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mm: unexport __get_user_pages()

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This patch unexports the low-level __get_user_pages() function.

Recent refactoring of the get_user_pages* functions allow flags to be
passed through get_user_pages() which eliminates the need for access to
this function from its one user, kvm.

We can see that the two calls to get_user_pages() which replace
__get_user_pages() in kvm_main.c are equivalent by examining their call
stacks:

  get_user_page_nowait():
    get_user_pages(start, 1, flags, page, NULL)
    __get_user_pages_locked(current, current->mm, start, 1, page, NULL, NULL,
			    false, flags | FOLL_TOUCH)
    __get_user_pages(current, current->mm, start, 1,
		     flags | FOLL_TOUCH | FOLL_GET, page, NULL, NULL)

  check_user_page_hwpoison():
    get_user_pages(addr, 1, flags, NULL, NULL)
    __get_user_pages_locked(current, current->mm, addr, 1, NULL, NULL, NULL,
			    false, flags | FOLL_TOUCH)
    __get_user_pages(current, current->mm, addr, 1, flags | FOLL_TOUCH, NULL,
		     NULL, NULL)

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Lorenzo Stoakes 2016-10-24 10:57:25 +01:00 committed by Linus Torvalds
parent 272ddc8b37
commit 0d73175982
4 changed files with 6 additions and 13 deletions
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4
include/linux/mm.h
View File

@ -1271,10 +1271,6 @@ extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *
extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
void *buf, int len, unsigned int gup_flags);
long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int foll_flags, struct page **pages,
struct vm_area_struct **vmas, int *nonblocking);
long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,

3
mm/gup.c
View File

@ -526,7 +526,7 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
* instead of __get_user_pages. __get_user_pages should be used only if
* you need some special @gup_flags.
*/
long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
struct vm_area_struct **vmas, int *nonblocking)
@ -631,7 +631,6 @@ next_page:
} while (nr_pages);
return i;
}
EXPORT_SYMBOL(__get_user_pages);
bool vma_permits_fault(struct vm_area_struct *vma, unsigned int fault_flags)
{

2
mm/nommu.c
View File

@ -109,7 +109,7 @@ unsigned int kobjsize(const void *objp)
return PAGE_SIZE << compound_order(page);
}
long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int foll_flags, struct page **pages,
struct vm_area_struct **vmas, int *nonblocking)

10
virt/kvm/kvm_main.c
View File

@ -1346,21 +1346,19 @@ unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *w
static int get_user_page_nowait(unsigned long start, int write,
struct page **page)
{
int flags = FOLL_TOUCH | FOLL_NOWAIT | FOLL_HWPOISON | FOLL_GET;
int flags = FOLL_NOWAIT | FOLL_HWPOISON;
if (write)
flags |= FOLL_WRITE;
return __get_user_pages(current, current->mm, start, 1, flags, page,
NULL, NULL);
return get_user_pages(start, 1, flags, page, NULL);
}
static inline int check_user_page_hwpoison(unsigned long addr)
{
int rc, flags = FOLL_TOUCH | FOLL_HWPOISON | FOLL_WRITE;
int rc, flags = FOLL_HWPOISON | FOLL_WRITE;
rc = __get_user_pages(current, current->mm, addr, 1,
flags, NULL, NULL, NULL);
rc = get_user_pages(addr, 1, flags, NULL, NULL);
return rc == -EHWPOISON;
}