lib: use PFN_PHYS() in devmem_is_allowed()

hulk inclusion
category: bugfix
bugzilla: 176713 https://gitee.com/openeuler/kernel/issues/I4DDEL

Reference: https://lore.kernel.org/stable/20210731025057.78825-1-wangliang101@huawei.com/

--------------------------------

The physical address may exceed 32 bits on 32-bit systems with more than
32 bits of physcial address,use PFN_PHYS() in devmem_is_allowed(), or the
physical address may overflow and be truncated.

We found this bug when mapping a high addresses through devmem tool, when
CONFIG_STRICT_DEVMEM is enabled on the ARM with ARM_LPAE and devmem is
used to map a high address that is not in the iomem address range, an
unexpected error indicating no permission is returned.

This bug was initially introduced from v2.6.37, and the function was moved
to lib when v5.11.

Link: https://lkml.kernel.org/r/20210731025057.78825-1-wangliang101@huawei.com
Fixes: 087aaffc ("ARM: implement CONFIG_STRICT_DEVMEM by disabling access to RAM via /dev/mem")
Fixes: 527701ed ("lib: Add a generic version of devmem_is_allowed()")
Signed-off-by: NLiang Wang <wangliang101@huawei.com>
Reviewed-by: NLuis Chamberlain <mcgrof@kernel.org>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Liang Wang <wangliang101@huawei.com>
Cc: Xiaoming Ni <nixiaoming@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: <stable@vger.kernel.org>	[2.6.37+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
[KF: fix devmem_is_allowed() on ARM]
Signed-off-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: NTong Tiangen <tongtiangen@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm/mm/mmap.c

@@ -179,7 +179,7 @@ int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
  */
 int devmem_is_allowed(unsigned long pfn)
 {
-	if (iomem_is_exclusive(pfn << PAGE_SHIFT))
+	if (iomem_is_exclusive(PFN_PHYS(pfn)))
 		return 0;
 	if (!page_is_ram(pfn))
 		return 1;