static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
int write, struct page **pages, int *nr)
{
unsigned long next;
pud_t *pudp;
pudp = pud_offset(&pgd, addr);
do {
pud_t pud = READ_ONCE(*pudp);
next = pud_addr_end(addr, end);
if (pud_none(pud))
return 0;
if (pud_huge(pud)) {
if (!gup_hugepte((pte_t *)pudp, PUD_SIZE, addr, next,
write, pages, nr))
return 0;
} else if (is_hugepd(pudp)) {
if (!gup_hugepd((hugepd_t *)pudp, PUD_SHIFT,
addr, next, write, pages, nr))
return 0;
} else if (!gup_pmd_range(pud, addr, next, write, pages, nr))
return 0;
} while (pudp++, addr = next, addr != end);
return 1;
}
static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
int write, struct page **pages, int *nr)
{
unsigned long next;
pmd_t *pmdp;
pmdp = pmd_offset(&pud, addr);
do {
pmd_t pmd = ACCESS_ONCE(*pmdp);
next = pmd_addr_end(addr, end);
/*
* If we find a splitting transparent hugepage we
* return zero. That will result in taking the slow
* path which will call wait_split_huge_page()
* if the pmd is still in splitting state
*/
if (pmd_none(pmd) || pmd_trans_splitting(pmd))
return 0;
if (pmd_huge(pmd) || pmd_large(pmd)) {
if (!gup_hugepte((pte_t *)pmdp, PMD_SIZE, addr, next,
write, pages, nr))
return 0;
} else if (is_hugepd(pmdp)) {
if (!gup_hugepd((hugepd_t *)pmdp, PMD_SHIFT,
addr, next, write, pages, nr))
return 0;
} else if (!gup_pte_range(pmd, addr, next, write, pages, nr))
return 0;
} while (pmdp++, addr = next, addr != end);
return 1;
}
static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
int write, struct page **pages, int *nr)
{
unsigned long next;
pmd_t *pmdp;
pmdp = pmd_offset(&pud, addr);
do {
pmd_t pmd = READ_ONCE(*pmdp);
next = pmd_addr_end(addr, end);
/*
* If we find a splitting transparent hugepage we
* return zero. That will result in taking the slow
* path which will call wait_split_huge_page()
* if the pmd is still in splitting state
*/
if (pmd_none(pmd) || pmd_trans_splitting(pmd))
return 0;
if (pmd_huge(pmd) || pmd_large(pmd)) {
/*
* NUMA hinting faults need to be handled in the GUP
* slowpath for accounting purposes and so that they
* can be serialised against THP migration.
*/
if (pmd_numa(pmd))
return 0;
if (!gup_hugepte((pte_t *)pmdp, PMD_SIZE, addr, next,
write, pages, nr))
return 0;
} else if (is_hugepd(pmdp)) {
if (!gup_hugepd((hugepd_t *)pmdp, PMD_SHIFT,
addr, next, write, pages, nr))
return 0;
} else if (!gup_pte_range(pmd, addr, next, write, pages, nr))
return 0;
} while (pmdp++, addr = next, addr != end);
return 1;
}
int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages)
{
struct mm_struct *mm = current->mm;
unsigned long addr, len, end;
unsigned long next;
unsigned long flags;
pgd_t *pgdp;
int nr = 0;
pr_devel("%s(%lx,%x,%s)\n", __func__, start, nr_pages, write ? "write" : "read");
start &= PAGE_MASK;
addr = start;
len = (unsigned long) nr_pages << PAGE_SHIFT;
end = start + len;
if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ,
start, len)))
return 0;
pr_devel(" aligned: %lx .. %lx\n", start, end);
/*
* XXX: batch / limit 'nr', to avoid large irq off latency
* needs some instrumenting to determine the common sizes used by
* important workloads (eg. DB2), and whether limiting the batch size
* will decrease performance.
*
* It seems like we're in the clear for the moment. Direct-IO is
* the main guy that batches up lots of get_user_pages, and even
* they are limited to 64-at-a-time which is not so many.
*/
/*
* This doesn't prevent pagetable teardown, but does prevent
* the pagetables from being freed on powerpc.
*
* So long as we atomically load page table pointers versus teardown,
* we can follow the address down to the the page and take a ref on it.
*/
local_irq_save(flags);
pgdp = pgd_offset(mm, addr);
do {
pgd_t pgd = READ_ONCE(*pgdp);
pr_devel(" %016lx: normal pgd %p\n", addr,
(void *)pgd_val(pgd));
next = pgd_addr_end(addr, end);
if (pgd_none(pgd))
break;
if (pgd_huge(pgd)) {
if (!gup_hugepte((pte_t *)pgdp, PGDIR_SIZE, addr, next,
write, pages, &nr))
break;
} else if (is_hugepd(pgdp)) {
if (!gup_hugepd((hugepd_t *)pgdp, PGDIR_SHIFT,
addr, next, write, pages, &nr))
break;
} else if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
break;
} while (pgdp++, addr = next, addr != end);
local_irq_restore(flags);
return nr;
}
int get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages)
{
struct mm_struct *mm = current->mm;
unsigned long addr, len, end;
unsigned long next;
pgd_t *pgdp;
int nr = 0;
pr_devel("%s(%lx,%x,%s)\n", __func__, start, nr_pages, write ? "write" : "read");
start &= PAGE_MASK;
addr = start;
len = (unsigned long) nr_pages << PAGE_SHIFT;
end = start + len;
if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ,
start, len)))
goto slow_irqon;
pr_devel(" aligned: %lx .. %lx\n", start, end);
/*
* XXX: batch / limit 'nr', to avoid large irq off latency
* needs some instrumenting to determine the common sizes used by
* important workloads (eg. DB2), and whether limiting the batch size
* will decrease performance.
*
* It seems like we're in the clear for the moment. Direct-IO is
* the main guy that batches up lots of get_user_pages, and even
* they are limited to 64-at-a-time which is not so many.
*/
/*
* This doesn't prevent pagetable teardown, but does prevent
* the pagetables from being freed on powerpc.
*
* So long as we atomically load page table pointers versus teardown,
* we can follow the address down to the the page and take a ref on it.
*/
local_irq_disable();
pgdp = pgd_offset(mm, addr);
do {
pgd_t pgd = *pgdp;
pr_devel(" %016lx: normal pgd %p\n", addr,
(void *)pgd_val(pgd));
next = pgd_addr_end(addr, end);
if (pgd_none(pgd))
goto slow;
if (pgd_huge(pgd)) {
if (!gup_hugepte((pte_t *)pgdp, PGDIR_SIZE, addr, next,
write, pages, &nr))
goto slow;
} else if (is_hugepd(pgdp)) {
if (!gup_hugepd((hugepd_t *)pgdp, PGDIR_SHIFT,
addr, next, write, pages, &nr))
goto slow;
} else if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
goto slow;
} while (pgdp++, addr = next, addr != end);
local_irq_enable();
VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
return nr;
{
int ret;
slow:
local_irq_enable();
slow_irqon:
pr_devel(" slow path ! nr = %d\n", nr);
/* Try to get the remaining pages with get_user_pages */
start += nr << PAGE_SHIFT;
pages += nr;
down_read(&mm->mmap_sem);
ret = get_user_pages(current, mm, start,
(end - start) >> PAGE_SHIFT, write, 0, pages, NULL);
up_read(&mm->mmap_sem);
/* Have to be a bit careful with return values */
if (nr > 0) {
if (ret < 0)
ret = nr;
else
ret += nr;
}
return ret;
}
}