csky: VDSO and rt_sigreturn

/* 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;

}

/* 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 */

/* 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 */

// 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;

}