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

[Stefan Weil]

Stefan Weil schrieb:
> This patch replaces the compile time options SH4_SINGLE_STEP,
> DO_SINGLE_STEP and MIPS_SINGLE_STEP
> by a command line option -singlestep.
>
> It also adds single step mode for targets which did not have a compile
> time option,
> so all system emulations can be used with -singlestep. Please note that
> I did only run a short test for i386 and mips targets.
>
> A new monitor command is provided to enable or disable single step mode.
> The monitor command "info status" was modified to display single step
> mode when activated.
>
> Single stepping in Qemu's system emulation mode is useful to see the cpu
> state
> for each cpu instruction when used with -d in_asm,cpu. It is also a
> simple way to slow down the emulation.
>
> The patch does not add single step mode for Qemu's user mode emulation.
> Would this be useful, too?
>
> Kind regards
> Stefan Weil
>
>   

Hello,

here is an update of the patch. Please apply it to Qemu trunk.

Regards
Stefan Weil


Add new command line option 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/target-sh4/translate.c
===================================================================
--- trunk.orig/target-sh4/translate.c   2009-02-01 19:12:41.000000000 +0100
+++ trunk/target-sh4/translate.c        2009-02-01 19:18:33.000000000 +0100
@@ -1896,9 +1896,8 @@
            break;
         if (num_insns >= max_insns)
             break;
-#ifdef SH4_SINGLE_STEP
-       break;
-#endif
+        if (vm_singlestep)
+            break;
     }
     if (tb->cflags & CF_LAST_IO)
         gen_io_end();
Index: trunk/target-cris/translate.c
===================================================================
--- trunk.orig/target-cris/translate.c  2009-02-01 19:12:41.000000000 +0100
+++ trunk/target-cris/translate.c       2009-02-01 19:18:33.000000000 +0100
@@ -3271,6 +3271,7 @@
                        break;
        } while (!dc->is_jmp && !dc->cpustate_changed
                 && gen_opc_ptr < gen_opc_end
+                && !vm_singlestep
                 && (dc->pc < next_page_start)
                  && num_insns < max_insns);
 
Index: trunk/target-alpha/translate.c
===================================================================
--- trunk.orig/target-alpha/translate.c 2009-02-01 19:12:41.000000000 +0100
+++ trunk/target-alpha/translate.c      2009-02-01 19:18:33.000000000 +0100
@@ -2413,11 +2413,10 @@
         if (env->singlestep_enabled) {
             gen_excp(&ctx, EXCP_DEBUG, 0);
             break;
-       }
+        }
 
-#if defined (DO_SINGLE_STEP)
-        break;
-#endif
+        if (vm_singlestep)
+            break;
     }
     if (ret != 1 && ret != 3) {
         tcg_gen_movi_i64(cpu_pc, ctx.pc);
Index: trunk/vl.c
===================================================================
--- trunk.orig/vl.c     2009-02-01 19:12:41.000000000 +0100
+++ trunk/vl.c  2009-02-01 19:18:33.000000000 +0100
@@ -193,6 +193,7 @@
 int nb_nics;
 NICInfo nd_table[MAX_NICS];
 int vm_running;
+int vm_singlestep;
 static int rtc_utc = 1;
 static int rtc_date_offset = -1; /* -1 means no change */
 int cirrus_vga_enabled = 1;
@@ -3984,6 +3985,7 @@
            "-parallel dev   redirect the parallel port to char device 'dev'\n"
            "-monitor dev    redirect the monitor to char device 'dev'\n"
            "-pidfile file   write PID to 'file'\n"
+           "-singlestep     always run in singlestep mode\n"
            "-S              freeze CPU at startup (use 'c' to start 
execution)\n"
            "-s              wait gdb connection to port\n"
            "-p port         set gdb connection port [default=%s]\n"
@@ -4119,6 +4121,7 @@
     QEMU_OPTION_parallel,
     QEMU_OPTION_monitor,
     QEMU_OPTION_pidfile,
+    QEMU_OPTION_singlestep,
     QEMU_OPTION_S,
     QEMU_OPTION_s,
     QEMU_OPTION_p,
@@ -4238,6 +4241,7 @@
     { "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 },
Index: trunk/target-ppc/translate.c
===================================================================
--- trunk.orig/target-ppc/translate.c   2009-02-01 19:12:41.000000000 +0100
+++ trunk/target-ppc/translate.c        2009-02-01 19:18:33.000000000 +0100
@@ -38,7 +38,6 @@
 #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
 
@@ -8305,9 +8304,9 @@
              */
             break;
         }
-#if defined (DO_SINGLE_STEP)
-        break;
-#endif
+
+        if (vm_singlestep)
+            break;
     }
     if (tb->cflags & CF_LAST_IO)
         gen_io_end();
Index: trunk/target-mips/translate.c
===================================================================
--- trunk.orig/target-mips/translate.c  2009-02-01 19:12:41.000000000 +0100
+++ trunk/target-mips/translate.c       2009-02-01 19:18:33.000000000 +0100
@@ -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))
@@ -8247,9 +8246,9 @@
 
         if (num_insns >= max_insns)
             break;
-#if defined (MIPS_SINGLE_STEP)
-        break;
-#endif
+
+        if (vm_singlestep)
+            break;
     }
     if (tb->cflags & CF_LAST_IO)
         gen_io_end();
Index: trunk/monitor.c
===================================================================
--- trunk.orig/monitor.c        2009-02-01 19:12:41.000000000 +0100
+++ trunk/monitor.c     2009-02-01 19:18:33.000000000 +0100
@@ -489,6 +489,18 @@
     cpu_set_log(mask);
 }
 
