You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 
 

27 lines
687 B

// SPDX-License-Identifier: GPL-2.0-only
/*
* A generic version of devmem_is_allowed.
*
* Based on arch/arm64/mm/mmap.c
*
* Copyright (C) 2020 Google, Inc.
* Copyright (C) 2012 ARM Ltd.
*/
#include <linux/mm.h>
#include <linux/ioport.h>
/*
* devmem_is_allowed() checks to see if /dev/mem access to a certain address
* is valid. The argument is a physical page number. We mimic x86 here by
* disallowing access to system RAM as well as device-exclusive MMIO regions.
* This effectively disable read()/write() on /dev/mem.
*/
int devmem_is_allowed(unsigned long pfn)
{
if (iomem_is_exclusive(pfn << PAGE_SHIFT))
return 0;
if (!page_is_ram(pfn))
return 1;
return 0;
}