diff mbox series

[RESEND,6/8] parisc: Use mmap_base, not mmap_legacy_base, as low_limit for bottom-up mmap

Message ID 20190620050328.8942-7-alex@ghiti.fr (mailing list archive)
State Awaiting Upstream
Headers show
Series Fix mmap base in bottom-up mmap | expand

Commit Message

Alexandre Ghiti June 20, 2019, 5:03 a.m. UTC
Bottom-up mmap scheme is used twice:

- for legacy mode, in which mmap_legacy_base and mmap_base are equal.

- in case of mmap failure in top-down mode, where there is no need to go
through the whole address space again for the bottom-up fallback: the goal
of this fallback is to find, as a last resort, space between the top-down
mmap base and the stack, which is the only place not covered by the
top-down mmap.

Then this commit removes the usage of mmap_legacy_base field from parisc
code.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/parisc/kernel/sys_parisc.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

Comments

Helge Deller June 25, 2019, 2:09 p.m. UTC | #1
On 20.06.19 07:03, Alexandre Ghiti wrote:
> Bottom-up mmap scheme is used twice:
>
> - for legacy mode, in which mmap_legacy_base and mmap_base are equal.
>
> - in case of mmap failure in top-down mode, where there is no need to go
> through the whole address space again for the bottom-up fallback: the goal
> of this fallback is to find, as a last resort, space between the top-down
> mmap base and the stack, which is the only place not covered by the
> top-down mmap.
>
> Then this commit removes the usage of mmap_legacy_base field from parisc
> code.
>
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>

Boot-tested on parisc and seems to work nicely, thus:

Acked-by: Helge Deller <deller@gmx.de>

Helge



> ---
>  arch/parisc/kernel/sys_parisc.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
> index 5d458a44b09c..e987f3a8eb0b 100644
> --- a/arch/parisc/kernel/sys_parisc.c
> +++ b/arch/parisc/kernel/sys_parisc.c
> @@ -119,7 +119,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
>
>  	info.flags = 0;
>  	info.length = len;
> -	info.low_limit = mm->mmap_legacy_base;
> +	info.low_limit = mm->mmap_base;
>  	info.high_limit = mmap_upper_limit(NULL);
>  	info.align_mask = last_mmap ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
>  	info.align_offset = shared_align_offset(last_mmap, pgoff);
> @@ -240,13 +240,11 @@ static unsigned long mmap_legacy_base(void)
>   */
>  void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
>  {
> -	mm->mmap_legacy_base = mmap_legacy_base();
> -	mm->mmap_base = mmap_upper_limit(rlim_stack);
> -
>  	if (mmap_is_legacy()) {
> -		mm->mmap_base = mm->mmap_legacy_base;
> +		mm->mmap_base = mmap_legacy_base();
>  		mm->get_unmapped_area = arch_get_unmapped_area;
>  	} else {
> +		mm->mmap_base = mmap_upper_limit(rlim_stack);
>  		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
>  	}
>  }
>
Alexandre Ghiti June 26, 2019, 5:20 a.m. UTC | #2
On 6/25/19 10:09 AM, Helge Deller wrote:
> On 20.06.19 07:03, Alexandre Ghiti wrote:
>> Bottom-up mmap scheme is used twice:
>>
>> - for legacy mode, in which mmap_legacy_base and mmap_base are equal.
>>
>> - in case of mmap failure in top-down mode, where there is no need to go
>> through the whole address space again for the bottom-up fallback: the goal
>> of this fallback is to find, as a last resort, space between the top-down
>> mmap base and the stack, which is the only place not covered by the
>> top-down mmap.
>>
>> Then this commit removes the usage of mmap_legacy_base field from parisc
>> code.
>>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> Boot-tested on parisc and seems to work nicely, thus:
>
> Acked-by: Helge Deller <deller@gmx.de>

Thanks Helge,

Alex

>
> Helge
>
>
>
>> ---
>>   arch/parisc/kernel/sys_parisc.c | 8 +++-----
>>   1 file changed, 3 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
>> index 5d458a44b09c..e987f3a8eb0b 100644
>> --- a/arch/parisc/kernel/sys_parisc.c
>> +++ b/arch/parisc/kernel/sys_parisc.c
>> @@ -119,7 +119,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
>>
>>   	info.flags = 0;
>>   	info.length = len;
>> -	info.low_limit = mm->mmap_legacy_base;
>> +	info.low_limit = mm->mmap_base;
>>   	info.high_limit = mmap_upper_limit(NULL);
>>   	info.align_mask = last_mmap ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
>>   	info.align_offset = shared_align_offset(last_mmap, pgoff);
>> @@ -240,13 +240,11 @@ static unsigned long mmap_legacy_base(void)
>>    */
>>   void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
>>   {
>> -	mm->mmap_legacy_base = mmap_legacy_base();
>> -	mm->mmap_base = mmap_upper_limit(rlim_stack);
>> -
>>   	if (mmap_is_legacy()) {
>> -		mm->mmap_base = mm->mmap_legacy_base;
>> +		mm->mmap_base = mmap_legacy_base();
>>   		mm->get_unmapped_area = arch_get_unmapped_area;
>>   	} else {
>> +		mm->mmap_base = mmap_upper_limit(rlim_stack);
>>   		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
>>   	}
>>   }
>>
diff mbox series

Patch

diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
index 5d458a44b09c..e987f3a8eb0b 100644
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -119,7 +119,7 @@  unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 
 	info.flags = 0;
 	info.length = len;
-	info.low_limit = mm->mmap_legacy_base;
+	info.low_limit = mm->mmap_base;
 	info.high_limit = mmap_upper_limit(NULL);
 	info.align_mask = last_mmap ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
 	info.align_offset = shared_align_offset(last_mmap, pgoff);
@@ -240,13 +240,11 @@  static unsigned long mmap_legacy_base(void)
  */
 void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
 {
-	mm->mmap_legacy_base = mmap_legacy_base();
-	mm->mmap_base = mmap_upper_limit(rlim_stack);
-
 	if (mmap_is_legacy()) {
-		mm->mmap_base = mm->mmap_legacy_base;
+		mm->mmap_base = mmap_legacy_base();
 		mm->get_unmapped_area = arch_get_unmapped_area;
 	} else {
+		mm->mmap_base = mmap_upper_limit(rlim_stack);
 		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
 	}
 }