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 5.6-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-5.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b0a61c26b3050c9411e853fdaf6acc441074f432
Author: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Date: Wed Apr 29 16:10:50 2020 +0100
arm64: vdso: Add -fasynchronous-unwind-tables to cflags
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>
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index dd2514bb1511f..3862cad2410cf 100644
--- 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)
