[lttng-dev] lttng_lib_ring_buffer: section 24 reloc 0 sym '': relocation 42 out of range

[lttng-dev] lttng_lib_ring_buffer: section 24 reloc 0 sym '': relocation 42 out of range

[Lukasz Domowy]

Hello,

First - of all: thank you very much for efforts to develop and
maintain LTTng. It's very useful tool!
I used it so far on PowerPC targets and now I try to run it on ARM:
Cyclone5 ARMv7 CPU.

When trying to run LTTng I get:

# lttng list --kernel
[ 2012.822578] lttng_lib_ring_buffer: section 24 reloc 0 sym '':
relocation 42 out of range (0x7f05827c -> 0xc0cd7358)
Error: Unable to list kernel events: Kernel tracer not available
Error: Command error

Do you have any hints how to fix it?

I found https://bugs.lttng.org/issues/1173 but enabling
CONFIG_ARM_MODULE_PLTS did not help.

I use LTTng from Yocto 3.0.2 with custom kernel 4.14.134-rt63-rt:

# lttng -V
lttng (LTTng Trace Control) 2.10.7 - KeKriek

All options recommended from documentation are enabled:
root at cyclone5:~# zcat /proc/config.gz | grep -i modules
CONFIG_DEFCONFIG_LIST="/lib/modules/$UNAME_RELEASE/.config"
CONFIG_MODULES_USE_ELF_REL=y
CONFIG_MODULES=y
CONFIG_MODULES_TREE_LOOKUP=y
# Xtables combined modules
# User Modules And Translation Layers
root at cyclone5:~# zcat /proc/config.gz | grep -i kallsyms
CONFIG_KALLSYMS=y
# CONFIG_KALLSYMS_ABSOLUTE_PERCPU is not set
CONFIG_KALLSYMS_BASE_RELATIVE=y
root at cyclone5:~# zcat /proc/config.gz | grep -i high_res_timers
CONFIG_HIGH_RES_TIMERS=y
root at cyclone5:~# zcat /proc/config.gz | grep -i tracepoints
CONFIG_TRACEPOINTS=y
CONFIG_HAVE_SYSCALL_TRACEPOINTS=y

Thank you in advance!

Best regards,
Lukasz

[lttng-dev] lttng_lib_ring_buffer: section 24 reloc 0 sym '': relocation 42 out of range

[Jonathan Rajotte-Julien]

Hi Lukasz,

Is the problem reproducible on the qemu arm target (yocto) ?

On Thu, May 28, 2020 at 01:51:12PM +0200, Lukasz Domowy via lttng-dev wrote:
> Hello,
> 
> First - of all: thank you very much for efforts to develop and
> maintain LTTng. It's very useful tool!
> I used it so far on PowerPC targets and now I try to run it on ARM:
> Cyclone5 ARMv7 CPU.
> 
> When trying to run LTTng I get:
> 
> # lttng list --kernel
> [ 2012.822578] lttng_lib_ring_buffer: section 24 reloc 0 sym '':
> relocation 42 out of range (0x7f05827c -> 0xc0cd7358)
> Error: Unable to list kernel events: Kernel tracer not available
> Error: Command error
> 
> Do you have any hints how to fix it?
> 
> I found https://bugs.lttng.org/issues/1173 but enabling
> CONFIG_ARM_MODULE_PLTS did not help.
> 
> I use LTTng from Yocto 3.0.2 with custom kernel 4.14.134-rt63-rt:
> 
> # lttng -V
> lttng (LTTng Trace Control) 2.10.7 - KeKriek
> 
> All options recommended from documentation are enabled:
> root at cyclone5:~# zcat /proc/config.gz | grep -i modules
> CONFIG_DEFCONFIG_LIST="/lib/modules/$UNAME_RELEASE/.config"
> CONFIG_MODULES_USE_ELF_REL=y
> CONFIG_MODULES=y
> CONFIG_MODULES_TREE_LOOKUP=y
> # Xtables combined modules
> # User Modules And Translation Layers
> root at cyclone5:~# zcat /proc/config.gz | grep -i kallsyms
> CONFIG_KALLSYMS=y
> # CONFIG_KALLSYMS_ABSOLUTE_PERCPU is not set
> CONFIG_KALLSYMS_BASE_RELATIVE=y
> root at cyclone5:~# zcat /proc/config.gz | grep -i high_res_timers
> CONFIG_HIGH_RES_TIMERS=y
> root at cyclone5:~# zcat /proc/config.gz | grep -i tracepoints
> CONFIG_TRACEPOINTS=y
> CONFIG_HAVE_SYSCALL_TRACEPOINTS=y
> 
> Thank you in advance!
> 
> Best regards,
> Lukasz
> _______________________________________________
> lttng-dev mailing list
> lttng-dev at lists.lttng.org
> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

-- 
Jonathan Rajotte-Julien
EfficiOS

[lttng-dev] lttng_lib_ring_buffer: section 24 reloc 0 sym '': relocation 42 out of range

[Mathieu Desnoyers]

----- On May 28, 2020, at 7:51 AM, lttng-dev lttng-dev at lists.lttng.org wrote:

> Hello,
> 
> First - of all: thank you very much for efforts to develop and
> maintain LTTng. It's very useful tool!
> I used it so far on PowerPC targets and now I try to run it on ARM:
> Cyclone5 ARMv7 CPU.
> 
> When trying to run LTTng I get:
> 
> # lttng list --kernel
> [ 2012.822578] lttng_lib_ring_buffer: section 24 reloc 0 sym '':
> relocation 42 out of range (0x7f05827c -> 0xc0cd7358)
> Error: Unable to list kernel events: Kernel tracer not available
> Error: Command error
> 
> Do you have any hints how to fix it?

Hrm, there is very little handcrafted assembly within the lttng_lib_ring_buffer.ko
module. Especially not large chunks of handcrafted assembly. I suspect a compiler
issue.

From a freshly booted system, if you issue "modprobe lttng_lib_ring_buffer",
so you get the same error ?

Also, what is your exact compiler version ?

Thanks,

Mathieu


> 
> I found https://bugs.lttng.org/issues/1173 but enabling
> CONFIG_ARM_MODULE_PLTS did not help.
> 
> I use LTTng from Yocto 3.0.2 with custom kernel 4.14.134-rt63-rt:
> 
> # lttng -V
> lttng (LTTng Trace Control) 2.10.7 - KeKriek
> 
> All options recommended from documentation are enabled:
> root at cyclone5:~# zcat /proc/config.gz | grep -i modules
> CONFIG_DEFCONFIG_LIST="/lib/modules/$UNAME_RELEASE/.config"
> CONFIG_MODULES_USE_ELF_REL=y
> CONFIG_MODULES=y
> CONFIG_MODULES_TREE_LOOKUP=y
> # Xtables combined modules
> # User Modules And Translation Layers
> root at cyclone5:~# zcat /proc/config.gz | grep -i kallsyms
> CONFIG_KALLSYMS=y
> # CONFIG_KALLSYMS_ABSOLUTE_PERCPU is not set
> CONFIG_KALLSYMS_BASE_RELATIVE=y
> root at cyclone5:~# zcat /proc/config.gz | grep -i high_res_timers
> CONFIG_HIGH_RES_TIMERS=y
> root at cyclone5:~# zcat /proc/config.gz | grep -i tracepoints
> CONFIG_TRACEPOINTS=y
> CONFIG_HAVE_SYSCALL_TRACEPOINTS=y
> 
> Thank you in advance!
> 
> Best regards,
> Lukasz
> _______________________________________________
> lttng-dev mailing list
> lttng-dev at lists.lttng.org
> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com