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Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error |
Date: |
Mon, 25 Apr 2011 22:29:27 +0200 |
User-agent: |
Mutt/1.5.20 (2009-06-14) |
On Fri, Apr 22, 2011 at 06:14:06PM +0400, Igor Kovalenko wrote:
> On Fri, Apr 22, 2011 at 2:39 AM, Laurent Desnogues
> <address@hidden> wrote:
> > On Thu, Apr 21, 2011 at 9:45 PM, Igor Kovalenko
> > <address@hidden> wrote:
> >> On Thu, Apr 21, 2011 at 7:44 PM, Laurent Desnogues
> >> <address@hidden> wrote:
> >>> On Thu, Apr 21, 2011 at 4:57 PM, Artyom Tarasenko <address@hidden> wrote:
> >>>> On Tue, Apr 12, 2011 at 4:14 AM, Igor Kovalenko
> >>>> <address@hidden> wrote:
> >>>>>>> Do you have public test case?
> >>>>>>> It is possible to code this delay slot write test but real issue may
> >>>>>>> be corruption elsewhere.
> >>>>
> >>>> The test case is trivial: it's just the two instructions, branch and
> >>>> wrpr.
> >>>>
> >>>>> In theory there could be multiple issues including compiler induced
> >>>>> ones.
> >>>>> I'd prefer to see some kind of reproducible testcase.
> >>>>
> >>>> Ok, attached a 40 byte long test (the first 32 bytes are not used and
> >>>> needed only because the bios entry point is 0x20).
> >>>>
> >>>> $ git pull && make && sparc64-softmmu/qemu-system-sparc64 -bios
> >>>> test-wrpr.bin -nographic
> >>>> Already up-to-date.
> >>>> make[1]: Nothing to be done for `all'.
> >>>> /mnt/terra/projects/vanilla/qemu/tcg/tcg.c:1892: tcg fatal error
> >>>> Aborted
> >>>
> >>> The problem seems to be that wrpr is using a non-local
> >>> TCG tmp (cpu_tmp0).
> >>
> >> Just tried the test case with write to %pil - seems like write itself is
> >> OK.
> >> The issue appears to be with save_state() call since adding save_state
> >> to %pil case provokes the same tcg abort.
> >
> > The problem is that cpu_tmp0, not being a local tmp, doesn't
> > need to be saved across helper calls. This results in the
> > TCG "optimizer" getting rid of it even though it's later used.
> > Look at the log and you'll see what I mean :-)
>
> I'm not very comfortable with tcg yet. Would it be possible to teach
> optimizer working with delay slots? Or do I look in the wrong place.
>
The problem is not on the TCG side, but on the target-sparc/translate.c
side:
| case 0x32: /* wrwim, V9 wrpr */
| {
| if (!supervisor(dc))
| goto priv_insn;
| tcg_gen_xor_tl(cpu_tmp0, cpu_src1, cpu_src2);
| #ifdef TARGET_SPARC64
Here cpu_tmp0 is loaded. cpu_tmp0 is a TCG temp, which means it is not
saved across TCG branches.
[...]
| case 6: // pstate
| save_state(dc, cpu_cond);
| gen_helper_wrpstate(cpu_tmp0);
| dc->npc = DYNAMIC_PC;
| break;
save_state() calls save_npc(), which in turns might call
gen_generic_branch():
| static inline void gen_generic_branch(target_ulong npc1, target_ulong npc2,
| TCGv r_cond)
| {
| int l1, l2;
|
| l1 = gen_new_label();
| l2 = gen_new_label();
|
| tcg_gen_brcondi_tl(TCG_COND_EQ, r_cond, 0, l1);
|
| tcg_gen_movi_tl(cpu_npc, npc1);
| tcg_gen_br(l2);
|
| gen_set_label(l1);
| tcg_gen_movi_tl(cpu_npc, npc2);
| gen_set_label(l2);
| }
And here is the TCG branch, which drop the TCG temp cpu_temp0.
The solution is either to rewrite gen_generic_branch() without TCG
branches, or to use a TCG temp local instead of a TCG temp.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, (continued)
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Artyom Tarasenko, 2011/04/10
- Message not available
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Artyom Tarasenko, 2011/04/10
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Igor Kovalenko, 2011/04/10
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Artyom Tarasenko, 2011/04/11
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Igor Kovalenko, 2011/04/11
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Artyom Tarasenko, 2011/04/21
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Laurent Desnogues, 2011/04/21
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Igor Kovalenko, 2011/04/21
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Laurent Desnogues, 2011/04/21
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Igor Kovalenko, 2011/04/22
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error,
Aurelien Jarno <=
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Igor Kovalenko, 2011/04/25
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Artyom Tarasenko, 2011/04/26
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Igor Kovalenko, 2011/04/26
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Artyom Tarasenko, 2011/04/26
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Blue Swirl, 2011/04/26
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Igor Kovalenko, 2011/04/26
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Blue Swirl, 2011/04/26
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Igor Kovalenko, 2011/04/26
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Blue Swirl, 2011/04/27
- Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error, Artyom Tarasenko, 2011/04/27