mirror of https://gitee.com/openkylin/linux.git
28 lines
687 B
C
28 lines
687 B
C
|
// 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;
|
||
|
|
}
|