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Michael Neuling 6a404806df powerpc: Avoid link stack corruption in MMU on syscall entry path 
Currently we use the link register to branch up high in the early MMU on
syscall entry path.  Unfortunately, this trashes the link stack as the
address we are going to is not associated with the earlier mflr.

This patch simply converts us to used the count register (volatile over
syscalls anyway) instead.  This is much better at predicting in this
scenario and doesn't trash link stack causing a bunch of additional
branch mispredicts later.  Benchmarking this on POWER8 saves a bunch of
cycles on Anton's null syscall benchmark here:
   http://ozlabs.org/~anton/junkcode/null_syscall.c

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-03-05 16:56:28 +11:00
..
alpha arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS 2013-02-27 19:10:23 -08:00
arc ARC: split elf.h into uapi and export it for userspace 2013-02-27 20:00:26 +05:30
arm Merge branch 'for-linus' of git://git.linaro.org/people/rmk/linux-arm 2013-03-03 11:54:39 -08:00
arm64 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2013-03-02 08:34:06 -08:00
avr32 arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS 2013-02-27 19:10:23 -08:00
blackfin Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
c6x Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
cris Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
frv arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS 2013-02-27 19:10:23 -08:00
h8300 arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS 2013-02-27 19:10:23 -08:00
hexagon Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
ia64 hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00
m32r Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
m68k Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
metag ImgTec Meta architecture changes for v3.9-rc1 2013-03-03 12:06:09 -08:00
microblaze arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS 2013-02-27 19:10:23 -08:00
mips Merge git://www.linux-watchdog.org/linux-watchdog 2013-03-03 10:23:29 -08:00
mn10300 arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS 2013-02-27 19:10:23 -08:00
openrisc arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS 2013-02-27 19:10:23 -08:00
parisc Merge branch 'fixes-for-3.9-latest' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux 2013-03-03 12:57:38 -08:00
powerpc powerpc: Avoid link stack corruption in MMU on syscall entry path 2013-03-05 16:56:28 +11:00
s390 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-03-03 13:23:03 -08:00
score arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS 2013-02-27 19:10:23 -08:00
sh hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00
sparc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2013-03-02 08:34:06 -08:00
tile arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS 2013-02-27 19:10:23 -08:00
um Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2013-02-23 18:50:11 -08:00
unicore32 arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS 2013-02-27 19:10:23 -08:00
x86 Bug-fixes: 2013-03-03 14:22:53 -08:00
xtensa arch Kconfig: centralise CONFIG_ARCH_NO_VIRT_TO_BUS 2013-02-27 19:10:23 -08:00
.gitignore
Kconfig ImgTec Meta architecture changes for v3.9-rc1 2013-03-03 12:06:09 -08:00