mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-11 04:18:39 +08:00
mm: cleanup __get_user_pages()
Get rid of two nested loops over nr_pages, extract vma flags checking to separate function and other random cleanups. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov
Linus Torvalds
parent
1674448345
commit
fa5bb2093a
218
mm/gup.c
218
mm/gup.c
@ -315,6 +315,44 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
|
||||
{
|
||||
vm_flags_t vm_flags = vma->vm_flags;
|
||||
|
||||
if (vm_flags & (VM_IO | VM_PFNMAP))
|
||||
return -EFAULT;
|
||||
|
||||
if (gup_flags & FOLL_WRITE) {
|
||||
if (!(vm_flags & VM_WRITE)) {
|
||||
if (!(gup_flags & FOLL_FORCE))
|
||||
return -EFAULT;
|
||||
/*
|
||||
* We used to let the write,force case do COW in a
|
||||
* VM_MAYWRITE VM_SHARED !VM_WRITE vma, so ptrace could
|
||||
* set a breakpoint in a read-only mapping of an
|
||||
* executable, without corrupting the file (yet only
|
||||
* when that file had been opened for writing!).
|
||||
* Anon pages in shared mappings are surprising: now
|
||||
* just reject it.
|
||||
*/
|
||||
if (!is_cow_mapping(vm_flags)) {
|
||||
WARN_ON_ONCE(vm_flags & VM_MAYWRITE);
|
||||
return -EFAULT;
|
||||
}
|
||||
}
|
||||
} else if (!(vm_flags & VM_READ)) {
|
||||
if (!(gup_flags & FOLL_FORCE))
|
||||
return -EFAULT;
|
||||
/*
|
||||
* Is there actually any vma we can reach here which does not
|
||||
* have VM_MAYREAD set?
|
||||
*/
|
||||
if (!(vm_flags & VM_MAYREAD))
|
||||
return -EFAULT;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* __get_user_pages() - pin user pages in memory
|
||||
* @tsk: task_struct of target task
|
||||
@ -369,9 +407,9 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
|
||||
unsigned int gup_flags, struct page **pages,
|
||||
struct vm_area_struct **vmas, int *nonblocking)
|
||||
{
|
||||
long i;
|
||||
unsigned long vm_flags;
|
||||
long i = 0;
|
||||
unsigned int page_mask;
|
||||
struct vm_area_struct *vma = NULL;
|
||||
|
||||
if (!nr_pages)
|
||||
return 0;
|
||||
@ -386,124 +424,82 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
|
||||
if (!(gup_flags & FOLL_FORCE))
|
||||
gup_flags |= FOLL_NUMA;
|
||||
|
||||
i = 0;
|
||||
|
||||
do {
|
||||
struct vm_area_struct *vma;
|
||||
struct page *page;
|
||||
unsigned int foll_flags = gup_flags;
|
||||
unsigned int page_increm;
|
||||
|
||||
vma = find_extend_vma(mm, start);
|
||||
if (!vma && in_gate_area(mm, start)) {
|
||||
int ret;
|
||||
ret = get_gate_page(mm, start & PAGE_MASK, gup_flags,
|
||||
&vma, pages ? &pages[i] : NULL);
|
||||
if (ret)
|
||||
goto efault;
|
||||
page_mask = 0;
|
||||
goto next_page;
|
||||
}
|
||||
|
||||
if (!vma)
|
||||
goto efault;
|
||||
vm_flags = vma->vm_flags;
|
||||
if (vm_flags & (VM_IO | VM_PFNMAP))
|
||||
goto efault;
|
||||
|
||||
if (gup_flags & FOLL_WRITE) {
|
||||
if (!(vm_flags & VM_WRITE)) {
|
||||
if (!(gup_flags & FOLL_FORCE))
|
||||
goto efault;
|
||||
/*
|
||||
* We used to let the write,force case do COW
|
||||
* in a VM_MAYWRITE VM_SHARED !VM_WRITE vma, so
|
||||
* ptrace could set a breakpoint in a read-only
|
||||
* mapping of an executable, without corrupting
|
||||
* the file (yet only when that file had been
|
||||
* opened for writing!). Anon pages in shared
|
||||
* mappings are surprising: now just reject it.
|
||||
*/
|
||||
if (!is_cow_mapping(vm_flags)) {
|
||||
WARN_ON_ONCE(vm_flags & VM_MAYWRITE);
|
||||
goto efault;
|
||||
}
|
||||
}
|
||||
} else {
|
||||
if (!(vm_flags & VM_READ)) {
|
||||
if (!(gup_flags & FOLL_FORCE))
|
||||
goto efault;
|
||||
/*
|
||||
* Is there actually any vma we can reach here
|
||||
* which does not have VM_MAYREAD set?
