kernel_optimize_test/arch
Dave Martin 6f685c5cdd ARM: 6781/1: Thumb-2: Work around buggy Thumb-2 short branch relocations in gas
Various binutils versions can resolve Thumb-2 branches to
locally-defined, preemptible global symbols as short-range "b.n"
branch instructions.

This is a problem, because there's no guarantee the final
destination of the symbol, or any candidate locations for a
trampoline, are within range of the branch.  For this reason, the
kernel does not support fixing up the R_ARM_THM_JUMP11 (102)
relocation in modules at all, and it makes little sense to add
support.

The symptom is that the kernel fails with an "unsupported
relocation" error when loading some modules.

Until fixed tools are available, passing
-fno-optimize-sibling-calls to gcc should prevent gcc generating
code which hits this problem, at the cost of a bit of extra runtime
stack usage in some cases.

The problem is described in more detail at:
    https://bugs.launchpad.net/binutils-linaro/+bug/725126

Only Thumb-2 kernels are affected.

This patch adds a new CONFIG_THUMB2_AVOID_R_ARM_THM_JUMP11 config
option which adds -fno-optimize-sibling-calls to CFLAGS_MODULE
when building a Thumb-2 kernel.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-03-10 16:49:06 +00:00
..
alpha alpha: Use generic irq Kconfig 2011-01-21 11:55:31 +01:00
arm ARM: 6781/1: Thumb-2: Work around buggy Thumb-2 short branch relocations in gas 2011-03-10 16:49:06 +00:00
avr32 avr32: add missing include causing undefined pgtable_page_* references 2011-01-26 12:35:15 +01:00
blackfin blackfin: Use generic irq Kconfig 2011-01-21 11:55:31 +01:00
cris cris: Use generic irq Kconfig 2011-01-21 11:55:25 +01:00
frv frv: Use generic irq Kconfig 2011-01-21 11:55:32 +01:00
h8300 h8300: Use generic irq Kconfig 2011-01-21 11:55:24 +01:00
ia64 ia64: Use generic irq Kconfig 2011-01-21 11:55:32 +01:00
m32r m32r: Convert to generic irq Kconfig 2011-01-21 11:55:30 +01:00
m68k m68k/amiga: Fix "debug=mem" 2011-01-23 11:24:42 +01:00
m68knommu m68knommu: Use generic irq Kconfig 2011-01-21 11:55:32 +01:00
microblaze microblaze: Use generic irq Kconfig 2011-01-21 11:55:32 +01:00
mips genirq: Remove __do_IRQ 2011-01-21 11:55:31 +01:00
mn10300 mn10300: Use generic irq Kconfig 2011-01-21 11:55:33 +01:00
parisc console: rename acquire/release_console_sem() to console_lock/unlock() 2011-01-26 10:50:06 +10:00
powerpc Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-01-25 05:26:47 +10:00
s390 Merge branch 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6 2011-01-14 08:47:26 -08:00
score score: Use generic irq Kconfig 2011-01-21 11:55:34 +01:00
sh Merge branch 'sh-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6 2011-01-26 09:00:17 +10:00
sparc sparc: Use generic irq Kconfig 2011-01-21 11:55:34 +01:00
tile tile: Use generic irq Kconfig 2011-01-21 11:55:34 +01:00
um um: Use generic irq Kconfig 2011-01-21 11:55:35 +01:00
x86 Merge branch 'stable/bug-fixes-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen 2011-01-28 12:24:34 +10:00
xtensa kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
.gitignore
Kconfig [S390] mutex: Introduce arch_mutex_cpu_relax() 2011-01-05 12:47:31 +01:00