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Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits

Started by"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
First post2017-03-20 06:20 +0100
Last post2017-03-24 10:40 +0100
Articles 4 — 2 participants

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  Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-03-20 06:20 +0100
    Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above  47-bits "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-03-24 10:10 +0100
      Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above  47-bits "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-03-24 10:20 +0100
        Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above  47-bits "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-03-24 10:40 +0100

#1604177 — Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits

From"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Date2017-03-20 06:20 +0100
SubjectRe: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits
Message-ID<tmXTz-8lw-1@gated-at.bofh.it>
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> writes:
 @@ -168,6 +182,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
>  	unsigned long addr = addr0;
>  	struct vm_unmapped_area_info info;
>  
> +	addr = mpx_unmapped_area_check(addr, len, flags);
> +	if (IS_ERR_VALUE(addr))
> +		return addr;
> +
>  	/* requested length too big for entire address space */
>  	if (len > TASK_SIZE)
>  		return -ENOMEM;
> @@ -192,6 +210,14 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
>  	info.length = len;
>  	info.low_limit = PAGE_SIZE;
>  	info.high_limit = mm->mmap_base;
> +
> +	/*
> +	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
> +	 * in the full address space.
> +	 */
> +	if (addr > DEFAULT_MAP_WINDOW)
> +		info.high_limit += TASK_SIZE - DEFAULT_MAP_WINDOW;
> +

Is this ok for 32 bit application ?


>  	info.align_mask = 0;
>  	info.align_offset = pgoff << PAGE_SHIFT;
>  	if (filp) {


-aneesh

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#1608248 — Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits

From"Kirill A. Shutemov" <kirill@shutemov.name>
Date2017-03-24 10:10 +0100
SubjectRe: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits
Message-ID<totom-7Is-13@gated-at.bofh.it>
In reply to#1604177
On Mon, Mar 20, 2017 at 10:40:20AM +0530, Aneesh Kumar K.V wrote:
> "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> writes:
>  @@ -168,6 +182,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
> >  	unsigned long addr = addr0;
> >  	struct vm_unmapped_area_info info;
> >  
> > +	addr = mpx_unmapped_area_check(addr, len, flags);
> > +	if (IS_ERR_VALUE(addr))
> > +		return addr;
> > +
> >  	/* requested length too big for entire address space */
> >  	if (len > TASK_SIZE)
> >  		return -ENOMEM;
> > @@ -192,6 +210,14 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
> >  	info.length = len;
> >  	info.low_limit = PAGE_SIZE;
> >  	info.high_limit = mm->mmap_base;
> > +
> > +	/*
> > +	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
> > +	 * in the full address space.
> > +	 */
> > +	if (addr > DEFAULT_MAP_WINDOW)
> > +		info.high_limit += TASK_SIZE - DEFAULT_MAP_WINDOW;
> > +
> 
> Is this ok for 32 bit application ?

DEFAULT_MAP_WINDOW is equal to TASK_SIZE on 32-bit, so it's nop and will
be compile out.

-- 
 Kirill A. Shutemov

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#1608258 — Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits

From"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Date2017-03-24 10:20 +0100
SubjectRe: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits
Message-ID<toty2-7Nu-7@gated-at.bofh.it>
In reply to#1608248

On Friday 24 March 2017 02:34 PM, Kirill A. Shutemov wrote:
> On Mon, Mar 20, 2017 at 10:40:20AM +0530, Aneesh Kumar K.V wrote:
>> "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> writes:
>>  @@ -168,6 +182,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
>>>  	unsigned long addr = addr0;
>>>  	struct vm_unmapped_area_info info;
>>>
>>> +	addr = mpx_unmapped_area_check(addr, len, flags);
>>> +	if (IS_ERR_VALUE(addr))
>>> +		return addr;
>>> +
>>>  	/* requested length too big for entire address space */
>>>  	if (len > TASK_SIZE)
>>>  		return -ENOMEM;
>>> @@ -192,6 +210,14 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
>>>  	info.length = len;
>>>  	info.low_limit = PAGE_SIZE;
>>>  	info.high_limit = mm->mmap_base;
>>> +
>>> +	/*
>>> +	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
>>> +	 * in the full address space.
>>> +	 */
>>> +	if (addr > DEFAULT_MAP_WINDOW)
>>> +		info.high_limit += TASK_SIZE - DEFAULT_MAP_WINDOW;
>>> +
>>
>> Is this ok for 32 bit application ?
>
> DEFAULT_MAP_WINDOW is equal to TASK_SIZE on 32-bit, so it's nop and will
> be compile out.
>

That is not about CONFIG_X86_32 but about 32 bit application on a 64 bit 
kernel. I guess we will never find addr > DEFAULT_MAP_WINDOW with
a 32 bit app ?

-aneesh

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#1608272 — Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits

From"Kirill A. Shutemov" <kirill@shutemov.name>
Date2017-03-24 10:40 +0100
SubjectRe: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits
Message-ID<totRn-7Xq-7@gated-at.bofh.it>
In reply to#1608258
On Fri, Mar 24, 2017 at 02:44:10PM +0530, Aneesh Kumar K.V wrote:
> 
> 
> On Friday 24 March 2017 02:34 PM, Kirill A. Shutemov wrote:
> > On Mon, Mar 20, 2017 at 10:40:20AM +0530, Aneesh Kumar K.V wrote:
> > > "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> writes:
> > >  @@ -168,6 +182,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
> > > >  	unsigned long addr = addr0;
> > > >  	struct vm_unmapped_area_info info;
> > > > 
> > > > +	addr = mpx_unmapped_area_check(addr, len, flags);
> > > > +	if (IS_ERR_VALUE(addr))
> > > > +		return addr;
> > > > +
> > > >  	/* requested length too big for entire address space */
> > > >  	if (len > TASK_SIZE)
> > > >  		return -ENOMEM;
> > > > @@ -192,6 +210,14 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
> > > >  	info.length = len;
> > > >  	info.low_limit = PAGE_SIZE;
> > > >  	info.high_limit = mm->mmap_base;
> > > > +
> > > > +	/*
> > > > +	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
> > > > +	 * in the full address space.
> > > > +	 */
> > > > +	if (addr > DEFAULT_MAP_WINDOW)
> > > > +		info.high_limit += TASK_SIZE - DEFAULT_MAP_WINDOW;
> > > > +
> > > 
> > > Is this ok for 32 bit application ?
> > 
> > DEFAULT_MAP_WINDOW is equal to TASK_SIZE on 32-bit, so it's nop and will
> > be compile out.
> > 
> 
> That is not about CONFIG_X86_32 but about 32 bit application on a 64 bit
> kernel. I guess we will never find addr > DEFAULT_MAP_WINDOW with
> a 32 bit app ?

I have local change to avoid this within 32-bit syscall, but I'll need to
recheck everthing.

-- 
 Kirill A. Shutemov

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