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f81f8ad56f
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Nadav Amit f81f8ad56f x86/bug: Macrofy the BUG table section handling, to work around GCC inlining bugs 
As described in:

  77b0bf55bc: ("kbuild/Makefile: Prepare for using macros in inline assembly code to work around asm() related GCC inlining bugs")

GCC's inlining heuristics are broken with common asm() patterns used in
kernel code, resulting in the effective disabling of inlining.

The workaround is to set an assembly macro and call it from the inline
assembly block. As a result GCC considers the inline assembly block as
a single instruction. (Which it isn't, but that's the best we can get.)

This patch increases the kernel size:

      text     data     bss      dec     hex  filename
  18146889 10225380 2957312 31329581 1de0d2d  ./vmlinux before
  18147336 10226688 2957312 31331336 1de1408  ./vmlinux after (+1755)

But enables more aggressive inlining (and probably better branch decisions).

The number of static text symbols in vmlinux is much lower:

 Before: 40218
 After:  40053 (-165)

The assembly code gets harder to read due to the extra macro layer.

[ mingo: Rewrote the changelog. ]

Tested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181003213100.189959-7-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-10-04 11:25:00 +02:00
..
acpi ACPICA: Update version to 20180810 2018-08-14 23:49:13 +02:00
asm-generic x86/bug: Macrofy the BUG table section handling, to work around GCC inlining bugs 2018-10-04 11:25:00 +02:00
clocksource
crypto crypto: scatterwalk - remove scatterwalk_samebuf() 2018-08-03 18:06:04 +08:00
drm Revert "drm/panel: Add device_link from panel device to DRM device" 2018-09-27 11:00:42 -04:00
dt-bindings ARM: SoC: late updates 2018-08-25 14:12:36 -07:00
keys
kvm KVM: arm/arm64: vgic-v3: Add core support for Group0 SGIs 2018-08-12 12:06:34 +01:00
linux x86/objtool: Use asm macros to work around GCC inlining bugs 2018-10-04 11:24:58 +02:00
math-emu
media - New Drivers 2018-08-20 15:38:44 -07:00
memory
misc
net NFC: Fix the number of pipes 2018-09-18 19:55:01 -07:00
pcmcia pcmcia: remove long deprecated pcmcia_request_exclusive_irq() function 2018-08-18 12:30:42 -07:00
ras
rdma Second merge window update 2018-08-23 15:34:48 -07:00
scsi SCSI misc on 20180815 2018-08-15 22:06:26 -07:00
soc Various updates to soc/fsl for 4.19 2018-07-26 00:12:56 -07:00
sound ASoC: Fixes for v4.19 2018-09-17 18:59:21 +02:00
target scsi: target: add session removal function 2018-08-02 15:29:31 -04:00
trace Merge branch 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2018-08-24 13:19:27 -07:00
uapi Revert "uapi/linux/keyctl.h: don't use C++ reserved keyword as a struct member name" 2018-09-25 13:28:58 +02:00
video fbdev changes for v4.19: 2018-08-23 15:44:58 -07:00
xen xen/balloon: add runtime control for scrubbing ballooned out pages 2018-09-14 08:51:10 -04:00