9 files changed, 882 insertions, 0 deletions
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
new file mode 100644
index 000000000..42b708202
--- /dev/null
+++ b/arch/arm64/kernel/vdso.c
@@ -0,0 +1,257 @@
+/*
+ * VDSO implementation for AArch64 and vector page setup for AArch32.
+ *
+ * Copyright (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ */
+
+#include <linux/cache.h>
+#include <linux/clocksource.h>
+#include <linux/elf.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/gfp.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/signal.h>
+#include <linux/slab.h>
+#include <linux/timekeeper_internal.h>
+#include <linux/vmalloc.h>
+
+#include <asm/cacheflush.h>
+#include <asm/signal32.h>
+#include <asm/vdso.h>
+#include <asm/vdso_datapage.h>
+
+extern char vdso_start[], vdso_end[];
+static unsigned long vdso_pages __ro_after_init;
+
+/*
+ * The vDSO data page.
+ */
+static union {
+	struct vdso_data	data;
+	u8			page[PAGE_SIZE];
+} vdso_data_store __page_aligned_data;
+struct vdso_data *vdso_data = &vdso_data_store.data;
+
+#ifdef CONFIG_COMPAT
+/*
+ * Create and map the vectors page for AArch32 tasks.
+ */
+static struct page *vectors_page[1] __ro_after_init;
+
+static int __init alloc_vectors_page(void)
+{
+	extern char __kuser_helper_start[], __kuser_helper_end[];
+	extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
+
+	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
+	int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start;
+	unsigned long vpage;
+
+	vpage = get_zeroed_page(GFP_ATOMIC);
+
+	if (!vpage)
+		return -ENOMEM;
+
+	/* kuser helpers */
+	memcpy((void *)vpage + 0x1000 - kuser_sz, __kuser_helper_start,
+		kuser_sz);
+
+	/* sigreturn code */
+	memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET,
+               __aarch32_sigret_code_start, sigret_sz);
+
+	flush_icache_range(vpage, vpage + PAGE_SIZE);
+	vectors_page[0] = virt_to_page(vpage);
+
+	return 0;
+}
+arch_initcall(alloc_vectors_page);
+
+int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
+{
+	struct mm_struct *mm = current->mm;
+	unsigned long addr = AARCH32_VECTORS_BASE;
+	static const struct vm_special_mapping spec = {
+		.name	= "[vectors]",
+		.pages	= vectors_page,
+
+	};
+	void *ret;
+
+	if (down_write_killable(&mm->mmap_sem))
+		return -EINTR;
+	current->mm->context.vdso = (void *)addr;
+
+	/* Map vectors page at the high address. */
+	ret = _install_special_mapping(mm, addr, PAGE_SIZE,
+				       VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,
+				       &spec);
+
+	up_write(&mm->mmap_sem);
+
+	return PTR_ERR_OR_ZERO(ret);
+}
+#endif /* CONFIG_COMPAT */
+
+static int vdso_mremap(const struct vm_special_mapping *sm,
+		struct vm_area_struct *new_vma)
+{
+	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
+	unsigned long vdso_size = vdso_end - vdso_start;
+
+	if (vdso_size != new_size)
+		return -EINVAL;
+
+	current->mm->context.vdso = (void *)new_vma->vm_start;
+
+	return 0;
+}
+
+static struct vm_special_mapping vdso_spec[2] __ro_after_init = {
+	{
+		.name	= "[vvar]",
+	},
+	{
+		.name	= "[vdso]",
+		.mremap = vdso_mremap,
+	},
+};
+
+static int __init vdso_init(void)
+{
+	int i;
+	struct page **vdso_pagelist;
+	unsigned long pfn;
+
+	if (memcmp(vdso_start, "\177ELF", 4)) {
+		pr_err("vDSO is not a valid ELF object!\n");
+		return -EINVAL;
+	}
+
+	vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
+
