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Subject[PATCH v19 7/7] x86/vdso: Insert endbr32/endbr64 to vDSO
Date
From: "H.J. Lu" <hjl.tools@gmail.com>

When Indirect Branch Tracking (IBT) is enabled, vDSO functions may be
called indirectly, and must have ENDBR32 or ENDBR64 as the first
instruction. The compiler must support -fcf-protection=branch so that it
can be used to compile vDSO.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/entry/vdso/Makefile | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 02e3e42f380b..ff7b56feb5c3 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -93,6 +93,10 @@ endif

$(vobjs): KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)

+ifdef CONFIG_X86_CET
+$(vobjs) $(vobjs32): KBUILD_CFLAGS += -fcf-protection=branch
+endif
+
#
# vDSO code runs in userspace and -pg doesn't help with profiling anyway.
#
--
2.21.0
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