linux-kernel - Re: [PATCHv4 06/10] xen: Switch to using __pa

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Message-ID: <b7bcf276-6983-7eef-07a9-890ad7158789@redhat.com>
Date:   Tue, 29 Nov 2016 14:42:58 -0800
From:   Laura Abbott <labbott@...hat.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Mark Rutland <mark.rutland@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        David Vrabel <david.vrabel@...rix.com>,
        Juergen Gross <jgross@...e.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        linux-arm-kernel@...ts.infradead.org,
        xen-devel@...ts.xenproject.org
Subject: Re: [PATCHv4 06/10] xen: Switch to using __pa_symbol

On 11/29/2016 02:26 PM, Boris Ostrovsky wrote:
> On 11/29/2016 01:55 PM, Laura Abbott wrote:
>> __pa_symbol is the correct macro to use on kernel
>> symbols. Switch to this from __pa.
>>
>> Signed-off-by: Laura Abbott <labbott@...hat.com>
>> ---
>> Found during a sweep of the kernel. Untested.
>> ---
>>  drivers/xen/xenbus/xenbus_dev_backend.c | 2 +-
>>  drivers/xen/xenfs/xenstored.c           | 2 +-
>>  2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/xen/xenbus/xenbus_dev_backend.c b/drivers/xen/xenbus/xenbus_dev_backend.c
>> index 4a41ac9..31ca2bf 100644
>> --- a/drivers/xen/xenbus/xenbus_dev_backend.c
>> +++ b/drivers/xen/xenbus/xenbus_dev_backend.c
>> @@ -99,7 +99,7 @@ static int xenbus_backend_mmap(struct file *file, struct vm_area_struct *vma)
>>  		return -EINVAL;
>>  
>>  	if (remap_pfn_range(vma, vma->vm_start,
>> -			    virt_to_pfn(xen_store_interface),
>> +			    PHYS_PFN(__pa_symbol(xen_store_interface)),
>>  			    size, vma->vm_page_prot))
>>  		return -EAGAIN;
>>  
>> diff --git a/drivers/xen/xenfs/xenstored.c b/drivers/xen/xenfs/xenstored.c
>> index fef20db..21009ea 100644
>> --- a/drivers/xen/xenfs/xenstored.c
>> +++ b/drivers/xen/xenfs/xenstored.c
>> @@ -38,7 +38,7 @@ static int xsd_kva_mmap(struct file *file, struct vm_area_struct *vma)
>>  		return -EINVAL;
>>  
>>  	if (remap_pfn_range(vma, vma->vm_start,
>> -			    virt_to_pfn(xen_store_interface),
>> +			    PHYS_PFN(__pa_symbol(xen_store_interface)),
>>  			    size, vma->vm_page_prot))
>>  		return -EAGAIN;
>>  
> 
> 
> I suspect this won't work --- xen_store_interface doesn't point to a
> kernel symbol.
> 
> -boris
> 

I reviewed this again and yes you are right. I missed that this
was a pointer and not just a symbol so I think this patch can
just be dropped.

Thanks,
Laura