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linux-next/arch/powerpc
Thiago Jung Bauermann 61ed9cfb1b powerpc/kprobes: Remove kretprobe_trampoline_holder.
Fixes the following testsuite failure:

  $ sudo ./perf test -v kallsyms
   1: vmlinux symtab matches kallsyms                          :
  --- start ---
  test child forked, pid 12489
  Using /proc/kcore for kernel object code
  Looking at the vmlinux_path (8 entries long)
  Using /boot/vmlinux for symbols
  0xc00000000003d300: diff name v: .kretprobe_trampoline_holder k: kretprobe_trampoline
  Maps only in vmlinux:
   c00000000086ca38-c000000000879b6c 87ca38 [kernel].text.unlikely
   c000000000879b6c-c000000000bf0000 889b6c [kernel].meminit.text
   c000000000bf0000-c000000000c53264 c00000 [kernel].init.text
   c000000000c53264-d000000004250000 c63264 [kernel].exit.text
   d000000004250000-d000000004450000 0 [libcrc32c]
   d000000004450000-d000000004620000 0 [xfs]
   d000000004620000-d000000004680000 0 [autofs4]
   d000000004680000-d0000000046e0000 0 [x_tables]
   d0000000046e0000-d000000004780000 0 [ip_tables]
   d000000004780000-d0000000047e0000 0 [rng_core]
   d0000000047e0000-ffffffffffffffff 0 [pseries_rng]
  Maps in vmlinux with a different name in kallsyms:
  Maps only in kallsyms:
   d000000000000000-f000000000000000 1000000000010000 [kernel.kallsyms]
   f000000000000000-ffffffffffffffff 3000000000010000 [kernel.kallsyms]
  test child finished with -1
  ---- end ----
  vmlinux symtab matches kallsyms: FAILED!

The problem is that the kretprobe_trampoline symbol looks like this:

  $ eu-readelf -s /boot/vmlinux G kretprobe_trampoline
   2431: c000000001302368     24 NOTYPE  LOCAL  DEFAULT       37 kretprobe_trampoline_holder
   2432: c00000000003d300      8 FUNC    LOCAL  DEFAULT        1 .kretprobe_trampoline_holder
  97543: c00000000003d300      0 NOTYPE  GLOBAL DEFAULT        1 kretprobe_trampoline

Its type is NOTYPE, and its size is 0, and this is a problem because
symbol-elf.c:dso__load_sym skips function symbols that are not STT_FUNC
or STT_GNU_IFUNC (this is determined by elf_sym__is_function). Even
if the type is changed to STT_FUNC, when dso__load_sym calls
symbols__fixup_duplicate, the kretprobe_trampoline symbol is dropped in
favour of .kretprobe_trampoline_holder because the latter has non-zero
size (as determined by choose_best_symbol).

With this patch, all vmlinux symbols match /proc/kallsyms and the
testcase passes.

Commit c1c355ce14 ("x86/kprobes: Get rid of
kretprobe_trampoline_holder()") gets rid of kretprobe_trampoline_holder
altogether on x86. This commit does the same on powerpc. This change
introduces no regressions on the perf and ftracetest testsuite results.

Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2016-06-21 15:30:49 +10:00
..
boot Merge branch 'for-4.7-dw' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata 2016-05-23 18:19:21 -07:00
configs powerpc updates for 4.6 2016-03-19 15:38:41 -07:00
crypto powerpc: Various typo fixes 2016-06-14 13:58:26 +10:00
include cxl: Add support for CAPP DMA mode 2016-06-16 23:10:26 +10:00
kernel powerpc/kprobes: Remove kretprobe_trampoline_holder. 2016-06-21 15:30:49 +10:00
kvm powerpc: Define and use PPC64_ELF_ABI_v2/v1 2016-06-14 13:58:27 +10:00
lib powerpc: Introduce asm-prototypes.h 2016-06-16 22:39:54 +10:00
math-emu
mm powerpc/mm: Ensure "special" zones are empty 2016-06-16 16:03:21 +10:00
net net: filter: make JITs zero A for SKF_AD_ALU_XOR_X 2016-01-06 00:43:52 -05:00
oprofile powerpc: Various typo fixes 2016-06-14 13:58:26 +10:00
perf powerpc: Various typo fixes 2016-06-14 13:58:26 +10:00
platforms cxl: Add support for CAPP DMA mode 2016-06-16 23:10:26 +10:00
scripts powerpc/ftrace: Add Kconfig & Make glue for mprofile-kernel 2016-03-07 14:53:56 +11:00
sysdev DAX error handling for 4.7 2016-05-26 19:34:26 -07:00
xmon powerpc/xmon: Fix SPR read/write commands and add command to dump SPRs 2016-05-11 21:54:07 +10:00
Kconfig printk/nmi: generic solution for safe printk in NMI 2016-05-20 17:58:30 -07:00
Kconfig.debug powerpc/mm: Always use STRICT_MM_TYPECHECKS 2016-05-01 18:32:14 +10:00
Makefile Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/scottwood/linux into next 2016-03-14 20:05:14 +11:00
relocs_check.sh powerpc: Convert relocs_check to a shell script using grep 2015-03-23 14:47:39 +11:00