Date: Sun, 4 Dec 2016 13:32:32 -0500 From: Lee D <embaudarm@gmail.com> To: freebsd-hackers@freebsd.org Subject: Please help me understand "Translation Fault" in custom device drivers, and how to debug Message-ID: <CANC_bnPtD%2Bay9OQmZHjgzbcEq75mFNss6O7QCUY6Yg0tnVZ-Fw@mail.gmail.com>
next in thread | raw e-mail | index | archive | help
Hello,
I need help understanding what a translation fault is, and how to debug
it. I have googled like crazy but can't seem to find any detailed
information.
I am working on an embedded system using an ARM processor, and consequently
am writing a bunch of device device drivers for my custom hardware.
I am having a problem with occasional crashes when kldload'ing my modules
in a boot script. I get various errors, including "Translation Fault" (L1
or L2), "Alignment Fault", "vm_fault", and "undefined instruction in
kernel". My code works 95% of the time though.
I never see any crashes while running, so I don't think this is a flaky
hardware problem.
Any suggestions on what kernel debugger commands to enter to gather
information would also be helpful. Here are the commands I am currently
recording the output of when I get a crash:
db> bt
db> ps
db> show intr
db> show proc 618
db> show allpcpu
db> show allrman
db> show intrcnt
db> show proc
db> show procvm
For a single concrete example, here is a backtrace of a device driver that
failed with a translation fault on kldload. This BT is unique in that it
actually seems to contain useful information. Most of the backtraces just
show some abort/exeception related calls and then say "Unable to unwind
into user space" (paraphrased), leaving me no info about where my crash
happened.
FreeBSD 10.3
Thanks,
Lee
db> bt
Tracing pid 622 tid 100079 td 0xc2d68000
db_trace_self() at db_trace_self
pc = 0xc057a1e4 lr = 0xc0137c68 (db_stack_trace+0x108)
sp = 0xde966670 fp = 0xde966688
r10 = 0xc074b240
db_stack_trace() at db_stack_trace+0x108
pc = 0xc0137c68 lr = 0xc013760c (db_command+0x294)
sp = 0xde966690 fp = 0xde966730
r4 = 0x00000000 r5 = 0x00000000
r6 = 0x00000000
db_command() at db_command+0x294
pc = 0xc013760c lr = 0xc0137364 (db_command_loop+0x78)
sp = 0xde966738 fp = 0xde966748
r4 = 0xc05c7ed4 r5 = 0xc05dd87c
r6 = 0xc074b22c r7 = 0xde966978
r8 = 0x00000001 r9 = 0xc0673520
r10 = 0xc0740f44
db_command_loop() at db_command_loop+0x78
pc = 0xc0137364 lr = 0xc0139e6c (db_trap+0x108)
sp = 0xde966750 fp = 0xde966870
r4 = 0x00000000 r5 = 0xc074b238
r6 = 0xc0740f70
db_trap() at db_trap+0x108
pc = 0xc0139e6c lr = 0xc02ec8f8 (kdb_trap+0x188)
sp = 0xde966878 fp = 0xde966898
r4 = 0x00000000 r5 = 0x00000017
r6 = 0xc0740f70 r7 = 0xde966978
kdb_trap() at kdb_trap+0x188
pc = 0xc02ec8f8 lr = 0xc05919ec (abort_fatal+0x1d4)
sp = 0xde9668a0 fp = 0xde9668b8
r4 = 0xde966978 r5 = 0x00000013
r6 = 0x00000004 r7 = 0x00000007
r8 = 0x00000017 r9 = 0x00000004
r10 = 0x00000000
abort_fatal() at abort_fatal+0x1d4
pc = 0xc05919ec lr = 0xc0591818 (abort_fatal)
sp = 0xde9668c0 fp = 0xde966970
r4 = 0xde966978 r5 = 0x00000007
r6 = 0x00000013 r7 = 0x00000017
r8 = 0x00000000
abort_fatal() at abort_fatal
pc = 0xc0591818 lr = 0xc057bf20 (exception_exit)
