[PATCHv4 10/33] x86/gup: add 5-level paging support

From: Kirill A. Shutemov
Date: Mon Mar 06 2017 - 09:04:42 EST


It's simply extension for one more page table level.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/mm/gup.c | 33 +++++++++++++++++++++++++++------
1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 99c7805a9693..eb407cf0f6d3 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -76,9 +76,9 @@ static void undo_dev_pagemap(int *nr, int nr_start, struct page **pages)
}

/*
- * 'pteval' can come from a pte, pmd or pud. We only check
+ * 'pteval' can come from a pte, pmd, pud or p4d. We only check
* _PAGE_PRESENT, _PAGE_USER, and _PAGE_RW in here which are the
- * same value on all 3 types.
+ * same value on all 4 types.
*/
static inline int pte_allows_gup(unsigned long pteval, int write)
{
@@ -290,13 +290,13 @@ static noinline int gup_huge_pud(pud_t pud, unsigned long addr,
return 1;
}

-static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
+static int gup_pud_range(p4d_t p4d, unsigned long addr, unsigned long end,
int write, struct page **pages, int *nr)
{
unsigned long next;
pud_t *pudp;

- pudp = pud_offset(&pgd, addr);
+ pudp = pud_offset(&p4d, addr);
do {
pud_t pud = *pudp;

@@ -315,6 +315,27 @@ static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
return 1;
}

+static int gup_p4d_range(pgd_t pgd, unsigned long addr, unsigned long end,
+ int write, struct page **pages, int *nr)
+{
+ unsigned long next;
+ p4d_t *p4dp;
+
+ p4dp = p4d_offset(&pgd, addr);
+ do {
+ p4d_t p4d = *p4dp;
+
+ next = p4d_addr_end(addr, end);
+ if (p4d_none(p4d))
+ return 0;
+ BUILD_BUG_ON(p4d_large(p4d));
+ if (!gup_pud_range(p4d, addr, next, write, pages, nr))
+ return 0;
+ } while (p4dp++, addr = next, addr != end);
+
+ return 1;
+}
+
/*
* Like get_user_pages_fast() except its IRQ-safe in that it won't fall
* back to the regular GUP.
@@ -363,7 +384,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
next = pgd_addr_end(addr, end);
if (pgd_none(pgd))
break;
- if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
+ if (!gup_p4d_range(pgd, addr, next, write, pages, &nr))
break;
} while (pgdp++, addr = next, addr != end);
local_irq_restore(flags);
@@ -435,7 +456,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
next = pgd_addr_end(addr, end);
if (pgd_none(pgd))
goto slow;
- if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
+ if (!gup_p4d_range(pgd, addr, next, write, pages, &nr))
goto slow;
} while (pgdp++, addr = next, addr != end);
local_irq_enable();
--
2.11.0