arm64: vdso: Substitute gettimeofday() with C implementation

To take advantage of the commonly defined vdso interface for gettimeofday()
the architectural code requires an adaptation.

Re-implement the gettimeofday VDSO in C in order to use lib/vdso.

With the new implementation arm64 gains support for CLOCK_BOOTTIME
and CLOCK_TAI.

[ tglx: Reformatted the function line breaks ]

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Shijith Thotton <sthotton@marvell.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Huw Davies <huw@codeweavers.com>
Link: https://lkml.kernel.org/r/20190621095252.32307-5-vincenzo.frascino@arm.com

1 files changed, 27 insertions, 7 deletions

diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index fa230ff09aa1..3acfc813e966 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -6,7 +6,12 @@
 # Heavily based on the vDSO Makefiles for other archs.
 #
 
-obj-vdso := gettimeofday.o note.o sigreturn.o
+# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
+# the inclusion of generic Makefile.
+ARCH_REL_TYPE_ABS := R_AARCH64_JUMP_SLOT|R_AARCH64_GLOB_DAT|R_AARCH64_ABS64
+include $(srctree)/lib/vdso/Makefile
+
+obj-vdso := vgettimeofday.o note.o sigreturn.o
 
 # Build rules
 targets := $(obj-vdso) vdso.so vdso.so.dbg
@@ -15,6 +20,24 @@ obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
 ldflags-y := -shared -nostdlib -soname=linux-vdso.so.1 --hash-style=sysv \
 		--build-id -n -T
 
+ccflags-y := -fno-common -fno-builtin -fno-stack-protector
+ccflags-y += -DDISABLE_BRANCH_PROFILING
+
+VDSO_LDFLAGS := -Bsymbolic
+
+CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os
+KBUILD_CFLAGS			+= $(DISABLE_LTO)
+KASAN_SANITIZE			:= n
+UBSAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
+KCOV_INSTRUMENT			:= n
+
+ifeq ($(c-gettimeofday-y),)
+CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny
+else
+CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -include $(c-gettimeofday-y)
+endif
+
 # Disable gcov profiling for VDSO code
 GCOV_PROFILE := n
 
@@ -28,6 +51,7 @@ $(obj)/vdso.o : $(obj)/vdso.so
 # Link rule for the .so file, .lds has to be first
 $(obj)/vdso.so.dbg: $(obj)/vdso.lds $(obj-vdso) FORCE
 	$(call if_changed,ld)
+	$(call if_changed,vdso_check)
 
 # Strip rule for the .so file
 $(obj)/%.so: OBJCOPYFLAGS := -S
@@ -42,13 +66,9 @@ quiet_cmd_vdsosym = VDSOSYM $@
 include/generated/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE
 	$(call if_changed,vdsosym)
 
-# Assembly rules for the .S files
-$(obj-vdso): %.o: %.S FORCE
-	$(call if_changed_dep,vdsoas)
-
 # Actual build commands
-quiet_cmd_vdsoas = VDSOA   $@
-      cmd_vdsoas = $(CC) $(a_flags) -c -o $@ $<
+quiet_cmd_vdsocc = VDSOCC   $@
+      cmd_vdsocc = $(CC) $(a_flags) $(c_flags) -c -o $@ $<
 
 # Install commands for the unstripped file
 quiet_cmd_vdso_install = INSTALL $@