Re: [Qemu-devel] [PATCH] Add single stepping option for all targets

[Stefan Weil]

Aurelien Jarno schrieb:
>
> Given those explanations and the comments from other people, I am fine
> with this option. I still have some comments though (see below).

Please see my comments and an updated patch below.

>
>
>> ...
>> Index: trunk/vl.c
>> ===================================================================
>> --- trunk.orig/vl.c 2009-03-13 17:07:47.000000000 +0100
>> +++ trunk/vl.c 2009-03-13 17:08:01.000000000 +0100
>> @@ -211,6 +211,7 @@
>> int nb_nics;
>> NICInfo nd_table[MAX_NICS];
>> int vm_running;
>> +int vm_singlestep;
>
> You create a new variable. By the way, I think that calling it
> singlestep is better, and matches the naming of other options
> variable (like daemonize, graphic_rotate). You should define it
> to a default value of 0.
>

Calling those option variables option_singlestep, option_daemonize
might even be a better solution...

I called it vm_singlestep because it is somehow similar to vm_running.
It is a variable which indicates a certain state of QEMU's VM.
Nevertheless I renamed it to singlestep in my new patch.

The default value is already 0 because all globals in C/C++ have this
default value (BSS segment). An explicit value just increases the size
of the executable (only by 4 (or 8) bytes in this case, I admit).

Today, there is no consistent usage of global default values. Some
globals are explicitly set to zero, others not. I personally use
explicit default values only when they are needed (!= 0).

Please feel free to add a "= 0" if you think this should be QEMU's standard.


>> @@ -4221,6 +4223,7 @@
>> QEMU_OPTION_parallel,
>> QEMU_OPTION_monitor,
>> QEMU_OPTION_pidfile,
>> + QEMU_OPTION_singlestep,
>> QEMU_OPTION_S,
>> QEMU_OPTION_s,
>> QEMU_OPTION_p,
>> @@ -4345,6 +4348,7 @@
>> { "parallel", HAS_ARG, QEMU_OPTION_parallel },
>> { "monitor", HAS_ARG, QEMU_OPTION_monitor },
>> { "pidfile", HAS_ARG, QEMU_OPTION_pidfile },
>> + { "singlestep", 0, QEMU_OPTION_singlestep },
>> { "S", 0, QEMU_OPTION_S },
>> { "s", 0, QEMU_OPTION_s },
>> { "p", HAS_ARG, QEMU_OPTION_p },
>
> This option is never parsed, so the -singlestep option doesn't work.

True. The parser code got lost somewhere from my first to this
incomplete patch
because of many, many merges in the meantime.

The new patch fixes this.

So I hope this will be the last iteration and the patch will finally
find its
way to QEMU trunk.


Regards

Stefan




Add new command line option -singlestep for tcg single stepping.

This replaces a compile time option for some targets and adds
this feature to targets which did not have a compile time option.

Add monitor command to enable or disable single step mode.

Modify monitor command "info status" to display single step mode.


Signed-off-by: Stefan Weil <address@hidden>

Index: trunk/bsd-user/main.c
===================================================================
--- trunk.orig/bsd-user/main.c  2009-03-30 11:29:04.000000000 +0200
+++ trunk/bsd-user/main.c       2009-03-30 11:30:43.000000000 +0200
@@ -33,6 +33,8 @@
 
 #define DEBUG_LOGFILE "/tmp/qemu.log"
 
+int singlestep;
+
 static const char *interp_prefix = CONFIG_QEMU_PREFIX;
 const char *qemu_uname_release = CONFIG_UNAME_RELEASE;
 extern char **environ;
@@ -378,6 +380,7 @@
            "Debug options:\n"
            "-d options   activate log (logfile=%s)\n"
            "-p pagesize  set the host page size to 'pagesize'\n"
+           "-singlestep  always run in singlestep mode\n"
            "-strace      log system calls\n"
            "\n"
            "Environment variables:\n"
@@ -500,6 +503,8 @@
                 usage();
             }
             optind++;
+        } else if (!strcmp(r, "singlestep")) {
+            singlestep = 1;
         } else if (!strcmp(r, "strace")) {
             do_strace = 1;
         } else
Index: trunk/darwin-user/main.c
===================================================================
--- trunk.orig/darwin-user/main.c       2009-03-30 11:29:04.000000000 +0200
+++ trunk/darwin-user/main.c    2009-03-30 11:30:43.000000000 +0200
@@ -41,6 +41,8 @@
 #include <mach/mach_init.h>
 #include <mach/vm_map.h>
 
