mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

ARM: 8995/1: drop Thumb-2 workaround for ancient binutils 

The CONFIG_THUMB2_AVOID_R_ARM_THM_JUMP11 workaround addresses an issue
which was fixed before the oldest supported binutils (2.23 at this time)
were released. So we can remove it now.

Acked-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Ard Biesheuvel 2020-07-21 09:21:08 +01:00 committed by Russell King
parent 4d44a399b5
commit 67b0141bd1
2 changed files with 0 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
arch/arm/Kconfig
View File

@ -1422,37 +1422,6 @@ config THUMB2_KERNEL
If unsure, say N.
config THUMB2_AVOID_R_ARM_THM_JUMP11
bool "Work around buggy Thumb-2 short branch relocations in gas"
depends on THUMB2_KERNEL && MODULES
default y
help
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.
Unless you are sure your tools don't have this problem, say Y.
config ARM_PATCH_IDIV
bool "Runtime patch udiv/sdiv instructions into __aeabi_{u}idiv()"
depends on CPU_32v7 && !XIP_KERNEL

4
arch/arm/Makefile
View File

@ -123,10 +123,6 @@ AFLAGS_NOWARN :=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W)
ifeq ($(CONFIG_THUMB2_KERNEL),y)
CFLAGS_ISA :=-mthumb -Wa,-mimplicit-it=always $(AFLAGS_NOWARN)
AFLAGS_ISA :=$(CFLAGS_ISA) -Wa$(comma)-mthumb
# Work around buggy relocation from gas if requested:
ifeq ($(CONFIG_THUMB2_AVOID_R_ARM_THM_JUMP11),y)
KBUILD_CFLAGS_MODULE +=-fno-optimize-sibling-calls
endif
else
CFLAGS_ISA :=$(call cc-option,-marm,) $(AFLAGS_NOWARN)
AFLAGS_ISA :=$(CFLAGS_ISA)