From: Vincenzo Frascino <vincenzo.frascino@arm.com>
Date: Thu, 7 May 2020 11:40:49 +0100
Subject: arm64: vdso: Add --eh-frame-hdr to ldflags
Git-commit: 7e9f5e6629f62865e67b8a02a5b522dd9af890bd
Patch-mainline: v5.8-rc1
References: git-fixes

LLVM's unwinder depends on the .eh_frame_hdr being present for
unwinding. However, when compiling Linux with GCC, the section
is not present in the vdso library object and when compiling
with Clang, it is present, but it has zero length.

With GCC the problem was not spotted because libgcc unwinder does
not require the .eh_frame_hdr section to be present.

Add --eh-frame-hdr to ldflags to correctly generate and populate
the section for both GCC and LLVM.

Fixes: 28b1a824a4f44 ("arm64: vdso: Substitute gettimeofday() with C implementation")
Reported-by: Tamas Zsoldos <tamas.zsoldos@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Tested-by: Tamas Zsoldos <tamas.zsoldos@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20200507104049.47834-1-vincenzo.frascino@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
---
 arch/arm64/kernel/vdso/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index abf61c96edbc..95e9e444ca93 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -22,7 +22,7 @@ obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
 # routines, as x86 does (see 6f121e548f83 ("x86, vdso: Reimplement vdso.so
 # preparation in build-time C")).
 ldflags-y := -shared -nostdlib -soname=linux-vdso.so.1 --hash-style=sysv \
-		-Bsymbolic --build-id -n -T
+		-Bsymbolic --eh-frame-hdr --build-id -n -T
 
 ccflags-y := -fno-common -fno-builtin -fno-stack-protector -ffixed-x18
 ccflags-y += -DDISABLE_BRANCH_PROFILING
-- 
2.29.2