+	/* Allocate the vDSO pagelist, plus a page for the data. */
+	vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *),
+				GFP_KERNEL);
+	if (vdso_pagelist == NULL)
+		return -ENOMEM;
+
+	/* Grab the vDSO data page. */
+	vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data));
+
+
+	/* Grab the vDSO code pages. */
+	pfn = sym_to_pfn(vdso_start);
+
+	for (i = 0; i < vdso_pages; i++)
+		vdso_pagelist[i + 1] = pfn_to_page(pfn + i);
+
+	vdso_spec[0].pages = &vdso_pagelist[0];
+	vdso_spec[1].pages = &vdso_pagelist[1];
+
+	return 0;
+}
+arch_initcall(vdso_init);
+
+int arch_setup_additional_pages(struct linux_binprm *bprm,
+				int uses_interp)
+{
+	struct mm_struct *mm = current->mm;
+	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
+	void *ret;
+
+	vdso_text_len = vdso_pages << PAGE_SHIFT;
+	/* Be sure to map the data page */
+	vdso_mapping_len = vdso_text_len + PAGE_SIZE;
+
+	if (down_write_killable(&mm->mmap_sem))
+		return -EINTR;
+	vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
+	if (IS_ERR_VALUE(vdso_base)) {
+		ret = ERR_PTR(vdso_base);
+		goto up_fail;
+	}
+	ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
+				       VM_READ|VM_MAYREAD,
+				       &vdso_spec[0]);
+	if (IS_ERR(ret))
+		goto up_fail;
+
+	vdso_base += PAGE_SIZE;
+	mm->context.vdso = (void *)vdso_base;
+	ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
+				       VM_READ|VM_EXEC|
+				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+				       &vdso_spec[1]);
+	if (IS_ERR(ret))
+		goto up_fail;
+
+
+	up_write(&mm->mmap_sem);
+	return 0;
+
+up_fail:
+	mm->context.vdso = NULL;
+	up_write(&mm->mmap_sem);
+	return PTR_ERR(ret);
+}
+
+/*
+ * Update the vDSO data page to keep in sync with kernel timekeeping.
+ */
+void update_vsyscall(struct timekeeper *tk)
+{
+	u32 use_syscall = !tk->tkr_mono.clock->archdata.vdso_direct;
+
+	++vdso_data->tb_seq_count;
+	smp_wmb();
+
+	vdso_data->use_syscall			= use_syscall;
+	vdso_data->xtime_coarse_sec		= tk->xtime_sec;
+	vdso_data->xtime_coarse_nsec		= tk->tkr_mono.xtime_nsec >>
+							tk->tkr_mono.shift;
+	vdso_data->wtm_clock_sec		= tk->wall_to_monotonic.tv_sec;
+	vdso_data->wtm_clock_nsec		= tk->wall_to_monotonic.tv_nsec;
+
+	/* Read without the seqlock held by clock_getres() */
+	WRITE_ONCE(vdso_data->hrtimer_res, hrtimer_resolution);
+
+	if (!use_syscall) {
+		/* tkr_mono.cycle_last == tkr_raw.cycle_last */
+		vdso_data->cs_cycle_last	= tk->tkr_mono.cycle_last;
+		vdso_data->raw_time_sec         = tk->raw_sec;
+		vdso_data->raw_time_nsec        = tk->tkr_raw.xtime_nsec;
+		vdso_data->xtime_clock_sec	= tk->xtime_sec;
+		vdso_data->xtime_clock_nsec	= tk->tkr_mono.xtime_nsec;
+		vdso_data->cs_mono_mult		= tk->tkr_mono.mult;
+		vdso_data->cs_raw_mult		= tk->tkr_raw.mult;
+		/* tkr_mono.shift == tkr_raw.shift */
+		vdso_data->cs_shift		= tk->tkr_mono.shift;
+	}
+
+	smp_wmb();
+	++vdso_data->tb_seq_count;
+}
+
+void update_vsyscall_tz(void)
+{
+	vdso_data->tz_minuteswest	= sys_tz.tz_minuteswest;
+	vdso_data->tz_dsttime		= sys_tz.tz_dsttime;
+}
diff --git a/arch/arm64/kernel/vdso/.gitignore b/arch/arm64/kernel/vdso/.gitignore
new file mode 100644
index 000000000..f8b69d842
--- /dev/null
+++ b/arch/arm64/kernel/vdso/.gitignore
@@ -0,0 +1 @@
+vdso.lds
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
new file mode 100644
index 000000000..b215c712d
--- /dev/null
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Building a vDSO image for AArch64.
