Merge pull request #173 from riscv/no_progbuf3

Add support for abstract debug access to CSRs and FPRs

2 files changed, 98 insertions, 35 deletions

diff --git a/riscv/debug_module.cc b/riscv/debug_module.cc
index 12956a5..39e1ae0 100644
--- a/riscv/debug_module.cc
+++ b/riscv/debug_module.cc
@@ -24,6 +24,10 @@ debug_module_t::debug_module_t(sim_t *sim, unsigned progbufsize, unsigned max_bu
   debug_abstract_start(debug_progbuf_start - debug_abstract_size*4),
   sim(sim)
 {
+  D(fprintf(stderr, "debug_data_start=0x%x\n", debug_data_start));
+  D(fprintf(stderr, "debug_progbuf_start=0x%x\n", debug_progbuf_start));
+  D(fprintf(stderr, "debug_abstract_start=0x%x\n", debug_abstract_start));
+
   program_buffer = new uint8_t[program_buffer_bytes];
 
   memset(halted, 0, sizeof(halted));
@@ -489,51 +493,110 @@ bool debug_module_t::perform_abstract_command()
       return true;
     }
 
+    unsigned i = 0;
     if (get_field(command, AC_ACCESS_REGISTER_TRANSFER)) {
 
-      if (regno < 0x1000 || regno >= 0x1020) {
-        abstractcs.cmderr = CMDERR_NOTSUP;
-        return true;
-      }
+      if (regno < 0x1000 && progbufsize < 2) {
+        // Make the debugger use the program buffer if it's available, so it
+        // can test both use cases.
+        write32(debug_abstract, i++, csrw(S0, CSR_DSCRATCH));
+
+        if (write) {
+          switch (size) {
+            case 2:
+              write32(debug_abstract, i++, lw(S0, ZERO, debug_data_start));
+              break;
+            case 3:
+              write32(debug_abstract, i++, ld(S0, ZERO, debug_data_start));
+              break;
+            default:
+              abstractcs.cmderr = CMDERR_NOTSUP;
+              return true;
+          }
+          write32(debug_abstract, i++, csrw(S0, regno));
+
+        } else {
+          write32(debug_abstract, i++, csrr(S0, regno));
+          switch (size) {
+            case 2:
+              write32(debug_abstract, i++, sw(S0, ZERO, debug_data_start));
+              break;
+            case 3:
+              write32(debug_abstract, i++, sd(S0, ZERO, debug_data_start));
+              break;
+            default:
+              abstractcs.cmderr = CMDERR_NOTSUP;
+              return true;
+          }
+        }
+        write32(debug_abstract, i++, csrr(S0, CSR_DSCRATCH));
+
+      } else if (regno >= 0x1000 && regno < 0x1020) {
+        unsigned regnum = regno - 0x1000;
+
+        switch (size) {
+          case 2:
+            if (write)
+              write32(debug_abstract, i++, lw(regnum, ZERO, debug_data_start));
+            else
+              write32(debug_abstract, i++, sw(regnum, ZERO, debug_data_start));
+            break;
+          case 3:
+            if (write)
+              write32(debug_abstract, i++, ld(regnum, ZERO, debug_data_start));
+            else
+              write32(debug_abstract, i++, sd(regnum, ZERO, debug_data_start));
+            break;
+          default:
+            abstractcs.cmderr = CMDERR_NOTSUP;
+            return true;
+        }
 
-      unsigned regnum = regno - 0x1000;
+      } else if (regno >= 0x1020 && regno < 0x1040) {
+        // Don't force the debugger to use progbuf if it exists, so the
+        // debugger has to make the decision not to use abstract commands to
+        // access 64-bit FPRs on 32-bit targets.
+        unsigned fprnum = regno - 0x1020;
+
+        if (write) {
+          switch (size) {
+            case 2:
+              write32(debug_abstract, i++, flw(fprnum, ZERO, debug_data_start));
+              break;
+            case 3:
+              write32(debug_abstract, i++, fld(fprnum, ZERO, debug_data_start));
+              break;
+            default:
+              abstractcs.cmderr = CMDERR_NOTSUP;
+              return true;
+          }
 
-      switch (size) {
-      case 2:
-        if (write)
-          write32(debug_abstract, 0, lw(regnum, ZERO, debug_data_start));
-        else
-          write32(debug_abstract, 0, sw(regnum, ZERO, debug_data_start));
-        break;
-      case 3:
-        if (write)
-          write32(debug_abstract, 0, ld(regnum, ZERO, debug_data_start));
-        else
-          write32(debug_abstract, 0, sd(regnum, ZERO, debug_data_start));
-        break;
-        /*
-          case 4:
-          if (write)
-          write32(debug_rom_code, 0, lq(regnum, ZERO, debug_data_start));
-          else
-          write32(debug_rom_code, 0, sq(regnum, ZERO, debug_data_start));
-          break;
-        */
-      default:
+        } else {
+          switch (size) {
+            case 2:
+              write32(debug_abstract, i++, fsw(fprnum, ZERO, debug_data_start));
+              break;
+            case 3:
+              write32(debug_abstract, i++, fsd(fprnum, ZERO, debug_data_start));
+              break;
+            default:
+              abstractcs.cmderr = CMDERR_NOTSUP;
+              return true;
+          }
+        }
+
+      } else {
         abstractcs.cmderr = CMDERR_NOTSUP;
         return true;
       }
-    } else {
-      //NOP
-      write32(debug_abstract, 0, addi(ZERO, ZERO, 0));
     }
 
     if (get_field(command, AC_ACCESS_REGISTER_POSTEXEC)) {
-      // Since the next instruction is what we will use, just use nother NOP
-      // to get there.
-      write32(debug_abstract, 1, addi(ZERO, ZERO, 0));
+      write32(debug_abstract, i,
+          jal(ZERO, debug_progbuf_start - debug_abstract_start - 4 * i));
+      i++;
     } else {
-      write32(debug_abstract, 1, ebreak());
+      write32(debug_abstract, i++, ebreak());
     }
 
     debug_rom_flags[dmcontrol.hartsel] |= 1 << DEBUG_ROM_FLAG_GO;
diff --git a/riscv/debug_module.h b/riscv/debug_module.h
index 36037b4..82c449e 100644
--- a/riscv/debug_module.h
+++ b/riscv/debug_module.h
@@ -100,7 +100,7 @@ class debug_module_t : public abstract_device_t
     static const unsigned debug_data_start = 0x380;
     unsigned debug_progbuf_start;
 
-    static const unsigned debug_abstract_size = 2;
+    static const unsigned debug_abstract_size = 5;
     unsigned debug_abstract_start;
 
     static const unsigned hartsellen = 10;