From: Laurent Vivier <laurent@vivier.eu>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Richard Henderson <rth@twiddle.net>,
QEMU Developers <qemu-devel@nongnu.org>,
Andreas Schwab <schwab@linux-m68k.org>,
Alexander Graf <agraf@suse.de>, Greg Ungerer <gerg@uclinux.org>
Subject: Re: [Qemu-devel] [PATCH 51/52] target-m68k: add cmpm
Date: Sun, 8 May 2016 11:07:11 +0200 [thread overview]
Message-ID: <c8d87fbc-6b40-4ca5-08b7-cd1441757b54@vivier.eu> (raw)
In-Reply-To: <CAFEAcA9Satcm6Rzou+cCJPp0J3k1q-EdFwkBMmrUdiToMOqXrw@mail.gmail.com>
Le 07/05/2016 à 23:50, Peter Maydell a écrit :
> On 7 May 2016 at 20:01, Laurent Vivier <laurent@vivier.eu> wrote:
>>
>>
>> Le 07/05/2016 à 00:00, Richard Henderson a écrit :
>>> On 05/04/2016 11:21 AM, Laurent Vivier wrote:
>>>> + reg = AREG(insn, 0);
>>>> + src = gen_load(s, opsize, reg, 1);
>>>> + tcg_gen_addi_i32(reg, reg, opsize_bytes(opsize));
>>>> +
>>>> + reg = AREG(insn, 9);
>>>> + dest = gen_load(s, opsize, reg, 1);
>>>> + tcg_gen_addi_i32(reg, reg, opsize_bytes(opsize));
>>>
>>> Delay the writeback to the first areg until after the second load.
>>
>> We can't delay because we can have "cmpm (%a0)+,(%a0)+" that is used to
>> compare two consecutive memory contents.
>
> If you write back to the first areg before the second
> load, don't you get the wrong value as seen by the
> exception handler if the second load faults?
>
> Usually you want to use the updated value for the
> purposes of calculating the address to use in the
> second load, but you don't want to actually update
> the guest CPU register until after the load has
> happened, in case it faults.
>
> (Disclaimer: I'm just assuming that on a fault no
> registers are updated, but if that wasn't the case the OS
> wouldn't be able to cleanly restart the instruction after
> fixing up a page fault, so it seems like a good guess.)
You're right.
But I didn't really care here of the page faults because m68k only
supports non privileged instructions: coldfire is used in semi-hosting
mode (no MMU) and 680x0-like machine has no hardware (I use it in
linux-user mode).
I'm working on a Quadra 800 [1] emulation where I have added all the
needed hardware and privileged instructions, and of course, I have to
re-work all the memory access because of what you have described above...
But I'm going to try to update this series taking care of the memory
access fault as much as possible.
Laurent
[1] https://github.com/vivier/qemu-m68k/tree/q800-v2.4.0
next prev parent reply other threads:[~2016-05-08 9:07 UTC|newest]
Thread overview: 131+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-04 20:11 [Qemu-devel] [PATCH 00/52] 680x0 instructions emulation Laurent Vivier
2016-05-04 20:11 ` [Qemu-devel] [PATCH 01/52] target-m68k: fix DEBUG_DISPATCH Laurent Vivier
2016-05-06 16:34 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 02/52] target-m68k: Build the opcode table only once to avoid multithreading issues Laurent Vivier
2016-05-06 16:35 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 03/52] target-m68k: define m680x0 CPUs and features Laurent Vivier
2016-05-06 16:35 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 04/52] target-m68k: manage scaled index Laurent Vivier
2016-05-06 16:36 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 05/52] target-m68k: introduce read_imXX() functions Laurent Vivier
2016-05-06 16:36 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 06/52] target-m68k: set disassembler mode to 680x0 or coldfire Laurent Vivier
2016-05-06 16:37 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 07/52] target-m68k: add bkpt instruction Laurent Vivier
2016-05-06 16:42 ` Richard Henderson
