lkml.org 
[lkml]   [2019]   [May]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.1 125/128] s390/mm: make the pxd_offset functions more robust
Date
From: Martin Schwidefsky <schwidefsky@de.ibm.com>

commit d1874a0c2805fcfa9162c972d6b7541e57adb542 upstream.

Change the way how pgd_offset, p4d_offset, pud_offset and pmd_offset
walk the page tables. pgd_offset now always calculates the index for
the top-level page table and adds it to the pgd, this is either a
segment table offset for a 2-level setup, a region-3 offset for 3-levels,
region-2 offset for 4-levels, or a region-1 offset for a 5-level setup.
The other three functions p4d_offset, pud_offset and pmd_offset will
only add the respective offset if they dereference the passed pointer.

With the new way of walking the page tables a sequence like this from
mm/gup.c now works:

pgdp = pgd_offset(current->mm, addr);
pgd = READ_ONCE(*pgdp);
p4dp = p4d_offset(&pgd, addr);
p4d = READ_ONCE(*p4dp);
pudp = pud_offset(&p4d, addr);
pud = READ_ONCE(*pudp);
pmdp = pmd_offset(&pud, addr);
pmd = READ_ONCE(*pmdp);

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/s390/include/asm/pgtable.h | 67 +++++++++++++++++++++++++---------------
arch/s390/mm/gup.c | 33 +++++++------------
2 files changed, 55 insertions(+), 45 deletions(-)

--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1204,42 +1204,67 @@ static inline pte_t mk_pte(struct page *
#define pmd_index(address) (((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
#define pte_index(address) (((address) >> PAGE_SHIFT) & (PTRS_PER_PTE-1))

-#define pgd_offset(mm, address) ((mm)->pgd + pgd_index(address))
-#define pgd_offset_k(address) pgd_offset(&init_mm, address)
-#define pgd_offset_raw(pgd, addr) ((pgd) + pgd_index(addr))
-
#define pmd_deref(pmd) (pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN)
#define pud_deref(pud) (pud_val(pud) & _REGION_ENTRY_ORIGIN)
#define p4d_deref(pud) (p4d_val(pud) & _REGION_ENTRY_ORIGIN)
#define pgd_deref(pgd) (pgd_val(pgd) & _REGION_ENTRY_ORIGIN)

-static inline p4d_t *p4d_offset(pgd_t *pgd, unsigned long address)
+/*
+ * The pgd_offset function *always* adds the index for the top-level
+ * region/segment table. This is done to get a sequence like the
+ * following to work:
+ * pgdp = pgd_offset(current->mm, addr);
+ * pgd = READ_ONCE(*pgdp);
+ * p4dp = p4d_offset(&pgd, addr);
+ * ...
+ * The subsequent p4d_offset, pud_offset and pmd_offset functions
+ * only add an index if they dereferenced the pointer.
+ */
+static inline pgd_t *pgd_offset_raw(pgd_t *pgd, unsigned long address)
{
- p4d_t *p4d = (p4d_t *) pgd;
+ unsigned long rste;
+ unsigned int shift;

- if ((pgd_val(*pgd) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R1)
- p4d = (p4d_t *) pgd_deref(*pgd);
- return p4d + p4d_index(address);
+ /* Get the first entry of the top level table */
+ rste = pgd_val(*pgd);
+ /* Pick up the shift from the table type of the first entry */
+ shift = ((rste & _REGION_ENTRY_TYPE_MASK) >> 2) * 11 + 20;
+ return pgd + ((address >> shift) & (PTRS_PER_PGD - 1));
}

-static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address)
+#define pgd_offset(mm, address) pgd_offset_raw(READ_ONCE((mm)->pgd), address)
+#define pgd_offset_k(address) pgd_offset(&init_mm, address)
+
+static inline p4d_t *p4d_offset(pgd_t *pgd, unsigned long address)
{
- pud_t *pud = (pud_t *) p4d;
+ if ((pgd_val(*pgd) & _REGION_ENTRY_TYPE_MASK) >= _REGION_ENTRY_TYPE_R1)
+ return (p4d_t *) pgd_deref(*pgd) + p4d_index(address);
+ return (p4d_t *) pgd;
+}

- if ((p4d_val(*p4d) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R2)
- pud = (pud_t *) p4d_deref(*p4d);
- return pud + pud_index(address);
+static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address)
+{
+ if ((p4d_val(*p4d) & _REGION_ENTRY_TYPE_MASK) >= _REGION_ENTRY_TYPE_R2)
+ return (pud_t *) p4d_deref(*p4d) + pud_index(address);
+ return (pud_t *) p4d;
}

static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
{
- pmd_t *pmd = (pmd_t *) pud;
+ if ((pud_val(*pud) & _REGION_ENTRY_TYPE_MASK) >= _REGION_ENTRY_TYPE_R3)
+ return (pmd_t *) pud_deref(*pud) + pmd_index(address);
+ return (pmd_t *) pud;
+}

