1 files changed, 79 insertions, 4 deletions

diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index dadea7d4324d..79b105d1ff73 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -11,21 +11,94 @@
 #include <linux/jump_label.h>
 
 DECLARE_STATIC_KEY_TRUE(pkey_disabled);
-#define ARCH_VM_PKEY_FLAGS 0
+extern int pkeys_total; /* total pkeys as per device tree */
+extern u32 initial_allocation_mask; /* bits set for reserved keys */
+
+/*
+ * Define these here temporarily so we're not dependent on patching linux/mm.h.
+ * Once it's updated we can drop these.
+ */
+#ifndef VM_PKEY_BIT0
+# define VM_PKEY_SHIFT	VM_HIGH_ARCH_BIT_0
+# define VM_PKEY_BIT0	VM_HIGH_ARCH_0
+# define VM_PKEY_BIT1	VM_HIGH_ARCH_1
+# define VM_PKEY_BIT2	VM_HIGH_ARCH_2
+# define VM_PKEY_BIT3	VM_HIGH_ARCH_3
+# define VM_PKEY_BIT4	VM_HIGH_ARCH_4
+#endif
+
+#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
+			    VM_PKEY_BIT3 | VM_PKEY_BIT4)
+
+#define arch_max_pkey() pkeys_total
+
+#define pkey_alloc_mask(pkey) (0x1 << pkey)
+
+#define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
+
+#define __mm_pkey_allocated(mm, pkey) {	\
+	mm_pkey_allocation_map(mm) |= pkey_alloc_mask(pkey); \
+}
+
+#define __mm_pkey_free(mm, pkey) {	\
+	mm_pkey_allocation_map(mm) &= ~pkey_alloc_mask(pkey);	\
+}
+
+#define __mm_pkey_is_allocated(mm, pkey)	\
+	(mm_pkey_allocation_map(mm) & pkey_alloc_mask(pkey))
+
+#define __mm_pkey_is_reserved(pkey) (initial_allocation_mask & \
+				       pkey_alloc_mask(pkey))
 
 static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
 {
-	return false;
+	/* A reserved key is never considered as 'explicitly allocated' */
+	return ((pkey < arch_max_pkey()) &&
+		!__mm_pkey_is_reserved(pkey) &&
+		__mm_pkey_is_allocated(mm, pkey));
 }
 
+/*
+ * Returns a positive, 5-bit key on success, or -1 on failure.
+ * Relies on the mmap_sem to protect against concurrency in mm_pkey_alloc() and
+ * mm_pkey_free().
+ */
 static inline int mm_pkey_alloc(struct mm_struct *mm)
 {
-	return -1;
+	/*
+	 * Note: this is the one and only place we make sure that the pkey is
+	 * valid as far as the hardware is concerned. The rest of the kernel
+	 * trusts that only good, valid pkeys come out of here.
+	 */
+	u32 all_pkeys_mask = (u32)(~(0x0));
+	int ret;
+
+	if (static_branch_likely(&pkey_disabled))
+		return -1;
+
+	/*
+	 * Are we out of pkeys? We must handle this specially because ffz()
+	 * behavior is undefined if there are no zeros.
+	 */
+	if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
+		return -1;
+
+	ret = ffz((u32)mm_pkey_allocation_map(mm));
+	__mm_pkey_allocated(mm, ret);
+	return ret;
 }
 
 static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
 {
-	return -EINVAL;
+	if (static_branch_likely(&pkey_disabled))
+		return -1;
+
+	if (!mm_pkey_is_allocated(mm, pkey))
+		return -EINVAL;
+
+	__mm_pkey_free(mm, pkey);
+
+	return 0;
 }
 
 /*
@@ -48,4 +121,6 @@ static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 {
 	return 0;
 }
+
+extern void pkey_mm_init(struct mm_struct *mm);
 #endif /*_ASM_POWERPC_KEYS_H */