kernel-fxtec-pro1x/arch/m68k
Finn Thain fcbf12e23d m68k: Add -ffreestanding to CFLAGS
commit 28713169d879b67be2ef2f84dcf54905de238294 upstream.

This patch fixes a build failure when using GCC 8.1:

/usr/bin/ld: block/partitions/ldm.o: in function `ldm_parse_tocblock':
block/partitions/ldm.c:153: undefined reference to `strcmp'

This is caused by a new optimization which effectively replaces a
strncmp() call with a strcmp() call. This affects a number of strncmp()
call sites in the kernel.

The entire class of optimizations is avoided with -fno-builtin, which
gets enabled by -ffreestanding. This may avoid possible future build
failures in case new optimizations appear in future compilers.

I haven't done any performance measurements with this patch but I did
count the function calls in a defconfig build. For example, there are now
23 more sprintf() calls and 39 fewer strcpy() calls. The effect on the
other libc functions is smaller.

If this harms performance we can tackle that regression by optimizing
the call sites, ideally using semantic patches. That way, clang and ICC
builds might benfit too.

Cc: stable@vger.kernel.org
Reference: https://marc.info/?l=linux-m68k&m=154514816222244&w=2
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-23 20:10:00 +01:00
..
68000
amiga
apollo
atari
bvme6000
coldfire
configs
emu
fpsp040
hp300
ifpsp060
include
kernel m68k: Fix memblock-related crashes 2019-01-13 09:51:02 +01:00
lib
mac
math-emu
mm m68k: Fix memblock-related crashes 2019-01-13 09:51:02 +01:00
mvme16x
mvme147
q40
sun3
sun3x
tools/amiga
install.sh
Kconfig
Kconfig.bus
Kconfig.cpu
Kconfig.debug
Kconfig.devices
Kconfig.machine
Makefile m68k: Add -ffreestanding to CFLAGS 2019-03-23 20:10:00 +01:00