|
||||
*/
|
||||
if (!(vm_flags & VM_MAYREAD))
|
||||
goto efault;
|
||||
}
|
||||
}
|
||||
|
||||
if (is_vm_hugetlb_page(vma)) {
|
||||
i = follow_hugetlb_page(mm, vma, pages, vmas,
|
||||
&start, &nr_pages, i, gup_flags);
|
||||
continue;
|
||||
}
|
||||
|
||||
do {
|
||||
struct page *page;
|
||||
unsigned int foll_flags = gup_flags;
|
||||
unsigned int page_increm;
|
||||
|
||||
/*
|
||||
* If we have a pending SIGKILL, don't keep faulting
|
||||
* pages and potentially allocating memory.
|
||||
*/
|
||||
if (unlikely(fatal_signal_pending(current)))
|
||||
return i ? i : -ERESTARTSYS;
|
||||
|
||||
cond_resched();
|
||||
while (!(page = follow_page_mask(vma, start,
|
||||
foll_flags, &page_mask))) {
|
||||
/* first iteration or cross vma bound */
|
||||
if (!vma || start >= vma->vm_end) {
|
||||
vma = find_extend_vma(mm, start);
|
||||
if (!vma && in_gate_area(mm, start)) {
|
||||
int ret;
|
||||
ret = faultin_page(tsk, vma, start, &foll_flags,
|
||||
nonblocking);
|
||||
switch (ret) {
|
||||
case 0:
|
||||
break;
|
||||
case -EFAULT:
|
||||
case -ENOMEM:
|
||||
case -EHWPOISON:
|
||||
return i ? i : ret;
|
||||
case -EBUSY:
|
||||
return i;
|
||||
case -ENOENT:
|
||||
goto next_page;
|
||||
default:
|
||||
BUG();
|
||||
}
|
||||
cond_resched();
|
||||
ret = get_gate_page(mm, start & PAGE_MASK,
|
||||
gup_flags, &vma,
|
||||
pages ? &pages[i] : NULL);
|
||||
if (ret)
|
||||
return i ? : ret;
|
||||
page_mask = 0;
|
||||
goto next_page;
|
||||
}
|
||||
if (IS_ERR(page))
|
||||
return i ? i : PTR_ERR(page);
|
||||
if (pages) {
|
||||
pages[i] = page;
|
||||
|
||||
flush_anon_page(vma, page, start);
|
||||
flush_dcache_page(page);
|
||||
page_mask = 0;
|
||||
if (!vma || check_vma_flags(vma, gup_flags))
|
||||
return i ? : -EFAULT;
|
||||
if (is_vm_hugetlb_page(vma)) {
|
||||
i = follow_hugetlb_page(mm, vma, pages, vmas,
|
||||
&start, &nr_pages, i,
|
||||
gup_flags);
|
||||
continue;
|
||||
}
|
||||
}
|
||||
retry:
|
||||
/*
|
||||
* If we have a pending SIGKILL, don't keep faulting pages and
|
||||
* potentially allocating memory.
|
||||
*/
|
||||
if (unlikely(fatal_signal_pending(current)))
|
||||
return i ? i : -ERESTARTSYS;
|
||||
cond_resched();
|
||||
page = follow_page_mask(vma, start, foll_flags, &page_mask);
|
||||
if (!page) {
|
||||
int ret;
|
||||
ret = faultin_page(tsk, vma, start, &foll_flags,
|
||||
nonblocking);
|
||||
switch (ret) {
|
||||
case 0:
|
||||
goto retry;
|
||||
case -EFAULT:
|
||||
case -ENOMEM:
|
||||
case -EHWPOISON:
|
||||
return i ? i : ret;
|
||||
case -EBUSY:
|
||||
return i;
|
||||
case -ENOENT:
|
||||
goto next_page;
|
||||
}
|
||||
BUG();
|
||||
}
|
||||
if (IS_ERR(page))
|
||||
return i ? i : PTR_ERR(page);
|
||||
if (pages) {
|
||||
pages[i] = page;
|
||||
flush_anon_page(vma, page, start);
|
||||
flush_dcache_page(page);
|
||||
page_mask = 0;
|
||||
}
|
||||
next_page:
|
||||
if (vmas) {
|
||||
vmas[i] = vma;
|
||||
page_mask = 0;
|
||||
}
|
||||
page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
|
||||
if (page_increm > nr_pages)
|
||||
page_increm = nr_pages;
|
||||
i += page_increm;
|
||||
start += page_increm * PAGE_SIZE;
|
||||
nr_pages -= page_increm;
|
||||
} while (nr_pages && start < vma->vm_end);
|
||||
if (vmas) {
|
||||
vmas[i] = vma;
|
||||
page_mask = 0;
|
||||
}
|
||||
page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
|
||||
if (page_increm > nr_pages)
|
||||
page_increm = nr_pages;
|
||||
i += page_increm;
|
||||
start += page_increm * PAGE_SIZE;
|
||||
nr_pages -= page_increm;
|
||||
} while (nr_pages);
|
||||
return i;
|
||||
efault:
|
||||
return i ? : -EFAULT;
|
||||
}
|
||||
EXPORT_SYMBOL(__get_user_pages);
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user