Date: Sat, 4 May 2013 14:41:02 -0700 From: Tim Kientzle <tim@kientzle.com> To: freebsd-arm@freebsd.org, Warner Losh <imp@bsdimp.com> Subject: Re: Is this related to the general panic discussed in freebsd-current? Message-ID: <CCABA43A-6D7E-4310-9F68-AEE54C88F431@kientzle.com> In-Reply-To: <5183BF8C.4040406@thieprojects.ch> References: <51835891.4050409@thieprojects.ch> <03971BD1-4ADE-4435-BDD0-B94B62634F1D@bsdimp.com> <5183BF8C.4040406@thieprojects.ch>
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On May 3, 2013, at 6:45 AM, Werner Thie wrote:
> On 5/3/13 3:13 PM, Warner Losh wrote:
>> On May 3, 2013, at 12:26 AM, Werner Thie wrote:
>>
>>> Hi all
>>>
>>> just came around yesterday to start playing with crochet, built an image and KDB entering panic when booting
>>>
>>> FreeBSD 10.0-CURRENT #0 r250144M: Thu May 2 10:10:20 CEST 2013
>>> root@xtools:/usr/home/wthie/proj/crochet-freebsd/work/obj/arm.armv6/usr/local/src/sys/BEAGLEBONE arm
>>> FreeBSD clang version 3.3 (trunk 178860) 20130405
>>> WARNING: WITNESS option enabled, expect reduced performance.
>>> panic: acquiring blockable sleep lock with spinlock or critical section held (rw) pmap pv global @ /usr/local/src/sys/arm/arm/pmap-v6.c:1187
>>> KDB: enter: panic
>>> [ thread pid 0 tid 0 ]
>>> Stopped at $d: ldrb r15, [r15, r15, ror r15]!
I think I've managed to isolate this to the stack_capture function in sys/arm/arm/stack_machdep.c.
Here's the breadcrumb trail I've followed so far:
1. Witness is complaining about pmap_fault_fixup trying to acquire the "pmap pv global" lock before it dies.
2. Inserted printfs, found that pmap_fault_fixup was being called from data_abort_handler (in sys/arm/arm/trap.c).
3. Uncommenting the printf in data_abort_handler gives the next step:
data abort: fault address=0xe28db008 (from pc=0xc0519d08 lr=0xc0519d14)
4. According to objdump, the PC address above is in stack_save (actually, the inlined version of stack_capture), in sys/arm/arm/stack_machdep.c.
If I add a printf() to the middle of stack_capture, the kernel boots. So it definitely smells like a code-generation error of some sort.
I'm going to start digging through the assembly next.
Tim
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