+#
+# Author: Will Deacon <will.deacon@arm.com>
+# Heavily based on the vDSO Makefiles for other archs.
+#
+
+obj-vdso := gettimeofday.o note.o sigreturn.o
+
+# Build rules
+targets := $(obj-vdso) vdso.so vdso.so.dbg
+obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
+
+ccflags-y := -shared -fno-common -fno-builtin
+ccflags-y += -nostdlib -Wl,-soname=linux-vdso.so.1 \
+		$(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
+
+# Disable gcov profiling for VDSO code
+GCOV_PROFILE := n
+
+# Workaround for bare-metal (ELF) toolchains that neglect to pass -shared
+# down to collect2, resulting in silent corruption of the vDSO image.
+ccflags-y += -Wl,-shared
+
+obj-y += vdso.o
+extra-y += vdso.lds
+CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
+
+# Force dependency (incbin is bad)
+$(obj)/vdso.o : $(obj)/vdso.so
+
+# Link rule for the .so file, .lds has to be first
+$(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso)
+	$(call if_changed,vdsold)
+
+# Strip rule for the .so file
+$(obj)/%.so: OBJCOPYFLAGS := -S
+$(obj)/%.so: $(obj)/%.so.dbg FORCE
+	$(call if_changed,objcopy)
+
+# Generate VDSO offsets using helper script
+gen-vdsosym := $(srctree)/$(src)/gen_vdso_offsets.sh
+quiet_cmd_vdsosym = VDSOSYM $@
+define cmd_vdsosym
+	$(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@
+endef
+
+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_vdsold = VDSOL   $@
+      cmd_vdsold = $(CC) $(c_flags) -Wl,-n -Wl,-T $^ -o $@
+quiet_cmd_vdsoas = VDSOA   $@
+      cmd_vdsoas = $(CC) $(a_flags) -c -o $@ $<
+
+# Install commands for the unstripped file
+quiet_cmd_vdso_install = INSTALL $@
+      cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@
+
+vdso.so: $(obj)/vdso.so.dbg
+	@mkdir -p $(MODLIB)/vdso
+	$(call cmd,vdso_install)
+
+vdso_install: vdso.so
diff --git a/arch/arm64/kernel/vdso/gen_vdso_offsets.sh b/arch/arm64/kernel/vdso/gen_vdso_offsets.sh
new file mode 100755
index 000000000..0664acaf6
--- /dev/null
+++ b/arch/arm64/kernel/vdso/gen_vdso_offsets.sh
@@ -0,0 +1,16 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+#
+# Match symbols in the DSO that look like VDSO_*; produce a header file
+# of constant offsets into the shared object.
+#
+# Doing this inside the Makefile will break the $(filter-out) function,
+# causing Kbuild to rebuild the vdso-offsets header file every time.
+#
+# Author: Will Deacon <will.deacon@arm.com
+#
+
+LC_ALL=C
+sed -n -e 's/^00*/0/' -e \
+'s/^\([0-9a-fA-F]*\) . VDSO_\([a-zA-Z0-9_]*\)$/\#define vdso_offset_\2\t0x\1/p'
diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
new file mode 100644
index 000000000..b6faf8b5d
--- /dev/null
+++ b/arch/arm64/kernel/vdso/gettimeofday.S
@@ -0,0 +1,334 @@
+/*
+ * Userspace implementations of gettimeofday() and friends.
+ *
+ * Copyright (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include <asm/unistd.h>
+
+#define NSEC_PER_SEC_LO16	0xca00
+#define NSEC_PER_SEC_HI16	0x3b9a
+
+vdso_data	.req	x6
+seqcnt		.req	w7
+w_tmp		.req	w8
+x_tmp		.req	x8
+
+/*
+ * Conventions for macro arguments:
+ * - An argument is write-only if its name starts with "res".
+ * - All other arguments are read-only, unless otherwise specified.