+int singlestep;
+
 const char *interp_prefix = "";
 
 asm(".zerofill __STD_PROG_ZONE, __STD_PROG_ZONE, __std_prog_zone, 0x0dfff000");
@@ -751,6 +753,7 @@
            "-d options   activate log (logfile='%s')\n"
            "-g wait for gdb on port 1234\n"
            "-p pagesize  set the host page size to 'pagesize'\n",
+           "-singlestep  always run in singlestep mode\n"
            TARGET_ARCH,
            TARGET_ARCH,
            interp_prefix,
@@ -842,6 +845,8 @@
 #endif
                 exit(1);
             }
+        } else if (!strcmp(r, "singlestep")) {
+            singlestep = 1;
         } else
         {
             usage();
Index: trunk/exec-all.h
===================================================================
--- trunk.orig/exec-all.h       2009-03-30 11:29:04.000000000 +0200
+++ trunk/exec-all.h    2009-03-30 11:30:43.000000000 +0200
@@ -381,6 +381,8 @@
 
 #endif
 
+extern int singlestep;
+
 typedef void (CPUDebugExcpHandler)(CPUState *env);
 
 CPUDebugExcpHandler *cpu_set_debug_excp_handler(CPUDebugExcpHandler *handler);
Index: trunk/linux-user/main.c
===================================================================
--- trunk.orig/linux-user/main.c        2009-03-30 11:29:04.000000000 +0200
+++ trunk/linux-user/main.c     2009-03-30 11:30:43.000000000 +0200
@@ -39,6 +39,8 @@
 
 char *exec_path;
 
+int singlestep;
+
 static const char *interp_prefix = CONFIG_QEMU_PREFIX;
 const char *qemu_uname_release = CONFIG_UNAME_RELEASE;
 
@@ -2217,6 +2219,7 @@
            "Debug options:\n"
            "-d options   activate log (logfile=%s)\n"
            "-p pagesize  set the host page size to 'pagesize'\n"
+           "-singlestep  always run in singlestep mode\n"
            "-strace      log system calls\n"
            "\n"
            "Environment variables:\n"
@@ -2359,6 +2362,8 @@
             }
         } else if (!strcmp(r, "drop-ld-preload")) {
             (void) envlist_unsetenv(envlist, "LD_PRELOAD");
+        } else if (!strcmp(r, "singlestep")) {
+            singlestep = 1;
         } else if (!strcmp(r, "strace")) {
             do_strace = 1;
         } else
Index: trunk/monitor.c
===================================================================
--- trunk.orig/monitor.c        2009-03-30 11:29:04.000000000 +0200
+++ trunk/monitor.c     2009-03-30 11:43:16.000000000 +0200
@@ -527,6 +527,17 @@
     cpu_set_log(mask);
 }
 
+static void do_singlestep(Monitor *mon, const char *option)
+{
+    if (!option || !strcmp(option, "on")) {
+        singlestep = 1;
+    } else if (!strcmp(option, "off")) {
+        singlestep = 0;
+    } else {
+        monitor_printf(mon, "unexpected option %s\n", option);
+    }
+}
+
 static void do_stop(Monitor *mon)
 {
     vm_stop(EXCP_INTERRUPT);
@@ -1510,9 +1521,13 @@
 
 static void do_info_status(Monitor *mon)
 {
-    if (vm_running)
-       monitor_printf(mon, "VM status: running\n");
-    else
+    if (vm_running) {
+        if (singlestep) {
+            monitor_printf(mon, "VM status: running (single step mode)\n");
+        } else {
+            monitor_printf(mon, "VM status: running\n");
+        }
+    } else
        monitor_printf(mon, "VM status: paused\n");
 }
 
@@ -1643,6 +1658,8 @@
       "tag|id", "restore a VM snapshot from its tag or id" },
     { "delvm", "s", do_delvm,
       "tag|id", "delete a VM snapshot from its tag or id" },
+    { "singlestep", "s?", do_singlestep,
+      "[on|off]", "run emulation in singlestep mode or switch to normal mode", 
},
     { "stop", "", do_stop,
       "", "stop emulation", },
     { "c|cont", "", do_cont,
Index: trunk/qemu-doc.texi
===================================================================
--- trunk.orig/qemu-doc.texi    2009-03-30 11:29:04.000000000 +0200
+++ trunk/qemu-doc.texi 2009-03-30 11:30:43.000000000 +0200
@@ -490,6 +490,10 @@
 @item delvm @var{tag}|@var{id}
 Delete the snapshot identified by @var{tag} or @var{id}.
 
address@hidden singlestep [off]
+Run the emulation in single step mode.
+If called with option off, the emulation returns to normal mode.
+
 @item stop
 Stop emulation.
 
