From: Will Deacon Date: Fri, 19 Jun 2015 12:56:33 +0000 (+0100) Subject: arm64: vdso: work-around broken ELF toolchains in Makefile X-Git-Tag: firefly_0821_release~176^2~1475^2~13 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=6f1a6ae87c0c60d7c462ef8fd071f291aa7a9abb;p=firefly-linux-kernel-4.4.55.git arm64: vdso: work-around broken ELF toolchains in Makefile When building the kernel with a bare-metal (ELF) toolchain, the -shared option may not be passed down to collect2, resulting in silent corruption of the vDSO image (in particular, the DYNAMIC section is omitted). The effect of this corruption is that the dynamic linker fails to find the vDSO symbols and libc is instead used for the syscalls that we intended to optimise (e.g. gettimeofday). Functionally, there is no issue as the sigreturn trampoline is still intact and located by the kernel. This patch fixes the problem by explicitly passing -shared to the linker when building the vDSO. Cc: Reported-by: Szabolcs Nagy Reported-by: James Greenlaigh Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas --- diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile index ff3bddea482d..f6fe17d88da5 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -15,6 +15,10 @@ ccflags-y := -shared -fno-common -fno-builtin ccflags-y += -nostdlib -Wl,-soname=linux-vdso.so.1 \ $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) +# Workaround for bare-metal (ELF) toolchains that neglect to pass -shared +# down to collect2, resulting in silent corruption of the vDSO image. +ccflags-y += -Wl,-shared + obj-y += vdso.o extra-y += vdso.lds vdso-offsets.h CPPFLAGS_vdso.lds += -P -C -U$(ARCH)