3 files changed, 84 insertions, 7 deletions

diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
index 1ea0baef1175..72198c64e646 100644
--- a/arch/x86/include/asm/mmu.h
+++ b/arch/x86/include/asm/mmu.h
@@ -23,6 +23,14 @@ typedef struct {
 	const struct vdso_image *vdso_image;	/* vdso image in use */
 
 	atomic_t perf_rdpmc_allowed;	/* nonzero if rdpmc is allowed */
+#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+	/*
+	 * One bit per protection key says whether userspace can
+	 * use it or not.  protected by mmap_sem.
+	 */
+	u16 pkey_allocation_map;
+	s16 execute_only_pkey;
+#endif
 } mm_context_t;
 
 #ifdef CONFIG_SMP
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index af0251fc85ed..8e0a9fe86de4 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -108,7 +108,16 @@ static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 static inline int init_new_context(struct task_struct *tsk,
 				   struct mm_struct *mm)
 {
+	#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+	if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
+		/* pkey 0 is the default and always allocated */
+		mm->context.pkey_allocation_map = 0x1;
+		/* -1 means unallocated or invalid */
+		mm->context.execute_only_pkey = -1;
+	}
+	#endif
 	init_new_context_ldt(tsk, mm);
+
 	return 0;
 }
 static inline void destroy_context(struct mm_struct *mm)
@@ -263,5 +272,4 @@ static inline bool arch_pte_access_permitted(pte_t pte, bool write)
 {
 	return __pkru_allows_pkey(pte_flags_pkey(pte_flags(pte)), write);
 }
-
 #endif /* _ASM_X86_MMU_CONTEXT_H */
diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h
index 666ffc862ef7..b406889de0db 100644
--- a/arch/x86/include/asm/pkeys.h
+++ b/arch/x86/include/asm/pkeys.h
@@ -1,12 +1,7 @@
 #ifndef _ASM_X86_PKEYS_H
 #define _ASM_X86_PKEYS_H
 
-#define PKEY_DEDICATED_EXECUTE_ONLY 15
-/*
- * Consider the PKEY_DEDICATED_EXECUTE_ONLY key unavailable.
- */
-#define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? \
-		PKEY_DEDICATED_EXECUTE_ONLY : 1)
+#define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? 16 : 1)
 
 extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 		unsigned long init_val);
@@ -40,4 +35,70 @@ extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 
 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | VM_PKEY_BIT3)
 
+#define mm_pkey_allocation_map(mm)	(mm->context.pkey_allocation_map)
+#define mm_set_pkey_allocated(mm, pkey) do {		\
+	mm_pkey_allocation_map(mm) |= (1U << pkey);	\
+} while (0)
+#define mm_set_pkey_free(mm, pkey) do {			\
+	mm_pkey_allocation_map(mm) &= ~(1U << pkey);	\
+} while (0)
+
+static inline
+bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
+{
+	return mm_pkey_allocation_map(mm) & (1U << pkey);
+}
+
+/*
+ * Returns a positive, 4-bit key on success, or -1 on failure.
+ */
+static inline
+int mm_pkey_alloc(struct mm_struct *mm)
+{
+	/*
+	 * 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.
+	 */
+	u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1);
+	int ret;
+
+	/*
+	 * 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(mm_pkey_allocation_map(mm));
+
+	mm_set_pkey_allocated(mm, ret);
+
+	return ret;
+}
+
+static inline
+int mm_pkey_free(struct mm_struct *mm, int pkey)
+{
+	/*
+	 * pkey 0 is special, always allocated and can never
+	 * be freed.
+	 */
+	if (!pkey)
+		return -EINVAL;
+	if (!mm_pkey_is_allocated(mm, pkey))
+		return -EINVAL;
+
+	mm_set_pkey_free(mm, pkey);
+
+	return 0;
+}
+
+extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
+		unsigned long init_val);
+extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
+		unsigned long init_val);
+
 #endif /*_ASM_X86_PKEYS_H */