perf: cannot resolve kernel symbols

From: Jean Pihet
Date: Tue Sep 17 2013 - 08:02:35 EST


Hi,

I am running the perf record and report commands, which are running OK
but I do not get any kernel symbol resolved when using a built and
installed kernel.
Using the distro installed kernel is OK though.
The setup is: Marvell ARMv7 quad core, Linaro Ubuntu release.

Here are the commands in use:
- perf record -g dwarf -- stress --cpu 2 --io 2 --vm 2 --timeout 1s
- perf report -vvv

With a vmlinux found at /lib/modules/<version>/build I get the
following in the trace output:
...
Looking at the vmlinux_path (6 entries long)
Using /lib/modules/3.11.0-00003-g0d4d4a1/build/vmlinux for symbols
...
dso: [kernel.kallsyms]
(/lib/modules/3.11.0-00003-g0d4d4a1/build/vmlinux, Functions, loaded,
0000000000000000000000000000000000000000)
c00081c0-c00081c3 g asm_do_IRQ
...
dso: [kernel.kallsyms].head.text ([kernel.kallsyms], Functions, loaded, 00000000
00000000000000000000000000000000)
c0008000-c0008077 g stext
c0008000-c0008000 g _text
c0008084-c0008127 l __create_page_tables
...
dso: [kernel.kallsyms].init.text ([kernel.kallsyms], Functions, loaded, 00000000
00000000000000000000000000000000)
c04f3260-c04f32af l __fixup_smp


Without any vmlinux found I get the following:
...
Looking at the vmlinux_path (6 entries long)
Using /proc/kallsyms for symbols
...
dso: [kernel.kallsyms] ([kernel.kallsyms], Functions, loaded,
0000000000000000000000000000000000000000)
0-beffffff l __vectors_start
dso: [kernel.kallsyms] ([kernel.kallsyms], Variables, NOT loaded,
0000000000000000000000000000000000000000)
dso: stress (/usr/bin/stress, Functions, loaded,
bdf57306ab106fb0ce9835c95dae5b173f238b61)
...


In any case the symbols are not resolved although vmlinux contains
symbols and /proc/kallsyms is accessible and working correctly.
Any idea on where to look at? I guess the problem is in the kernel installation.

Thx & regards,
Jean
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