csky: VDSO and rt_sigreturn

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

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

4 files changed, 138 insertions, 0 deletions

diff --git a/arch/csky/abiv1/inc/abi/vdso.h b/arch/csky/abiv1/inc/abi/vdso.h
new file mode 100644
index 000000000000..14352f524f1d
--- /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 000000000000..b60d4a070326
--- /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 000000000000..d963d691f3a1
--- /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 000000000000..60ff7adfad1d
--- /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;
+}