2016-05-07 7:08 ` Laurent Vivier
2016-05-04 20:11 ` [Qemu-devel] [PATCH 08/52] target-m68k: define operand sizes Laurent Vivier
2016-05-06 16:43 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 09/52] target-m68k: set PAGE_BITS to 12 for m68k Laurent Vivier
2016-05-06 16:44 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 10/52] target-m68k: REG() macro cleanup Laurent Vivier
2016-05-06 16:44 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 11/52] target-m68k: allow to update flags with operation on words and bytes Laurent Vivier
2016-05-06 16:45 ` Richard Henderson
2016-05-07 7:19 ` Laurent Vivier
2016-05-04 20:11 ` [Qemu-devel] [PATCH 12/52] target-m68k: Replace helper_xflag_lt with setcond Laurent Vivier
2016-05-04 20:11 ` [Qemu-devel] [PATCH 13/52] target-m68k: update CPU flags management Laurent Vivier
2016-05-06 16:46 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 14/52] target-m68k: update move to/from ccr/sr Laurent Vivier
2016-05-06 16:47 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 15/52] target-m68k: don't update cc_dest in helpers Laurent Vivier
2016-05-06 16:47 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 16/52] target-m68k: update CPU flags management Laurent Vivier
2016-05-06 16:47 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 17/52] target-m68k: Print flags properly Laurent Vivier
2016-05-04 20:11 ` [Qemu-devel] [PATCH 18/52] target-m68k: Some fixes to SR and flags management Laurent Vivier
2016-05-06 16:49 ` Richard Henderson
2016-05-04 20:11 ` [Qemu-devel] [PATCH 19/52] target-m68k: terminate cpu dump with newline Laurent Vivier
2016-05-06 16:49 ` Richard Henderson
2016-05-06 17:41 ` Andreas Schwab
2016-05-04 20:12 ` [Qemu-devel] [PATCH 20/52] target-m68k: Remove incorrect clearing of cc_x Laurent Vivier
2016-05-04 20:12 ` [Qemu-devel] [PATCH 21/52] target-m68k: Reorg flags handling Laurent Vivier
2016-05-06 16:51 ` Richard Henderson
2016-05-04 20:12 ` [Qemu-devel] [PATCH 22/52] target-m68k: Introduce DisasCompare Laurent Vivier
2016-05-04 20:12 ` [Qemu-devel] [PATCH 23/52] target-m68k: Use setcond for scc Laurent Vivier
2016-05-04 20:12 ` [Qemu-devel] [PATCH 24/52] target-m68k: Optimize some comparisons Laurent Vivier
2016-05-04 20:12 ` [Qemu-devel] [PATCH 25/52] target-m68k: Optimize gen_flush_flags Laurent Vivier
2016-05-04 20:12 ` [Qemu-devel] [PATCH 26/52] target-m68k: Inline shifts Laurent Vivier
2016-05-06 16:53 ` Richard Henderson
2016-05-04 20:12 ` [Qemu-devel] [PATCH 27/52] target-m68k: Inline addx, subx, negx Laurent Vivier
2016-05-04 20:12 ` [Qemu-devel] [PATCH 28/52] target-m68k: add addx/subx/negx ops Laurent Vivier
2016-05-06 17:11 ` Richard Henderson
2016-05-04 20:12 ` [Qemu-devel] [PATCH 29/52] target-m68k: factorize flags computing Laurent Vivier
2016-05-06 17:11 ` Richard Henderson
2016-05-04 20:12 ` [Qemu-devel] [PATCH 30/52] target-m68k: add scc/dbcc Laurent Vivier
2016-05-06 17:18 ` Richard Henderson
2016-05-06 17:44 ` Andreas Schwab
2016-05-04 20:12 ` [Qemu-devel] [PATCH 31/52] target-m68k: some bit ops cleanup Laurent Vivier
2016-05-06 17:20 ` Richard Henderson
2016-05-04 20:12 ` [Qemu-devel] [PATCH 32/52] target-m68k: bitfield ops Laurent Vivier
2016-05-06 19:11 ` Richard Henderson
2016-05-04 21:08 ` [Qemu-devel] [PATCH 33/52] target-m68k: inline divu/divs Laurent Vivier
2016-05-04 21:08 ` [Qemu-devel] [PATCH 34/52] target-m68k: add 64bit mull Laurent Vivier
2016-05-06 19:48 ` Richard Henderson
2016-05-04 21:08 ` [Qemu-devel] [PATCH 35/52] target-m68k: inline rotate ops Laurent Vivier
2016-05-06 20:28 ` Richard Henderson
2016-05-04 21:08 ` [Qemu-devel] [PATCH 36/52] target-m68k: inline shift ops Laurent Vivier
2016-05-06 20:53 ` Richard Henderson
