[PATCH 21/25] powerpc: introduce get_pte_pkey() helper

[Ram Pai <linuxram@us.ibm.com>]

get_pte_pkey() helper returns the pkey associated with
a address corresponding to a given mm_struct.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
 arch/powerpc/include/asm/book3s/64/mmu-hash.h |    5 +++++
 arch/powerpc/mm/hash_utils_64.c               |   24 ++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
index 2e22357..8716031 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
@@ -451,6 +451,11 @@ extern int hash_page(unsigned long ea, unsigned long access, unsigned long trap,
 int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
 		     pte_t *ptep, unsigned long trap, unsigned long flags,
 		     int ssize, unsigned int shift, unsigned int mmu_psize);
+
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+u16 get_pte_pkey(struct mm_struct *mm, unsigned long address);
+#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 extern int __hash_page_thp(unsigned long ea, unsigned long access,
 			   unsigned long vsid, pmd_t *pmdp, unsigned long trap,
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index a739a2d..5917d45 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -1572,6 +1572,30 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
 	local_irq_restore(flags);
 }
 
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+/*
+ * return the protection key associated with the given address
+ * and the mm_struct.
+ */
+u16 get_pte_pkey(struct mm_struct *mm, unsigned long address)
+{
+	pte_t *ptep;
+	u16 pkey = 0;
+	unsigned long flags;
+
+	if (!mm || !mm->pgd)
+		return 0;
+
+	local_irq_save(flags);
+	ptep = find_linux_pte(mm->pgd, address, NULL, NULL);
+	if (ptep)
+		pkey = pte_to_pkey_bits(pte_val(READ_ONCE(*ptep)));
+	local_irq_restore(flags);
+
+	return pkey;
+}
+#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 static inline void tm_flush_hash_page(int local)
 {
-- 
1.7.1