linux/tools/perf/arch
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
..
alpha perf tools: Add empty Build files for architectures lacking them 2015-08-06 16:24:15 -03:00
arc/annotate perf annotate: Introduce basic support for ARC 2018-12-17 14:59:42 -03:00
arm tools lib: Adopt zalloc()/zfree() from tools/perf 2019-07-09 10:13:26 -03:00
arm64 tools lib: Adopt zalloc()/zfree() from tools/perf 2019-07-09 10:13:26 -03:00
csky perf annotate: Add csky support 2019-07-01 22:50:41 -03:00
mips perf tools: Add empty Build files for architectures lacking them 2015-08-06 16:24:15 -03:00
nds32 perf tools: Rename build libperf to perf 2019-02-14 15:18:08 -03:00
parisc perf tools: Add empty Build files for architectures lacking them 2015-08-06 16:24:15 -03:00
powerpc tools lib: Adopt zalloc()/zfree() from tools/perf 2019-07-09 10:13:26 -03:00
s390 perf annotate: Fix s390 gap between kernel end and module start 2019-08-08 15:41:25 -03:00
sh treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
sparc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
x86 tools include UAPI: Sync x86's syscalls_64.tbl and generic unistd.h to pick up clone3 and pidfd_open 2019-07-26 12:31:28 -03:00
xtensa treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
Build perf tools: Rename build libperf to perf 2019-02-14 15:18:08 -03:00
common.c tools lib: Adopt zalloc()/zfree() from tools/perf 2019-07-09 10:13:26 -03:00
common.h perf machine: Record if a arch has a single user/kernel address space 2018-12-17 14:54:07 -03:00