp
+++ b/src/vm/interp/vm_tgc5c.cpp
@@ -333,10 +333,14 @@ typename vm_base<ARCH>::virt_addr_t vm_impl<ARCH>::execute_inst(finish_cond_e co
     while(!this->core.should_stop() &&
             !(is_icount_limit_enabled(cond) && icount >= count_limit) &&
             !(is_fcount_limit_enabled(cond) && fetch_count >= count_limit)){
-        fetch_count++;
+        if(this->debugging_enabled())
+            this->tgt_adapter->check_continue(*PC);
+        pc.val=*PC;
         if(fetch_ins(pc, data)!=iss::Ok){
-            this->do_sync(POST_SYNC, std::numeric_limits<unsigned>::max());
-            pc.val = super::core.enter_trap(std::numeric_limits<uint64_t>::max(), pc.val, 0);
+            if(this->sync_exec && PRE_SYNC) this->do_sync(PRE_SYNC, std::numeric_limits<unsigned>::max());
+            process_spawn_blocks();
+            if(this->sync_exec && POST_SYNC) this->do_sync(PRE_SYNC, std::numeric_limits<unsigned>::max());
+            pc.val = super::core.enter_trap(arch::traits<ARCH>::RV_CAUSE_FETCH_ACCESS<<16, pc.val, 0);
         } else {
             if (is_jump_to_self_enabled(cond) &&
                     (instr == 0x0000006f || (instr&0xffff)==0xa001)) throw simulation_stopped(0); // 'J 0' or 'C.J 0'
@@ -2673,11 +2677,11 @@ typename vm_base<ARCH>::virt_addr_t vm_impl<ARCH>::execute_inst(finish_cond_e co
                 icount++;
                 instret++;
             }
-            cycle++;
-            pc.val=*NEXT_PC;
-            this->core.reg.PC = this->core.reg.NEXT_PC;
+            *PC = *NEXT_PC;
             this->core.reg.trap_state =  this->core.reg.pending_trap;
         }
+        fetch_count++;
+        cycle++;
     }
     return pc;
 }