From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57008) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XhE3m-0002LP-34 for qemu-devel@nongnu.org; Thu, 23 Oct 2014 04:47:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XhE3g-0002CR-Nc for qemu-devel@nongnu.org; Thu, 23 Oct 2014 04:47:54 -0400 Received: from greensocs.com ([178.33.234.66]:57022) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XhE3g-0002C6-CH for qemu-devel@nongnu.org; Thu, 23 Oct 2014 04:47:48 -0400 Message-ID: <5448C0B1.3010801@greensocs.com> Date: Thu, 23 Oct 2014 10:47:45 +0200 From: Frederic Konrad MIME-Version: 1.0 References: <20141022113831.9548.36452.stgit@PASHA-ISP> <5447A8BB.1060707@greensocs.com> <000901cfee86$3c9f1280$b5dd3780$@Dovgaluk@ispras.ru> <5448B0B3.9040702@greensocs.com> <000e01cfee96$3a1ce130$ae56a390$@Dovgaluk@ispras.ru> In-Reply-To: <000e01cfee96$3a1ce130$ae56a390$@Dovgaluk@ispras.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] i386: fix breakpoints handling in icount mode List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Pavel Dovgaluk , qemu-devel@nongnu.org Cc: pbonzini@redhat.com, zealot351@gmail.com, maria.klimushenkova@ispras.ru, mark.burton@greensocs.com, batuzovk@ispras.ru On 23/10/2014 09:52, Pavel Dovgaluk wrote: >> From: Frederic Konrad [mailto:fred.konrad@greensocs.com] >> On 23/10/2014 07:57, Pavel Dovgaluk wrote: >>>> From: Frederic Konrad [mailto:fred.konrad@greensocs.com] >>>> On 22/10/2014 13:38, Pavel Dovgalyuk wrote: >>>> >>>> Hi Pavel, >>>>> This patch fixes instructions counting when execution is stopped on >>>>> breakpoint (e.g. set from gdb). Without a patch extra instruction is translated >>>>> and icount is incremented by invalid value (which equals to number of >>>>> executed instructions + 1). >>>>> >>>>> Signed-off-by: Pavel Dovgalyuk >>>>> --- >>>>> target-i386/translate.c | 3 ++- >>>>> 1 files changed, 2 insertions(+), 1 deletions(-) >>>>> >>>>> diff --git a/target-i386/translate.c b/target-i386/translate.c >>>>> index 1284173..193cf9f 100644 >>>>> --- a/target-i386/translate.c >>>>> +++ b/target-i386/translate.c >>>>> @@ -8000,7 +8000,7 @@ static inline void gen_intermediate_code_internal(X86CPU *cpu, >>>>> if (bp->pc == pc_ptr && >>>>> !((bp->flags & BP_CPU) && (tb->flags & HF_RF_MASK))) { >>>>> gen_debug(dc, pc_ptr - dc->cs_base); >>>>> - break; >>>>> + goto done_generating; >>>> This makes sense to me. >>>> But I don't see why you don't just "break" like the other instruction in >>>> this loop? >>> Single break will just exit the breakpoints iteration loop. I'll need an additional flag >>> to break the translation loop. ARM does the same thing, anyway :) >> Yes that's what I mentioned. >>>>> } >>>>> } >>>>> } >>>>> @@ -8049,6 +8049,7 @@ static inline void gen_intermediate_code_internal(X86CPU *cpu, >>>>> break; >>>>> } >>>>> } >>>>> +done_generating: >>>>> if (tb->cflags & CF_LAST_IO) >>>>> gen_io_end(); >>>> Is there any reason why you don't jump over this two lines in case of a >>>> breakpoint? >>> Shouldn't we switch off can_do_io flag if it was switched on? >> Yes but can we switch on can_do_io if we have a breakpoint? >> >> The code is not shown in this patch but there is: >> >> if (num_insns + 1 == max_insns && (tb->cflags & CF_LAST_IO)) >> gen_io_start(); >> >> I think you can't reach this code if you exit the translation loop? > This is not the only gen_io_start call. It is called from some of the instructions' > translation functions, that could precede the breakpoint. > > Pavel Dovgalyuk > > True, there are 8 others place where gen_io_start is called in this file, but they seems to be each time followed by a gen_io_end? eg: static inline void gen_ins(DisasContext *s, TCGMemOp ot) { if (use_icount) gen_io_start(); gen_string_movl_A0_EDI(s); /* Note: we must do this dummy write first to be restartable in case of page fault. */ tcg_gen_movi_tl(cpu_T[0], 0); gen_op_st_v(s, ot, cpu_T[0], cpu_A0); tcg_gen_trunc_tl_i32(cpu_tmp2_i32, cpu_regs[R_EDX]); tcg_gen_andi_i32(cpu_tmp2_i32, cpu_tmp2_i32, 0xffff); gen_helper_in_func(ot, cpu_T[0], cpu_tmp2_i32); gen_op_st_v(s, ot, cpu_T[0], cpu_A0); gen_op_movl_T0_Dshift(ot); gen_op_add_reg_T0(s->aflag, R_EDI); if (use_icount) gen_io_end(); }