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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>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.