[PATCH v3] arch/arm/Kconfig: default ARM_MODULE_PLTS to 'y'

From: Anders Roxell
Date: Mon Mar 05 2018 - 09:34:20 EST


While testing multi_v7_defconfig with config fragments that makes the
kernel size to grow. The kernel fails to load simple modules, as
reported by kselftest:

[ 34.107620] test_printf: section 4 reloc 2 sym 'memset': relocation
28 out of range (0xbf046044 -> 0xc109f720)
selftests: printf.sh [FAIL]

The problem that is seen when enabling too much in the kernel without
enabling ARM_MODULE_PLTS, is that the top of the kernel gets out of
reach from the bottom of the module area.

Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Anders Roxell <anders.roxell@xxxxxxxxxx>
---
arch/arm/Kconfig | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 7e3d53575486..6831f2d4ee75 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1701,6 +1701,7 @@ config ARCH_WANT_GENERAL_HUGETLB
config ARM_MODULE_PLTS
bool "Use PLTs to allow module memory to spill over into vmalloc area"
depends on MODULES
+ default y
help
Allocate PLTs when loading modules so that jumps and calls whose
targets are too far away for their relative offsets to be encoded
@@ -1711,7 +1712,8 @@ config ARM_MODULE_PLTS
rounding up to page size, the actual memory footprint is usually
the same.

- Say y if you are getting out of memory errors while loading modules
+ Disabling this is usually safe for small single-platform
+ configurations. If unsure, say y.

source "mm/Kconfig"

--
2.11.0