+static void do_singlestep(const char *option)
+{
+    qemu_printf("setting vm_singlestep to %s\n", option);
+    if (!option) {
+        vm_singlestep = 1;
+    } else if (!strcmp(option, "off")) {
+        vm_singlestep = 0;
+    } else {
+        term_printf("unexpected option %s\n", option);
+    }
+}
+
 static void do_stop(void)
 {
     vm_stop(EXCP_INTERRUPT);
@@ -1403,9 +1415,13 @@
 
 static void do_info_status(void)
 {
-    if (vm_running)
-       term_printf("VM status: running\n");
-    else
+    if (vm_running) {
+        if (vm_singlestep) {
+            term_printf("VM status: running (single step mode)\n");
+        } else {
+            term_printf("VM status: running\n");
+        }
+    } else
        term_printf("VM status: paused\n");
 }
 
@@ -1455,6 +1471,8 @@
       "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,
+      "[off]", "run emulation in singlestep mode or switch to normal mode", },
     { "stop", "", do_stop,
       "", "stop emulation", },
     { "c|cont", "", do_cont,
Index: trunk/target-i386/translate.c
===================================================================
--- trunk.orig/target-i386/translate.c  2009-02-01 19:12:41.000000000 +0100
+++ trunk/target-i386/translate.c       2009-02-01 19:18:33.000000000 +0100
@@ -7661,6 +7661,11 @@
             gen_eob(dc);
             break;
         }
+        if (vm_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-arm/translate.c
===================================================================
--- trunk.orig/target-arm/translate.c   2009-02-01 19:12:41.000000000 +0100
+++ trunk/target-arm/translate.c        2009-02-01 19:18:33.000000000 +0100
@@ -8788,7 +8788,7 @@
          * ensures prefetch aborts occur at the right place.  */
         num_insns ++;
     } while (!dc->is_jmp && gen_opc_ptr < gen_opc_end &&
-             !env->singlestep_enabled &&
+             !env->singlestep_enabled && !vm_singlestep &&
              dc->pc < next_page_start &&
              num_insns < max_insns);
 
Index: trunk/target-m68k/translate.c
===================================================================
--- trunk.orig/target-m68k/translate.c  2009-02-01 19:12:41.000000000 +0100
+++ trunk/target-m68k/translate.c       2009-02-01 19:18:33.000000000 +0100
@@ -3028,7 +3028,7 @@
        disas_m68k_insn(env, dc);
         num_insns++;
     } while (!dc->is_jmp && gen_opc_ptr < gen_opc_end &&
-             !env->singlestep_enabled &&
+             !env->singlestep_enabled && !vm_singlestep &&
              (pc_offset) < (TARGET_PAGE_SIZE - 32) &&
              num_insns < max_insns);
 
Index: trunk/target-sparc/translate.c
===================================================================
--- trunk.orig/target-sparc/translate.c 2009-02-01 19:12:41.000000000 +0100
+++ trunk/target-sparc/translate.c      2009-02-01 19:18:33.000000000 +0100
@@ -4858,7 +4858,7 @@
             break;
         /* if single step mode, we generate only one instruction and
            generate an exception */
-        if (env->singlestep_enabled) {
+        if (env->singlestep_enabled || vm_singlestep) {
             tcg_gen_movi_tl(cpu_pc, dc->pc);
             tcg_gen_exit_tb(0);
             break;
Index: trunk/qemu-doc.texi
===================================================================
--- trunk.orig/qemu-doc.texi    2009-02-01 19:12:41.000000000 +0100
+++ trunk/qemu-doc.texi 2009-02-01 19:18:33.000000000 +0100
@@ -1064,6 +1064,9 @@
 @item -s
 Wait gdb connection to port 1234 (@pxref{gdb_usage}).
 
address@hidden -singlestep
+Run the emulation in single step mode.
+
 @item -p @var{port}
 Change gdb connection port.  @var{port} can be either a decimal number
 to specify a TCP port, or a host device (same devices as the serial port).
@@ -1383,6 +1386,10 @@
 @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.
 
Index: trunk/exec-all.h
===================================================================
--- trunk.orig/exec-all.h       2009-02-01 19:18:18.000000000 +0100
+++ trunk/exec-all.h    2009-02-01 19:18:33.000000000 +0100
@@ -386,6 +386,12 @@
 
 #endif
 
+#if defined(CONFIG_USER_ONLY)
+# define vm_singlestep 0
+#else
+extern int vm_singlestep;
+#endif
+
 typedef void (CPUDebugExcpHandler)(CPUState *env);
 
 CPUDebugExcpHandler *cpu_set_debug_excp_handler(CPUDebugExcpHandler *handler);