path: root/arch
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authorAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>2018-08-22 22:46:04 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2018-08-23 12:16:01 +1000
commitbd0dbb73e01306a1060e56f81e5fe287be936477 (patch)
treec9fca4a21b66504708a415be3f63b5a4d03573a6 /arch
parent810e9f86f36f59f1d6f6710220c49afe0c705f38 (diff)
powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid.
When splitting a huge pmd pte, we need to mark the pmd entry invalid. We can do that by clearing _PAGE_PRESENT bit. But then that will be taken as a swap pte. In order to differentiate between the two use a software pte bit when invalidating. For regular pte, due to bd5050e38aec ("powerpc/mm/radix: Change pte relax sequence to handle nest MMU hang") we need to mark the pte entry invalid when relaxing access permission. Instead of marking pte_none which can result in different page table walk routines possibly skipping this pte entry, invalidate it but still keep it marked present. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch')
1 files changed, 17 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 676118743a06..13a688fc8cd0 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -44,6 +44,16 @@
#define _PAGE_PTE 0x4000000000000000UL /* distinguishes PTEs from pointers */
#define _PAGE_PRESENT 0x8000000000000000UL /* pte contains a translation */
+ * We need to mark a pmd pte invalid while splitting. We can do that by clearing
+ * the _PAGE_PRESENT bit. But then that will be taken as a swap pte. In order to
+ * differentiate between two use a SW field when invalidating.
+ *
+ * We do that temporary invalidate for regular pte entry in ptep_set_access_flags
+ *
+ * This is used only when _PAGE_PRESENT is cleared.
+ */
* Top and bottom bits of RPN which can be used by hash
@@ -568,7 +578,13 @@ static inline pte_t pte_clear_savedwrite(pte_t pte)
static inline int pte_present(pte_t pte)
- return !!(pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT));
+ /*
+ * A pte is considerent present if _PAGE_PRESENT is set.
+ * We also need to consider the pte present which is marked
+ * invalid during ptep_set_access_flags. Hence we look for _PAGE_INVALID
+ * if we find _PAGE_PRESENT cleared.
+ */
+ return !!(pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_INVALID));