mirror of
https://github.com/torvalds/linux.git
synced 2024-11-23 12:42:02 +00:00
527701eda5
As part of adding support for STRICT_DEVMEM to the RISC-V port, Zong provided a devmem_is_allowed() implementation that's exactly the same as all the others I checked. Instead I'm adding a generic version, which will soon be used. Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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;
|
|
}
|