Hang with isync

[Manoj Sharma]

This is the stack trace.

Registers:
GPR00: 00069030 C01F3000 C01F1080 00000000 00048000 C0639F48 C01F1080
FFFFFC18
GPR08: C02203FC 00000020 C0638000 C01F31B0 42FEE022 1056A7F8 00FE502A
00000000
GPR16: 00000000 FFC44232 00000000 00000000 FFC441EC 00080000 00010000
0000000A
GPR24: 00000000 0007CD80 00000CE0 00000000 00000000 C02B0000 00000000
C02B0000

NIP; c0005da4 _<_nmask_and_or_msr+0x18/0x20 [kernel]>
Trace; c0025328 _<check_pgt_cache+0x20/0x30 [kernel]>
Trace; c0004f4c _<idled+0x58/0x70 [kernel]>
Trace; c0004f74 _<cpu_idle+0x10/0x24 [kernel]>
Trace; c00012b0 _<rest_init+0x30/0x40 [kernel]>
Trace; c02a45a4 _<start_kernel+0x168/0x17c [kernel]>
Trace; c0000250 _<skpinv+0x1f8/0x234 [kernel]>


On 9/20/06, Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:
>
> On Tue, 2006-09-19 at 18:16 -0700, Manoj Sharma wrote:
> >         Hi,
> >
> >         We use linux kernel 2.4.20 on ppc405 and the system hangs once
> >         in a while when isync gets called in this function:
> >
> >         _GLOBAL(_nmask_and_or_msr)
> >             mfmsr   r0      /* Get current msr */
> >             andc    r0,r0,r3    /* And off the bits set in r3 (first
> >         parm) */`
> >             or  r0,r0,r4    /* Or on the bits in r4 (second parm) */
> >             sync            /* Some chip revs have problems here... */
> >             isync
> >             mtmsr   r0      /* Update machine state */
> >             isync
> >             blr         /* Done */
> >
> >          2.5 onwards, I find that "sync; isync" has been replaced by a
> >         macro SYNC (defined only for 601). I don't find it in any
> >         changelog and reason for the change.
> >
> >         Can someone give some information on this change?
>
> Regardless of the change... on 2.4, _nmask_and_or_msr() was used for a
> number of things. We would need to know where it was called from with
> what values as arguments to have an idea of what's going wrong. It's
> probably not dying on the isync, but rather on the following mtmsr due
> to a problem with the values passed in....
>
> Ben.
>
>
>
>
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