add iodebug support for all rings complement bochs-emu#64 (bochs-emu#66)

This PR is for "I/O Interface to Bochs Debugger" from ring3 (port range:
**0x8A00 - 0x8A01**)

PR bochs-emu#64 was for E9 HACK (port **0xE9**)

By enabling the iodebug's 'all_rings' option, you can utilize the port
I/O Interface to Bochs Debugger from ring3. This PR allows the code
running inside Bochs (ring3) to monitor memory ranges, trace individual
instructions, and observe register values during execution.


https://bochs.sourceforge.io/doc/docbook/development/debugger-advanced.html

IMO very useful for:

- user-mode sandbox (ex Cuckoo)
- malware analysis
- API/SYSCALL hook/monitor from ring3
- automation + instrumentation from user mode code
...

A complement for PR bochs-emu#64

**This PR is 100% backward compatibility**

![IODEBUG ALL
RINGS](https://github.com/bochs-emu/Bochs/assets/9882181/6308ad0f-c189-43f3-a92b-dccde3542ad6)

btw, @stlintel I'm not certain about:
- if misc is the ideal location for this.. should I create a new
iodebug-option for this?
- should I remove the #if in 'new bx_param_bool_c'?
- the new .bochsrc entry makes sense for you?

bochs/.bochsrc

@@ -1319,6 +1319,19 @@ speaker: enabled=1, mode=sound, volume=15
 #=======================================================================
 #port_e9_hack: enabled=1
 
+#=======================================================================
+# IODEBUG:
+# I/O Interface to Bochs Debugger plugin allows the code running inside 
+# Bochs to monitor memory ranges, trace individual instructions, and 
+# observe register values during execution. By enabling the 'all_rings' 
+# option, you can utilize the iodebug ports from ring3. For more 
+# information, refer to "Advanced debugger usage" documentation.
+#
+# Example:
+#   iodebug: all_rings=1
+#=======================================================================
+#iodebug: all_rings=1
+
 #=======================================================================
 # fullscreen: ONLY IMPLEMENTED ON AMIGA
 #             Request that Bochs occupy the entire screen instead of a

bochs/PARAM_TREE.txt

@@ -286,6 +286,7 @@ sound
 misc
   port_e9_hack
   port_e9_hack_all_rings
+  iodebug_all_rings
   gdbstub
     port
     text_base

bochs/config.cc

@@ -1686,6 +1686,15 @@ void bx_init_options()
       "Debug messages written to i/o port 0xE9 from ring3 will be displayed on console",
       0);
 
+#if BX_SUPPORT_IODEBUG
+// iodebug all rings
+  new bx_param_bool_c(misc,
+      "iodebug_all_rings",
+      "Enable iodebug ports for all rings",
+      "I/O Interface to Bochs Debugger plugin for all rings",
+      0);
+#endif
+
   // GDB stub
   menu = new bx_list_c(misc, "gdbstub", "GDB Stub Options");
   menu->set_options(menu->SHOW_PARENT | menu->USE_BOX_TITLE);
@@ -1771,6 +1780,9 @@ void bx_init_options()
   misc->add(SIM->get_param(BXPN_USER_SHORTCUT));
   misc->add(SIM->get_param(BXPN_PORT_E9_HACK));
   misc->add(SIM->get_param(BXPN_PORT_E9_HACK_ALL_RINGS));
+  #if BX_SUPPORT_IODEBUG
+  misc->add(SIM->get_param(BXPN_IODEBUG_ALL_RINGS));
+  #endif
   misc->set_options(misc->SHOW_PARENT | misc->SHOW_GROUP_NAME);
 }
 