+ */
+
+	.macro	seqcnt_acquire
+9999:	ldr	seqcnt, [vdso_data, #VDSO_TB_SEQ_COUNT]
+	tbnz	seqcnt, #0, 9999b
+	dmb	ishld
+	.endm
+
+	.macro	seqcnt_check fail
+	dmb	ishld
+	ldr	w_tmp, [vdso_data, #VDSO_TB_SEQ_COUNT]
+	cmp	w_tmp, seqcnt
+	b.ne	\fail
+	.endm
+
+	.macro	syscall_check fail
+	ldr	w_tmp, [vdso_data, #VDSO_USE_SYSCALL]
+	cbnz	w_tmp, \fail
+	.endm
+
+	.macro get_nsec_per_sec res
+	mov	\res, #NSEC_PER_SEC_LO16
+	movk	\res, #NSEC_PER_SEC_HI16, lsl #16
+	.endm
+
+	/*
+	 * Returns the clock delta, in nanoseconds left-shifted by the clock
+	 * shift.
+	 */
+	.macro	get_clock_shifted_nsec res, cycle_last, mult
+	/* Read the virtual counter. */
+	isb
+	mrs	x_tmp, cntvct_el0
+	/* Calculate cycle delta and convert to ns. */
+	sub	\res, x_tmp, \cycle_last
+	/* We can only guarantee 56 bits of precision. */
+	movn	x_tmp, #0xff00, lsl #48
+	and	\res, x_tmp, \res
+	mul	\res, \res, \mult
+	/*
+	 * Fake address dependency from the value computed from the counter
+	 * register to subsequent data page accesses so that the sequence
+	 * locking also orders the read of the counter.
+	 */
+	and	x_tmp, \res, xzr
+	add	vdso_data, vdso_data, x_tmp
+	.endm
+
+	/*
+	 * Returns in res_{sec,nsec} the REALTIME timespec, based on the
+	 * "wall time" (xtime) and the clock_mono delta.
+	 */
+	.macro	get_ts_realtime res_sec, res_nsec, \
+			clock_nsec, xtime_sec, xtime_nsec, nsec_to_sec
+	add	\res_nsec, \clock_nsec, \xtime_nsec
+	udiv	x_tmp, \res_nsec, \nsec_to_sec
+	add	\res_sec, \xtime_sec, x_tmp
+	msub	\res_nsec, x_tmp, \nsec_to_sec, \res_nsec
+	.endm
+
+	/*
+	 * Returns in res_{sec,nsec} the timespec based on the clock_raw delta,
+	 * used for CLOCK_MONOTONIC_RAW.
+	 */
+	.macro	get_ts_clock_raw res_sec, res_nsec, clock_nsec, nsec_to_sec
+	udiv	\res_sec, \clock_nsec, \nsec_to_sec
+	msub	\res_nsec, \res_sec, \nsec_to_sec, \clock_nsec
+	.endm
+
+	/* sec and nsec are modified in place. */
+	.macro add_ts sec, nsec, ts_sec, ts_nsec, nsec_to_sec
+	/* Add timespec. */
+	add	\sec, \sec, \ts_sec
+	add	\nsec, \nsec, \ts_nsec
+
+	/* Normalise the new timespec. */
+	cmp	\nsec, \nsec_to_sec
+	b.lt	9999f
+	sub	\nsec, \nsec, \nsec_to_sec
+	add	\sec, \sec, #1
+9999:
+	cmp	\nsec, #0
+	b.ge	9998f
+	add	\nsec, \nsec, \nsec_to_sec
+	sub	\sec, \sec, #1
+9998:
+	.endm
+
+	.macro clock_gettime_return, shift=0
+	.if \shift == 1
+	lsr	x11, x11, x12
+	.endif
+	stp	x10, x11, [x1, #TSPEC_TV_SEC]
+	mov	x0, xzr
+	ret
+	.endm
+
+	.macro jump_slot jumptable, index, label
+	.if (. - \jumptable) != 4 * (\index)
+	.error "Jump slot index mismatch"
+	.endif
+	b	\label
+	.endm
+
+	.text
+
+/* int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz); */
+ENTRY(__kernel_gettimeofday)
+	.cfi_startproc
+	adr	vdso_data, _vdso_data
+	/* If tv is NULL, skip to the timezone code. */
+	cbz	x0, 2f
+
+	/* Compute the time of day. */
+1:	seqcnt_acquire
+	syscall_check fail=4f
