mmap.c

/*
 * arch/sh/mm/mmap.c
 *
 * Copyright (C) 2008 - 2009  Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
#include <linux/mman.h>
#include <linux/module.h>
#include <asm/page.h>
#include <asm/processor.h>

unsigned long shm_align_mask = PAGE_SIZE - 1;	/* Sane caches */
EXPORT_SYMBOL(shm_align_mask);

#ifdef CONFIG_MMU
static const pgprot_t protection_map[16] = {
	[VM_NONE]					= PAGE_NONE,
	[VM_READ]					= PAGE_READONLY,
	[VM_WRITE]					= PAGE_COPY,
	[VM_WRITE | VM_READ]				= PAGE_COPY,
	[VM_EXEC]					= PAGE_EXECREAD,
	[VM_EXEC | VM_READ]				= PAGE_EXECREAD,
	[VM_EXEC | VM_WRITE]				= PAGE_COPY,
	[VM_EXEC | VM_WRITE | VM_READ]			= PAGE_COPY,
	[VM_SHARED]					= PAGE_NONE,
	[VM_SHARED | VM_READ]				= PAGE_READONLY,
	[VM_SHARED | VM_WRITE]				= PAGE_WRITEONLY,
	[VM_SHARED | VM_WRITE | VM_READ]		= PAGE_SHARED,
	[VM_SHARED | VM_EXEC]				= PAGE_EXECREAD,
	[VM_SHARED | VM_EXEC | VM_READ]			= PAGE_EXECREAD,
	[VM_SHARED | VM_EXEC | VM_WRITE]		= PAGE_RWX,
	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= PAGE_RWX
};
DECLARE_VM_GET_PAGE_PROT

/*
 * To avoid cache aliases, we map the shared page with same color.
 */
static inline unsigned long COLOUR_ALIGN(unsigned long addr,
					 unsigned long pgoff)
{
	unsigned long base = (addr + shm_align_mask) & ~shm_align_mask;
	unsigned long off = (pgoff << PAGE_SHIFT) & shm_align_mask;

	return base + off;
}

unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
	unsigned long len, unsigned long pgoff, unsigned long flags,
	vm_flags_t vm_flags)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	int do_colour_align;
	struct vm_unmapped_area_info info = {};

	if (flags & MAP_FIXED) {
		/* We do not accept a shared mapping if it would violate
		 * cache aliasing constraints.
		 */
		if ((flags & MAP_SHARED) &&
		    ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
			return -EINVAL;
		return addr;
	}

	if (unlikely(len > TASK_SIZE))
		return -ENOMEM;

	do_colour_align = 0;
	if (filp || (flags & MAP_SHARED))
		do_colour_align = 1;

	if (addr) {
		if (do_colour_align)
			addr = COLOUR_ALIGN(addr, pgoff);
		else
			addr = PAGE_ALIGN(addr);

		vma = find_vma(mm, addr);
		if (TASK_SIZE - len >= addr &&
		    (!vma || addr + len <= vm_start_gap(vma)))
			return addr;
	}

	info.length = len;
	info.low_limit = TASK_UNMAPPED_BASE;
	info.high_limit = TASK_SIZE;
	info.align_mask = do_colour_align ? (PAGE_MASK & shm_align_mask) : 0;
	info.align_offset = pgoff << PAGE_SHIFT;
	return vm_unmapped_area(&info);
}

unsigned long
arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
			  const unsigned long len, const unsigned long pgoff,
			  const unsigned long flags, vm_flags_t vm_flags)
{
	struct vm_area_struct *vma;
	struct mm_struct *mm = current->mm;
	unsigned long addr = addr0;
	int do_colour_align;
	struct vm_unmapped_area_info info = {};

	if (flags & MAP_FIXED) {
		/* We do not accept a shared mapping if it would violate
		 * cache aliasing constraints.
		 */
		if ((flags & MAP_SHARED) &&
		    ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
			return -EINVAL;
		return addr;
	}

	if (unlikely(len > TASK_SIZE))
		return -ENOMEM;

	do_colour_align = 0;
	if (filp || (flags & MAP_SHARED))
		do_colour_align = 1;

	/* requesting a specific address */
	if (addr) {
		if (do_colour_align)
			addr = COLOUR_ALIGN(addr, pgoff);
		else
			addr = PAGE_ALIGN(addr);

		vma = find_vma(mm, addr);
		if (TASK_SIZE - len >= addr &&
		    (!vma || addr + len <= vm_start_gap(vma)))
			return addr;
	}

	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
	info.length = len;
	info.low_limit = PAGE_SIZE;
	info.high_limit = mm->mmap_base;
	info.align_mask = do_colour_align ? (PAGE_MASK & shm_align_mask) : 0;
	info.align_offset = pgoff << PAGE_SHIFT;
	addr = vm_unmapped_area(&info);

	/*
	 * A failed mmap() very likely causes application failure,
	 * so fall back to the bottom-up function here. This scenario
	 * can happen with large stack limits and large mmap()
	 * allocations.
	 */
	if (addr & ~PAGE_MASK) {
		VM_BUG_ON(addr != -ENOMEM);
		info.flags = 0;
		info.low_limit = TASK_UNMAPPED_BASE;
		info.high_limit = TASK_SIZE;
		addr = vm_unmapped_area(&info);
	}

	return addr;
}
#endif /* CONFIG_MMU */

/*
 * You really shouldn't be using read() or write() on /dev/mem.  This
 * might go away in the future.
 */
int valid_phys_addr_range(phys_addr_t addr, size_t count)
{
	if (addr < __MEMORY_START)
		return 0;
	if (addr + count > __pa(high_memory))
		return 0;

	return 1;
}

int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
{
	return 1;
}