@@ -3221,6 +3233,21 @@ static int parse_line_formatted(const char *context, int num_params, char *param
     if (parse_port_e9_hack(context, (const char **)(params + 1), num_params - 1) < 0) {
       return -1;
     }
+  } else if (!strcmp(params[0], "iodebug")) {
+#if BX_SUPPORT_IODEBUG
+    if (num_params != 2) {
+      PARSE_ERR(("%s: iodebug directive: wrong # args.", context));
+    }
+    if (!strncmp(params[1], "all_rings=", 10)) {
+      if (parse_param_bool(params[1], 10, BXPN_IODEBUG_ALL_RINGS) < 0) {
+        PARSE_ERR(("%s: all_rings option malformed.", context));
+      }
+    } else {
+      PARSE_ERR(("%s: iodebug: invalid parameter %s", context, params[1]));
+    }
+#else
+    PARSE_WARN(("%s: Bochs is not compiled with iodebug support", context));
+#endif
   } else if (!strcmp(params[0], "load32bitOSImage")) {
     PARSE_ERR(("%s: load32bitOSImage: This legacy feature is no longer supported.", context));
   } else if (SIM->is_addon_option(params[0])) {
@@ -3577,6 +3604,9 @@ int bx_write_configuration(const char *rc, int overwrite)
   bx_write_debugger_options(fp);
   fprintf(fp, "port_e9_hack: enabled=%d\n", SIM->get_param_bool(BXPN_PORT_E9_HACK)->get());
   fprintf(fp, "port_e9_hack_all_rings: enabled=%d\n", SIM->get_param_bool(BXPN_PORT_E9_HACK_ALL_RINGS)->get());
+  #if BX_SUPPORT_IODEBUG
+  fprintf(fp, "iodebug_all_rings: enabled=%d\n", SIM->get_param_bool(BXPN_IODEBUG_ALL_RINGS)->get());
+  #endif
   fprintf(fp, "private_colormap: enabled=%d\n", SIM->get_param_bool(BXPN_PRIVATE_COLORMAP)->get());
 #if BX_WITH_AMIGAOS
   fprintf(fp, "fullscreen: enabled=%d\n", SIM->get_param_bool(BXPN_FULLSCREEN)->get());

bochs/cpu/io.cc

@@ -869,6 +869,12 @@ bool BX_CPP_AttrRegparmN(3) BX_CPU_C::allow_io(bxInstruction_c *i, Bit16u port,
   if (0xe9 == port && port_e9_hack_all_rings)
     return(1); // port e9 hack can be used by unprivileged code
 
+#if BX_SUPPORT_IODEBUG
+  static bool iodebug_all_rings = SIM->get_param_bool(BXPN_IODEBUG_ALL_RINGS)->get();
+  if (0x8A00 == (port & 0xfffe) && iodebug_all_rings)
+    return(1); // iodebug ports (0x8A00 & 0x8A01) can be used by unprivileged code
+#endif /* if BX_SUPPORT_IODEBUG */
+
   if (BX_CPU_THIS_PTR cr0.get_PE() && (BX_CPU_THIS_PTR get_VM() || (CPL > BX_CPU_THIS_PTR get_IOPL())))
   {
     if (BX_CPU_THIS_PTR tr.cache.valid==0 ||

bochs/doc/docbook/user/user.dbk

@@ -5218,6 +5218,20 @@ option, you can utilize the port e9 hack from ring3.
 </para>
 </section>
 
+<section><title>IODEBUG</title>
+<para>
+Example:
+<screen>
+  iodebug: all_rings=1
+</screen>
+I/O Interface to Bochs Debugger plugin allows the code running inside 
+Bochs to monitor memory ranges, trace individual instructions, and 
+observe register values during execution. By enabling the 'all_rings' 
+option, you can utilize the iodebug ports from ring3. For more 
+information, refer to "Advanced debugger usage" documentation.
+</para>
+</section>
+
 </section> <!--end of bochsrc section-->
 
 <section id="keymap"><title>How to write your own keymap table</title>

bochs/param_names.h

@@ -176,6 +176,7 @@
 #define BXPN_SOUND_ES1370                "sound.es1370"
 #define BXPN_PORT_E9_HACK                "misc.port_e9_hack"
 #define BXPN_PORT_E9_HACK_ALL_RINGS      "misc.port_e9_hack_all_rings"
+#define BXPN_IODEBUG_ALL_RINGS           "misc.iodebug_all_rings"
 #define BXPN_GDBSTUB                     "misc.gdbstub"
 #define BXPN_LOG_FILENAME                "log.filename"
 #define BXPN_LOG_PREFIX                  "log.prefix"