- if ((pud_val(*pud) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3)
- pmd = (pmd_t *) pud_deref(*pud);
- return pmd + pmd_index(address);
+static inline pte_t *pte_offset(pmd_t *pmd, unsigned long address)
+{
+ return (pte_t *) pmd_deref(*pmd) + pte_index(address);
}

+#define pte_offset_kernel(pmd, address) pte_offset(pmd, address)
+#define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)
+#define pte_unmap(pte) do { } while (0)
+
#define pfn_pte(pfn,pgprot) mk_pte_phys(__pa((pfn) << PAGE_SHIFT),(pgprot))
#define pte_pfn(x) (pte_val(x) >> PAGE_SHIFT)
#define pte_page(x) pfn_to_page(pte_pfn(x))
@@ -1249,12 +1274,6 @@ static inline pmd_t *pmd_offset(pud_t *p
#define p4d_page(p4d) pfn_to_page(p4d_pfn(p4d))
#define pgd_page(pgd) pfn_to_page(pgd_pfn(pgd))

-/* Find an entry in the lowest level page table.. */
-#define pte_offset(pmd, addr) ((pte_t *) pmd_deref(*(pmd)) + pte_index(addr))
-#define pte_offset_kernel(pmd, address) pte_offset(pmd,address)
-#define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)
-#define pte_unmap(pte) do { } while (0)
-
static inline pmd_t pmd_wrprotect(pmd_t pmd)
{
pmd_val(pmd) &= ~_SEGMENT_ENTRY_WRITE;
--- a/arch/s390/mm/gup.c
+++ b/arch/s390/mm/gup.c
@@ -18,7 +18,7 @@
* inlines everything into a single function which results in too much
* register pressure.
*/
-static inline int gup_pte_range(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
+static inline int gup_pte_range(pmd_t pmd, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
{
struct page *head, *page;
@@ -27,7 +27,7 @@ static inline int gup_pte_range(pmd_t *p

mask = (write ? _PAGE_PROTECT : 0) | _PAGE_INVALID | _PAGE_SPECIAL;

- ptep = ((pte_t *) pmd_deref(pmd)) + pte_index(addr);
+ ptep = pte_offset_map(&pmd, addr);
do {
pte = *ptep;
barrier();
@@ -93,16 +93,13 @@ static inline int gup_huge_pmd(pmd_t *pm
}


-static inline int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr,
+static inline 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, pmd;

- pmdp = (pmd_t *) pudp;
- if ((pud_val(pud) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3)
- pmdp = (pmd_t *) pud_deref(pud);
- pmdp += pmd_index(addr);
+ pmdp = pmd_offset(&pud, addr);
do {
pmd = *pmdp;
barrier();
@@ -120,7 +117,7 @@ static inline int gup_pmd_range(pud_t *p
if (!gup_huge_pmd(pmdp, pmd, addr, next,
write, pages, nr))
return 0;
- } else if (!gup_pte_range(pmdp, pmd, addr, next,
+ } else if (!gup_pte_range(pmd, addr, next,
write, pages, nr))
return 0;
} while (pmdp++, addr = next, addr != end);
@@ -166,16 +163,13 @@ static int gup_huge_pud(pud_t *pudp, pud
return 1;
}

-static inline int gup_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr,
+static inline 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, pud;

- pudp = (pud_t *) p4dp;
- if ((p4d_val(p4d) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R2)
- pudp = (pud_t *) p4d_deref(p4d);
- pudp += pud_index(addr);
+ pudp = pud_offset(&p4d, addr);
do {
pud = *pudp;
barrier();
@@ -186,7 +180,7 @@ static inline int gup_pud_range(p4d_t *p
if (!gup_huge_pud(pudp, pud, addr, next, write, pages,
nr))
return 0;
- } else if (!gup_pmd_range(pudp, pud, addr, next, write, pages,
+ } else if (!gup_pmd_range(pud, addr, next, write, pages,
nr))
return 0;
} while (pudp++, addr = next, addr != end);
@@ -194,23 +188,20 @@ static inline int gup_pud_range(p4d_t *p
return 1;
}

-static inline int gup_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr,
+static inline 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, p4d;

- p4dp = (p4d_t *) pgdp;
- if ((pgd_val(pgd) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R1)
- p4dp = (p4d_t *) pgd_deref(pgd);
- p4dp += p4d_index(addr);
+ p4dp = p4d_offset(&pgd, addr);
do {
p4d = *p4dp;
barrier();
next = p4d_addr_end(addr, end);
if (p4d_none(p4d))
return 0;
- if (!gup_pud_range(p4dp, p4d, addr, next, write, pages, nr))
+ if (!gup_pud_range(p4d, addr, next, write, pages, nr))
return 0;
} while (p4dp++, addr = next, addr != end);

@@ -253,7 +244,7 @@ int __get_user_pages_fast(unsigned long
next = pgd_addr_end(addr, end);
if (pgd_none(pgd))
break;
- if (!gup_p4d_range(pgdp, 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);

\
 
 \ /
  Last update: 2019-05-20 14:37    [W:0.469 / U:3.104 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site