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Thomas Richter b9c0a64901 perf annotate: Fix s390 gap between kernel end and module start
During execution of command 'perf top' the error message:

   Not enough memory for annotating '__irf_end' symbol!)

is emitted from this call sequence:
  __cmd_top
    perf_top__mmap_read
      perf_top__mmap_read_idx
        perf_event__process_sample
          hist_entry_iter__add
            hist_iter__top_callback
              perf_top__record_precise_ip
                hist_entry__inc_addr_samples
                  symbol__inc_addr_samples
                    symbol__get_annotation
                      symbol__alloc_hist

In this function the size of symbol __irf_end is calculated. The size of
a symbol is the difference between its start and end address.

When the symbol was read the first time, its start and end was set to:

   symbol__new: __irf_end 0xe954d0-0xe954d0

which is correct and maps with /proc/kallsyms:

   root@s8360046:~/linux-4.15.0/tools/perf# fgrep _irf_end /proc/kallsyms
   0000000000e954d0 t __irf_end
   root@s8360046:~/linux-4.15.0/tools/perf#

In function symbol__alloc_hist() the end of symbol __irf_end is

  symbol__alloc_hist sym:__irf_end start:0xe954d0 end:0x3ff80045a8

which is identical with the first module entry in /proc/kallsyms

This results in a symbol size of __irf_req for histogram analyses of
70334140059072 bytes and a malloc() for this requested size fails.

The root cause of this is function
  __dso__load_kallsyms()
  +-> symbols__fixup_end()

Function symbols__fixup_end() enlarges the last symbol in the kallsyms
map:

   # fgrep __irf_end /proc/kallsyms
   0000000000e954d0 t __irf_end
   #

to the start address of the first module:
   # cat /proc/kallsyms | sort  | egrep ' [tT] '
   ....
   0000000000e952d0 T __security_initcall_end
   0000000000e954d0 T __initramfs_size
   0000000000e954d0 t __irf_end
   000003ff800045a8 T fc_get_event_number       [scsi_transport_fc]
   000003ff800045d0 t store_fc_vport_disable    [scsi_transport_fc]
   000003ff800046a8 T scsi_is_fc_rport  [scsi_transport_fc]
   000003ff800046d0 t fc_target_setup   [scsi_transport_fc]

On s390 the kernel is located around memory address 0x200, 0x10000 or
0x100000, depending on linux version. Modules however start some- where
around 0x3ff xxxx xxxx.

This is different than x86 and produces a large gap for which histogram
allocation fails.

Fix this by detecting the kernel's last symbol and do no adjustment for
it. Introduce a weak function and handle s390 specifics.

Reported-by: Klaus Theurich <klaus.theurich@de.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
Link: http://lkml.kernel.org/r/20190724122703.3996-2-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-08-08 15:41:25 -03:00
arch SPDX fixes for 5.3-rc2 2019-07-28 10:00:06 -07:00
block for-linus-20190726-2 2019-07-26 19:20:34 -07:00
certs Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs" 2019-07-10 18:43:43 -07:00
crypto USB / PHY patches for 5.3-rc1 2019-07-11 15:40:06 -07:00
Documentation USB fixes for 5.3-rc2 2019-07-28 09:52:35 -07:00
drivers virtio, vhost: bugfixes 2019-07-29 11:34:12 -07:00
fs SPDX fixes for 5.3-rc2 2019-07-28 10:00:06 -07:00
include virtio, vhost: bugfixes 2019-07-29 11:34:12 -07:00
init Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
ipc Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-07-27 21:22:33 -07:00
lib test_firmware: fix a memory leak bug 2019-07-25 14:39:52 +02:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm virtio, vhost: bugfixes 2019-07-29 11:34:12 -07:00
net tcp: be more careful in tcp_fragment() 2019-07-21 20:41:24 -07:00
samples treewide: remove SPDX "WITH Linux-syscall-note" from kernel-space headers again 2019-07-25 11:05:10 +02:00
scripts Kbuild fixes for v5.3 2019-07-28 10:35:04 -07:00
security meminit fix 2019-07-28 12:33:15 -07:00
sound sound fixes for 5.3-rc2 2019-07-26 10:23:45 -07:00
tools perf annotate: Fix s390 gap between kernel end and module start 2019-08-08 15:41:25 -03:00
usr kbuild: enable arch/s390/include/uapi/asm/zcrypt.h for uapi header test 2019-07-23 10:45:46 +02:00
virt Documentation: move Documentation/virtual to Documentation/virt 2019-07-24 10:52:11 +02:00
.clang-format Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-17 11:26:25 -07:00
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COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Remove references to dead website. 2019-07-19 12:22:04 -07:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Char/Misc driver fixes for 5.3-rc2 2019-07-28 10:26:10 -07:00
Makefile Linux 5.3-rc2 2019-07-28 12:47:02 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.

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.