In some situations the libdw unwinder stopped working properly. I.e.
with libunwind we see:
~~~~~
heaptrack_gui 2228 135073.400112: 641314 cycles:
e8ed _dl_fixup (/usr/lib/ld-2.25.so)
15f06 _dl_runtime_resolve_sse_vex (/usr/lib/ld-2.25.so)
ed94c KDynamicJobTracker::KDynamicJobTracker (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0)
608f3 _GLOBAL__sub_I_kdynamicjobtracker.cpp (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0)
f199 call_init.part.0 (/usr/lib/ld-2.25.so)
f2a5 _dl_init (/usr/lib/ld-2.25.so)
db9 _dl_start_user (/usr/lib/ld-2.25.so)
~~~~~
But with libdw and without this patch this sample is not properly
unwound:
~~~~~
heaptrack_gui 2228 135073.400112: 641314 cycles:
e8ed _dl_fixup (/usr/lib/ld-2.25.so)
15f06 _dl_runtime_resolve_sse_vex (/usr/lib/ld-2.25.so)
ed94c KDynamicJobTracker::KDynamicJobTracker (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0)
~~~~~
Debug output showed me that libdw found a module for the last frame
address, but it thinks it belongs to /usr/lib/ld-2.25.so. This patch
double-checks what libdw sees and what perf knows. If the mappings
mismatch, we now report the elf known to perf. This fixes the situation
above, and the libdw unwinder produces the same stack as libunwind.
Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20170602143753.16907-1-milian.wolff@kdab.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The following tests are failing on powerpc:
# perf test break
18: Breakpoint overflow signal handler : FAILED!
19: Breakpoint overflow sampling : FAILED!
The powerpc kenel so far does not have support to even create
instruction breakpoints using the perf event interface, so those tests
fail early in the config phase.
I added a '->is_supported()' callback to test struct to be able to
disable specific tests. It seems better than putting ifdefs directly to
the test array.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20170601205450.GA398@krava
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The decompress_kmodule() decompresses kernel modules in order to load
symbols from it. In the DSO_BINARY_TYPE__BUILD_ID_CACHE case, it needs
the full file path to extract the file extension to determine the
decompression method. But overwriting 'name' will fail the
decompression since it might point to a non-existing old file.
Instead, use dso->long_name for having the correct extension and use the
real filename to decompress.
In the DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP case, both names should
be the same. This allows resolving symbols in the old modules.
Before:
$ perf report -i perf.data.old | grep scsi_mod
0.00% cc1 [scsi_mod] [k] 0x0000000000004aa6
0.00% as [scsi_mod] [k] 0x00000000000099e1
0.00% cc1 [scsi_mod] [k] 0x0000000000009830
0.00% cc1 [scsi_mod] [k] 0x0000000000001b8f
After:
0.00% cc1 [scsi_mod] [k] scsi_handle_queue_ramp_up
0.00% as [scsi_mod] [k] scsi_sg_alloc
0.00% cc1 [scsi_mod] [k] scsi_setup_cmnd
0.00% cc1 [scsi_mod] [k] scsi_get_command
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: kernel-team@lge.com
Link: http://lkml.kernel.org/r/20170531120105.21731-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When perf processes build-id event, it creates DSOs with the build-id.
But it didn't set the module short name (like '[module-name]') so when
processing a kernel mmap event of the module, it cannot found the DSO as
it only checks the short names.
That leads for perf to create a same DSO without the build-id info and
it'll lookup the system path even if the DSO is already in the build-id
cache. After kernel was updated, perf cannot find the DSO and cannot
show symbols in it anymore.
You can see this if you have an old data file (w/ old kernel version):
$ perf report -i perf.data.old -v |& grep scsi_mod
build id event received for /lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz : cafe1ce6ca13a98a5d9ed3425cde249e57a27fc1
Failed to open /lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz, continuing without symbols
...
The second message didn't show the build-id. With this patch:
$ perf report -i perf.data.old -v |& grep scsi_mod
build id event received for /lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz: cafe1ce6ca13a98a5d9ed3425cde249e57a27fc1
/lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz with build id cafe1ce6ca13a98a5d9ed3425cde249e57a27fc1 not found, continuing without symbols
...
Now it shows the build-id but still cannot load the symbol table. This
is a different problem which will be fixed in the next patch.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: kernel-team@lge.com
Link: http://lkml.kernel.org/r/20170531120105.21731-1-namhyung@kernel.org
[ Fix the build on older compilers (debian <= 8, fedora <= 21, etc) wrt kmod_path var init ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The s390 architecture maps sys_mmap (nr 90) into sys_old_mmap. For this
reason perf trace can't find the proper syscall event to get args format
from and displays it wrongly as 'continued'.
To fix that fill the "alias" field with "old_mmap" for trace's mmap record
to get the correct translation.
Before:
0.042 ( 0.011 ms): vest/43052 fstat(statbuf: 0x3ffff89fd90 ) = 0
0.042 ( 0.028 ms): vest/43052 ... [continued]: mmap()) = 0x3fffd6e2000
0.072 ( 0.025 ms): vest/43052 read(buf: 0x3fffd6e2000, count: 4096 ) = 6
After:
0.045 ( 0.011 ms): fstat(statbuf: 0x3ffff8a0930 ) = 0
0.057 ( 0.018 ms): mmap(arg: 0x3ffff8a0858 ) = 0x3fffd14a000
0.076 ( 0.025 ms): read(buf: 0x3fffd14a000, count: 4096 ) = 6
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20170531113557.19175-1-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
