DISABLE_BRANCH_PROFILING turns off branch profiling (i.e. a
redefinition of 'if'). Branch profiling depends on a bunch of
kernel-internal symbols and generates extra output sections, none of
which are useful or functional in the vDSO.
It's currently turned off for vclock_gettime.c, but vgetcpu.c also
triggers branch profiling, so just turn it off in the makefile.
This fixes the build on some configurations: the vdso could contain
undefined symbols, and the fake section table overflowed due to
ftrace's added sections.
Signed-off-by: Andy Lutomirski <l...@amacapital.net>
---
arch/x86/vdso/Makefile | 4 +++-
arch/x86/vdso/vclock_gettime.c | 3 ---
2 files changed, 3 insertions(+), 4 deletions(-)
diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index 68a15c4..61b04fe 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -66,7 +66,8 @@ $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso2c FORCE
#
CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64
\
$(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \
- -fno-omit-frame-pointer -foptimize-sibling-calls
+ -fno-omit-frame-pointer -foptimize-sibling-calls \
+ -DDISABLE_BRANCH_PROFILING
$(vobjs): KBUILD_CFLAGS += $(CFL)
@@ -149,6 +150,7 @@ KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic
KBUILD_CFLAGS_32 += $(call cc-option, -fno-stack-protector)
KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls)
KBUILD_CFLAGS_32 += -fno-omit-frame-pointer
+KBUILD_CFLAGS_32 += -DDISABLE_BRANCH_PROFILING
$(vdso32-images:%=$(obj)/%.dbg): KBUILD_CFLAGS = $(KBUILD_CFLAGS_32)
$(vdso32-images:%=$(obj)/%.dbg): $(obj)/vdso32-%.so.dbg: FORCE \
diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index b2e4f49..9793322 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -11,9 +11,6 @@
* Check with readelf after changing.
*/
-/* Disable profiling for userspace code: */
-#define DISABLE_BRANCH_PROFILING
-
#include <uapi/linux/time.h>
#include <asm/vgtod.h>
#include <asm/hpet.h>
--
1.9.3
--
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