From: Ralf Baechle <ralf@linux-mips.org>
To: "Nori, Soma Sekhar" <nsekhar@ti.com>
Cc: linux-mips@linux-mips.org, "Iyer, Suraj" <ssiyer@ti.com>
Subject: Re: do_ri exception in Linux (MIPS 4kec)
Date: Mon, 27 Dec 2004 13:30:09 +0100 [thread overview]
Message-ID: <20041227123009.GB25442@linux-mips.org> (raw)
In-Reply-To: <F6B01C6242515443BB6E5DDD63AE935F60FFFF@dbde2k01.itg.ti.com>
On Thu, Dec 23, 2004 at 04:58:03PM +0530, Nori, Soma Sekhar wrote:
> We are using montavista Linux version 2.4.17, gcc version 2.95.3 running on MIPS 4kec.
>
> Here is the dump:
> $0 : 00000000 0044def4 000001ac 0000006b 00000000 7fff7c08 00000001 00000000
> $8 : 0000fc00 00000001 00000000 941524d0 00004700 00000000 97fc3ea0 7fff7c08
> $16: 100048a4 100029d8 100029d8 10003020 00000000 7fff7dc8 10003b60 2d8e2163
> $24: 00000001 2ab7bc30 10008e70 7fff7bf0 04000000 00439e50
> Hi : 00000000
> Lo : 00000001
> epc : 00439e84 Not tainted
> Status: 0000fc13
> Cause : 10800028
> Process sh (pid: 18, stackpage=97fc2000)
> Stack: 00000001 00000000 2abd0ff0 7fff7c28 10008e70 00000000 10008e6c 00000000
> 100049a0 0042f188 00000000 100029d8 00000001 00000001 7fff7f04 10008e70
> 00427fe4 00427f00 00000000 00000000 10002764 10008e70 10008e70 00000000
> 00000000 00000000 10008e70 00422734 00000001 00000001 7fff7f04 10008e70
> 10008e70 00000003 10008e70 004315cc 00000001 00000000 10002764 00000000
> 10008e70 ...
> Call Trace:
> Code: 00000000 2421dd48 00220821 <8c220000> 00000000 005c1021 00400008 0000
> 0000 8f99802c
>
> The epc is not in kernel space and ksymoops did not provide any info. The epc keeps changing to different locations in user space over multiple runs.
In a case like this you're likely dealing with double exceptions. Your
code is taking an exception and the exception handler while running with
c0_status set is taking another exception. If the first exception handler
is still running with the c0_status.exl bit set the CPU when taking the
second exception it will not record the PC of the second exception and
you will have a seemingly unexplainable exception.
A few processors have the nasty habit of throwing RI receptions or do
similarly weird things when executing code that is mapped through multiple
TLB pages but the 4kEC shouldn't.
Ralf
next prev parent reply other threads:[~2004-12-27 12:30 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-23 11:28 do_ri exception in Linux (MIPS 4kec) Nori, Soma Sekhar
2004-12-23 11:28 ` Nori, Soma Sekhar
2004-12-27 12:30 ` Ralf Baechle [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-12-28 14:41 Nori, Soma Sekhar
2004-12-28 14:41 ` Nori, Soma Sekhar
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