@@ -2370,6 +2374,8 @@
 Act as if the host page size was 'pagesize' bytes
 @item -g port
 Wait gdb connection to port
address@hidden -singlestep
+Run the emulation in single step mode.
 @end table
 
 Environment variables:
@@ -2488,6 +2494,8 @@
 Activate log (logfile=/tmp/qemu.log)
 @item -p pagesize
 Act as if the host page size was 'pagesize' bytes
address@hidden -singlestep
+Run the emulation in single step mode.
 @end table
 
 @node BSD User space emulator
@@ -2550,6 +2558,8 @@
 Activate log (logfile=/tmp/qemu.log)
 @item -p pagesize
 Act as if the host page size was 'pagesize' bytes
address@hidden -singlestep
+Run the emulation in single step mode.
 @end table
 
 @node compilation
Index: trunk/qemu-options.hx
===================================================================
--- trunk.orig/qemu-options.hx  2009-03-30 11:29:03.000000000 +0200
+++ trunk/qemu-options.hx       2009-03-30 11:30:43.000000000 +0200
@@ -1209,6 +1209,13 @@
 from a script.
 ETEXI
 
+DEF("singlestep", 0, QEMU_OPTION_singlestep, \
+    "-singlestep   always run in singlestep mode\n")
+STEXI
address@hidden -singlestep
+Run the emulation in single step mode.
+ETEXI
+
 DEF("S", 0, QEMU_OPTION_S, \
     "-S              freeze CPU at startup (use 'c' to start execution)\n")
 STEXI
Index: trunk/target-alpha/translate.c
===================================================================
--- trunk.orig/target-alpha/translate.c 2009-03-30 11:29:04.000000000 +0200
+++ trunk/target-alpha/translate.c      2009-03-30 11:59:18.000000000 +0200
@@ -2412,11 +2412,11 @@
         if (env->singlestep_enabled) {
             gen_excp(&ctx, EXCP_DEBUG, 0);
             break;
-       }
+        }
 
-#if defined (DO_SINGLE_STEP)
-        break;
-#endif
+        if (singlestep) {
+            break;
+        }
     }
     if (ret != 1 && ret != 3) {
         tcg_gen_movi_i64(cpu_pc, ctx.pc);
Index: trunk/target-arm/translate.c
===================================================================
--- trunk.orig/target-arm/translate.c   2009-03-30 11:29:04.000000000 +0200
+++ trunk/target-arm/translate.c        2009-03-30 11:53:46.000000000 +0200
@@ -8791,6 +8791,7 @@
         num_insns ++;
     } while (!dc->is_jmp && gen_opc_ptr < gen_opc_end &&
              !env->singlestep_enabled &&
+             !singlestep &&
              dc->pc < next_page_start &&
              num_insns < max_insns);
 
Index: trunk/target-cris/translate.c
===================================================================
--- trunk.orig/target-cris/translate.c  2009-03-30 11:29:04.000000000 +0200
+++ trunk/target-cris/translate.c       2009-03-30 11:52:58.000000000 +0200
@@ -3272,6 +3272,7 @@
                        break;
        } while (!dc->is_jmp && !dc->cpustate_changed
                 && gen_opc_ptr < gen_opc_end
+                 && !singlestep
                 && (dc->pc < next_page_start)
                  && num_insns < max_insns);
 
Index: trunk/target-i386/translate.c
===================================================================
--- trunk.orig/target-i386/translate.c  2009-03-30 11:29:04.000000000 +0200
+++ trunk/target-i386/translate.c       2009-03-30 11:30:43.000000000 +0200
@@ -7651,6 +7651,11 @@
             gen_eob(dc);
             break;
         }
+        if (singlestep) {
+            gen_jmp_im(pc_ptr - dc->cs_base);
+            gen_eob(dc);
+            break;
+        }
     }
     if (tb->cflags & CF_LAST_IO)
         gen_io_end();
Index: trunk/target-m68k/translate.c
===================================================================
--- trunk.orig/target-m68k/translate.c  2009-03-30 11:29:03.000000000 +0200
+++ trunk/target-m68k/translate.c       2009-03-30 11:54:26.000000000 +0200
@@ -3031,6 +3031,7 @@
         num_insns++;
     } while (!dc->is_jmp && gen_opc_ptr < gen_opc_end &&
              !env->singlestep_enabled &&
+             !singlestep &&
              (pc_offset) < (TARGET_PAGE_SIZE - 32) &&
              num_insns < max_insns);
 
