mips: Add support for generic vDSO

The mips vDSO library requires some adaptations to take advantage of the
newly introduced generic vDSO library.

Introduce the following changes:
 - Modification of vdso.c to be compliant with the common vdso datapage
 - Use of lib/vdso for gettimeofday

Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
[paul.burton@mips.com: Prepend $(src) to config-n32-o32-env.c path.]
Signed-off-by: Paul Burton <paul.burton@mips.com>

6 files changed, 89 insertions, 90 deletions

diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
index 7221df24cb23..de853c6aab28 100644
--- a/arch/mips/vdso/Makefile
+++ b/arch/mips/vdso/Makefile
@@ -1,6 +1,12 @@
 # SPDX-License-Identifier: GPL-2.0
 # Objects to go into the VDSO.
-obj-vdso-y := elf.o gettimeofday.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_MIPS_JUMP_SLOT|R_MIPS_GLOB_DAT
+include $(srctree)/lib/vdso/Makefile
+
+obj-vdso-y := elf.o vgettimeofday.o sigreturn.o
 
 # Common compiler flags between ABIs.
 ccflags-vdso := \
@@ -15,15 +21,31 @@ ifdef CONFIG_CC_IS_CLANG
 ccflags-vdso += $(filter --target=%,$(KBUILD_CFLAGS))
 endif
 
+#
+# The -fno-jump-tables flag only prevents the compiler from generating
+# jump tables but does not prevent the compiler from emitting absolute
+# offsets.
 cflags-vdso := $(ccflags-vdso) \
 	$(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \
-	-O2 -g -fPIC -fno-strict-aliasing -fno-common -fno-builtin -G 0 \
-	-DDISABLE_BRANCH_PROFILING \
+	-O3 -g -fPIC -fno-strict-aliasing -fno-common -fno-builtin -G 0 \
+	-fno-stack-protector -fno-jump-tables -DDISABLE_BRANCH_PROFILING \
 	$(call cc-option, -fno-asynchronous-unwind-tables) \
 	$(call cc-option, -fno-stack-protector)
 aflags-vdso := $(ccflags-vdso) \
 	-D__ASSEMBLY__ -Wa,-gdwarf-2
 
+ifneq ($(c-gettimeofday-y),)
+CFLAGS_vgettimeofday.o = -include $(c-gettimeofday-y)
+
+# config-n32-o32-env.c prepares the environment to build a 32bit vDSO
+# library on a 64bit kernel.
+# Note: Needs to be included before than the generic library.
+CFLAGS_vgettimeofday-o32.o = -include $(src)/config-n32-o32-env.c -include $(c-gettimeofday-y)
+CFLAGS_vgettimeofday-n32.o = -include $(src)/config-n32-o32-env.c -include $(c-gettimeofday-y)
+endif
+
+CFLAGS_REMOVE_vgettimeofday.o = -pg
+
 #
 # For the pre-R6 code in arch/mips/vdso/vdso.h for locating
 # the base address of VDSO, the linker will emit a R_MIPS_PC32
@@ -48,6 +70,8 @@ VDSO_LDFLAGS := \
 	$(addprefix -Wl$(comma),$(filter -E%,$(KBUILD_CFLAGS))) \
 	-nostdlib -shared -Wl,--hash-style=sysv -Wl,--build-id
 
+CFLAGS_REMOVE_vdso.o = -pg
+
 GCOV_PROFILE := n
 UBSAN_SANITIZE := n
 
@@ -96,6 +120,7 @@ $(obj)/vdso.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) $(native-abi)
 
 $(obj)/vdso.so.dbg.raw: $(obj)/vdso.lds $(obj-vdso) FORCE
 	$(call if_changed,vdsold)
+	$(call if_changed,vdso_check)
 
 $(obj)/vdso-image.c: $(obj)/vdso.so.dbg.raw $(obj)/vdso.so.raw \
                      $(obj)/genvdso FORCE
@@ -134,6 +159,7 @@ $(obj)/vdso-o32.lds: $(src)/vdso.lds.S FORCE
 
 $(obj)/vdso-o32.so.dbg.raw: $(obj)/vdso-o32.lds $(obj-vdso-o32) FORCE
 	$(call if_changed,vdsold)
+	$(call if_changed,vdso_check)
 
 $(obj)/vdso-o32-image.c: VDSO_NAME := o32
 $(obj)/vdso-o32-image.c: $(obj)/vdso-o32.so.dbg.raw $(obj)/vdso-o32.so.raw \
@@ -174,6 +200,7 @@ $(obj)/vdso-n32.lds: $(src)/vdso.lds.S FORCE
 
 $(obj)/vdso-n32.so.dbg.raw: $(obj)/vdso-n32.lds $(obj-vdso-n32) FORCE
 	$(call if_changed,vdsold)
+	$(call if_changed,vdso_check)
 
 $(obj)/vdso-n32-image.c: VDSO_NAME := n32
 $(obj)/vdso-n32-image.c: $(obj)/vdso-n32.so.dbg.raw $(obj)/vdso-n32.so.raw \
diff --git a/arch/mips/vdso/config-n32-o32-env.c b/arch/mips/vdso/config-n32-o32-env.c
new file mode 100644
index 000000000000..da4994b2b3e5
--- /dev/null
+++ b/arch/mips/vdso/config-n32-o32-env.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Configuration file for O32 and N32 binaries.
+ * Note: To be included before lib/vdso/gettimeofday.c
+ */
+#if defined(CONFIG_MIPS32_O32) || defined(CONFIG_MIPS32_N32)
+/*
+ * In case of a 32 bit VDSO for a 64 bit kernel fake a 32 bit kernel
+ * configuration.
+ */
+#undef CONFIG_64BIT
+
+#define CONFIG_32BIT 1
+#define CONFIG_GENERIC_ATOMIC64 1
+
+#endif
+
diff --git a/arch/mips/vdso/elf.S b/arch/mips/vdso/elf.S
index e7543e8f426c..a25cb147f1ca 100644
--- a/arch/mips/vdso/elf.S
+++ b/arch/mips/vdso/elf.S
@@ -4,7 +4,7 @@
  * Author: Alex Smith <alex.smith@imgtec.com>
  */
 