+	ldr	x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
+	/* w11 = cs_mono_mult, w12 = cs_shift */
+	ldp	w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
+	ldp	x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
+
+	get_nsec_per_sec res=x9
+	lsl	x9, x9, x12
+
+	get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
+	seqcnt_check fail=1b
+	get_ts_realtime res_sec=x10, res_nsec=x11, \
+		clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
+
+	/* Convert ns to us. */
+	mov	x13, #1000
+	lsl	x13, x13, x12
+	udiv	x11, x11, x13
+	stp	x10, x11, [x0, #TVAL_TV_SEC]
+2:
+	/* If tz is NULL, return 0. */
+	cbz	x1, 3f
+	ldp	w4, w5, [vdso_data, #VDSO_TZ_MINWEST]
+	stp	w4, w5, [x1, #TZ_MINWEST]
+3:
+	mov	x0, xzr
+	ret
+4:
+	/* Syscall fallback. */
+	mov	x8, #__NR_gettimeofday
+	svc	#0
+	ret
+	.cfi_endproc
+ENDPROC(__kernel_gettimeofday)
+
+#define JUMPSLOT_MAX CLOCK_MONOTONIC_COARSE
+
+/* int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp); */
+ENTRY(__kernel_clock_gettime)
+	.cfi_startproc
+	cmp	w0, #JUMPSLOT_MAX
+	b.hi	syscall
+	adr	vdso_data, _vdso_data
+	adr	x_tmp, jumptable
+	add	x_tmp, x_tmp, w0, uxtw #2
+	br	x_tmp
+
+	ALIGN
+jumptable:
+	jump_slot jumptable, CLOCK_REALTIME, realtime
+	jump_slot jumptable, CLOCK_MONOTONIC, monotonic
+	b	syscall
+	b	syscall
+	jump_slot jumptable, CLOCK_MONOTONIC_RAW, monotonic_raw
+	jump_slot jumptable, CLOCK_REALTIME_COARSE, realtime_coarse
+	jump_slot jumptable, CLOCK_MONOTONIC_COARSE, monotonic_coarse
+
+	.if (. - jumptable) != 4 * (JUMPSLOT_MAX + 1)
+	.error	"Wrong jumptable size"
+	.endif
+
+	ALIGN
+realtime:
+	seqcnt_acquire
+	syscall_check fail=syscall
+	ldr	x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
+	/* w11 = cs_mono_mult, w12 = cs_shift */
+	ldp	w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
+	ldp	x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
+
+	/* All computations are done with left-shifted nsecs. */
+	get_nsec_per_sec res=x9
+	lsl	x9, x9, x12
+
+	get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
+	seqcnt_check fail=realtime
+	get_ts_realtime res_sec=x10, res_nsec=x11, \
+		clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
+	clock_gettime_return shift=1
+
+	ALIGN
+monotonic:
+	seqcnt_acquire
+	syscall_check fail=syscall
+	ldr	x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
+	/* w11 = cs_mono_mult, w12 = cs_shift */
+	ldp	w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
+	ldp	x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
+	ldp	x3, x4, [vdso_data, #VDSO_WTM_CLK_SEC]
+
+	/* All computations are done with left-shifted nsecs. */
+	lsl	x4, x4, x12
+	get_nsec_per_sec res=x9
+	lsl	x9, x9, x12
+
+	get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
+	seqcnt_check fail=monotonic
+	get_ts_realtime res_sec=x10, res_nsec=x11, \
+		clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
+
+	add_ts sec=x10, nsec=x11, ts_sec=x3, ts_nsec=x4, nsec_to_sec=x9