Index: trunk/target-mips/translate.c
===================================================================
--- trunk.orig/target-mips/translate.c  2009-03-30 11:29:04.000000000 +0200
+++ trunk/target-mips/translate.c       2009-03-30 11:30:42.000000000 +0200
@@ -38,7 +38,6 @@
 
 //#define MIPS_DEBUG_DISAS
 //#define MIPS_DEBUG_SIGN_EXTENSIONS
-//#define MIPS_SINGLE_STEP
 
 /* MIPS major opcodes */
 #define MASK_OP_MAJOR(op)  (op & (0x3F << 26))
@@ -8140,9 +8139,9 @@
 
         if (num_insns >= max_insns)
             break;
-#if defined (MIPS_SINGLE_STEP)
-        break;
-#endif
+
+        if (singlestep)
+            break;
     }
     if (tb->cflags & CF_LAST_IO)
         gen_io_end();
Index: trunk/target-ppc/translate.c
===================================================================
--- trunk.orig/target-ppc/translate.c   2009-03-30 11:29:04.000000000 +0200
+++ trunk/target-ppc/translate.c        2009-03-30 11:57:29.000000000 +0200
@@ -39,7 +39,6 @@
 #define GDBSTUB_SINGLE_STEP 0x4
 
 /* Include definitions for instructions classes and implementations flags */
-//#define DO_SINGLE_STEP
 //#define PPC_DEBUG_DISAS
 //#define DO_PPC_STATISTICS
 
@@ -8288,15 +8287,13 @@
             gen_exception(ctxp, POWERPC_EXCP_TRACE);
         } else if (unlikely(((ctx.nip & (TARGET_PAGE_SIZE - 1)) == 0) ||
                             (env->singlestep_enabled) ||
+                            singlestep ||
                             num_insns >= max_insns)) {
             /* if we reach a page boundary or are single stepping, stop
              * generation
              */
             break;
         }
-#if defined (DO_SINGLE_STEP)
-        break;
-#endif
     }
     if (tb->cflags & CF_LAST_IO)
         gen_io_end();
Index: trunk/target-sh4/translate.c
===================================================================
--- trunk.orig/target-sh4/translate.c   2009-03-30 11:29:03.000000000 +0200
+++ trunk/target-sh4/translate.c        2009-03-30 11:30:42.000000000 +0200
@@ -1929,9 +1929,8 @@
            break;
         if (num_insns >= max_insns)
             break;
-#ifdef SH4_SINGLE_STEP
-       break;
-#endif
+        if (singlestep)
+            break;
     }
     if (tb->cflags & CF_LAST_IO)
         gen_io_end();
Index: trunk/target-sparc/translate.c
===================================================================
--- trunk.orig/target-sparc/translate.c 2009-03-30 11:29:04.000000000 +0200
+++ trunk/target-sparc/translate.c      2009-03-30 11:30:43.000000000 +0200
@@ -4838,7 +4838,7 @@
             break;
         /* if single step mode, we generate only one instruction and
            generate an exception */
-        if (env->singlestep_enabled) {
+        if (env->singlestep_enabled || singlestep) {
             tcg_gen_movi_tl(cpu_pc, dc->pc);
             tcg_gen_exit_tb(0);
             break;
Index: trunk/vl.c
===================================================================
--- trunk.orig/vl.c     2009-03-30 11:29:04.000000000 +0200
+++ trunk/vl.c  2009-03-30 11:30:42.000000000 +0200
@@ -212,6 +212,7 @@
 int nb_nics;
 NICInfo nd_table[MAX_NICS];
 int vm_running;
+int singlestep;
 static int autostart;
 static int rtc_utc = 1;
 static int rtc_date_offset = -1; /* -1 means no change */
@@ -4669,6 +4670,9 @@
             case QEMU_OPTION_bios:
                 bios_name = optarg;
                 break;
+            case QEMU_OPTION_singlestep:
+                singlestep = 1;
+                break;
             case QEMU_OPTION_S:
                 autostart = 0;
                 break;