Unable to access debug information from modules in linux-image-extra

[Alain Kalker]

I've setup and installed kernel dbgsym package as documented.
Using systemtap, I'm unable to list any probes from modules which are in the "linux-image-extra-$(uname -r)" package.

This is easy to verify using the following commands:

$ for i in $(lsmod | awk '{ print $1 }'); \
    do \
        echo; echo --- $i ---; \
        sudo stap -L "module(\"$i\").function(\"\*\")"; \
    done

Only modules which are in "linux-image-$(uname -r)" package get their function probes listed, other modules produce no output.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: linux-image-3.5.0-18-generic 3.5.0-18.29
ProcVersionSignature: Ubuntu 3.5.0-18.29-generic 3.5.7
Uname: Linux 3.5.0-18-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.6.1-0ubuntu6
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: miki 2272 F.... pulseaudio
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
Date: Sat Nov 10 07:10:33 2012
HibernationDevice: RESUME=UUID=0454653b-a512-49e9-a0c5-856819222789
InstallationDate: Installed on 2011-11-12 (363 days ago)
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
IwConfig:
 eth0 no wireless extensions.

 lo no wireless extensions.
Lsusb:
 Bus 001 Device 004: ID 1058:0704 Western Digital Technologies, Inc. Passport External HDD
 Bus 002 Device 002: ID 04d9:1603 Holtek Semiconductor, Inc. Keyboard
 Bus 002 Device 003: ID 046d:c001 Logitech, Inc. N48/M-BB48 [FirstMouse Plus]
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: FUJITSU SIEMENS MS-7504VP
MarkForUpload: True
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=nl_NL.UTF-8
 SHELL=/bin/bash
ProcFB: 0 VESA VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.5.0-18-generic root=UUID=fd6406dd-bae3-42db-809d-8f232d1ee6ea ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.5.0-18-generic N/A
 linux-backports-modules-3.5.0-18-generic N/A
 linux-firmware 1.95
RfKill:

SourcePackage: linux
UpgradeStatus: Upgraded to quantal on 2012-11-06 (4 days ago)
dmi.bios.date: 08/11/2008
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: V1.16
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: MS-7504VP
dmi.board.vendor: FUJITSU SIEMENS
dmi.board.version: 1.0
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: FUJITSU SIEMENS
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrV1.16:bd08/11/2008:svnFUJITSUSIEMENS:pnMS-7504VP:pvr1.0:rvnFUJITSUSIEMENS:rnMS-7504VP:rvr1.0:cvnFUJITSUSIEMENS:ct3:cvrToBeFilledByO.E.M.:
dmi.product.name: MS-7504VP
dmi.product.version: 1.0
dmi.sys.vendor: FUJITSU SIEMENS

[Brad Figg (brad-figg)]

This change was made by a bot.

[Alain Kalker (miki4242)]

BuildID's seem to match, also `readelf` indicates there is debug info available for the following module:

$ file /lib/modules/3.5.0-18-generic/kernel/drivers/media/dvb/dvb-usb/dvb-usb-anysee.ko
/lib/modules/3.5.0-18-generic/kernel/drivers/media/dvb/dvb-usb/dvb-usb-anysee.ko: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), BuildID[sha1]=0x484dfe34c2c5193cf55711f5adff9f2043c8e010, not stripped

$ file /usr/lib/debug/lib/modules/3.5.0-18-generic/kernel/drivers/media/dvb/dvb-usb/dvb-usb-anysee.ko
/usr/lib/debug/lib/modules/3.5.0-18-generic/kernel/drivers/media/dvb/dvb-usb/dvb-usb-anysee.ko: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), BuildID[sha1]=0x484dfe34c2c5193cf55711f5adff9f2043c8e010, not stripped

Yet systemtap lists no probes for this module.

[Joseph Salisbury (jsalisbury)]

Can you provide a pointer to the documentation you followed to install the kernel dbgsym package? I'll see if I can also reproduce the issue.

Also, can provide an example module from linux-image-$(uname -r) that provides it's function probes as expected?

[Alain Kalker (miki4242)]

Sure :-) I followed this guide: http://sourceware.org/systemtap/wiki/SystemtapOnUbuntu

Make sure to substitude 'quantal' for 'precise' in the 'General ddeb repository configuration' section.
The apt-key is the same for Quantal.

For a module in linux-image, try

$ sudo stap -L 'module("parport").function("*")'

For a module _not_ in linux-image, e.g. in linux-image-extra, try

$ sudo stap -L 'module("parport_serial").function("*")'

(Note: the -L instead of -l adds function parameter descriptions to the output, a very cool feature :-) )

[Alain Kalker (miki4242)]

Also, ignore the comments on kernel support and support for userspace probes, Ubuntu Quantal has both.

[Alain Kalker (miki4242)]

Sorry for the many posts, please note that the linux-image dbgsym package is _large_.
linux-image-3.5.0-17-generic-dbgsym will expand to 2395318 Kbytes (yes, that's more than 2.2 Gigs), and is about a ~600MB download, so make sure you're on a fat internet pipe and have some time to spare.