Now that we have _PAGE_READ use that to implement prot none. With this
prot_none is _PAGE_PRESENT with none of the access bits set. While
hashing we map that to PP bit 00.
With this implementation, we will now take a prot fault for prot none
ptes, whereas before, we never inserted such a pte to hash. Hence we
always got nohpte fault before.
This is in preparation to remove _PAGE_USER from book3s 64
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/book3s/64/hash.h | 18 ++++++++----------
arch/powerpc/mm/hash_utils_64.c | 15 +++++++++++----
arch/powerpc/mm/hugetlbpage.c | 2 +-
arch/powerpc/mm/pgtable-hash64.c | 6 ++----
4 files changed, 22 insertions(+), 19 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/hash.h
b/arch/powerpc/include/asm/book3s/64/hash.h
index 9153bda5f395..244f2c322c43 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -21,6 +21,7 @@
#define _PAGE_EXEC 0x00001 /* execute permission */
#define _PAGE_RW 0x00002 /* read & write access allowed */
#define _PAGE_READ 0x00004 /* read access allowed */
+#define _PAGE_RWX (_PAGE_READ | _PAGE_RW | _PAGE_EXEC)
#define _PAGE_USER 0x00008 /* page may be accessed by userspace */
#define _PAGE_GUARDED 0x00010 /* G: guarded (side-effect) page */
/* M (memory coherence) is always set in the HPTE, so we don't need it here */
@@ -176,10 +177,12 @@
#define PAGE_SHARED __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW)
#define PAGE_SHARED_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW | \
_PAGE_EXEC)
-#define PAGE_COPY __pgprot(_PAGE_BASE | _PAGE_USER )
-#define PAGE_COPY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
-#define PAGE_READONLY __pgprot(_PAGE_BASE | _PAGE_USER )
-#define PAGE_READONLY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
+#define PAGE_COPY __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_READ )
+#define PAGE_COPY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_READ| \
+ _PAGE_EXEC)
+#define PAGE_READONLY __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_READ)
+#define PAGE_READONLY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_READ| \
+ _PAGE_EXEC)
#define __P000 PAGE_NONE
#define __P001 PAGE_READONLY
@@ -392,15 +395,10 @@ static inline pte_t pte_clear_soft_dirty(pte_t pte)
#endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */
#ifdef CONFIG_NUMA_BALANCING
-/*
- * These work without NUMA balancing but the kernel does not care. See the
- * comment in include/asm-generic/pgtable.h . On powerpc, this will only
- * work for user pages and always return true for kernel pages.
- */
static inline int pte_protnone(pte_t pte)
{
return (pte_val(pte) &
- (_PAGE_PRESENT | _PAGE_USER)) == _PAGE_PRESENT;
+ (_PAGE_PRESENT | _PAGE_RWX)) == _PAGE_PRESENT;
}
#endif /* CONFIG_NUMA_BALANCING */
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 96b52bd3da8f..79b81cd0d254 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -173,9 +173,11 @@ unsigned long htab_convert_pte_flags(unsigned long
pteflags)
* and there is no kernel RO (_PAGE_KERNEL_RO).
* User area is mapped with PP=0x2 for read/write
* or PP=0x3 for read-only (including writeable but clean pages).
+ * We also map user prot none as with PP=00.
*/
if (pteflags & _PAGE_USER) {
- rflags |= 0x2;
+ if ((pteflags & _PAGE_READ) || (pteflags & _PAGE_RW))
+ rflags |= 0x2;
if (!((pteflags & _PAGE_RW) && (pteflags & _PAGE_DIRTY)))
rflags |= 0x1;
}
@@ -933,7 +935,7 @@ void demote_segment_4k(struct mm_struct *mm, unsigned long
addr)
* Userspace sets the subpage permissions using the subpage_prot system call.
*
* Result is 0: full permissions, _PAGE_RW: read-only,
- * _PAGE_USER or _PAGE_USER|_PAGE_RW: no access.
+ * _PAGE_RWX: no access.
*/
static int subpage_protection(struct mm_struct *mm, unsigned long ea)
{
@@ -959,8 +961,13 @@ static int subpage_protection(struct mm_struct *mm,
unsigned long ea)
/* extract 2-bit bitfield for this 4k subpage */
spp >>= 30 - 2 * ((ea >> 12) & 0xf);
- /* turn 0,1,2,3 into combination of _PAGE_USER and _PAGE_RW */
- spp = ((spp & 2) ? _PAGE_USER : 0) | ((spp & 1) ? _PAGE_RW : 0);
+ /*
+ * 0 -> full premission
+ * 1 -> Read only
+ * 2 -> no access.
+ * We return the flag that need to be cleared.
+ */
+ spp = ((spp & 2) ? _PAGE_RWX : 0) | ((spp & 1) ? _PAGE_RW : 0);
return spp;
}
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 196e69a3c472..17ca4827dd87 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -604,7 +604,7 @@ int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned
long addr,
end = pte_end;
pte = READ_ONCE(*ptep);
- mask = _PAGE_PRESENT | _PAGE_USER;
+ mask = _PAGE_PRESENT | _PAGE_USER | _PAGE_READ;
if (write)
mask |= _PAGE_RW;
diff --git a/arch/powerpc/mm/pgtable-hash64.c b/arch/powerpc/mm/pgtable-hash64.c
index b5e7e8efef1e..341bbf7d8891 100644
--- a/arch/powerpc/mm/pgtable-hash64.c
+++ b/arch/powerpc/mm/pgtable-hash64.c
@@ -231,8 +231,7 @@ void set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep,
* _PAGE_PRESENT, but we can be sure that it is not in hpte.
* Hence we can use set_pte_at for them.
*/
- VM_WARN_ON((pte_val(*ptep) & (_PAGE_PRESENT | _PAGE_USER)) ==
- (_PAGE_PRESENT | _PAGE_USER));
+ VM_WARN_ON(pte_present(*ptep) && !pte_protnone(*ptep));
/*
* Add the pte bit when tryint set a pte
@@ -433,8 +432,7 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp, pmd_t pmd)
{
#ifdef CONFIG_DEBUG_VM
- WARN_ON((pmd_val(*pmdp) & (_PAGE_PRESENT | _PAGE_USER)) ==
- (_PAGE_PRESENT | _PAGE_USER));
+ WARN_ON(pte_present(pmd_pte(*pmd)) && !pte_protnone(pmd_pte(*pmd)));
assert_spin_locked(&mm->page_table_lock);
WARN_ON(!pmd_trans_huge(pmd));
#endif
--
2.5.0
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