+	clock_gettime_return shift=1
+
+	ALIGN
+monotonic_raw:
+	seqcnt_acquire
+	syscall_check fail=syscall
+	ldr	x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
+	/* w11 = cs_raw_mult, w12 = cs_shift */
+	ldp	w12, w11, [vdso_data, #VDSO_CS_SHIFT]
+	ldp	x13, x14, [vdso_data, #VDSO_RAW_TIME_SEC]
+
+	/* All computations are done with left-shifted nsecs. */
+	get_nsec_per_sec res=x9
+	lsl	x9, x9, x12
+
+	get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
+	seqcnt_check fail=monotonic_raw
+	get_ts_clock_raw res_sec=x10, res_nsec=x11, \
+		clock_nsec=x15, nsec_to_sec=x9
+
+	add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
+	clock_gettime_return shift=1
+
+	ALIGN
+realtime_coarse:
+	seqcnt_acquire
+	ldp	x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC]
+	seqcnt_check fail=realtime_coarse
+	clock_gettime_return
+
+	ALIGN
+monotonic_coarse:
+	seqcnt_acquire
+	ldp	x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC]
+	ldp	x13, x14, [vdso_data, #VDSO_WTM_CLK_SEC]
+	seqcnt_check fail=monotonic_coarse
+
+	/* Computations are done in (non-shifted) nsecs. */
+	get_nsec_per_sec res=x9
+	add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
+	clock_gettime_return
+
+	ALIGN
+syscall: /* Syscall fallback. */
+	mov	x8, #__NR_clock_gettime
+	svc	#0
+	ret
+	.cfi_endproc
+ENDPROC(__kernel_clock_gettime)
+
+/* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res); */
+ENTRY(__kernel_clock_getres)
+	.cfi_startproc
+	cmp	w0, #CLOCK_REALTIME
+	ccmp	w0, #CLOCK_MONOTONIC, #0x4, ne
+	ccmp	w0, #CLOCK_MONOTONIC_RAW, #0x4, ne
+	b.ne	1f
+
+	adr	vdso_data, _vdso_data
+	ldr	w2, [vdso_data, #CLOCK_REALTIME_RES]
+	b	2f
+1:
+	cmp	w0, #CLOCK_REALTIME_COARSE
+	ccmp	w0, #CLOCK_MONOTONIC_COARSE, #0x4, ne
+	b.ne	4f
+	ldr	x2, 5f
+2:
+	cbz	x1, 3f
+	stp	xzr, x2, [x1]
+
+3:	/* res == NULL. */
+	mov	w0, wzr
+	ret
+
+4:	/* Syscall fallback. */
+	mov	x8, #__NR_clock_getres
+	svc	#0
+	ret
+5:
+	.quad	CLOCK_COARSE_RES
+	.cfi_endproc
+ENDPROC(__kernel_clock_getres)
diff --git a/arch/arm64/kernel/vdso/note.S b/arch/arm64/kernel/vdso/note.S
new file mode 100644
index 000000000..e20483b10
--- /dev/null
+++ b/arch/arm64/kernel/vdso/note.S
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ *
+ * This supplies .note.* sections to go into the PT_NOTE inside the vDSO text.
+ * Here we can supply some information useful to userland.
+ */
+
+#include <linux/uts.h>
+#include <linux/version.h>
+#include <linux/elfnote.h>
+#include <linux/build-salt.h>
+
+ELFNOTE_START(Linux, 0, "a")
+	.long LINUX_VERSION_CODE
+ELFNOTE_END
+
+BUILD_SALT
diff --git a/arch/arm64/kernel/vdso/sigreturn.S b/arch/arm64/kernel/vdso/sigreturn.S
new file mode 100644
index 000000000..20d98effa
--- /dev/null
+++ b/arch/arm64/kernel/vdso/sigreturn.S
@@ -0,0 +1,37 @@
+/*
+ * Sigreturn trampoline for returning from a signal when the SA_RESTORER
+ * flag is not set.