-#include "vdso.h"
+#include <asm/vdso/vdso.h>
 
 #include <asm/isa-rev.h>
 
diff --git a/arch/mips/vdso/sigreturn.S b/arch/mips/vdso/sigreturn.S
index c3597632874b..e5c0ab98ab46 100644
--- a/arch/mips/vdso/sigreturn.S
+++ b/arch/mips/vdso/sigreturn.S
@@ -4,7 +4,7 @@
  * Author: Alex Smith <alex.smith@imgtec.com>
  */
 
-#include "vdso.h"
+#include <asm/vdso/vdso.h>
 
 #include <uapi/asm/unistd.h>
 
diff --git a/arch/mips/vdso/vdso.h b/arch/mips/vdso/vdso.h
deleted file mode 100644
index 14b1931be69c..000000000000
--- a/arch/mips/vdso/vdso.h
+++ /dev/null
@@ -1,85 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/*
- * Copyright (C) 2015 Imagination Technologies
- * Author: Alex Smith <alex.smith@imgtec.com>
- */
-
-#include <asm/sgidefs.h>
-
-#if _MIPS_SIM != _MIPS_SIM_ABI64 && defined(CONFIG_64BIT)
-
-/* Building 32-bit VDSO for the 64-bit kernel. Fake a 32-bit Kconfig. */
-#undef CONFIG_64BIT
-#define CONFIG_32BIT 1
-#ifndef __ASSEMBLY__
-#include <asm-generic/atomic64.h>
-#endif
-#endif
-
-#ifndef __ASSEMBLY__
-
-#include <asm/asm.h>
-#include <asm/page.h>
-#include <asm/vdso.h>
-
-static inline unsigned long get_vdso_base(void)
-{
-	unsigned long addr;
-
-	/*
-	 * We can't use cpu_has_mips_r6 since it needs the cpu_data[]
-	 * kernel symbol.
-	 */
-#ifdef CONFIG_CPU_MIPSR6
-	/*
-	 * lapc <symbol> is an alias to addiupc reg, <symbol> - .
-	 *
-	 * We can't use addiupc because there is no label-label
-	 * support for the addiupc reloc
-	 */
-	__asm__("lapc	%0, _start			\n"
-		: "=r" (addr) : :);
-#else
-	/*
-	 * Get the base load address of the VDSO. We have to avoid generating
-	 * relocations and references to the GOT because ld.so does not peform
-	 * relocations on the VDSO. We use the current offset from the VDSO base
-	 * and perform a PC-relative branch which gives the absolute address in
-	 * ra, and take the difference. The assembler chokes on
-	 * "li %0, _start - .", so embed the offset as a word and branch over
-	 * it.
-	 *
-	 */
-
-	__asm__(
-	"	.set push				\n"
-	"	.set noreorder				\n"
-	"	bal	1f				\n"
-	"	 nop					\n"
-	"	.word	_start - .			\n"
-	"1:	lw	%0, 0($31)			\n"
-	"	" STR(PTR_ADDU) " %0, $31, %0		\n"
-	"	.set pop				\n"
-	: "=r" (addr)
-	:
-	: "$31");
-#endif /* CONFIG_CPU_MIPSR6 */
-
-	return addr;
-}
-
-static inline const union mips_vdso_data *get_vdso_data(void)
-{
-	return (const union mips_vdso_data *)(get_vdso_base() - PAGE_SIZE);
-}
-
-#ifdef CONFIG_CLKSRC_MIPS_GIC
-
-static inline void __iomem *get_gic(const union mips_vdso_data *data)
-{
-	return (void __iomem *)data - PAGE_SIZE;
-}
-
-#endif /* CONFIG_CLKSRC_MIPS_GIC */
-
-#endif /* __ASSEMBLY__ */
diff --git a/arch/mips/vdso/vgettimeofday.c b/arch/mips/vdso/vgettimeofday.c
new file mode 100644
index 000000000000..1c46dace041e
--- /dev/null
+++ b/arch/mips/vdso/vgettimeofday.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * MIPS64 and compat userspace implementations of gettimeofday()
+ * and similar.
+ *
+ * Copyright (C) 2015 Imagination Technologies
+ * Copyright (C) 2018 ARM Limited
+ *
+ */
+#include <linux/time.h>
+#include <linux/types.h>
+
+#if _MIPS_SIM != _MIPS_SIM_ABI64
+int __vdso_clock_gettime(clockid_t clock,
+			 struct old_timespec32 *ts)
+{
+	return __cvdso_clock_gettime32(clock, ts);
+}
+
+int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
+			struct timezone *tz)
+{
+	return __cvdso_gettimeofday(tv, tz);
+}
+
+#else
+
+int __vdso_clock_gettime(clockid_t clock,
+			 struct __kernel_timespec *ts)
+{
+	return __cvdso_clock_gettime(clock, ts);
+}
+
+int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
+			struct timezone *tz)
+{
+	return __cvdso_gettimeofday(tv, tz);
+}
+
+#endif