Re: [AT91RM9200] further run-time problems (jffs2, Oops in __update_rq_clock, IPSec)
Russell King - ARM Linux <linux <at> arm.linux.org.uk>
2007-11-12 15:19:57 GMT
On Mon, Nov 12, 2007 at 03:45:04PM +0100, Guennadi Liakhovetski wrote:
> 2. There has been an Oops once in vi...
>
> Unable to handle kernel paging request at virtual address e5dcc3ec
> pgd = c135c000
> [e5dcc3ec] *pgd=00000000
> Internal error: Oops: 5 [#1]
> Modules linked in:
> CPU: 0 Not tainted (2.6.23.1-ga63c3b88-dirty #52)
> PC is at __update_rq_clock+0x4c/0x140
> LR is at __update_rq_clock+0x28/0x140
> pc : [<c0033e38>] lr : [<c0033e14>] psr: 60000093
> sp : c1517b08 ip : e5dcc010 fp : c0117b3c
> r10: c025125c r9 : 00000001 r8 : 00000000
> r7 : 00000000 r6 : c1cc9720 r5 : e5dcc3ec r4 : e2be3800
> r3 : 00989680 r2 : ffffd430 r1 : 00989665 r0 : e2be3800
> Flags: nZCv IRQs off nt user
> Control: c000717f Table: 2135c000 DAC: 00000015
> Process vi (pid: 2017, stack limit = 0xc1516258)
> Stack: (0xc1517b08 to 0xc1518000)
> Backtrace: frame pointer underflow
^^^^^^^^^^^^^^ hint.
> Backtrace aborted due to bad frame pointer <c0117b3c>
> Code: e0c88005 e51bc034 e3580000 e28c5ff7 (e8950060)
>
> __update_rq_clock:
> @ args = 0, pretend = 0, frame = 12
> @ frame_needed = 1, uses_anonymous_args = 0
> mov ip, sp @,
> stmfd sp!, {r4, r5, r6, r7, r8, r9, sl, fp, ip, lr, pc} @,
> sub fp, ip, #4 @,,
> sub sp, sp, #12 @,,
> ldr r3, .L33+8 @ tmp108,
> add r4, r0, #996 @ prev_raw, rq,
> ldmia r4, {r4-r5} @ prev_raw
> str r0, [fp, #-52] @ tmp12,
> mov lr, pc
> bx r3 @ tmp108
> str r0, [fp, #-48] @, now
> str r1, [fp, #-44] @, now
> mov r8, r1 @ delta,
> mov r7, r0 @ delta,
> subs r7, r7, r4 @ delta, delta, prev_raw
> sbc r8, r8, r5 @ delta, delta, prev_raw
> ldr ip, [fp, #-52] @,
> cmp r8, #0 @ delta,
> add r5, ip, #988 @ clock.432, rq,
> ldmia r5, {r5-r6} @ clock.432
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Notice where 'r5' comes from - 'ip', which comes from '[fp, #-52]'.
Now read through from the start of the function and see what value 'fp'
is supposed to have.
sp at the ldmia instruction is currently at 0xc1517b08. Add 12.
There's 11 registers pushed into the stack, so add 44 bytes. This
is the value of 'ip' and 'sp' after the first instruction. This
gives a value of 0xc1517b40.
To confirm this, here's the state which the stmfd instruction saved
onto the stack:
7b00: c0314974 c1517b18 c0046378 ffffd43a c1cc9860 c1cc9720
A B C r4 r5 r6
7b20: c02f4554 c1516000 00000001 c025125c c1517b64 c1517b40 c0250a74 c0033dfc
r7 r8 r9 sl fp ip lr pc
That means 'fp' after the first 'sub' instruction should be 0xc1517b3c.
However, it is actually 0xc0117b3c. Note that these two values look
very similar. The difference is only 0x01400000. Two bit errors in
SDRAM?
The other thing to consider is sched_clock() - the 'bx' instruction
you've marked above is calling that function. Is it messing up the
frame pointer?
Also note that r8, r1 and r5 values. The code immediately before which
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