sp = 0xde966978 fp = 0xde966a00
r4 = 0x00000000 r5 = 0x00000000
r6 = 0x00000000 r7 = 0xc2643440
r8 = 0xffffffec
exception_exit() at exception_exit
pc = 0xc057bf20 lr = 0xc02866c0 (free+0xc0)
sp = 0xde9669c8 fp = 0xde966a00
r0 = 0x00000000 r1 = 0x00000001
r2 = 0xffffffec r3 = 0x00000000
r4 = 0xc26b2900 r5 = 0xc0740d50
r6 = 0x00000000 r7 = 0x00000000
r8 = 0x00000000 r9 = 0xc2643440
r10 = 0xffffffec r12 = 0x00000002
device_probe_child() at device_probe_child+0x298
pc = 0xc02e1110 lr = 0xc02e1d00 (device_probe+0x40)
sp = 0xde966a08 fp = 0xde966a18
r4 = 0xc26b2900 r5 = 0xffffffff
r6 = 0x00000000 r7 = 0xc26b2d00
r8 = 0xc06869f8 r9 = 0xc0692ec0
r10 = 0x00000000
device_probe() at device_probe+0x40
pc = 0xc02e1d00 lr = 0xc02e389c (bus_generic_driver_added+0x88)
sp = 0xde966a20 fp = 0xde966a28
r4 = 0xc26b2900 r5 = 0xc2e2ff14
r6 = 0x00000000
bus_generic_driver_added() at bus_generic_driver_added+0x88
pc = 0xc02e389c lr = 0xc02e02a0 (devclass_driver_added+0x80)
sp = 0xde966a30 fp = 0xde966a48
r4 = 0xc2e2ff14 r5 = 0xc2643440
devclass_driver_added() at devclass_driver_added+0x80
pc = 0xc02e02a0 lr = 0xc02e0208 (devclass_add_driver+0x12c)
sp = 0xde966a50 fp = 0xde966a70
r4 = 0xc2e2ff14 r5 = 0xc2e2ff90
r6 = 0x7fffffff r7 = 0xc274d520
r8 = 0xc2643440
devclass_add_driver() at devclass_add_driver+0x12c
pc = 0xc02e0208 lr = 0xc02e5224 (driver_module_handler+0x1ec)
sp = 0xde966a78 fp = 0xde966a98
r4 = 0xc2e2fefc r5 = 0xc0692340
r6 = 0xc2c7fd00 r7 = 0x00000000
r8 = 0xc074cbac r9 = 0xc2c7fd00
r10 = 0xc2643440
driver_module_handler() at driver_module_handler+0x1ec
pc = 0xc02e5224 lr = 0xc0289a8c (module_register_init+0x1fc)
sp = 0xde966aa0 fp = 0xde966ad0
r4 = 0xc074cb80 r5 = 0xc0692340
r6 = 0xc2c7fd00 r7 = 0xc2e27970
r8 = 0xc074cbac r9 = 0xc0730ea8
r10 = 0xc2e2fec0
module_register_init() at module_register_init+0x1fc
pc = 0xc0289a8c lr = 0xc027b430 (linker_load_module+0xc78)
sp = 0xde966ad8 fp = 0xde966d38
r4 = 0xc074cbac r5 = 0xc0692340
r6 = 0xc072f9e0 r7 = 0xc2e27d7c
r8 = 0xc2c7fd00 r9 = 0xc274d8c0
r10 = 0xc072f9b0
linker_load_module() at linker_load_module+0xc78
pc = 0xc027b430 lr = 0xc027d398 (kern_kldload+0x128)
sp = 0xde966d40 fp = 0xde966d70
r4 = 0xde966d78 r5 = 0x00000000
r6 = 0xc26d5800 r7 = 0x00000001
r8 = 0xc072f9b0 r9 = 0xc072f9e0
r10 = 0x00000000
kern_kldload() at kern_kldload+0x128
pc = 0xc027d398 lr = 0xc027d508 (sys_kldload+0x64)
sp = 0xde966d78 fp = 0xde966d88
r4 = 0xc2d68000 r5 = 0xc26d5800
r6 = 0x00000000 r7 = 0x00000000
r8 = 0xde966df0 r9 = 0xc2daa670
sys_kldload() at sys_kldload+0x64
pc = 0xc027d508 lr = 0xc05908fc (swi_handler+0x5e8)
sp = 0xde966d90 fp = 0xde966e48
r4 = 0xc2d68000 r5 = 0xde966e50
r6 = 0xbffffe58
swi_handler() at swi_handler+0x5e8
pc = 0xc05908fc lr = 0xc057beb0 (swi_exit)
sp = 0xde966e50 fp = 0xbffffe18
r4 = 0xbfffff42 r5 = 0x00000000
r6 = 0xbffffe58 r7 = 0x00000130
r8 = 0x00000000 r9 = 0xbffff9dc
r10 = 0x00000000
swi_exit() at swi_exit
pc = 0xc057beb0 lr = 0xc057beb0 (swi_exit)
sp = 0xde966e50 fp = 0xbffffe18
Unable to unwind further
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CANC_bnPtD%2Bay9OQmZHjgzbcEq75mFNss6O7QCUY6Yg0tnVZ-Fw>