On 01/07/2016 01:01 AM, Dave Hansen wrote:
> From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
>
> For protection keys, we need to understand whether protections
> should be enforced in software or not. In general, we enforce
> protections when working on our own task, but not when on others.
> We call these "current" and "foreign" operations.
>
> This introduces two new get_user_pages() variants:
>
> get_current_user_pages()
> get_foreign_user_pages()
>
> get_current_user_pages() is a drop-in replacement for when
> get_user_pages() was called with (current, current->mm, ...) as
> arguments. Using it makes a few of the call sites look a bit
> nicer.
>
> get_foreign_user_pages() is a replacement for when
> get_user_pages() is called on non-current tsk/mm.
>
> We leave a stub get_user_pages() around with a __deprecated
> warning.
Hm when replying to previous version I assumed this is because there are many
get_user_pages() callers remaining. But now I see there are just 3 drivers not
converted by this patch? In that case I would favor to convert get_user_pages()
to become what is now get_current_user_pages(). This would be much more
consistent IMHO. We don't need to cater to out-of-tree modules?
Sorry, I should have looked thoroughly on the previous reply, not just assume.
> This also effectively turns get_user_pages_unlocked() in to
> get_user_pages_unlocked_current() since it no longer gets a
> tsk/mm passed in. I thought that would be too long of a name if
> we added "_current" on there. BTW, if someone wants the
> get_user_pages_unlocked() behavior with a non-current tsk/mm,
> they just have to use __get_user_pages_unlocked() directly.
>
> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> Cc: vbabka@xxxxxxx
> ---
Also (but moot if you accept my suggestion):
> diff -puN mm/nommu.c~get_current_user_pages mm/nommu.c
> --- a/mm/nommu.c~get_current_user_pages 2016-01-06 15:50:02.230003599 -0800
> +++ b/mm/nommu.c 2016-01-06 15:50:02.259004906 -0800
> @@ -182,7 +182,7 @@ finish_or_fault:
> * slab page or a secondary page from a compound page
> * - don't permit access to VMAs that don't support it, such as I/O mappings
> */
> -long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
> +long get_foreign_user_pages(struct task_struct *tsk, struct mm_struct *mm,
> unsigned long start, unsigned long nr_pages,
> int write, int force, struct page **pages,
> struct vm_area_struct **vmas)
> @@ -199,35 +199,41 @@ long get_user_pages(struct task_struct *
> }
> EXPORT_SYMBOL(get_user_pages);
I think you need to change the export here as you did in gup.c
>
> -long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
> - unsigned long start, unsigned long nr_pages,
> +long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
> int write, int force, struct page **pages,
> int *locked)
> {
> - return get_user_pages(tsk, mm, start, nr_pages, write, force,
> - pages, NULL);
> + return get_user_pages(current, current->mm, start, nr_pages, write,
> + force, pages, NULL);
Why not use the _current variant here?
> }
> EXPORT_SYMBOL(get_user_pages_locked);
>
> -long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
> - unsigned long start, unsigned long nr_pages,
> +long get_current_user_pages(unsigned long start, unsigned long nr_pages,
> + int write, int force, struct page **pages,
> + struct vm_area_struct **vmas)
> +{
> + return get_foreign_user_pages(current, current->mm, start, nr_pages,
> + write, force, pages, vmas);
> +}
> +EXPORT_SYMBOL(get_current_user_pages);
> +
> +long __get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> int write, int force, struct page **pages,
> unsigned int gup_flags)
> {
> long ret;
> - down_read(&mm->mmap_sem);
> - ret = get_user_pages(tsk, mm, start, nr_pages, write, force,
> - pages, NULL);
> - up_read(&mm->mmap_sem);
> + down_read(¤t->mm->mmap_sem);
> + ret = get_current_user_pages(start, nr_pages, write, force,
> + pages, NULL);
> + up_read(¤t->mm->mmap_sem);
> return ret;
> }
> EXPORT_SYMBOL(__get_user_pages_unlocked);
>
> -long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
> - unsigned long start, unsigned long nr_pages,
> +long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> int write, int force, struct page **pages)
> {
> - return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write,
> + return __get_user_pages_unlocked(start, nr_pages, write,
> force, pages, 0);
> }
> EXPORT_SYMBOL(get_user_pages_unlocked);
> diff -puN mm/process_vm_access.c~get_current_user_pages mm/process_vm_access.c
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