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commit12a6d2940bupstream. On s390 the modules loaded in memory have the text segment located after the GOT and Relocation table. This can be seen with this output: [root@m35lp76 perf]# fgrep qeth /proc/modules qeth 151552 1 qeth_l2, Live 0x000003ff800b2000 ... [root@m35lp76 perf]# cat /sys/module/qeth/sections/.text 0x000003ff800b3990 [root@m35lp76 perf]# There is an offset of 0x1990 bytes. The size of the qeth module is 151552 bytes (0x25000 in hex). The location of the GOT/relocation table at the beginning of a module is unique to s390. commit203d8a4aa6("perf s390: Fix 'start' address of module's map") adjusts the start address of a module in the map structures, but does not adjust the size of the modules. This leads to overlapping of module maps as this example shows: [root@m35lp76 perf] # ./perf report -D 0 0 0xfb0 [0xa0]: PERF_RECORD_MMAP -1/0: [0x3ff800b3990(0x25000) @ 0]: x /lib/modules/.../qeth.ko.xz 0 0 0x1050 [0xb0]: PERF_RECORD_MMAP -1/0: [0x3ff800d85a0(0x8000) @ 0]: x /lib/modules/.../ip6_tables.ko.xz The module qeth.ko has an adjusted start address modified to b3990, but its size is unchanged and the module ends at 0x3ff800d8990. This end address overlaps with the next modules start address of 0x3ff800d85a0. When the size of the leading GOT/Relocation table stored in the beginning of the text segment (0x1990 bytes) is subtracted from module qeth end address, there are no overlaps anymore: 0x3ff800d8990 - 0x1990 = 0x0x3ff800d7000 which is the same as 0x3ff800b2000 + 0x25000 = 0x0x3ff800d7000. To fix this issue, also adjust the modules size in function arch__fix_module_text_start(). Add another function parameter named size and reduce the size of the module when the text segment start address is changed. Output after: 0 0 0xfb0 [0xa0]: PERF_RECORD_MMAP -1/0: [0x3ff800b3990(0x23670) @ 0]: x /lib/modules/.../qeth.ko.xz 0 0 0x1050 [0xb0]: PERF_RECORD_MMAP -1/0: [0x3ff800d85a0(0x7a60) @ 0]: x /lib/modules/.../ip6_tables.ko.xz Reported-by: Stefan Liebler <stli@linux.ibm.com> Signed-off-by: Thomas Richter <tmricht@linux.ibm.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Hendrik Brueckner <brueckner@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: stable@vger.kernel.org Fixes:203d8a4aa6("perf s390: Fix 'start' address of module's map") Link: http://lkml.kernel.org/r/20190724122703.3996-1-tmricht@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
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.