+ *
+ * Copyright (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ */
+
+#include <linux/linkage.h>
+#include <asm/unistd.h>
+
+	.text
+
+	nop
+ENTRY(__kernel_rt_sigreturn)
+	.cfi_startproc
+	.cfi_signal_frame
+	.cfi_def_cfa	x29, 0
+	.cfi_offset	x29, 0 * 8
+	.cfi_offset	x30, 1 * 8
+	mov	x8, #__NR_rt_sigreturn
+	svc	#0
+	.cfi_endproc
+ENDPROC(__kernel_rt_sigreturn)
diff --git a/arch/arm64/kernel/vdso/vdso.S b/arch/arm64/kernel/vdso/vdso.S
new file mode 100644
index 000000000..82379a70e
--- /dev/null
+++ b/arch/arm64/kernel/vdso/vdso.S
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ */
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+#include <linux/const.h>
+#include <asm/page.h>
+
+	.globl vdso_start, vdso_end
+	.section .rodata
+	.balign PAGE_SIZE
+vdso_start:
+	.incbin "arch/arm64/kernel/vdso/vdso.so"
+	.balign PAGE_SIZE
+vdso_end:
+
+	.previous
diff --git a/arch/arm64/kernel/vdso/vdso.lds.S b/arch/arm64/kernel/vdso/vdso.lds.S
new file mode 100644
index 000000000..b3e6c4d5b
--- /dev/null
+++ b/arch/arm64/kernel/vdso/vdso.lds.S
@@ -0,0 +1,104 @@
+/*
+ * GNU linker script for the VDSO library.
+*
+ * Copyright (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ * Heavily based on the vDSO linker scripts for other archs.
+ */
+
+#include <linux/const.h>
+#include <asm/page.h>
+#include <asm/vdso.h>
+
+OUTPUT_FORMAT("elf64-littleaarch64", "elf64-bigaarch64", "elf64-littleaarch64")
+OUTPUT_ARCH(aarch64)
+
+SECTIONS
+{
+	PROVIDE(_vdso_data = . - PAGE_SIZE);
+	. = VDSO_LBASE + SIZEOF_HEADERS;
+
+	.hash		: { *(.hash) }			:text
+	.gnu.hash	: { *(.gnu.hash) }
+	.dynsym		: { *(.dynsym) }
+	.dynstr		: { *(.dynstr) }
+	.gnu.version	: { *(.gnu.version) }
+	.gnu.version_d	: { *(.gnu.version_d) }
+	.gnu.version_r	: { *(.gnu.version_r) }
+
+	/*
+	 * Discard .note.gnu.property sections which are unused and have
+	 * different alignment requirement from vDSO note sections.
+	 */
+	/DISCARD/	: {
+		*(.note.GNU-stack .note.gnu.property)
+	}
+	.note		: { *(.note.*) }		:text	:note
+
+	. = ALIGN(16);
+
+	.text		: { *(.text*) }			:text	=0xd503201f
+	PROVIDE (__etext = .);
+	PROVIDE (_etext = .);
+	PROVIDE (etext = .);
+
+	.eh_frame_hdr	: { *(.eh_frame_hdr) }		:text	:eh_frame_hdr
+	.eh_frame	: { KEEP (*(.eh_frame)) }	:text
+
+	.dynamic	: { *(.dynamic) }		:text	:dynamic
+
+	.rodata		: { *(.rodata*) }		:text
+
+	_end = .;
+	PROVIDE(end = .);
+
+	/DISCARD/	: {
+		*(.data .data.* .gnu.linkonce.d.* .sdata*)
+		*(.bss .sbss .dynbss .dynsbss)
+	}
+}
+
+/*
+ * We must supply the ELF program headers explicitly to get just one
+ * PT_LOAD segment, and set the flags explicitly to make segments read-only.
+ */
+PHDRS
+{
+	text		PT_LOAD		FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
+	dynamic		PT_DYNAMIC	FLAGS(4);		/* PF_R */
+	note		PT_NOTE		FLAGS(4);		/* PF_R */
+	eh_frame_hdr	PT_GNU_EH_FRAME;
+}
+
+/*
+ * This controls what symbols we export from the DSO.
+ */
+VERSION
+{
+	LINUX_2.6.39 {
+	global:
+		__kernel_rt_sigreturn;
+		__kernel_gettimeofday;
+		__kernel_clock_gettime;
+		__kernel_clock_getres;
+	local: *;
+	};
+}
+
+/*
+ * Make the sigreturn code visible to the kernel.
+ */
+VDSO_sigtramp		= __kernel_rt_sigreturn;