From: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
To: Richard Henderson <richard.henderson@linaro.org>, qemu-devel@nongnu.org
Cc: peter.maydell@linaro.org, Luc Michel <luc.michel@greensocs.com>
Subject: Re: [PULL for-5.1 3/3] tcg/cpu-exec: precise single-stepping after an interrupt
Date: Wed, 29 Jul 2020 08:31:25 +0300 [thread overview]
Message-ID: <4aa23af2-56f3-2ba2-12f8-b36d046d5e78@ispras.ru> (raw)
In-Reply-To: <20200717181623.2742758-4-richard.henderson@linaro.org>
On 17.07.2020 21:16, Richard Henderson wrote:
> When single-stepping with a debugger attached to QEMU, and when an
> interrupt is raised, the debugger misses the first instruction after
> the interrupt.
>
> Tested-by: Luc Michel <luc.michel@greensocs.com>
> Reviewed-by: Luc Michel <luc.michel@greensocs.com>
> Buglink: https://bugs.launchpad.net/qemu/+bug/757702
> Message-Id: <20200717163029.2737546-1-richard.henderson@linaro.org>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> accel/tcg/cpu-exec.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
> index 6a3d3a3cfc..66d38f9d85 100644
> --- a/accel/tcg/cpu-exec.c
> +++ b/accel/tcg/cpu-exec.c
> @@ -588,7 +588,13 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
> else {
> if (cc->cpu_exec_interrupt(cpu, interrupt_request)) {
> replay_interrupt();
> - cpu->exception_index = -1;
> + /*
> + * After processing the interrupt, ensure an EXCP_DEBUG is
> + * raised when single-stepping so that GDB doesn't miss the
> + * next instruction.
> + */
> + cpu->exception_index =
> + (cpu->singlestep_enabled ? EXCP_DEBUG : -1);
> *last_tb = NULL;
I just rebased my reverse debugging patches and noticed that this breaks
the debugging in record/replay icount mode for i386.
At some points "si" in remote gdb does nothing.
This happens because of CPU_INTERRUPT_POLL. These are not real
interrupts and converted into HW interrupt_request flags later.
Therefore we shouldn't stop when there is CPU_INTERRUPT_POLL request.
> }
> /* The target hook may have updated the 'cpu->interrupt_request';
>
Pavel Dovgalyuk
next prev parent reply other threads:[~2020-07-29 5:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-17 18:16 [PULL for-5.1 0/3] tcg patch queue Richard Henderson
2020-07-17 18:16 ` [PULL for-5.1 1/3] tcg: Save/restore vecop_list around minmax fallback Richard Henderson
2020-07-17 18:16 ` [PULL for-5.1 2/3] tcg/cpu-exec: precise single-stepping after an exception Richard Henderson
2020-07-17 18:16 ` [PULL for-5.1 3/3] tcg/cpu-exec: precise single-stepping after an interrupt Richard Henderson
2020-07-29 5:31 ` Pavel Dovgalyuk [this message]
2020-07-19 18:23 ` [PULL for-5.1 0/3] tcg patch queue Peter Maydell
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