arm64: vdso: Add -fasynchronous-unwind-tables to cflags
authorVincenzo Frascino <vincenzo.frascino@arm.com>
Wed, 29 Apr 2020 15:10:50 +0000 (16:10 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 6 May 2020 06:15:17 +0000 (08:15 +0200)
commit1de07eb54ab75bd475e73f80339f40dfbc67e3bc
tree9b00fb6f726532c4f8ab576dc274dc15aeeff605
parent73162ca8156f0d90f17995b82ca8ff7bb1d2cd5e
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@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/arm64/kernel/vdso/Makefile