v4.19.13 snapshot.
diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
new file mode 100644
index 0000000..582cb15
--- /dev/null
+++ b/arch/riscv/kernel/vdso.c
@@ -0,0 +1,125 @@
+/*
+ * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
+ * <benh@kernel.crashing.org>
+ * Copyright (C) 2012 ARM Limited
+ * Copyright (C) 2015 Regents of the University of California
+ *
+ * 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/>.
+ */
+
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/binfmts.h>
+#include <linux/err.h>
+
+#include <asm/vdso.h>
+
+extern char vdso_start[], vdso_end[];
+
+static unsigned int vdso_pages;
+static struct page **vdso_pagelist;
+
+/*
+ * 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;
+
+static int __init vdso_init(void)
+{
+ unsigned int i;
+
+ vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
+ vdso_pagelist =
+ kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
+ if (unlikely(vdso_pagelist == NULL)) {
+ pr_err("vdso: pagelist allocation failed\n");
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < vdso_pages; i++) {
+ struct page *pg;
+
+ pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
+ ClearPageReserved(pg);
+ vdso_pagelist[i] = pg;
+ }
+ vdso_pagelist[i] = virt_to_page(vdso_data);
+
+ 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_len;
+ int ret;
+
+ vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
+
+ down_write(&mm->mmap_sem);
+ vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
+ if (IS_ERR_VALUE(vdso_base)) {
+ ret = vdso_base;
+ goto end;
+ }
+
+ /*
+ * Put vDSO base into mm struct. We need to do this before calling
+ * install_special_mapping or the perf counter mmap tracking code
+ * will fail to recognise it as a vDSO (since arch_vma_name fails).
+ */
+ mm->context.vdso = (void *)vdso_base;
+
+ ret = install_special_mapping(mm, vdso_base, vdso_len,
+ (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
+ vdso_pagelist);
+
+ if (unlikely(ret))
+ mm->context.vdso = NULL;
+
+end:
+ up_write(&mm->mmap_sem);
+ return ret;
+}
+
+const char *arch_vma_name(struct vm_area_struct *vma)
+{
+ if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso))
+ return "[vdso]";
+ return NULL;
+}
+
+/*
+ * Function stubs to prevent linker errors when AT_SYSINFO_EHDR is defined
+ */
+
+int in_gate_area_no_mm(unsigned long addr)
+{
+ return 0;
+}
+
+int in_gate_area(struct mm_struct *mm, unsigned long addr)
+{
+ return 0;
+}
+
+struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
+{
+ return NULL;
+}