Commit 9012d011 authored by Masahiro Yamada's avatar Masahiro Yamada Committed by Linus Torvalds
Browse files

compiler: allow all arches to enable CONFIG_OPTIMIZE_INLINING

Commit 60a3cdd0 ("x86: add optimized inlining") introduced
CONFIG_OPTIMIZE_INLINING, but it has been available only for x86.

The idea is obviously arch-agnostic.  This commit moves the config entry
from arch/x86/Kconfig.debug to lib/Kconfig.debug so that all
architectures can benefit from it.

This can make a huge difference in kernel image size especially when
CONFIG_OPTIMIZE_FOR_SIZE is enabled.

For example, I got 3.5% smaller arm64 kernel for v5.1-rc1.

  dec       file
  18983424  arch/arm64/boot/Image.before
  18321920  arch/arm64/boot/Image.after

This also slightly improves the "Kernel hacking" Kconfig menu as
e61aca51 ("Merge branch 'kconfig-diet' from Dave Hansen') suggested;
this config option would be a good fit in the "compiler option" menu.

Link: http://lkml.kernel.org/r/20190423034959.13525-12-yamada.masahiro@socionext.com


Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Boris Brezillon <bbrezillon@kernel.org>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent efc344c5
......@@ -305,9 +305,6 @@ config ZONE_DMA32
config AUDIT_ARCH
def_bool y if X86_64
config ARCH_SUPPORTS_OPTIMIZED_INLINING
def_bool y
config ARCH_SUPPORTS_DEBUG_PAGEALLOC
def_bool y
......
......@@ -266,20 +266,6 @@ config CPA_DEBUG
---help---
Do change_page_attr() self-tests every 30 seconds.
config OPTIMIZE_INLINING
bool "Allow gcc to uninline functions marked 'inline'"
---help---
This option determines if the kernel forces gcc to inline the functions
developers have marked 'inline'. Doing so takes away freedom from gcc to
do what it thinks is best, which is desirable for the gcc 3.x series of
compilers. The gcc 4.x series have a rewritten inlining algorithm and
enabling this option will generate a smaller kernel there. Hopefully
this algorithm is so good that allowing gcc 4.x and above to make the
decision will become the default in the future. Until then this option
is there to test gcc for this.
If unsure, say N.
config DEBUG_ENTRY
bool "Debug low-level entry code"
depends on DEBUG_KERNEL
......
......@@ -140,8 +140,7 @@ struct ftrace_likely_data {
* Do not use __always_inline here, since currently it expands to inline again
* (which would break users of __always_inline).
*/
#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
!defined(CONFIG_OPTIMIZE_INLINING)
#if !defined(CONFIG_OPTIMIZE_INLINING)
#define inline inline __attribute__((__always_inline__)) __gnu_inline \
__maybe_unused notrace
#else
......
......@@ -318,6 +318,20 @@ config HEADERS_CHECK
exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
your build tree), to make sure they're suitable.
config OPTIMIZE_INLINING
bool "Allow compiler to uninline functions marked 'inline'"
help
This option determines if the kernel forces gcc to inline the functions
developers have marked 'inline'. Doing so takes away freedom from gcc to
do what it thinks is best, which is desirable for the gcc 3.x series of
compilers. The gcc 4.x series have a rewritten inlining algorithm and
enabling this option will generate a smaller kernel there. Hopefully
this algorithm is so good that allowing gcc 4.x and above to make the
decision will become the default in the future. Until then this option
is there to test gcc for this.
If unsure, say N.
config DEBUG_SECTION_MISMATCH
bool "Enable full Section mismatch analysis"
help
......
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