From: Russell King Date: Fri, 19 May 2017 15:35:56 +0000 (+0100) Subject: ARM: make configuration of userspace Thumb support an expert option X-Git-Tag: v4.13-rc1~92^2^2~4 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=1515b186c2359996b50241c1c6f79ff933d5112a;p=platform%2Fkernel%2Flinux-exynos.git ARM: make configuration of userspace Thumb support an expert option David Mosberger reports random segfaults and other problems when running his buildroot userspace. It turns out that his kernel did not have support for Thumb userspace, nor did his application, but glibc made use of Thumb instructions in glibc. The kernel Thumb support option already recommends being enabled, and is also so biased, but clearly this is not enough of a recommendation. So, hide this behind CONFIG_EXPERT as well, and include a note to indicate the potential issues if it's turned off and userspace Thumb mode is made use of. Reported-by: David Mosberger Signed-off-by: Russell King --- diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index c6c4c9c..4f68659 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -679,7 +679,7 @@ config ARCH_DMA_ADDR_T_64BIT bool config ARM_THUMB - bool "Support Thumb user binaries" if !CPU_THUMBONLY + bool "Support Thumb user binaries" if !CPU_THUMBONLY && EXPERT depends on CPU_THUMB_CAPABLE default y help @@ -690,6 +690,10 @@ config ARM_THUMB instruction set resulting in smaller binaries at the expense of slightly less efficient code. + If this option is disabled, and you run userspace that switches to + Thumb mode, signal handling will not work correctly, resulting in + segmentation faults or illegal instruction aborts. + If you don't know what this all is, saying Y is a safe choice. config ARM_THUMBEE