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Re: [Qemu-devel] [PATCH] Add single stepping option for all targets
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH] Add single stepping option for all targets |
Date: |
Tue, 3 Mar 2009 07:38:41 +0100 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Sun, Feb 01, 2009 at 08:51:13PM +0100, Stefan Weil wrote:
> 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.
Please find my comments below.
>
> 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 },
It might be a good idea to provide that as a subset of the -d option, as
it is clearly something only useful for debugging.
> 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);
Why only on system emulation mode? During my debugging session, I mostly
used single stepping by hardcoding it in the code on user mode.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net