objtool: Fix false positive warnings for functions with multiple switch statements

Ingo reported [1] some false positive objtool warnings:

  drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch
  drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2f3: frame pointer state mismatch
  ...

And so did the 0-day bot [2]:

  drivers/gpu/drm/radeon/cik.o: warning: objtool: cik_tiling_mode_table_init()+0x6ce: call without frame pointer save/setup
  drivers/gpu/drm/radeon/cik.o: warning: objtool: cik_tiling_mode_table_init()+0x72b: call without frame pointer save/setup
  ...

Both sets of warnings involve functions which have multiple switch
statements.  When there's more than one switch statement in a function,
objtool interprets all the switch jump tables as a single table.  If the
targets of one jump table assume a stack frame and the targets of
another one don't, it prints false positive warnings.

Fix the bug by detecting the size of each switch jump table.  For
multiple tables, each one ends where the next one begins.

[1] https://lkml.kernel.org/r/[email protected]
[2] https://lists.01.org/pipermail/kbuild-all/2016-March/018124.html

Reported-by: Ingo Molnar <[email protected]>
Reported-by: kbuild test robot <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Bernd Petrovitsch <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Chris J Arges <[email protected]>
Cc: Jiri Slaby <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Michal Marek <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Pedro Alves <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/2d7eecc6bc52d301f494b80f5fd62c2b6c895658.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions