Function Profiler broken on today's linux-next

[Felipe Balbi]

Hi again,

On Wed, Jul 16, 2014 at 11:41:41AM -0500, Felipe Balbi wrote:
> Hi,
> 
> On Wed, Jul 16, 2014 at 12:29:21PM -0400, Steven Rostedt wrote:
> > On Wed, 16 Jul 2014 11:23:28 -0500
> > Felipe Balbi <balbi at ti.com> wrote:
> > 
> > > Hi folks,
> > > 
> > > I was trying to use Kernel Function Profiler to figure out why my
> > > driver's IRQ handler is taking so much CPU time but to my surprise,
> > > whenever I try to trace anything, I get a "Unable to handle kernel
> > > paging request at virtual address XXXX" error.
> > > 
> > > Is anybody else seen that or did I screw up my Kernel config ?
> > 
> > No, it's probably my fault. The ftrace infrastructure is going through
> > an overhaul and some dramatic changes are happening. Although it has
> > passed all my tests, I can't cover everyone's configs and use cases.
> > 
> > Please send me your config and the steps you did to enable function
> > profiling. This is x86 correct? Other archs are already known to be
> > broken and I'm working on fixing them now.
> 
> .config attached. It's actually an ARM platform, I can help out with
> testing anything you need.

for the steps:

# mount -t debugfs none /debug
# cd /debug/tracing
# echo dwc3* > set_graph_function
# echo dwc3* > set_function_filter
# echo 1 > function_profile_enabled
# echo 1 > tracing_on
# modprobe g_zero # this binds g_zero to dwc3 and a few functions from
		  # dwc3 are called

KABOOM! (see below)

[   41.135792] Unable to handle kernel paging request at virtual address ed6c9170
[   41.143375] pgd = ec290000
[   41.146207] [ed6c9170] *pgd=ad60041e(bad)
[   41.150420] Internal error: Oops: 8000000d [#1] SMP ARM
[   41.155898] Modules linked in: g_zero(+) libcomposite configfs matrix_keypad lis3lv02d_i2c lis3lv02d input_polldev
[   41.166801] CPU: 0 PID: 1710 Comm: modprobe Tainted: G        W      3.16.0-rc5-next-20140715-00031-gb041877 #529
[   41.177559] task: ec0050c0 ti: ec288000 task.ti: ec288000
[   41.183217] PC is at 0xed6c9170
[   41.186507] LR is at 0xec289d44
[   41.189799] pc : [<ed6c9170>]    lr : [<ec289d44>]    psr: 00000013
[   41.189799] sp : ec289d1c  ip : ed6c9170  fp : ec289d24
[   41.201831] r10: 00000000  r9 : bf0288d8  r8 : bf0288b8
[   41.207303] r7 : bf03a7c4  r6 : ed6c9170  r5 : ed6c9170  r4 : ed465740
[   41.214139] r3 : ed6c9170  r2 : ed465740  r1 : c04d6bdc  r0 : bf0285c0
[   41.220977] Flags: nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[   41.228452] Control: 10c5387d  Table: ac290059  DAC: 00000015
[   41.234467] Process modprobe (pid: 1710, stack limit = 0xec288248)
[   41.240937] Stack: (0xec289d1c to 0xec28a000)
[   41.245510] 9d00:                                                                ec289d28
[   41.254095] 9d20: c000ecec c04d6be8 ed465740 bf03a7ec ed6c9170 bf03a7c4 ec289d7c ec289d48
[   41.262661] 9d40: bf028954 bf028594 ec289d74 ec289d58 c0419b9c ed4a9c00 bf03a7ec bf03a7ec
[   41.271239] 9d60: ed4a9c08 bf0288b8 bf0288d8 00000000 ec289d9c ec289d80 c04fc6fc bf0288e4
[   41.279817] 9d80: bf03a7ec c0b0ba8c bf03a7ec bf026e40 ec289db4 ec289da0 c04fca70 c04fc6b0
[   41.288387] 9da0: bf03a7c4 bf03a448 ec289ddc ec289db8 bf026c38 c04fc9fc c0a84060 c0a84060
[   41.296958] 9dc0: bf03d264 ec288030 00000000 ec2bea40 ec289dec ec289de0 bf03d278 bf026b98
[   41.305527] 9de0: ec289e84 ec289df0 c0008a54 bf03d270 ed000040 a0000013 ec289e14 ec289e08
[   41.314090] 9e00: c008cbb4 c008c9d4 ec289e4c ec289e18 c014afa4 c008cbac 0000001d ec2bea40
[   41.322634] 9e20: f0614000 ec2bea40 00000000 00000000 0000001e ec2bea40 f0614000 00000001
[   41.331190] 9e40: ec289e6c ec289e50 c0140f38 c014aed8 ec289f48 00000000 bf03a854 ec289f48
[   41.339739] 9e60: 00000000 bf03a854 00000018 00000000 00000000 bf03a848 ec289f44 ec289e88
[   41.348286] 9e80: c00c54ec c00089d0 ffff8000 00007fff c00c2854 c015aa78 0001d579 00000000
[   41.356835] 9ea0: f0614000 ec289f7c ec289f50 000000cc f06299e8 bf03a854 bf03aa44 b6fb27a0
[   41.365412] 9ec0: ec288008 00000000 00120720 00000000 0b300002 c0a881a4 00000001 00000000
[   41.373963] 9ee0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[   41.382513] 9f00: 00000000 00000000 00000000 00000000 00000000 00000000 ec289f34 00000000
[   41.391066] 9f20: 00000005 b6fb27a0 0000017b c000ee04 ec288000 00000000 ec289fa4 ec289f48
[   41.399635] 9f40: c00c5ad4 c00c3ed0 f0614000 0001d579 f0629218 f0629020 f0630ad8 00000a44
[   41.408192] 9f60: 00001024 00000000 00000000 00000000 00000032 00000033 00000019 0000001d
[   41.416747] 9f80: 0000000e 00000000 00000000 b6fb3d10 00000000 70f62c00 00000000 ec289fa8
[   41.425293] 9fa0: c000eb80 c00c5a68 b6fb3d10 00000000 00000005 b6fb27a0 00000000 b6fb40b8
[   41.433838] 9fc0: b6fb3d10 00000000 70f62c00 0000017b 00000000 00000000 00000000 b6fbe2d8
[   41.442401] 9fe0: becaa6d8 becaa6c8 b6fa70a4 b6ee4160 60000010 00000005 00000000 00000000
[   41.450958] Code: ed4a83c0 ed4a8b40 ed4a8340 00000000 (00000000) 
[   41.457327] ---[ end trace cb88537fdc8fa202 ]---
Segmentation fault

cheers

-- 
balbi
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