On 23/03/2015 09:52, Ingo Molnar wrote:
>
> * Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx> wrote:
>
>> Some architecture would like to be triggered when a memory area is moved
>> through the mremap system call.
>>
>> This patch is introducing a new arch_remap mm hook which is placed in the
>> path of mremap, and is called before the old area is unmapped (and the
>> arch_unmap hook is called).
>>
>> To no break the build, this patch adds the empty hook definition to the
>> architectures that were not using the generic hook's definition.
>>
>> Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx>
>> ---
>> arch/s390/include/asm/mmu_context.h | 6 ++++++
>> arch/um/include/asm/mmu_context.h | 5 +++++
>> arch/unicore32/include/asm/mmu_context.h | 6 ++++++
>> arch/x86/include/asm/mmu_context.h | 6 ++++++
>> include/asm-generic/mm_hooks.h | 6 ++++++
>> mm/mremap.c | 9 +++++++--
>> 6 files changed, 36 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
>> index 8fb3802f8fad..ddd861a490ba 100644
>> --- a/arch/s390/include/asm/mmu_context.h
>> +++ b/arch/s390/include/asm/mmu_context.h
>> @@ -131,4 +131,10 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
>> {
>> }
>>
>> +static inline void arch_remap(struct mm_struct *mm,
>> + unsigned long old_start, unsigned long old_end,
>> + unsigned long new_start, unsigned long new_end)
>> +{
>> +}
>> +
>> #endif /* __S390_MMU_CONTEXT_H */
>> diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h
>> index 941527e507f7..f499b017c1f9 100644
>> --- a/arch/um/include/asm/mmu_context.h
>> +++ b/arch/um/include/asm/mmu_context.h
>> @@ -27,6 +27,11 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
>> struct vm_area_struct *vma)
>> {
>> }
>> +static inline void arch_remap(struct mm_struct *mm,
>> + unsigned long old_start, unsigned long old_end,
>> + unsigned long new_start, unsigned long new_end)
>> +{
>> +}
>> /*
>> * end asm-generic/mm_hooks.h functions
>> */
>> diff --git a/arch/unicore32/include/asm/mmu_context.h b/arch/unicore32/include/asm/mmu_context.h
>> index 1cb5220afaf9..39a0a553172e 100644
>> --- a/arch/unicore32/include/asm/mmu_context.h
>> +++ b/arch/unicore32/include/asm/mmu_context.h
>> @@ -97,4 +97,10 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
>> {
>> }
>>
>> +static inline void arch_remap(struct mm_struct *mm,
>> + unsigned long old_start, unsigned long old_end,
>> + unsigned long new_start, unsigned long new_end)
>> +{
>> +}
>> +
>> #endif
>> diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
>> index 883f6b933fa4..75cb71f4be1e 100644
>> --- a/arch/x86/include/asm/mmu_context.h
>> +++ b/arch/x86/include/asm/mmu_context.h
>> @@ -172,4 +172,10 @@ static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
>> mpx_notify_unmap(mm, vma, start, end);
>> }
>>
>> +static inline void arch_remap(struct mm_struct *mm,
>> + unsigned long old_start, unsigned long old_end,
>> + unsigned long new_start, unsigned long new_end)
>> +{
>> +}
>> +
>> #endif /* _ASM_X86_MMU_CONTEXT_H */
>
> So instead of spreading these empty prototypes around mmu_context.h
> files, why not add something like this to the PPC definition:
>
> #define __HAVE_ARCH_REMAP
>
> and define the empty prototype for everyone else? It's a bit like how
> the __HAVE_ARCH_PTEP_* namespace works.
>
> That should shrink this patch considerably.
My idea was to mimic the MMU hook's definition. This new hook is in the
continuity of what have been done for arch_dup_mmap, arch_exit_mmap,
arch_unmap and arch_bprm_mm_init.
Do you think that there is a need to make this one in another way ?
Thanks,
Laurent.
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