linux-kernel - Re: [PATCH] powerpc/vdso: Separate vvar vma from vdso

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Message-ID: <8cd82b69-c8cc-8591-1f92-5c9400e00579@arista.com>
Date:   Wed, 31 Mar 2021 19:15:14 +0100
From:   Dmitry Safonov <dima@...sta.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org
Cc:     Dmitry Safonov <0x7f454c46@...il.com>,
        Andrei Vagin <avagin@...il.com>,
        Andy Lutomirski <luto@...nel.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev@...ts.ozlabs.org, stable@...r.kernel.org
Subject: Re: [PATCH] powerpc/vdso: Separate vvar vma from vdso

On 3/30/21 11:17 AM, Christophe Leroy wrote:
> 
> 
> Le 26/03/2021 à 20:17, Dmitry Safonov a écrit :
[..]
>> --- a/arch/powerpc/kernel/vdso.c
>> +++ b/arch/powerpc/kernel/vdso.c
>> @@ -55,10 +55,10 @@ static int vdso_mremap(const struct
>> vm_special_mapping *sm, struct vm_area_struc
>>   {
>>       unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
>>   -    if (new_size != text_size + PAGE_SIZE)
>> +    if (new_size != text_size)
>>           return -EINVAL;
> 
> In ARM64 you have removed the above test in commit 871402e05b24cb56
> ("mm: forbid splitting special mappings"). Do we need to keep it here ?
> 
>>   -    current->mm->context.vdso = (void __user *)new_vma->vm_start +
>> PAGE_SIZE;
>> +    current->mm->context.vdso = (void __user *)new_vma->vm_start;
>>         return 0;
>>   }
> 

Yes, right you are, this can be dropped.

Thanks,
          Dmitry