2018-03-05 14:36:09

by Anders Roxell

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

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 <[email protected]>
Signed-off-by: Anders Roxell <[email protected]>
---
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



2018-03-23 09:14:06

by Ard Biesheuvel

[permalink] [raw]
Subject: Re: [PATCH v3] arch/arm/Kconfig: default ARM_MODULE_PLTS to 'y'

On 5 March 2018 at 22:34, Anders Roxell <[email protected]> wrote:
> 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 <[email protected]>
> Signed-off-by: Anders Roxell <[email protected]>

Acked-by: Ard Biesheuvel <[email protected]>

> ---
> 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
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel