This is a note to let you know that I've just added the patch titled arm64: vdso: Add -fasynchronous-unwind-tables to cflags to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: arm64-vdso-add-fasynchronous-unwind-tables-to-cflags.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 1578e5d03112e3e9d37e1c4d95b6dfb734c73955 Mon Sep 17 00:00:00 2001 From: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> Date: Wed, 29 Apr 2020 16:10:50 +0100 Subject: arm64: vdso: Add -fasynchronous-unwind-tables to cflags From: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> commit 1578e5d03112e3e9d37e1c4d95b6dfb734c73955 upstream. On arm64 linux gcc uses -fasynchronous-unwind-tables -funwind-tables by default since gcc-8, so now the de facto platform ABI is to allow unwinding from async signal handlers. However on bare metal targets (aarch64-none-elf), and on old gcc, async and sync unwind tables are not enabled by default to avoid runtime memory costs. This means if linux is built with a baremetal toolchain the vdso.so may not have unwind tables which breaks the gcc platform ABI guarantee in userspace. Add -fasynchronous-unwind-tables explicitly to the vgettimeofday.o cflags to address the ABI change. Fixes: 28b1a824a4f4 ("arm64: vdso: Substitute gettimeofday() with C implementation") Cc: Will Deacon <will@xxxxxxxxxx> Reported-by: Szabolcs Nagy <szabolcs.nagy@xxxxxxx> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm64/kernel/vdso/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -32,7 +32,7 @@ UBSAN_SANITIZE := n OBJECT_FILES_NON_STANDARD := y KCOV_INSTRUMENT := n -CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny +CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -fasynchronous-unwind-tables ifneq ($(c-gettimeofday-y),) CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) Patches currently in stable-queue which might be from vincenzo.frascino@xxxxxxx are queue-5.4/arm64-vdso-add-fasynchronous-unwind-tables-to-cflags.patch