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UPSTREAM: arm64: vdso: Add -fasynchronous-unwind-tables to cflags

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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: 28b1a824a4 ("arm64: vdso: Substitute gettimeofday() with C implementation")
Cc: Will Deacon <will@kernel.org>
Reported-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 1578e5d031)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I5dbd078b47b250e1bcc09538ec52f1a2ceaa1714
This commit is contained in:
Vincenzo Frascino
2020-04-29 16:10:50 +01:00
committed by Greg Kroah-Hartman
parent f821ce6b3c
commit 730887909d
1 changed files with 1 additions and 1 deletions
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2
arch/arm64/kernel/vdso/Makefile
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@@ -33,7 +33,7 @@ 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)