linux-kernel - Re: [PATCH v2] lib: Use PFN_PHYS() in devmem_is

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Message-ID: <mhng-e101fb5a-2f16-45a0-8436-454ac2bf4223@palmerdabbelt-glaptop>
Date:   Tue, 03 Aug 2021 17:20:00 -0700 (PDT)
From:   Palmer Dabbelt <palmerdabbelt@...gle.com>
To:     wangkefeng.wang@...wei.com
CC:     wangliang101@...wei.com, mcgrof@...nel.org,
        linux-kernel@...r.kernel.org, Greg KH <gregkh@...uxfoundation.org>,
        linux@...linux.org.uk, linux-arm-kernel@...ts.infradead.org,
        stable@...r.kernel.org, wangle6@...wei.com,
        kepler.chenxin@...wei.com, nixiaoming@...wei.com
Subject:     Re: [PATCH v2] lib: Use PFN_PHYS() in devmem_is_allowed()

On Fri, 30 Jul 2021 00:04:05 PDT (-0700), wangkefeng.wang@...wei.com wrote:
>
> On 2021/7/30 14:49, Liang Wang wrote:
>> The physical address may exceed 32 bits on ARM(when ARM_LPAE enabled),
>> use PFN_PHYS() in devmem_is_allowed(), or the physical address may
>> overflow and be truncated.
>>
>> This bug was initially introduced from v2.6.37, and the function was moved
>> to lib when v5.10.
>>
>> Fixes: 087aaffcdf9c ("ARM: implement CONFIG_STRICT_DEVMEM by disabling access to RAM via /dev/mem")
>> Fixes: 527701eda5f1 ("lib: Add a generic version of devmem_is_allowed()")
>> Cc: stable@...r.kernel.org # v2.6.37
>> Signed-off-by: Liang Wang <wangliang101@...wei.com>
> Reviewed-by: Kefeng Wang <wangkefeng.wang@...wei.com>
>> ---
>> v2: update subject and changelog
>>   lib/devmem_is_allowed.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/lib/devmem_is_allowed.c b/lib/devmem_is_allowed.c
>> index c0d67c541849..60be9e24bd57 100644
>> --- a/lib/devmem_is_allowed.c
>> +++ b/lib/devmem_is_allowed.c
>> @@ -19,7 +19,7 @@
>>    */
>>   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;

Acked-by: Palmer Dabbelt <palmerdabbelt@...gle.com>

I only see the reply so I'm assuming this is going in through some other 
tree, but LMK if you want it via the RISC-V tree as IIRC we're using it 
too.

Thanks!