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Subject[tip:x86/urgent] x86/vdso: Pass --eh-frame-hdr to the linker
Commit-ID:  cd01544a268ad8ee5b1dfe42c4393f1095f86879
Author: Alistair Strachan <>
AuthorDate: Fri, 14 Dec 2018 14:36:37 -0800
Committer: Borislav Petkov <>
CommitDate: Sat, 15 Dec 2018 11:37:51 +0100

x86/vdso: Pass --eh-frame-hdr to the linker


379d98ddf413 ("x86: vdso: Use $LD instead of $CC to link")

accidentally broke unwinding from userspace, because ld would strip the
.eh_frame sections when linking.

Originally, the compiler would implicitly add --eh-frame-hdr when
invoking the linker, but when this Makefile was converted from invoking
ld via the compiler, to invoking it directly (like vmlinux does),
the flag was missed. (The EH_FRAME section is important for the VDSO
shared libraries, but not for vmlinux.)

Fix the problem by explicitly specifying --eh-frame-hdr, which restores
parity with the old method.

See relevant bug reports for additional info:

Fixes: 379d98ddf413 ("x86: vdso: Use $LD instead of $CC to link")
Reported-by: Florian Weimer <>
Reported-by: Carlos O'Donell <>
Reported-by: "H. J. Lu" <>
Signed-off-by: Alistair Strachan <>
Signed-off-by: Borislav Petkov <>
Tested-by: Laura Abbott <>
Cc: Andy Lutomirski <>
Cc: Carlos O'Donell <>
Cc: "H. Peter Anvin" <>
Cc: Ingo Molnar <>
Cc: Joel Fernandes <>
Cc: Laura Abbott <>
Cc: stable <>
Cc: Thomas Gleixner <>
Cc: X86 ML <>
arch/x86/entry/vdso/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 0624bf2266fd..5bfe2243a08f 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -171,7 +171,8 @@ quiet_cmd_vdso = VDSO $@
sh $(srctree)/$(src)/ '$(NM)' '$@'

VDSO_LDFLAGS = -shared $(call ld-option, --hash-style=both) \
- $(call ld-option, --build-id) -Bsymbolic
+ $(call ld-option, --build-id) $(call ld-option, --eh-frame-hdr) \
+ -Bsymbolic

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