From: Sven Schnelle <svens@stackframe.org>
To: Helge Deller <deller@gmx.de>
Cc: John David Anglin <dave.anglin@bell.net>,
linux-parisc <linux-parisc@vger.kernel.org>
Subject: Re: Your System ate a SPARC! Gah! in map_pages()
Date: Fri, 10 Dec 2021 20:53:39 +0100 [thread overview]
Message-ID: <87fsr0s0cc.fsf@x1.stackframe.org> (raw)
In-Reply-To: <8a56f234-1126-e068-a70c-3b333320ef14@gmx.de> (Helge Deller's message of "Wed, 8 Dec 2021 09:14:38 +0100")
Helge Deller <deller@gmx.de> writes:
> On 12/7/21 23:07, John David Anglin wrote:
>> On 2021-12-05 3:46 p.m., Helge Deller wrote:
>>>> 10574: 43 ff ff 40 ldb 1fa0(sr3,r31),r31
>>> This IIR is strange. We most likely don't touch userspace at this stage
>>> when the kernel boots, and...
>> I'm thinking IIR is sometimes unreliable. I see the same value
>> printed for the tst-minsigstksz-5 fault yet the actual fault
>> instruction was "ldi 1,r25".
>
> Good finding.
> It seems to be at least always unreliable if we get a trap 7 (Instruction access rights).
> In that case the CPU couldn't execute the instruction due to missing
> execute permissions. I believe the CPU simply didn't fetched the
> instruction and as such has stale content in IIR.
>
> I'm sending a patch to the list which marks IIR with a magic value in that case.
The same might happen with ISR and IOR - i wonder whether we should take
a few bit in struct pt_regs, store the interruption code there, and only
display the fields that are valid for a certain code? pt_regs has an
unused pad0 field (at least i think it's unused...) which we could use.
What's your take on this? I would prefer this over some magic values in
the oops output...
Sven
next prev parent reply other threads:[~2021-12-10 19:53 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-05 19:33 Your System ate a SPARC! Gah! in map_pages() John David Anglin
2021-12-05 20:46 ` Helge Deller
2021-12-05 21:00 ` John David Anglin
2021-12-05 23:05 ` John David Anglin
2021-12-06 18:41 ` Helge Deller
2021-12-06 19:07 ` John David Anglin
2021-12-07 15:36 ` John David Anglin
2021-12-07 22:07 ` John David Anglin
2021-12-08 8:14 ` Helge Deller
2021-12-10 19:53 ` Sven Schnelle [this message]
2021-12-10 21:14 ` Helge Deller
2021-12-10 21:18 ` John David Anglin
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