Pull livepatching fix from Petr Mladek:
 "Workaround for 'unreachable instruction' objtool warnings that happen
  with some compiler versions"

* tag 'livepatching-for-5.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
  Revert "kbuild: use -flive-patching when CONFIG_LIVEPATCH is enabled"

Use of the new -flive-patching flag was introduced with the following
commit:

  43bd3a95c98e ("kbuild: use -flive-patching when CONFIG_LIVEPATCH is enabled")

This flag has several drawbacks:

- It disables some optimizations, so it can have a negative effect on
  performance.

- According to the GCC documentation it's not compatible with LTO, which
  will become a compatibility issue as LTO support gets upstreamed in
  the kernel.

- It was intended to be used for source-based patch generation tooling,
  as opposed to binary-based patch generation tooling (e.g.,
  kpatch-build).  It probably should have at least been behind a
  separate config option so as not to negatively affect other livepatch
  users.

- Clang doesn't have the flag, so as far as I can tell, this method of
  generating patches is incompatible with Clang, which like LTO is
  becoming more mainstream.

- It breaks GCC's implicit noreturn detection for local functions.  This
  is the cause of several "unreachable instruction" objtool warnings.

- The broken noreturn detection is an obvious GCC regression, but we
  haven't yet gotten GCC developers to acknowledge that, which doesn't
  inspire confidence in their willingness to keep the feature working as
  optimizations are added or changed going forward.

- While there *is* a distro which relies on this flag for their distro
  livepatch module builds, there's not a publicly documented way to
  create safe livepatch modules with it.  Its use seems to be based on
  tribal knowledge.  It serves no benefit to those who don't know how to
  use it.

  (In fact, I believe the current livepatch documentation and samples
  are misleading and dangerous, and should be corrected.  Or at least
  amended with a disclaimer.  But I don't feel qualified to make such
  changes.)

Also, we have an idea for using objtool to detect function changes,
which could potentially obsolete the need for this flag anyway.

At this point the flag has no benefits for upstream which would
counteract the above drawbacks.  Revert it until it becomes more ready.

This reverts commit 43bd3a95c98e1a86b8b55d97f745c224ecff02b9.

Fixes: 43bd3a95c98e ("kbuild: use -flive-patching when CONFIG_LIVEPATCH is enabled")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/696262e997359666afa053fe7d1a9fb2bb373964.1595010490.git.jpoimboe@redhat.com

The '%' in filter/filter-out matches to any number of any characters,
including empty string.

So, '%config' matches to 'config', and '%install' to 'install'.

Drop the redundant patterns.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Recently 0day reported many strange performance changes (regression or
improvement), in which there was no obvious relation between the culprit
commit and the benchmark at the first look, and it causes people to doubt
the test itself is wrong.

Upon further check, many of these cases are caused by the change to the
alignment of kernel text or data, as whole text/data of kernel are linked
together, change in one domain may affect alignments of other domains.

gcc has an option '-falign-functions=n' to force text aligned, and with
that option enabled, some of those performance changes will be gone, like
[1][2][3].

Add this option so that developers and 0day can easily find performance
bump caused by text alignment change, as tracking these strange bump is
quite time consuming.  Though it can't help in other cases like data
alignment changes like [4].

Following is some size data for v5.7 kernel built with a RHEL config used
in 0day:

    text      data      bss	 dec	   filename
  19738771  13292906  5554236  38585913	 vmlinux.noalign
  19758591  13297002  5529660  38585253	 vmlinux.align32

Raw vmlinux size in bytes:

	v5.7		v5.7+align32
	253950832	254018000	+0.02%

Some benchmark data, most of them have no big change:

  * hackbench:		[ -1.8%,  +0.5%]

  * fsmark:		[ -3.2%,  +3.4%]  # ext4/xfs/btrfs

  * kbuild:		[ -2.0%,  +0.9%]

  * will-it-scale:	[ -0.5%,  +1.8%]  # mmap1/pagefault3

  * netperf:
    - TCP_CRR		[+16.6%, +97.4%]
    - TCP_RR		[-18.5%,  -1.8%]
    - TCP_STREAM	[ -1.1%,  +1.9%]

[1] https://lore.kernel.org/lkml/20200114085637.GA29297@shao2-debian/
[2] https://lore.kernel.org/lkml/20200330011254.GA14393@feng-iot/
[3] https://lore.kernel.org/lkml/1d98d1f0-fe84-6df7-f5bd-f4cb2cdb7f45@intel.com/
[4] https://lore.kernel.org/lkml/20200205123216.GO12867@shao2-debian/

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@intel.com>
Link: http://lkml.kernel.org/r/1595475001-90945-1-git-send-email-feng.tang@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>