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arm64: vdso: Add --eh-frame-hdr to ldflags
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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: 28b1a82 ("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>
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fvincenzo authored and willdeacon committed May 7, 2020
1 parent 1d09094 commit 7e9f5e6
Showing 1 changed file with 1 addition and 1 deletion.
2 changes: 1 addition & 1 deletion arch/arm64/kernel/vdso/Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -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
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