[PATCH v8 08/14] x86/vdso: Insert endbr32/endbr64 to vDSO

Yu-cheng Yu
2019-08-13T21:04:06Z

From: "H.J. Lu" <hjl.tools@gmail.com>

When Intel indirect branch tracking is enabled, functions in vDSO which
may be called indirectly must have endbr32 or endbr64 as the first
instruction. Compiler must support -fcf-protection=branch so that it
can be used to compile vDSO.

Acked-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/entry/vdso/Makefile | 12 +++++++++++-
arch/x86/entry/vdso/vdso-layout.lds.S | 1 +
2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 8df549138193..1e6a95881e73 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -114,13 +114,17 @@ vobjx32s := $(foreach F,$(vobjx32s-y),$(obj)/$F)

# Convert 64bit object file to x32 for x32 vDSO.
quiet_cmd_x32 = X32 $@
- cmd_x32 = $(OBJCOPY) -O elf32-x86-64 $< $@
+ cmd_x32 = $(OBJCOPY) -R .note.gnu.property -O elf32-x86-64 $< $@

$(obj)/%-x32.o: $(obj)/%.o FORCE
$(call if_changed,x32)

targets += vdsox32.lds $(vobjx32s-y)

+ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER
+ $(obj)/vclock_gettime.o $(obj)/vgetcpu.o $(obj)/vdso32/vclock_gettime.o: KBUILD_CFLAGS += -fcf-protection=branch
+endif
+
$(obj)/%.so: OBJCOPYFLAGS := -S
$(obj)/%.so: $(obj)/%.so.dbg FORCE
$(call if_changed,objcopy)
@@ -178,6 +182,12 @@ quiet_cmd_vdso = VDSO $@

VDSO_LDFLAGS = -shared --hash-style=both --build-id \
$(call ld-option, --eh-frame-hdr) -Bsymbolic
+ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER
+ VDSO_LDFLAGS += $(call ldoption, -z$(comma)ibt)
+endif
+ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER
+ VDSO_LDFLAGS += $(call ldoption, -z$(comma)shstk)
+endif
GCOV_PROFILE := n

quiet_cmd_vdso_and_check = VDSO $@
diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
index 93c6dc7812d0..3fea2ce318bc 100644
--- a/arch/x86/entry/vdso/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -52,6 +52,7 @@ SECTIONS
*(.gnu.linkonce.b.*)
} :text

+ .note.gnu.property : { *(.note.gnu.property) } :text :note
.note : { *(.note.*) } :text :note

.eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
--
2.17.1