2016-05-04 21:08 ` [Qemu-devel] [PATCH 37/52] target-m68k: add cas/cas2 ops Laurent Vivier
2016-05-06 21:29 ` Richard Henderson
2016-05-04 21:08 ` [Qemu-devel] [PATCH 38/52] target-m68k: add linkl Laurent Vivier
2016-05-06 21:30 ` Richard Henderson
2016-05-04 21:08 ` [Qemu-devel] [PATCH 39/52] target-m68k: movem Laurent Vivier
2016-05-06 21:45 ` Richard Henderson
2016-05-06 19:44 ` [Qemu-devel] [PATCH 33/52] target-m68k: inline divu/divs Richard Henderson
2016-05-04 21:20 ` [Qemu-devel] [PATCH 40/52] target-m68k: add exg ops Laurent Vivier
2016-05-04 21:20 ` [Qemu-devel] [PATCH 41/52] target-m68k: add addressing modes to not Laurent Vivier
2016-05-06 21:47 ` Richard Henderson
2016-05-04 21:20 ` [Qemu-devel] [PATCH 42/52] target-m68k: eor can manage word and byte operands Laurent Vivier
2016-05-06 21:48 ` Richard Henderson
2016-05-04 21:21 ` [Qemu-devel] [PATCH 43/52] target-m68k: or " Laurent Vivier
2016-05-06 21:49 ` Richard Henderson
2016-05-04 21:21 ` [Qemu-devel] [PATCH 44/52] target-m68k: and " Laurent Vivier
2016-05-06 21:49 ` Richard Henderson
2016-05-04 21:21 ` [Qemu-devel] [PATCH 45/52] target-m68k: suba/adda can manage word operand Laurent Vivier
2016-05-06 21:50 ` Richard Henderson
2016-05-04 21:21 ` [Qemu-devel] [PATCH 46/52] target-m68k: introduce byte and word cc_ops Laurent Vivier
2016-05-06 21:53 ` Richard Henderson
2016-05-04 21:21 ` [Qemu-devel] [PATCH 47/52] target-m68k: add addressing modes to neg Laurent Vivier
2016-05-06 21:54 ` Richard Henderson
2016-05-04 21:21 ` [Qemu-devel] [PATCH 48/52] target-m68k: add/sub manage word and byte operands Laurent Vivier
2016-05-06 21:57 ` Richard Henderson
2016-05-04 21:21 ` [Qemu-devel] [PATCH 49/52] target-m68k: cmp manages word and bytes operands Laurent Vivier
2016-05-06 21:57 ` Richard Henderson
2016-05-04 21:21 ` [Qemu-devel] [PATCH 50/52] target-m68k: immediate ops manage word and byte operands Laurent Vivier
2016-05-06 21:59 ` Richard Henderson
2016-05-04 21:21 ` [Qemu-devel] [PATCH 51/52] target-m68k: add cmpm Laurent Vivier
2016-05-06 22:00 ` Richard Henderson
2016-05-07 19:01 ` Laurent Vivier
2016-05-07 21:50 ` Peter Maydell
2016-05-08 9:07 ` Laurent Vivier [this message]
2016-05-08 10:44 ` Peter Maydell
2016-05-04 21:21 ` [Qemu-devel] [PATCH 52/52] target-m68k: sr/ccr cleanup Laurent Vivier
2016-05-06 22:02 ` Richard Henderson
2016-05-06 21:47 ` [Qemu-devel] [PATCH 40/52] target-m68k: add exg ops Richard Henderson
2016-05-06 9:35 ` [Qemu-devel] [PATCH 00/52] 680x0 instructions emulation Andreas Schwab
2016-05-06 9:54 ` Laurent Vivier
2016-05-06 10:15 ` Andreas Schwab
2016-05-06 11:40 ` John Paul Adrian Glaubitz
2016-05-06 12:44 ` Andreas Schwab
2016-05-06 13:02 ` John Paul Adrian Glaubitz
2016-05-06 13:24 ` Andreas Schwab
2016-05-06 13:45 ` John Paul Adrian Glaubitz
2016-05-06 13:48 ` Andreas Schwab
2016-05-06 13:53 ` John Paul Adrian Glaubitz
2016-05-06 13:53 ` Laurent Vivier
2016-05-06 13:58 ` Andreas Schwab
2016-05-06 14:25 ` Andreas Schwab
2016-05-06 14:47 ` Andreas Schwab
2016-05-06 11:40 ` John Paul Adrian Glaubitz
2016-05-06 11:45 ` Alexander Graf
2016-05-06 11:57 ` Laurent Vivier
2016-05-06 12:03 ` Peter Maydell
2016-05-12 21:17 ` John Paul Adrian Glaubitz
2016-05-12 21:20 ` Laurent Vivier
[not found] ` <D2F89431-FF87-456A-A628-7F8ADCDDAFC7@suse.de>
2016-05-12 21:25 ` John Paul Adrian Glaubitz
[not found] ` <C662446E-C86D-4838-83C5-14E8E6C52D2A@suse.de>
2016-05-12 21:32 ` John Paul Adrian Glaubitz
2016-05-12 21:30 ` Laurent Vivier
2016-05-06 10:06 ` Alexander Graf
2016-05-06 10:30 ` [Qemu-devel] [PATCH] MAINTAINERS: update M68K entry Laurent Vivier
2016-05-12 7:55 ` Thomas Huth
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