This patch adds files related to VDSO and our VDSO only support
rt_sigreturn.

Signed-off-by: Guo Ren <ren_...@c-sky.com>
Cc: Arnd Bergmann <a...@arndb.de>
---
 arch/csky/abiv1/inc/abi/vdso.h | 17 +++++++++
 arch/csky/abiv2/inc/abi/vdso.h | 23 +++++++++++
 arch/csky/include/asm/vdso.h   | 12 ++++++
 arch/csky/kernel/vdso.c        | 86 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 138 insertions(+)
 create mode 100644 arch/csky/abiv1/inc/abi/vdso.h
 create mode 100644 arch/csky/abiv2/inc/abi/vdso.h
 create mode 100644 arch/csky/include/asm/vdso.h
 create mode 100644 arch/csky/kernel/vdso.c

diff --git a/arch/csky/abiv1/inc/abi/vdso.h b/arch/csky/abiv1/inc/abi/vdso.h
new file mode 100644
index 0000000..14352f5
--- /dev/null
+++ b/arch/csky/abiv1/inc/abi/vdso.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/uaccess.h>
+
+static inline int setup_vdso_page(unsigned short *ptr)
+{
+       int err = 0;
+
+       /* movi r1, 127 */
+       err |= __put_user(0x67f1, ptr + 0);
+       /* addi r1, (139 - 127) */
+       err |= __put_user(0x20b1, ptr + 1);
+       /* trap 0 */
+       err |= __put_user(0x0008, ptr + 2);
+
+       return err;
+}
diff --git a/arch/csky/abiv2/inc/abi/vdso.h b/arch/csky/abiv2/inc/abi/vdso.h
new file mode 100644
index 0000000..b60d4a0
--- /dev/null
+++ b/arch/csky/abiv2/inc/abi/vdso.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ABI_CSKY_VDSO_H
+#define __ABI_CSKY_VDSO_H
+
+#include <linux/uaccess.h>
+
+static inline int setup_vdso_page(unsigned short *ptr)
+{
+       int err = 0;
+
+       /* movi r7, 173 */
+       err |= __put_user(0xea07, ptr);
+       err |= __put_user(0x008b,      ptr+1);
+
+       /* trap 0 */
+       err |= __put_user(0xc000,   ptr+2);
+       err |= __put_user(0x2020,   ptr+3);
+
+       return err;
+}
+
+#endif /* __ABI_CSKY_STRING_H */
diff --git a/arch/csky/include/asm/vdso.h b/arch/csky/include/asm/vdso.h
new file mode 100644
index 0000000..d963d69
--- /dev/null
+++ b/arch/csky/include/asm/vdso.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_CSKY_VDSO_H
+#define __ASM_CSKY_VDSO_H
+
+#include <abi/vdso.h>
+
+struct csky_vdso {
+       unsigned short rt_signal_retcode[4];
+};
+
+#endif /* __ASM_CSKY_VDSO_H */
diff --git a/arch/csky/kernel/vdso.c b/arch/csky/kernel/vdso.c
new file mode 100644
index 0000000..60ff7ad
--- /dev/null
+++ b/arch/csky/kernel/vdso.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/binfmts.h>
+#include <linux/elf.h>
+#include <linux/vmalloc.h>
+#include <linux/unistd.h>
+#include <linux/uaccess.h>
+
+#include <asm/vdso.h>
+#include <asm/cacheflush.h>
+
+static struct page *vdso_page;
+
+static int __init init_vdso(void)
+{
+       struct csky_vdso *vdso;
+       int err = 0;
+
+       vdso_page = alloc_page(GFP_KERNEL);
+       if (!vdso_page)
+               panic("Cannot allocate vdso");
+
+       vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
+       if (!vdso)
+               panic("Cannot map vdso");
+
+       clear_page(vdso);
+
+       err = setup_vdso_page(vdso->rt_signal_retcode);
+       if (err)
+               panic("Cannot set signal return code, err: %x.", err);
+
+       dcache_wb_range((unsigned long)vdso, (unsigned long)vdso + 16);
+
+       vunmap(vdso);
+
+       return 0;
+}
+subsys_initcall(init_vdso);
+
+int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+       int ret;
+       unsigned long addr;
+       struct mm_struct *mm = current->mm;
+
+       down_write(&mm->mmap_sem);
+
+       addr = get_unmapped_area(NULL, STACK_TOP, PAGE_SIZE, 0, 0);
+       if (IS_ERR_VALUE(addr)) {
+               ret = addr;
+               goto up_fail;
+       }
+
+       ret = install_special_mapping(
+                       mm,
+                       addr,
+                       PAGE_SIZE,
+                       VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+                       &vdso_page);
+       if (ret)
+               goto up_fail;
+
+       mm->context.vdso = (void *)addr;
+
+up_fail:
+       up_write(&mm->mmap_sem);
+       return ret;
+}
+
+const char *arch_vma_name(struct vm_area_struct *vma)
+{
+       if (vma->vm_mm == NULL)
+               return NULL;
+
+       if (vma->vm_start == (long)vma->vm_mm->context.vdso)
+               return "[vdso]";
+       else
+               return NULL;
+}
-- 
2.7.4

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