From: "Alex Bennée" <alex.bennee@linaro.org>
To: Bin Meng <bmeng.cn@gmail.com>
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
"qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>
Subject: Re: [PATCH 1/2] gdbstub: Set current_cpu for memory read write
Date: Tue, 12 Apr 2022 11:48:27 +0100 [thread overview]
Message-ID: <87sfqiziec.fsf@linaro.org> (raw)
In-Reply-To: <CAEUhbmVLkLbknHpOncFYQNU3H8_f58-Z7KcgvtEffGP=eaiPLg@mail.gmail.com>
Bin Meng <bmeng.cn@gmail.com> writes:
> On Sat, Apr 2, 2022 at 7:20 PM Bin Meng <bmeng.cn@gmail.com> wrote:
>>
>> On Tue, Mar 29, 2022 at 12:43 PM Bin Meng <bmeng.cn@gmail.com> wrote:
>> >
>> > On Mon, Mar 28, 2022 at 5:10 PM Peter Maydell <peter.maydell@linaro.org> wrote:
>> > >
>> > > On Mon, 28 Mar 2022 at 03:10, Bin Meng <bmeng.cn@gmail.com> wrote:
>> > > > IMHO it's too bad to just ignore this bug forever.
>> > > >
>> > > > This is a valid use case. It's not about whether we intentionally want
>> > > > to inspect the GIC register value from gdb. The case is that when
>> > > > single stepping the source codes it triggers the core dump for no
>> > > > reason if the instructions involved contain load/store to any of the
>> > > > GIC registers.
>> > >
>> > > Huh? Single-stepping the instruction should execute it inside
>> > > QEMU, which will do the load in the usual way. That should not
>> > > be going via gdbstub reads and writes.
>> >
>> > Yes, single-stepping the instruction is executed in the vCPU context,
>> > but a gdb client sends additional commands, more than just telling
>> > QEMU to execute a single instruction.
>> >
>> > For example, the following is the sequence a gdb client sent when doing a "si":
>> >
>> > gdbstub_io_command Received: Z0,100000,4
>> > gdbstub_io_reply Sent: OK
>> > gdbstub_io_got_ack Got ACK
>> > gdbstub_io_command Received: m18c430,4
>> > gdbstub_io_reply Sent: ff430091
>> > gdbstub_io_got_ack Got ACK
>> > gdbstub_io_command Received: vCont;s:p1.1;c:p1.-1
>> > gdbstub_op_stepping Stepping CPU 0
>> > gdbstub_op_continue_cpu Continuing CPU 1
>> > gdbstub_op_continue_cpu Continuing CPU 2
>> > gdbstub_op_continue_cpu Continuing CPU 3
>> > gdbstub_hit_break RUN_STATE_DEBUG
>> > gdbstub_io_reply Sent: T05thread:p01.01;
>> > gdbstub_io_got_ack Got ACK
>> > gdbstub_io_command Received: g
>> > gdbstub_io_reply Sent:
>> > 3848ed0000000000f08fa610000000000300000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001f90000000030a5ec000000000034c4180000000000c9030000
>> > gdbstub_io_got_ack Got ACK
>> > gdbstub_io_command Received: m18c434,4
>> > gdbstub_io_reply Sent: 00e004d1
>> > gdbstub_io_got_ack Got ACK
>> > gdbstub_io_command Received: m18c430,4
>> > gdbstub_io_reply Sent: ff430091
>> > gdbstub_io_got_ack Got ACK
>> > gdbstub_io_command Received: m18c434,4
>> > gdbstub_io_reply Sent: 00e004d1
>> > gdbstub_io_got_ack Got ACK
>> > gdbstub_io_command Received: m18c400,40
>> > gdbstub_io_reply Sent:
>> > ff4300d1e00300f980370058000040f900a00191000040f900b00091000040f900e004911e7800f9fe0340f91e0000f9ff43009100e004d174390094bb390094
>> > gdbstub_io_got_ack Got ACK
>> > gdbstub_io_command Received: mf9010000,4
>> >
>> > Here "mf9010000,4" triggers the bug where 0xf9010000 is the GIC register.
>> >
>> > This is not something QEMU can ignore or control. The logic is inside
>> > the gdb client.
>> >
>>
>> Ping for this series?
>>
>
> Ping?
Can you have a look at:
Subject: [RFC PATCH] gdb/gic: expose cpu_index via MxTxAttrs
Date: Tue, 12 Apr 2022 11:45:19 +0100
Message-Id: <20220412104519.201655-1-alex.bennee@linaro.org>
and let me know what you think?
--
Alex Bennée
prev parent reply other threads:[~2022-04-12 10:50 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-22 15:42 [PATCH 1/2] gdbstub: Set current_cpu for memory read write Bin Meng
2022-03-22 15:42 ` [PATCH 2/2] monitor/misc: Set current_cpu for memory dump Bin Meng
2022-03-22 15:56 ` [PATCH 1/2] gdbstub: Set current_cpu for memory read write Peter Maydell
2022-03-22 18:59 ` Philippe Mathieu-Daudé
2022-03-22 19:32 ` Peter Maydell
2022-03-24 3:10 ` Bin Meng
2022-03-24 10:27 ` Alex Bennée
2022-03-24 11:52 ` Peter Maydell
2022-03-28 2:10 ` Bin Meng
2022-03-28 9:09 ` Peter Maydell
2022-03-29 4:43 ` Bin Meng
2022-04-02 11:20 ` Bin Meng
2022-04-08 5:58 ` Bin Meng
2022-04-08 9:00 ` Alex Bennée
2022-04-12 10:48 ` Alex Bennée [this message]
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